6. Threat: Biological resource use
© Book Authors, CC BY 4.0 https://doi.org/10.11647/OBP.0234.06
Background
Biological resource use (as defined in this synopsis) includes the killing of mammals for food or sporting purposes, as well as logging and wood harvesting and the impact that this has on wild mammals. While hunting has a direct effect on mammal survival, logging and wood harvesting indirectly threaten mammals through habitat destruction and fragmentation, disturbance and increased access for hunting.
Hunting & Collecting Terrestrial Animals
6.1. Prohibit or restrict hunting of a species
https://www.conservationevidence.com/actions/2597
- Five studies evaluated the effects of prohibiting or restricting hunting of a mammal species. One study each was in Norway1, the USA2, South Africa3, Poland4 and Zimbabwe5.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (5 STUDIES)
- Abundance (2 studies): Two studies (including one before-and-after study), in the USA2 and Poland4, found that prohibiting hunting led to population increases of tule elk2 and wolves4.
- Survival (3 studies): A before-and-after study in Norway1 found that restricting or prohibiting hunting did not alter the number of brown bears killed. A study in Zimbabwe5 reported that banning the hunting, possession and trade of Temminck’s ground pangolins did not eliminate hunting of the species. A before-and-after study in South Africa3 found that increasing legal protection of leopards, along with reducing human-leopard conflict by promoting improved animal husbandry, was associated with increased survival.
BEHAVIOUR (0 STUDIES)
Background
Hunting may in some cases lead to reductions or local extinctions of mammal species. This intervention covers prohibiting or restricting hunting specifically where hunting is the major threat to a population of a species. For legal protection aimed at other threats see Habitat protection — Legally protect habitat for mammals.
A before-and-after study in 1908–1918 in Sweden and one in 1967–1977 in Norway (1) found that the number of brown bears Ursus arctos reported killed did not change significantly after hunting was prohibited. The number of brown bears reported killed over five years after legal protection was introduced (Sweden: 6.8 bears/year; Norway: 1.2 bears/year) did not differ significantly to that over the five years before legal protection (Sweden: 7.2 bears/year; Norway: 1.6 bears/year). Numbers of bears killed were obtained from national harvesting records. Bears were protected on Crown land in 1913 in Sweden and fully protected in 1972 in Norway. Bears could still be killed to protect livestock and for self-defence.
A before-and-after study in 1971–1998 in California, USA (2) found that numbers of tule elk Cervus canadensis nannodes increased after hunting was prohibited. The tule elk population grew from approximately 500 individuals in 1971 when it received official protection against hunting, to 2,000 individuals in 1989 and >3,000 individuals in 1998. Tule elk became officially protected in 1971. The bill prohibited hunting until the population reached 2,000 individuals. No monitoring or habitat details are provided. Other management interventions (not detailed) were carried out by California Department of Fish and Game during the length of the study.
A before-and-after study in 2003–2007, in a mixed woodland and grassland area in KwaZulu-Natal, South Africa (3) found that increasing legal protection of leopards Panthera pardus along with reducing human-leopard conflict, by promoting improved animal husbandry, was associated with increased leopard survival. The annual mortality rate of leopards in the three years after increased protection and improved husbandry were introduced (12–17%) was lower than during the two previous years (33–47%). Conditions to be met before a permit was issued to kill leopards that predated livestock were tightened in January 2005. New regulations required that there had to be at least three verifiable predation incidents within two months and further livestock protection steps were required. Additionally, selling permits to sports hunters was banned. Workshops in January–July 2005 promoted best practice in protecting livestock from predation (including corralling vulnerable animals, guarding herds, regularly changing grazing paddocks and disposing of carcasses). Twenty-six leopards were monitored by radio-tracking before actions were introduced (2003–2004) and 28 after they were introduced (2005–2007).
A study in 2001–2013 in a forest within an agricultural landscape across western Poland (4) found that after hunting was prohibited, wolves Canis lupus increased in number. Fourteen years after hunting was banned, the wolf population (139 wolves) was higher than three years after the ban was introduced (7–9 wolves). After five years, the first cases of wolf reproduction in the study area were confirmed. Of the 28 wolf deaths recorded, 17 were caused by traffic and seven animals were killed illegally. Wolf field signs (tracks, droppings, scratch marks), camera-trapping and howling simulation surveys were used by trained personnel to locate territories. Mortality reports were collated and verified where possible. Surveys prioritised areas with wolf reports and areas identified as being the most suitable habitat.
A study in 2010–2015 in Zimbabwe (5) reported that banning the hunting, possession and trade of Temminck’s ground pangolins Smutsia temminckii did not eliminate hunting of the species, but enforcement led to a higher number of confiscations. After a nationwide ban on hunting, possession and trade in 1975, a total of 65 Temminck’s ground pangolin seizures were made in 2010–2015. The number of pangolins confiscated increased over this period from 0–1/six-month period in 2010–2011 up to 4–13/six-month period in 2014–2015. Of 53 live pangolins seized, 32 were released back into the wild. In 1975, the Temminck’s ground pangolin was given full protection on Zimbabwe’s Specially Protected Species list. During the study period, all pangolins were listed in Appendix II of CITES. Pangolin seizure data for the period between October 2010 and July 2015 were compiled from information from Zimbabwean wildlife management authorities and courts, from the media and from an NGO.
(1) Swenson J.E., Wabakken P., Sandegren F., Bjärvall A., Franzén R. & Söderberg, A. (1995) The near extinction and recovery of brown bears in Scandinavia in relation to the bear management policies of Norway and Sweden. Wildlife Biology, 1, 11–25.
(2) Adess N. (1998) Tule elk; return of a species. National Park Service Point Reyes National Seashore, California, USA.
(3) Balme G.A., Slotow R. & Hunter L.T.B. (2009) Impact of conservation interventions on the dynamics and persistence of a persecuted leopard (Panthera pardus) population. Biological Conservation, 142, 2681–2690, https://doi.org/10.1016/j.biocon.2009.06.020
(4) Nowak S. & Mysłajek R.W. (2016) Wolf recovery and population dynamics in Western Poland, 2001–2012. Mammal Research, 61, 83–98, https://doi.org/10.1007/s13364-016-0263-3
(5) Shepherd C.R., Connelly E., Hywood L. & Cassey P. (2017) Taking a stand against illegal wildlife trade: the Zimbabwean approach to pangolin conservation. Oryx, 51, 280–285, https://doi.org/10.1017/s0030605316000119
6.2. Ban private ownership of hunted mammals
https://www.conservationevidence.com/actions/2602
- One study evaluated the effects of banning private ownership of hunted mammals. This study was in Sweden1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Survival (1 study): A before-and-after study in Sweden found that fewer brown bears were reported killed after the banning of private ownership of hunted bears.
BEHAVIOUR (0 STUDIES)
A before-and-after study in 1922–1932 in Sweden (1) found that after the banning of private ownership of hunted bears, fewer brown bears Ursus arctos were reported killed. Fewer brown bears were reported killed during the five years after the private ownership of hunted bears was banned (average 0.8 bears/county/year) than during the five years before the ban (8.2 bears/county/year). All killed brown bears became state property in 1927. Numbers of bears killed in 1922–1932 were obtained from national harvesting records.
(1) Swenson J.E., Wabakken P., Sandegren F., Bjärvall A., Franzén R. & Söderberg A. (1995) The near extinction and recovery of brown bears in Scandinavia in relation to the bear management policies of Norway and Sweden. Wildlife Biology, 1, 11–25.
6.3. Site management for target mammal species carried out by field sport practitioners
https://www.conservationevidence.com/actions/2605
- One study evaluated the effects of site management for a target mammal species being carried out by field sport practitioners. This study was in Ireland1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Abundance (1 study): A replicated, site comparison study in the Republic of Ireland1 found that sites managed for the sport of coursing Irish hares held more of this species than did the wider countryside.
BEHAVIOUR (0 STUDIES)
Background
Hunters and field sport participants may manage sites specifically to maintaining populations of their target mammal species. Management could include predator control and management of habitat features.
A replicated, site comparison study in 2003–2007 on 17 improved farmland sites in County Donegal, Republic of Ireland (1) found that sites managed for the sport of coursing Irish hares Lepus timidus hibernicus held more of this species than did the wider countryside. Accounting for differences in habitat, hare densities on coursing sites (96 hares/km2) were higher than on wider countryside sites (31 hares/km2). Eight sites managed for hare coursing were compared with nine sites containing suitable hare habitat in the wider countryside. Management for hare coursing included predator control, poaching deterrence, retaining fine scale habitat features, such as rush patches, and administering veterinary attention while holding hares captive prior to coursing events. Hares flushed by lines of 20–30 beaters were counted, in September–December of 2003–2007.
(1) Reid N., Magee C. & Montgomery W.I. (2010) Integrating field sports, hare population management and conservation. Acta Theriologica, 55, 61–71, https://doi.org/10.4098/j.at.0001-7051.030.2009
6.4. Set hunting quotas based on target species population trends
https://www.conservationevidence.com/actions/2607
- Three studies evaluated the effects of setting hunting quotas for mammals based on target species population trends. One study each was in Canada1, Spain2 and Norway3.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (3 STUDIES)
- Abundance (2 studies): Two studies, in Spain2 and Norway3, found that restricting hunting and basing quotas on population targets enabled population increases for Pyrenean chamois2 and Eurasian lynx3.
- Survival (1 study): A before-and-after study in Canada1 found that setting harvest quotas based on population trends, and lengthening the hunting season, did not decrease the number of cougars killed by hunters.
BEHAVIOUR (0 STUDIES)
Background
Management of wildlife species that are regarded as game animals may involve setting hunting quotas that are designed to enable the population to reach or remain at a particular level. Whilst many hunting systems use quotas, the studies included here are those based on mammal species with particular local conservation concerns rather than where quotas are based purely on maximising the harvest.
A before-and-after study in 1990–1991 in boreal forest in Alberta, Canada (1) found that setting harvest quotas based on the population trends of the target species, and increasing the length of the hunting season, did not decrease the number of cougars Puma concolor killed by hunters. After setting harvest quotas, the number of cougars killed was higher (54 animals) than before setting of harvest quotas (33 animals). In 1981–1989 radio collars were attached to 44 cougars and data collected used to estimate the population size. The area was divided into 11 Cougar Management Areas and quotas were set at 10% of the estimated population for each area. A further quota of 50% of the total harvest quota was set for female cougars. When either quota was reached, the hunting season within a specific area was closed.
A study in 1995–2007 in mixed forest, cliffs and meadows across three mountain massifs in Navarre and Aragon, Spain (2) found that, following imposition of hunting restrictions, populations of Pyrenean chamois Rupicapra pyrenaica pyrenaica increased. Results were not tested for statistical significance. The population at one massif rose from at least 33 in 1995 to at least 136 (an average growth rate of 15%/year) in 2007 and, at another massif, from at least 144 in 1996 to at least 455 (11%/year) in 2007. A third massif was occupied by eight chamois from at least 2002, with 11 there in 2007. The first two massifs cross regional jurisdictions. Hunting did not occur in one region, but was allowed in the other up to 1993, when it was temporarily banned. Limited hunting resumed in this region in 2006, based on 5% annual harvest. Hunting was not carried out in the third massif. Chamois were surveyed from dawn until midday in June and November each year, in 1995–2007.
A study in 1996–2008 in primarily forested areas in Norway (3) found that adaptive management, including basing hunting quotas on population trends, enabled Eurasian lynx Lynx lynx populations to recover after a population decline. Three years after modification of hunting quotas, the population of Lynx was higher (453 animals) than prior to modifications (259 animals). Before modifications of quotas, lynx populations had dropped from 411–486 to 259 over an eight-year period. Lynx harvests were uncapped up to 1992. From 1994, responsibility for setting hunting quotas was devolved to 18 counties and then transferred to eight regional units in 2005. The number of lynx family groups was estimated by collating records of lynx tracks along with records of young animals found dead or killed by vehicles or hunters. These data were extrapolated to form overall population estimates for 1996–2008.
(1) Ross I.P., Jalkotzy M.G. & Gunson J.R. (1996) The quota system of cougar harvest management in Alberta. Wildlife Society Bulletin, 24, 490–494.
(2) Herrero J., Garin I., Prada C. & García-Serrano A. (2010) Inter-agency coordination fosters the recovery of the Pyrenean chamois Rupicapra pyrenaica pyrenaica at its western limit. Oryx, 44, 529–532, https://doi.org/10.1017/s0030605310000761
(3) Linnell J.D.C., Broseth H., Odden J. & Nilsen E.B. (2010) Sustainably harvesting a large carnivore? Development of Eurasian lynx populations in Norway during 160 years of shifting policy. Environmental Management, 45, 1142–1154, https://doi.org/10.1007/s00267-010-9455-9
6.5. Prohibit or restrict hunting of particular sex/ breeding status/age animals
https://www.conservationevidence.com/actions/2609
- Two studies evaluated the effects of prohibiting or restricting hunting of particular sex, breeding status or age animals. Both studies were in the USA1,2.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (2 STUDIES)
- Reproduction (2 studies): Two replicated, before-and-after studies, in the USA1,2, found that limiting hunting of male deer did not increase the numbers of young deer/adult female.
- Population structure (1 study): A replicated, before-and-after study in the USA1 found that limiting hunting of older male elk resulted in an increased ratio of male:female elk.
BEHAVIOUR (0 STUDIES)
Background
Within some hunted populations of mammals, certain age or sex classes are favoured targets for hunters. This can result in altered population structures which can be detrimental to breeding success for example (e.g. Torres-Porras et al. 2014). Management of game mammals may, therefore, involve imposing specific hunting restrictions, so as to reduce or prohibit harvests of particular sex or age classes.
Torres-Porras J., Carranza J., Pérez-González J., Mateos C. & Alarcos S. (2014) The tragedy of the commons: unsustainable population structure of Iberian red deer in hunting estates. European Journal of Wildlife Research, 60, 351–357, https://doi.org/10.1007/s10344-013-0793-9
A replicated, before-and-after study in 1984–2000 in three forest and shrubland sites in Washington, USA (1) found that limiting hunting of adult male elk Cervus canadensis resulted in an increase in the numbers of males relative to females, but no change in numbers of calves relative to females. After hunting restrictions commenced, there were more male relative to female elk (6.7–12.9 males/100 females) than before hunting restrictions commenced (2.7–5.7 males/100 females). The abundance of calves relative to female elk did not change (after: 21–37 calves/100 females; before: 30–37 calves/100 females). The strategy of open-entry yearling hunting and limited hunting of elk ≥ 2.5 years old with branched antlers was introduced at one site in 1989 and at two sites in 1994. These sites were monitored in 1984–2000 and 1991–2000 respectively and covered 2,300–4,500 km2. Elk were counted from helicopters, and categorised by age and sex, in late February or early March each year.
A replicated, before-and-after study in 1983–1998 of four deer management areas in a largely forested region of Colorado, USA (2) found that restricting the harvest of male mule deer Odocoileus hemionus did not increase the number of fawns/adult female deer. After introduction of hunting restrictions, the fawn:adult female deer ratio declined by 7.5 fawns:100 adult females (absolute numbers not presented). During this time, harvests of male deer fell from an average of 788/management area/year to 209/management area/year and the ratio of male:female deer increased by 4.5:100 female deer. Harvests of male deer were unlimited up to 1990. Commencing in 1991 (one area), 1992 (two areas) and 1995 (one area), restrictions were imposed on harvests of male deer, resulting in a fall in average harvests from 788/year pre-restriction to 209/year post-restriction. Aerial deer surveys were carried out in December–January.
(1) Bender L.C., Fowler P.E., Bernatowicz J.A., Musser J.L. & Stream L.E. (2002) Effects of open-entry spike-bull, limited-entry branched-bull harvesting on elk composition in Washington. Wildlife Society Bulletin, 30, 1078–1084.
(2) Bishop C.J., White G.C., Freddy D.J. & Watkins B.E. (2005) Effect of limited antlered harvest on mule deer sex and age ratios. Wildlife Society Bulletin, 33, 662–668, https://doi.org/10.2193/0091-7648(2005)33[662:eolaho]2.0.co;2
6.6. Incentivise species protection through licensed trophy hunting
https://www.conservationevidence.com/actions/2610
- One study evaluated the effects on mammals of incentivising species protection through licensed trophy hunting. This study was in Nepal1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Abundance (1 study): A study in Nepal1 found that after trophy hunting started, bharal abundance increased, though the sex ratio of this species, and of Himalayan tahr, became skewed towards females.
BEHAVIOUR (0 STUDIES)
Background
Trophy hunting is the hunting of wild animals for recreation. Usually, this involves large or otherwise distinguished animals, such as large carnivores, or species with large antlers. The animal, or part of it, is kept by the hunter, often for display. Trophy hunting may provide financial support to local communities or conservation initiatives, through locally levied fees (Di Minin et al. 2016). This may increase the perceived value of maintaining populations of such species in the long term and may, hence, incentivise greater habitat and species protection in such areas.
Di Minin E., Leader-Williams N. & Bradshaw C.J.A. (2016) Banning trophy hunting will exacerbate biodiversity loss. Trends in Ecology & Evolution, 31, 99–102, https://doi.org/10.1016/j.tree.2015.12.006
A study in 1990–2011 in forest and grassland in a hunting reserve in Nepal (1) found that following commencement of trophy hunting, populations of bharal Pseudois nayaur increased, though the sex ratio of this species, and of Himalayan tahr Hemitragus jemlahicus, became skewed towards females. Twenty-one years after the establishment of trophy hunting, the estimated bharal population was higher (>1,500 animals) than three years after it was established (approximately 400 animals). The proportion of males to females was lower after 21 years (82:100) than three years after (129:100). A similar pattern was seen for the thar population (21 years after: 62:100; three years after: 214:100). The hunting reserve, covering 1,325 km2, was established in 1987. Trophy hunters, especially from outside Nepal, pay for the right to hunt male bharal and tahr. Females are not hunted. Data were collated from a range of sources, primarily derived from vantage point counts.
(1) Aryal A., Dhakal M., Panthi S., Yadav B.P., Shrestha U.B., Bencini R. Raubenheimer D. & Ji W. (2015) Is trophy hunting of bharal (blue sheep) and Himalayan tahr contributing to their conservation in Nepal? Hystrix, the Italian Journal of Mammalogy, 26, 85–88.
6.7. Use selective trapping methods in hunting activities
https://www.conservationevidence.com/actions/2611
- We found no studies that evaluated the effects on non-target mammals of using selective trapping methods in hunting activities.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Hunting using traps (such as snares, leg-hold traps or cage traps) can result in capture of rare, threatened or protected non-target species mammal (e.g. Andreasen et al. 2018). Measures to reduce such ‘bycatch’ might include setting a weight-sensitive release catch, placing traps in particular areas (or avoiding other areas) or only using specific baits.
Andreasen A.M., Stewart K.M., Sedinger J.S., Lackey C.W. & Beckmann J.P. (2018) Survival of cougars caught in non‐target foothold traps and snares. The Journal of Wildlife Management, 82, 906–917, https://doi.org/10.1002/jwmg.21445
6.8. Use wildlife refuges to reduce hunting impacts
https://www.conservationevidence.com/actions/2612
- Two studies evaluated the effects on mammal species of using wildlife refuges to reduce hunting impacts. One study was in Canada1 and one was in Mexico2.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (2 STUDIES)
- Abundance (2 studies): One of two replicated site comparison studies in Canada1 and Mexico2 found more moose in areas with limited hunting than in more heavily hunted areas1. The other study found mixed results with only one of five species being more numerous in a non-hunted refuge2.
BEHAVIOUR (0 STUDIES)
Background
To help protect or sustain populations of hunted species, refuges may be designated that have limited or not hunting. This intervention covers studies that assess the impact of such refuges where they lie adjacent to hunted areas.
See also: Habitat Protection — Legally protect habitat for mammals.
A replicated, site comparison study in 1984 of 24 forest blocks in Quebec, Canada (1) found more moose Alces alces in game reserves with limited hunting than in more heavily hunted areas. Games reserves held 0.28 moose/km2 compared to 0.06/km2 in adjacent hunted areas and 0.14/km2 in hunted areas ≥50 km away. Dispersal from game reserves was reported to sustain moose harvests in adjacent areas. Moose density was estimated by surveying 24 plots of 60 km2 each. Twelve plots were in areas that overlapped between game reserves with limited hunting (108 hunter-days/100 km2/year) and more heavily hunted adjacent areas (518 hunter-days/100 km2/year). Twelve plots were in hunting areas ≥50 km from a reserve (with 315 hunter-days/100 km2/year). Twelve transect lines/plot were surveyed from fixed-wing aircraft in January 1984.
A replicated, site comparison study in 2001 of four forest areas in Campeche, Mexico (2) found that one of five ungulate species was more numerous in a non-hunted refuge area compared to in hunted areas and two were more numerous in hunted areas. There were more white-lipped peccaries Tayassu pecari in non-hunted (0.24 tracks/km) than hunted (0.08 tracks/km) areas. White-tailed deer Odocoileus virginianus were more numerous in hunted areas (non-hunted: 0.24; hunted: 0.88 tracks/km) as was Central American tapir Tapirus bairdii (non-hunted: 0.03; hunted: 0.42 tracks/km). No differences between areas were found for brocket deer Mazama sp. (non-hunted: 6.4; hunted: 6.7 tracks/km) or collared peccary Pecari tajacu (non-hunted: 0.9; hunted: 1.0 tracks/km). Transects were established on land not hunted on since the 1980s, and on three adjacent hunted sites with similar habitat. Transects were ≥3 km from villages and had start points ≥2 km apart. Twenty-eight transects (total 57 km) were walked in the non-hunted area and 18–24 transects (35–70 km/site), were walked in hunted areas. Transects were walked in February–July 2001. Ungulate tracks within 1 m of transects were counted and recorded to species.
(1) Crête M. & Jolicoeur H. (1985) Comparing two systems of moose management for harvest. Wildlife Society Bulletin, 13, 464–469.
(2) Reyna-Hurtado R. & Tanner G.W. (2007) Ungulate relative abundance in hunted and non-hunted sites in Calakmul Forest (Southern Mexico). Biodiversity and Conservation, 16, 743–756, https://doi.org/10.1007/s10531-005-6198-7
6.9. Provide/increase anti-poaching patrols
https://www.conservationevidence.com/actions/2618
- Seven studies evaluated the effects of providing or increasing anti-poaching patrols on mammals. Two studies were in Thailand1,4 and one each was in Brazil2, Iran3, Lao People’s Democratic Republic5, South Africa6 and Tajikistan7.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (7 STUDIES)
- Abundance (6 studies): Two studies, in Thailand1 and Iran3, found more deer and small mammals1 and more urial sheep and Persian leopards3 close to ranger stations (from which anti-poaching patrols were carried out) than further from them. One of three before-and-after studies, in Brazil2, Thailand4 and Lao People’s Democratic Republic5, found that ranger patrols increased mammal abundance2. The other two studies found that patrols did not increase tiger abundance4,5. A site comparison study in Tajikistan7 found more snow leopard, argali, and ibex where anti-poaching patrols were conducted.
- Survival (1 study): A study in South Africa6 found that anti-poaching patrols did not deter African rhinoceros poaching.
BEHAVIOUR (0 STUDIES)
Background
Poaching is the illegal killing or taking of mammals or other wildlife species. It can lead to population declines or push species towards local extinctions (e.g. Wittemyer et al. 2014). In absence of enforcement, anti-poaching legislation may be insufficient to prevent declines (e.g. López-Bao et al. 2015). Patrols may be instigated to deter or to apprehend poachers.
López-Bao J.V., Blanco J.C., Rodríguez A., Godinho R., Sazatornil V., Alvares F., García E.J., Llaneza L., Rico M., Cortés Y., Palacios V. & Chapron G. (2015) Toothless wildlife protection laws. Biodiversity and Conservation, 24, 2105–2108, https://doi.org/10.1007/s10531-015-0914-8
Wittemyer G., Northrup J.M., Blanc J., Douglas-Hamilton I., Omondi P. & Burnham K.P. (2014) Illegal killing for ivory drives global decline in African elephants. Proceedings of the National Academy of Sciences, 111, 13117–13121, https://doi.org/10.1073/pnas.1403984111
A study in 2003–2007 in forest in a national park in central Thailand (1) found that, close to ranger stations, deer and small mammals were more abundant than further away. Sambar deer Rusa unicolor, red muntjac Muntiacus muntjak and a range of small prey species were more likely to be found close to ranger stations than further away (modelled result — data not presented). Poachers were also more likely to be found within 5 km of ranger stations than further away within the national park. Authors suggest that this may be due to roads making ranger stations more accessible and possibly complicity of ranger staff. The national park was 2,168 km2 in area. Camera traps were operated in 217 locations over 6,260 total trap nights from October 2003 to March 2007, to survey animals and poacher presence. Cameras were placed across 22 park management zones.
A before-and-after study in 1997–2008 in a protected area dominated by secondary Atlantic forest in Brazil (2) found that implementing ranger patrols increased mammal abundance and reduced hunting pressure. After the introduction of patrols by rangers, mammal abundance was higher (8.7 encounters/10 km walked) than before ranger patrols (5.1 encounters/10 km walked) and hunting pressure was lower (after: six encounters; before: 24 encounters). In May 1997–August 2004 and October 2007–November 2008, forest trails were censused for medium-sized and large mammals. A single observer walked at approximately 1 km/hour along trails 3–5 km long, pausing every 50 m to listen for animal sounds, and using binoculars and a headlamp at night to detect animals. Day censuses began within 1 hour of sunrise and night censuses within 1 hour of sunset. In total, 233 km of transects were walked.
A study in 2011–2013 in a steppe site in a national park in Iran (3) found that presence of ranger stations, which were bases for anti-poaching patrols, was associated with increased numbers of urial sheep Ovis vignei and Persian leopards Panthera pardus saxicolor. The density of urial sheep decreased with increasing distance from ranger station. This distance was also the best predictor of sheep flock sizes, which were larger closer to ranger stations. Leopards were also more likely to be found closer to ranger stations, though leopard abundance was best explained by urial sheep density. Results were presented as model coefficients. Urial sheep numbers and distribution were determined by distance sampling, along 186 km of line transects, surveyed from 22 January–19 February 2013, 15 August–8 September 2013 and 21–24 February 2014. Leopards were surveyed using 29 camera traps in January–March 2011.
A before-and-after study in 2005–2012 in a tropical dry forest reserve in the Western Forest Complex, Thailand (4) found that as anti-poaching patrols intensified, poaching incidents decreased, but the estimated tiger Panthera tigris abundance did not change significantly over seven years. The estimated tiger abundance was similar seven years after poaching patrols started to increase (56 tigers) compared to the year before poaching patrols started to increase (51 tigers). In the final two years of the study, when patrols were at their highest levels, there were 22 poaching incidents detected/1,000 km patrolled, compared to 24–30 incidents/1,000 km patrolled over the previous five years. The study was conducted in a 2,780-km2 reserve, adjacent to approximately 30 villages. In 2006–2012, there was an increase each year in the number of patrol days/year (from 1,031 in 2006 to 3,316 in 2012) and distance patrolled/year (5,979 km in 2006 to 12,907 km in 2012). Tigers were surveyed annually between 2005 and 2012, using camera traps across 524–1,094 km2 (137–2,000 locations/year, 910–3,869 camera-trap days/year). Paired camera traps were positioned along anticipated tiger travel routes.
A before-and-after study in 2007–2012 in a mainly grassland and forest protected area in Lao People’s Democratic Republic (5) found that increasing patrol intensity did not lead to higher tiger Panthera tigris abundance. Patrol effort was positively correlated with funding, but not with tiger abundance trends. The number of large tiger tracks (pads >7 cm wide) at the end of the six-year study period (3/1,000 km patrolled) was lower than that over the first three years (8/1,000 km patrolled). The proportion of collected carnivore scats that were from tigers decreased to 3.6% at the end of the study from 15.4–15.6% in the first two years. Patrol effort in a 5,950 km2 protected area increased from 1.7 days/part-time team in 2005–2007 to a peak of 22.7 days/full-time team in 2008–2009, then dropped by 4.2% in 2009–2012. Track data and scats were collected by foot patrols and other fieldworkers. Scats were identified to species by DNA analysis.
A study in 2011–2013 in a protected area in South Africa (6) found that where anti-poaching patrols were more common, poaching of African rhinoceros was also more common, but that there was no relationship between the amount of time rangers spent in a location and the likelihood of a poaching event. In areas that rangers visited more frequently, poaching of rhinoceros was more likely to occur. However, in areas where rangers spent more time patrolling, poaching was no more likely to occur. Data were reported as model results. Authors suggest that a range of factors, such as practicalities of access, may result in both more ranger visits and more poaching. Between September 2011 and September 2013, ranger locations were recorded at three-minute intervals in 0.25-km2 grid cells across the protected area. The location of rhinoceros poaching events, identified from monitoring by park authorities, was overlaid on to the same grid. The average frequency and duration of visits by rangers was calculated for each area where rhinoceros poaching occurred.
A site comparison study in 2012–2013 in two tundra sites in Tajikistan (7) found that, in an area where anti-poaching patrols were carried out, densities of snow leopard Panthera uncia, argali Ovis ammon polii, and ibex Capra sibirica were higher than in an area where no patrols were carried out. The area where anti-poaching patrols were carried out had a higher snow leopard density (0.7 individuals/100 km2) than where no patrols were carried out (0.5 individuals/100 km2). The same was true for argali (patrols: 11.0; no patrols: 0.1 individuals/100 km2) and ibex (patrols: 4.3; no patrols: 2.0 individuals/100 km2). One site was patrolled by 3–5 rangers year-round. The other site was not patrolled. In June and September 2012, thirty-seven camera traps were deployed at the patrolled site and 34 in the unpatrolled site. Photographs were used to identify individual snow leopards. In September–October 2013, at both sites, 20 randomly selected locations were surveyed for 90 minutes and the abundance of all ungulate species was recorded.
(1) Jenks K.E., Howard J. & Leimgruber P. (2012) Do ranger stations deter poaching activity in national parks in Thailand? Biotropica, 44, 826–833, https://doi.org/10.1111/j.1744-7429.2012.00869.x
(2) Flesher K.M. & Laufer J. (2013) Protecting wildlife in a heavily hunted biodiversity hotspot: a case study from the Atlantic Forest of Bahia, Brazil. Tropical Conservation Science, 6, 181–200, https://doi.org/10.1177/194008291300600202
(3) Ghoddousi A., Hamidi A.K., Soofi M., Khorozyan I., Kiabi B.H. & Waltert M. (2015) Effects of ranger stations on predator and prey distribution and abundance in an Iranian steppe landscape. Animal Conservation, 19, 273–280, https://doi.org/10.1111/acv.12240
(4) Duangchantrasiri S., Umponjan M., Simcharoen S., Pattanavibool A., Chaiwattana S., Maneerat S., Kumar N.S., Jathanna D., Srivathsa A. & Karanth K.U. (2016) Dynamics of a low‐density tiger population in Southeast Asia in the context of improved law enforcement. Conservation Biology, 30, 639–648, https://doi.org/10.1111/cobi.12655
(5) Johnson A., Goodrich J., Hansel T., Rasphone A., Saypanya S., Vongkhamheng C., Venevongphet & Strindberg S. (2016) To protect or neglect? Design, monitoring, and evaluation of a law enforcement strategy to recover small populations of wild tigers and their prey. Biological Conservation, 202, 99–109, https://doi.org/10.1016/j.biocon.2016.08.018
(6) Barichievy C., Munro L., Clinning G., Whittington-Jones B. & Masterson G. (2017) Do armed field-rangers deter rhino poachers? An empirical analysis. Biological Conservation, 209, 554–560, https://doi.org/10.1016/j.biocon.2017.03.017
(7) Kachel S.M., McCarthy K.P., McCarthy T.M. & Oshurmamadov, N. (2017) Investigating the potential impact of trophy hunting of wild ungulates on snow leopard Panthera uncia conservation in Tajikistan. Oryx, 5, 597–604, https://doi.org/10.1017/s0030605316000193
6.10. Make introduction of non-native mammals for sporting purposes illegal
https://www.conservationevidence.com/actions/2621
- We found no studies that evaluated the effects on native mammals of making introduction of non-native mammals for sporting purposes illegal.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Mammals introduced for sporting purposes may negatively affect native species. This may be through such processes as predation of native mammals (Saunders et al. 2010), through competition for resources or through hybridising with native species (Reid & Montgomery 2007). Banning importation of non-native mammals for sporting purposes could reduce or prevent further such threats.
Reid N. & Montgomery W.I. (2007) Is naturalisation of the brown hare in Ireland a threat to the endemic Irish hare? Biology and Environment: Proceedings of the Royal Irish Academy, 107B, 129–138, https://doi.org/10.3318/bioe.2007.107.3.129
Saunders G.R., Gentle M.N. & Dickman C.R. (2010) The impacts and management of foxes Vulpes vulpes in Australia. Mammal Review, 40, 181–211https://doi.org/10.1111/j.1365-2907.2010.00159.x
6.11. Commercially breed for the mammal production trade
https://www.conservationevidence.com/actions/2622
- We found no studies that evaluated the effects of commercially breeding mammals for trade on wild populations of those species.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Some mammal species have economic value for products derived from them, such as fur. Captive breeding of these species, on a commercial scale, could reduce incentives for hunting or trapping wild individuals. This could, in turn, relieve pressures on populations of rare or threatened species.
6.12. Promote sustainable alternative livelihoods
https://www.conservationevidence.com/actions/2623
- We found no studies that evaluated the effects of promoting sustainable alternative livelihoods on mammals.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Conserving biodiversity and eliminating poverty are linked global challenges. The poor, particularly the rural poor, depend on nature for many elements of their livelihoods, including food, fuel, shelter and medicines. By promoting sustainable alternative livelihoods, and/or livelihood diversification, the aim is to provide or encourage other sources of income that reduce pressure on natural resources, such as mammals, to sustainable levels. There is a wide diversity of potential alternative sources of income, which depend on the situation, but include activities such as the development of other small-scale productions systems, eco-tourism or craft work for example. Working alongside people who will ultimately benefit from conservation can build social capital, improve accountability, reduce poverty and result in more effective biodiversity conservation.
6.13. Promote mammal-related ecotourism
https://www.conservationevidence.com/actions/2624
- We found no studies that evaluated the effects on mammals of promoting mammal-related ecotourism.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Watching mammals as a recreational activity and has grown considerably in popularity over recent years (Dinets & Hall 2018) with nature-based tourism in general increasing in most countries (Balmford et al. 2009). This may result in conservation benefits, such as increased revenue to local conservation projects and assistance with collection of data. Negative impacts can include disturbance pressures at popular sites or increased development to support tourism-related activities. Assessing the net benefits of mammal-related ecotourism may be hampered by lack of population data (Buckley et al. 2016).
Balmford A., Beresford J., Green J., Naidoo R., Walpole M. & Manica A. (2009) A global perspective on trends in nature-based tourism. PLoS Biology, 7, e1000144, https://doi.org/10.1371/journal.pbio.1000144
Buckley R.C., Morrison C. & Castley J.G. (2016) Net effects of ecotourism on threatened species survival. PLoS ONE, 11, e0147988, https://doi.org/10.1371/journal.pone.0147988
Dinets V. & Hall J. (2018) Mammalwatching: A new source of support for science and conservation. International Journal of Biodiversity and Conservation, 10, 154–160, https://doi.org/10.5897/ijbc2017.1162
6.14. Ban exports of hunting trophies
https://www.conservationevidence.com/actions/2625
- One study evaluated the effects of banning exports of hunting trophies on wild mammals. This study was in Cameroon1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Abundance (1 study): A before-and-after study in Cameroon1 found similar hippopotamus abundances before and after a ban on exporting hippopotamus hunting trophies.
BEHAVIOUR (0 STUDIES)
Background
Trophy hunting is the hunting of wild animals for recreation. Usually, this involves large or otherwise distinguished animals, such as large carnivores, or species with large antlers. The animal, or part of it, is kept by the hunter, often for display. Some trophy hunting provides financial support to local communities or conservation, through locally levied fees (Minin et al. 2016). However, permitting exports of hunting trophies (often from developing countries to developed countries) may provide incentives for hunting at unsustainable levels (Lindsey et al. 2016) or may provide a route for importing illegally hunted trophies. Bans on trophy hunting exports are designed to remove this incentive and, hence, reduce incentives for the hunting of relevant species.
Lindsey P.A., Balme G.A., Funston P.F., Henschel P.H & Hunter L.T.B. (2016) Life after Cecil: channelling global outrage into funding for conservation in Africa. Conservation Letters, 9, 296–301, https://doi.org/10.1111/conl.12224
Minin E.D., Leader-Williams N. & Bradshaw C.J.A. (2016) Banning trophy hunting will exacerbate biodiversity loss. Trends in Ecology & Evolution, 31, 99–102, https://doi.org/10.1016/j.tree.2015.12.006
A before-and-after study in 2000–2014 along a river within and around Faro National Park, Cameroon (1) found similar numbers of hippopotamuses Hippopotamus amphibious before and after a ban on exporting of hippopotamus hunting trophies. Results were not tested for statistical significance. Two years after a ban on exporting hippopotamus hunting trophies, 685 hippopotamuses were counted, compared with 647 hippopotamuses counted 12 years before the ban and 525 counted four years before the ban. CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) suspended exports of hippopotamus trophies from Cameroon in 2012. In March 2014, hippopotamuses were counted over three days in the dry season, along 97 km of the Faro River. Animals were counted between 07:30 and 17:30 h, by two teams of 2–3 observers. Observers walked through the riverbed at a speed of 1–4 km/hour. Similar counting methods were used in 2000 and 2008 (twelve and four years before the ban respectively) but precise details are not given.
(1) Scholte P., Nguimkeng F. & Iyah E. (2017) Good news from north-central Africa: largest population of Vulnerable common hippopotamus Hippopotamus amphibius is stable. Oryx, 51, 218–221, https://doi.org/10.1017/s0030605315001258
Logging & Wood Harvesting
6.15. Use selective harvesting instead of clearcutting
https://www.conservationevidence.com/actions/2637
- Eight studies evaluated the effects on mammals of using selective harvesting instead of clearcutting. Four studies were in Canada1,3,6,8, three were in the USA2,4,5 and one was a review of studies in North America7.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A replicated, site comparison study in Canada8 found that harvesting trees selectively did not result in higher small mammal species richness compared to clearcutting.
POPULATION RESPONSE (7 STUDIES)
- Abundance (7 studies): One of six replicated, controlled or replicated, site comparison studies in the USA4,5 and Canada1,3,6,8 found more small mammals in selectively harvested forest stands than in fully harvested, regenerating stands4. Three studies found that selective harvesting did not increase small mammal abundance relative to clearcutting1,5,8. The other two studies found mixed results with one of four small mammal species being more numerous in selectively harvested stands3 or in selectively harvested stands only in some years6. A systematic review in North American forests7 found that partially harvested forests had more red-backed voles but not deer mice than did clearcut forests.
BEHAVIOUR (1 STUDY)
- Use (1 study): A site comparison study in the USA2 found that partially harvested forest was not used by snowshoe hares more than was largely clearcut forest.
Background
Clearcutting of large areas of forest can have substantial impacts on associated fauna. Selective logging is the removal of selected trees within a forest based on criteria such as diameter, height or species. Remaining trees are left in the stand, as opposed to clearcutting where all trees are felled. This intervention is similar to several others that involve harvesting some, but not all, trees. In this case, tree removal was largely based on forestry specifications, rather than designed spatially to retain undisturbed patches. This intervention covers a wide range of tree removal intensities. In some cases, management is for shelterwood, a specific forestry practice that involves gradually removing mature trees to allow growing space for younger trees that initially germinate in partial shade.
See also Fell trees in groups, leaving surrounding forest unharvested, Retain undisturbed patches during thinning operations, Use thinning of forest instead of clearcutting and Use patch retention harvesting instead of clearcutting.
A replicated, site comparison study in 1980 of a forest in Nova Scotia, Canada (1) found that selectively harvested plots, cut as shelterwood, did not host more small mammals than did clearcut plots. In shelterwood plots, average capture rates (10–31 small mammals/100 trap nights) did not differ significantly from those in clearcuts (12–27 small mammals/100 trap nights). The forest had regrown following fire 80 years previously. Three plots (average 3.6 ha) were clearcut 3–5-years previously and two plots (average 1.9 ha) were shelterwood cut, entailing removing a proportion of harvestable timber. Shelterwood plots had an average tree stem basal area of 9.4 m2/ha (compared to 25.9 m2/ha in adjacent unharvested forest). Small mammals were surveyed using snap traps for four consecutive nights and days, one or twice in each plot in July–August 1980.
A site comparison study in 1974–1977 of three mixed forest blocks in Maine, USA (2) did not find more snowshoe hares Lepus americanus in partially harvested forest than in largely clearcut forest. In a partially harvested forest, a lower proportion of transect sections (7.9%) contained hare tracks compared to in a largely clearcut forest (17.6%). However, patches of unharvested trees were included within the clearcut forest sampled, and tracks were most numerous in or close to these. Hare tracks were surveyed, 1–2 days after snowfall, over the winters of 1974–1975, 1975–1976 and 1976–1977. Tracks were counted on 15-m sections along 50 km of permanent lines through clearcut and partially harvested forest. Partial harvesting occurred in 1974–1977 and the clearcut forest was harvested in 1960–1975.
A replicated, controlled, before-and-after study in 1994–1998 of a coniferous forest in British Colombia, Canada (3) found that, when forest was harvested by single tree selection, one of four small mammal species was more abundant relative to clearcutting. Populations of all species did not differ between plots assigned for different treatments in the year before harvesting. After harvesting, there were more southern red-backed voles Clethrionomys gapperi in single tree selection plots (20.8–44.0/ha) than in clearcuts (0.1–10.8/ha). Long-tailed vole Microtus longicaudus was less abundant in single tree selection than clearcut plots (0.0–3.4 vs 2.6–16.2/ha) as was northwestern chipmunk Tamias amoenus (0.8–1.4 vs 1.9–6.0/ha). Deer Mouse Peromyscus maniculatus numbers were similar between treatments (single tree selection: 0.4–4.0/ha; clearcuts: 0.8–5.0/ha). Forest stands were c.30 ha. There were three replicates each of single tree selection (removing 33% of timber volume) and 10-ha clearcuts, harvested in winter 1994–1995. Small mammals were live-trapped in 1994–1998, over two consecutive nights, at 3-week intervals, from June or July to August or September.
A replicated, controlled study in 1997–1998 of a forest in Maine, USA (4) found more small mammals in selectively harvested forest stands than fully harvested, regenerating stands. Annual average catches were higher in partially harvested than fully harvested stands for the three most abundant species; red-backed vole Clethrionomys gapperi (partially harvested: 12.4–22.1; fully harvested: 2.5–5.0 voles/grid), deer mouse Peromyscus maniculatus (partially harvested: 4.9–12.5; fully harvested: 0–2.5 mice/grid) and short-tailed shrew Blarina brevicauda (partially harvested: 4.3–5.0; fully harvested: 0–3.0 shrews/grid). These comparisons were not tested for statistical significance. Seven stands were selectively harvested between 1992 and 1995, with 52–59% of basal tree area removed and 13 m2/ha basal area remaining. Two forest stands were clearcut between 1974 and 1984 and treated with the herbicide, glyphosate, 3–8 years post-harvest. Small mammals were surveyed in live trap grids, between 22 June and 28 July 1997 and between 21 June and 31 July 1998.
A replicated, controlled, before-and-after study in 1991–1997 of two second-growth forests in Arkansas and Oklahoma, USA (5) found that selectively harvesting isolated trees did not increase small mammal abundance relative clearcutting. Before harvesting, average small mammal abundances did not differ significantly between stands planned for different treatments (single tree selection: 2.7 small mammals/100 trap nights; clearcut: 0.9). Similarly, after harvesting, small mammal numbers did not differ significantly between single tree selection stands (6.4/100 trap nights) and clearcut stands (10.7). In each of four blocks of second-growth forest (59–69 years old at start of study), one stand was managed by single tree selection and one was clearcut, harvested in summer 1993. Tree basal area after harvesting was 15–16 m2/ha in single tree selection plots (compared to 24–32 m2/ha in unharvested forest). Stand extent was 13–28 ha. Small mammals were surveyed using an average of 67 Sherman live traps/stand, pre-harvest in 1991 and 1992, and post-harvest in 1995, 1997 and 1999. Traps were operated for seven consecutive nights during winter (December–January).
A replicated, controlled study in 1994–1997 of Douglas-fir Pseudotsuga menziesii forest in British Colombia, Canada (6) found that selective harvesting of trees increased one of four small mammal species abundance in the third and fourth, but not first and second, year after harvesting relative to clearcutting. There were more southern red-backed voles Myodes gapperi in the third and four year in all selectively logged treatments (6–17/plot) than in clearcut stands (0–1/plot), but similar numbers between treatments in the first two years (selective cut: 33–42/plot; clearcut: 13–34/plot). There were no differences between treatments for deer mouse Peromyscus maniculatus (selective cut: 1–15/plot; clearcut: 6–21/plot) or northwestern chipmunk Tamias amoenus (selective cut: 0–6/plot; clearcut: 0–6/plot). There were more meadow voles Microtus pennsylvanicus in clearcut stands (selective cut: 0–2/plot; clearcut: 3–14/plot). Forest stands, 20–25 ha in extent, were partially harvested in winter 1993–1994. Two each had 20% of timber volume removed by individual-tree selection, 35% removed by individual-tree selection on 50% of the area and 50% volume removed by individual-tree selection. These were compared with two 1.6-ha clearcut areas. Small mammals were live-trapped, at 2–4-week intervals, in May–October of 1994, 1995, and 1996 and in April–May 1997.
A systematic review in 2008 of 56 studies of small mammal responses to partial harvesting, clearcutting or wildfire in North American forests (7) found that partially harvested forests had more red-backed voles Myodes gapperi, but not deer mice Peromyscus maniculatus than did clearcut forests. Absolute abundances are not presented but vole numbers in partially harvested stands, 1–9 years after harvesting, were significantly higher than in clearcut stands. Deer mouse abundances did not differ significantly between partially harvested and clearcut stands. Meta-analyses were carried out on studies identified following a defined literature search procedure.
A replicated, site comparison study in 2006–2007 in a mixed temperate forest in Quebec, Canada (8) found that harvesting trees selectively did not result in higher small mammal species richness or abundance compared to clearcutting. Small mammal species richness did not vary along a gradient of retained conifer basal area that resulted from different felling densities (result presented as statistical model coefficient). The combined abundances of red-backed voles Myodes gapperi, masked shrews Sorex cinereus and deer mice Peromyscus maniculatus (which comprised 92% of individuals caught) did not vary with conifer basal area (result presented as statistical model coefficient). Four tree blocks were harvested in 2004–2005. Three or four harvesting treatments (each 20-ha extent) were applied in each block. Selective harvesting resulted in retention of 17–23%, 57–69% or 60–73% of standing timber. Clearcut areas had <10% of timber remaining. Small mammals were live-trapped, between 3 July and 25 August in 2006 and 2007.
(1) Swan D., Freedman B. & Dilworth T. (1984) Effects of various hardwood forest management practices on small mammals in central Nova Scotia. The Canadian Field-Naturalist, 98, 362–364.
(2) Monthey R.W. (1986) Responses of snowshoe hares, Lepus americanus, to timber harvesting in northern Maine. The Canadian Field-Naturalist, 100, 568–570.
(3) Klenner W. & Sullivan T.P. (2003) Partial and clearcut harvesting of high-elevation spruce–fir forests: implications for small mammal communities. Canadian Journal of Forest Research, 33, 2283–2296, https://doi.org/10.1139/x03-142
(4) Fuller A.K., Harrison D.J. & Lachowski H.J. (2004) Stand scale effects of partial harvesting and clearcutting on small mammals and forest structure. Forest Ecology and Management, 191, 373–386, https://doi.org/10.1016/j.foreco.2004.01.014
(5) Perry R.W. & Thill R.E. (2005) Small-mammal responses to pine regeneration treatments in the Ouachita Mountains of Arkansas and Oklahoma, USA. Forest Ecology and Management, 219, 81–94, https://doi.org/10.1016/j.foreco.2005.09.001
(6) Klenner W. & Sullivan T.P. (2009) Partial and clearcut harvesting of dry Douglas-fir forests: Implications for small mammal communities. Forest Ecology and Management, 257, 1078–1086, https://doi.org/10.1016/j.foreco.2008.11.012
(7) Zwolak R. (2009) A meta-analysis of the effects of wildfire, clearcutting, and partial harvest on the abundance of North American small mammals. Forest Ecology and Management, 258, 539–545, https://doi.org/10.1016/j.foreco.2009.05.033
(8) Le Blanc M-L., Fortin D., Darveau M. & Ruel J-C. (2010) Short term response of small mammals and forest birds to silvicultural practices differing in tree retention in irregular boreal forests. Ecoscience, 17, 334–342, https://doi.org/10.2980/17-3-3340
6.16. Use patch retention harvesting instead of clearcutting
https://www.conservationevidence.com/actions/2639
- Three studies evaluated the effects on mammals of using patch retention harvesting instead of clearcutting. Two studies were in Canada1,3 and one was in Australia2.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (3 STUDIES)
- Abundance (3 studies): Two replicated, controlled, before-and-after studies and a replicated, site comparison study in Canada1,3 and Australia2 found that retaining patches of unharvested trees instead of clearcutting whole forest stands increased or maintained numbers of some but not all small mammals. Higher abundances where tree patches were retained were found for southern red-backed voles1,3, bush rat2 and for female agile antechinus2. No benefit of retaining forest patches was found on abundances of deer mouse1, meadow vole1 and male agile antechinus2.
BEHAVIOUR (0 STUDIES)
Background
Removing trees, through clearcutting or clearfelling, can have substantial, usually negative, effects on forest mammals, through alteration of habitat and removal of food and shelter. Patch retention is the act of leaving groups of trees during harvesting, which may act as refugia to support forest fauna and enable its re-colonisation of the remainder of the forest as it regrows.
A replicated, controlled, before-and-after study in 1993–1996 of a boreal forest area in Alberta, Canada (1) found that retaining patches of unharvested trees enhanced numbers of red-backed voles Clethrionomys gapperi, but not of deer mice Peromyscus maniculatus or meadow voles Microtus pennsylvanicus, relative to those in fully harvested areas. Following harvesting, yearly peak red-backed vole population estimates were higher with retained tree patches (101–172 voles/plot) than without (53–91 voles/plot). Deer mice had similar abundance between treatments (patches: 107–148 mice/plot; no patches: 71–115 mice/plot). Meadow vole numbers were higher in fully harvested plots (patches: 0–24 voles/grid; no patches: 36–118). In a 6 × 6-km study area, four plots were managed during winter 1993–1994. In two plots, trees were felled, but leaving undisturbed 40-m diameter patches, comprising 10% of total tree basal area. In two other plots, trees were felled entirely. Small mammals were surveyed using 60 or 120 Longworth live traps/6 ha block. Traps were set for three nights and two days, at fortnightly or longer intervals, from May or June to August or September, in 1993–1996.
A replicated, controlled, before-and-after study in 2002–2009 of forest across three districts in Victoria, Australia (2) found that retaining forest islands when clearfelling reduced subsequent abundance declines after brash burning for some small mammal relative to in clearfelled areas. Average bush rat Rattus fuscipes abundance declined less following burning in island retention patches (before: 2.1; after: 1.6/grid) than in clearfelled patches (before: 1.2; after: 0.4/grid). Female agile antechinus Antechinus agilis abundance declined less following burning in island retention patches (before: 2.2; after: 1.5/grid) than in clearfelled patches (before: 1.0; after: 0.1/grid). However, male agile antechinus abundance declines were similar following burning in island retention patches (before: 1.1; after: 0.4/grid) and clearfelled patches (before: 0.5; after: 0.2/grid). Forest patches (coupes) of ≥15 ha were established in six blocks. In each block, one patch was entirely clearfelled, one was clearfelled, but retaining a 1.5-ha forest island and one was clearfelled, but retaining three 0.5-ha islands. Post-felling, blocks were prescribed burned to clear brash. Small mammals were surveyed using four live-trap grids in each patch. Three grids/patch were in retained forest islands. Surveys took place before felling, after felling and after burning. Treatments were staggered, so surveys spanned 2002 to 2009.
A replicated, site comparison study in 2015–2016 of a coniferous forest site in British Columbia, Canada (3) found that retaining patches of trees when harvesting sustained higher southern red-backed voles Myodes gapperi populations compared to clearfelling. Nineteen to 20 years post-harvest, there were more red-backed voles in patch retention plots (5.7/ha) than in clearfelled plots (3.3/ha). Harvesting, in 1996, comprised three replicate plots each of tree patch retention (10 m2/ha basal area, retained as a group — group sizes not stated) and clearfelling. Plot sizes ranged from 3.6–12.8 ha. Forest overstorey was mostly lodgepole pine Pinus contorta and Douglas fir Pseudotsuga menziesii, of average ages of 82–228 years. Following harvesting, sites were planted with lodgepole pine, Douglas fir and interior spruce Picea glauca × engelmannii seedlings in 1997. Small mammals were sampled at four-week intervals in May–October of 2015 and 2016. One live-trapping grid (49 traps across 1 ha) was located in each plot. Traps were set for two nights and one full day on each occasion.
(1) Moses R.A. & Boutin S. (2001) The influence of clearcut logging and residual leave material on small mammal populations in aspen-dominated boreal mixedwoods. Canadian Journal of Forest Research, 31, 483–495, https://doi.org/10.1139/x00-186
(2) Lindenmayer D.B., Knight E., McBurney L., Michael D. & Banks S.C. (2010) Small mammals and retention islands: An experimental study of animal response to alternative logging practices. Forest Ecology and Management, 260, 2070–2078, https://doi.org/10.1016/j.foreco.2010.08.047
(3) Sullivan T.P. & Sullivan D.S. (2017) Green-tree retention and recovery of an old-forest specialist, the southern red-backed vole (Myodes gapperi), 20 years after harvest. Wildlife Research, 44, 669–680, https://doi.org/10.1071/wr17065
6.17. Retain undisturbed patches during thinning operations
https://www.conservationevidence.com/actions/2640
- Two studies evaluated the effects on mammals of retaining undisturbed patches during thinning operations. Both studies were in the USA1,2.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (2 STUDIES)
- Use (2 studies): Two randomized, replicated, controlled studies (one also before-and-after) in the USA1,2 found that snowshoe hares1 and tassel-eared squirrels2 used retained undisturbed forest patches more than thinned areas.
Background
Thinning is a forestry practice that involves the selective removal of trees to reduce tree density and improve the growth rate, health and timber quality of remaining trees. Thinning has been done historically to maximize timber production but may have ecological benefits, such as opening up the canopy and allowing more light in, which may benefit some species. However, some species may benefit from the shelter available within retained undisturbed forest patches.
A randomized, replicated, controlled, before-and-after study in 2001–2003 of a coniferous forest in Montana, USA (1) found that snowshoe hares Lepus americanus used retained undisturbed patches more than they used thinned forest. More hare tracks were counted in undisturbed patches than in thinned areas when patches comprised 8% (undisturbed: 106; thinned: 25 tracks/km) and 35% (undisturbed: 107; thinned: 15 tracks/km) of the stand. The same was found for faecal pellet counts in 8% (undisturbed: 1.0; thinned: 0.2 pellets/tray) and 35% (undisturbed: 1.4; thinned: 0.1 pellets/tray) retention patches. After treatments were applied, hares increased use of undisturbed (before treatment: 29; after: 144 tracks/km) and mature (before treatment: 64–80; after: 88–181 tracks/km) stands, suggesting movements into these areas. Five conifer stands (10.5–14.0 ha), regenerating naturally after felling in 1985, were selected. Treatments were applied in June 2002 and comprised: thinning with five 0.2-ha unthinned patches (8%) retained (two stands), thinning with five 0.8-ha unthinned patches (35%) retained (two stands) and one undisturbed stand. Conifer density was 5,350–7,050/ha before and 656–750/ha after thinning. Two adjacent mature stands represented pre-harvest conditions. Hare-track density was assessed from December–March in 2001–2002 (prior to thinning) and 2002–2003 (after thinning). Faecal pellets were surveyed each winter within 50 trays in each stand, into which pellets accumulated during April snowmelt.
A randomized, replicated, controlled study in 2005–2007 of a ponderosa pine Pinus ponderosa forest in Northern Arizona, USA (2) found that tassel-eared squirrels Sciurus aberti made greater use of undisturbed than thinned forest. In winter 57% and during the rest of the year 51% of squirrel home range areas fell within undisturbed forest compared to 39% availability by extent in the study area. Squirrels also showed a preference for dense canopies. In winter, canopies with 51–75% cover accounted for 53% of squirrel use compared to 44% of resource availability. Thinning was carried out from 1998–2000. Seventeen-hectare blocks within a 10-km2 area were randomly assigned to no thinning and to low, medium and high-intensity thinning. A combination of these managements was applied to four additional blocks of approximately 40 ha each. Squirrel locations were monitored by radio-tracking from December 2005 to July 2007.
(1) Ausband D.E. & Baty G.R. (2005) Effects of precommercial thinning on snowshoe hare habitat use during winter in low-elevation montane forests. Canadian Journal of Forest Research, 35, 206–210, https://doi.org/10.1139/x04-152
(2) Loberger C.D., Theimer T.C., Rosenstock S.S. & Wightman C.S. (2011) Use of restoration-treated ponderosa pine forest by tassel-eared squirrels. Journal of Mammalogy, 92, 1021–1027, https://doi.org/10.1644/10-mamm-a-321.1
6.18. Clear or open patches in forests
https://www.conservationevidence.com/actions/2641
- Four studies evaluated the effects on mammals of clearing or opening patches in forests. Two studies were in the USA2,3, one was in Bolivia1 and one was in Canada4.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (4 STUDIES)
- Abundance (4 studies): Two of four replicated studies (including three controlled studies and a site comparison study), in Bolivia1, the USA2,3 and Canada4, found that creating gaps or open patches within forests did not increase small mammal abundance1,2 relative to uncut forest. One study found that it did increase small mammal abundance4 and one found increased abundance for one of four small mammal species3.
BEHAVIOUR (0 STUDIES)
Background
Gaps in forests can be natural features that add diversity to the habitat. They can be created by natural events, such as mature trees falling, and maintained by grazing animals. In absence of natural gaps (such as in a younger forest) artificially creating gaps may mimic the same conditions. This intervention considers some cases where gaps are created primarily as a conservation action and others where gaps are created as part of timber harvesting.
A replicated, site comparison study in 1998 of tropical forest in Bolivia (1) found that creating forests gaps, by selective felling, did not increase small mammal abundance relative to that in undisturbed forest. The number of small mammals trapped did not differ between large gaps (7.0/plot), small gaps (6.8/plot) and undisturbed forest (5.2/plot). Similarly, total species richness did not differ between large gaps (four species), small gaps (five species) and undisturbed forest (five species). Trees were harvested selectively, creating gaps, in June-October 1997. Within each of six blocks, one small gap (average 247 m2), one large gap (average 811 m2) and one undisturbed area (400 m2) were studied. Treatments in a block were separated by <100 m. Small mammals were monitored using eight Sherman live traps and a larger cage trap, set in each gap or undisturbed forest area, for six days each in April, July, and November 1998.
A replicated, controlled study in 1995–1997 of three stands in a coniferous forest in Washington, USA (2) found that creating gaps in forests did not increase abundances of most small mammal species. Species responses to treatments were not tested for statistical significance. Five to six years after gap creation, there were no clear treatment preferences among the most frequently recorded species, Trowbridge’s shrew Sorex trowbridgii (large gaps: 0.5–3.5/100 trap nights; forest: 0.0–3.8), Keen’s mouse Peromyscus keeni (large gaps: 3.1–5.4/100 trap nights; forest: 1.9–5.9) and southern red-backed vole Clethrionomys gapperi (large gaps: 0.5–1.9/100 trap nights; forest: 0.4–1.9). Seven years after gap creation, there was a similar lack of clear treatment preferences among the shrew species, montane shrew Sorex monticolus (medium gaps: 0.0–4.2/100 trap nights; large gaps: 0.3–0.6; forest: 0.6–1.2), Trowbridge’s shrew (medium gaps: 1.8–7.7/100 trap nights; large gaps: 1.2–5.7; forest: 2.1–4.8) and vagrant shrew Sorex vagrans (medium gaps: 0.0/100 trap nights; large gaps: 0.0–0.6; forest: 0.0–0.3). Gaps were created in 1990 in three Douglas-fir Pseudotsuga menziesii dominated stands, c.90, 140 and 500 years old. Gap diameters were 1 (large) and 0.6 and 0.4 (medium) times the average surrounding tree height. There were two replicates of each size/stand. Differing combinations of treatments and stands was sampled for small mammals in summer and autumn 1995–1997 using live traps, killing traps and pitfall traps.
A replicated, controlled, before-and-after study in 1994–1998 of a coniferous forest in British Colombia, Canada (3) found a greater abundance of one small mammal species when forest was harvested in small patches, relative to clearcutting, but not of three other species. Populations of all species did not differ between treatment plots in the pre-treatment year. After harvesting, there were more southern red-backed voles Clethrionomys gapperi in patch harvesting plots (0.1-ha patches: 18.7–49.7/ha; 1-ha patches: 18.0–38.1/ha) than in clearcuts (0.1–10.8/ha). Long-tailed voles Microtus longicaudus were less abundant in patch harvesting plots than clearcut plots (0.1-ha patches: 0.4–4.5/ha; 1-ha patches: 0.2–2.6/ha; clearcuts: 2.6–16.2/ha). Abundances were similar between treatments for northwestern chipmunk Tamias amoenus (0.1-ha patches: 2.9–3.4/ha; 1-ha patches: 2.2–2.4/ha; clearcuts: 3.7–6.0/ha) and deer mouse Peromyscus maniculatus (0.1-ha patches: 0.4–5.1/ha; 1-ha patches: 2.0–4.5/ha; clearcuts: 0.8–5.0/ha). Forest stands were c.30 ha. There were three replicate stands each harvested in winter 1994/95, with 0.1-ha patches, 1-ha patches and 10-ha clearcuts. Each involved removing 30% volume of timber. Small mammals were live-trapped in 1994–1998, over two consecutive nights, at 3-week intervals, from June or July to August or September.
A replicated, controlled, before-and-after study in 1991–1997 of two second-growth forests in Arkansas and Oklahoma, USA (4) found that felling small groups of trees increased small mammal abundance relative to unharvested stands, but not to clearcut stands. Before harvesting, average small mammal abundances were similar between stands planned for different treatments (unharvested: 2.5 small mammals/100 trap nights; small group felling: 2.2; clearcut: 0.9). After harvesting, more small mammals were caught in small group felling stands (6.7/100 trap nights) than in unharvested stands (1.7) but a similar number was caught in clearcut stands (10.7). In each of four blocks of second-growth forest (59–69 years old at start of study), one stand was managed by felling trees to create 3–10 openings of 0.04–1.9 ha, covering 6–14% of stand area, one was clearcut and one was unharvested. Harvesting was conducted in summer 1993. Stands covered 13–28 ha. Small mammals were surveyed using an average of 66.5 Sherman live traps/stand, pre-harvest in 1991 and 1992, and post-harvest in 1995, 1997 and 1999. Traps were operated for seven consecutive nights during winter (December–January).
(1) Fredericksen N.J., Fredericksen T.S., Flores B. & Rumiz D. (1999) Wildlife use of different-sized logging gaps in a tropical dry forest. Tropical Ecology, 40, 167–175.
(2) Gitzen R.A. & West S.D. (2002) Small mammal response to experimental canopy gaps in the southern Washington Cascades. Forest Ecology and Management, 168, 187–199, https://doi.org/10.1016/s0378-1127(01)00745-9
(3) Klenner W. & Sullivan T.P. (2003) Partial and clearcut harvesting of high-elevation spruce–fir forests: implications for small mammal communities. Canadian Journal of Forest Research, 33, 2283–2296, https://doi.org/10.1139/x03-142
(4) Perry R.W. & Thill R.E. (2005) Small-mammal responses to pine regeneration treatments in the Ouachita Mountains of Arkansas and Oklahoma, USA. Forest Ecology and Management, 219, 81–94, https://doi.org/10.1016/j.foreco.2005.09.001
6.19. Retain dead trees after uprooting
https://www.conservationevidence.com/actions/2642
- One study evaluated the effects on mammals of retaining dead trees after uprooting. This study was in the USA1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (1 STUDY)
- Use (1 study): A replicated, controlled study in the USA1 found that areas where trees were uprooted but left on site were used more by desert cottontails than were cleared areas.
Background
Management or restoration of some habitats involves removing trees. This may occur, for example, in sites where fire suppression has caused woodland to become denser than it has been historically. Retaining uprooted trees can increase structural diversity at ground level. This may in turn increase cover available to some mammal species.
A replicated, controlled study in 1965–1968 of pinyon-juniper forest at a site in New Mexico, USA (1) found that where trees were uprooted but left on site, more desert cottontail Sylvilagus audubonii faecal pellets were counted than in fully cleared areas. Results were not tested for statistical significance. Where uprooted trees were left, there were 3.2 cottontail pellets/ft2 compared to 1.0 pellets/ft2 where trees were uprooted and burned. In each of two blocks, there was one plot with all trees uprooted and left on site and one with all trees uprooted, piled up and burned. Plots covered 300–500 acres each. Treatments were carried out in 1965. Cottontail pellets were counted on randomly selected sample points on belts of l/400 acre within the middle of each plot, in 1968.
(1) Kundaeli J.N. & Reynolds H.G. (1972) Desert cottontail use of natural and modified pinyon-juniper woodland. Journal of Range Management, 25, 116–118.
6.20. Use thinning of forest instead of clearcutting
https://www.conservationevidence.com/actions/2643
- One study evaluated the effects on mammals of using thinning of forest instead of clearcutting. This study was in the USA1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (1 STUDY)
- Use (1 study): A replicated, controlled study in the USA1 found that thinned forest areas were used more by desert cottontails than were fully cleared or uncleared areas.
Background
Harvesting of timber within forests can be carried out by clearcutting sites or by various methods of harvesting a proportion of trees. By thinning, rather than felling a whole forest, larger areas would need to be managed in order to achieve the same timber harvest though some degree of forest cover can be retained over that area. Thinning forest may benefit some species that prefer an open forest structure whilst not having detrimental effects on forest mammals that clearcutting would be likely to have.
See also Thin trees within forest for where thinning is an intervention in woodland that would otherwise be left without removing trees.
A replicated, controlled study in 1965–1968 of pinyon-juniper forest at a site in New Mexico, USA (1) found that in areas where trees were thinned, more desert cottontail Sylvilagus audubonii faecal pellets were counted than in fully cleared areas or uncleared areas. Results were not tested for statistical significance. In thinned plots, there were 2.7 cottontail pellets/ft2 compared to 1.0 pellets/ft2 where trees were cleared (uprooted and burned) and 2.4 pellets/ft2 where trees were left unmanaged. In each of two blocks, there was one plot with trees thinned to 100 trees/acre, one with all trees uprooted, piled up and burned and one with trees left unmanaged. Plots covered 300–500 acres each. Treatments were carried out in 1965. Cottontail pellets were counted at randomly selected sample points in treatment plots in 1968.
(1) Kundaeli J.N. & Reynolds H.G. (1972) Desert cottontail use of natural and modified pinyon-juniper woodland. Journal of Range Management, 25, 116–118.
6.21. Remove competing vegetation to allow tree establishment in clearcut areas
https://www.conservationevidence.com/actions/2644
- Three studies evaluated the effects on mammals of removing competing vegetation to allow tree establishment in clearcut areas. Two studies were in Canada2,3 and one was in the USA1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (3 STUDIES)
- Use (3 studies): One of three studies (including two controlled studies and one site comparison study), in the USA1 and Canada2,3, found that, where competing vegetation was removed to allow tree establishment in clearcut areas, American martens used the areas more3. One study found mixed results for moose1 and one found no increase in site use by snowshoe hares2.
Background
Following felling of trees, for timber harvesting, a range of actions may be employed to accelerate forest regrowth. Tree establishment (either through natural regeneration or planting) may be inhibited by rapid growth of herbaceous or scrubby vegetation. This vegetation may be controlled or removed by use of herbicides or by using tools, such as brushsaws, to physically remove such vegetation. Using such techniques to allow or encourage forest regrowth in clearcut areas may speed up the time until such habitat becomes suitable for forest-dwelling mammals.
A randomized, controlled, before-and-after study in 1991–1993 in a coniferous forest in Maine, USA (1) found that moose Alces alces did not use herbidice-treated forest clearcuts more than untreated clearcuts 1–2 years after treatment but foraging and sleeping signs were more numerous on treated than untreated clearcuts 7–11 years after treatment. Moose track quantity was similar between plots in the year before herbicide application (treatment plots: 0.07 track groups/ha; untreated: 0.08). One to two years after treatment, there were no significant differences in total number of track groups (treated: 1.6–3.0/km; untreated: 2.6–5.1), pellet groups (treated: 0.1–0.2/km; untreated: 0.2–0.4) or moose beds (treated: 0.03–0.05/km; untreated: 0.13–0.26), but there were fewer foraging tracks in treated plots (treated: 0.4 track groups/km; untreated: 1.0 tracks/km). After 7–11 years, there were more foraging tracks in treated (2.1–4.3/km) than untreated (1.1–1.8) plots and more moose beds (treated: 0.35–0.55/km; untreated: 0.12–0.31). There were no differences between treatments for total track groups (treated: 5.3–7.7/km; untreated: 3.4–4.2) or pellet groups (treated: 0.8–0.9/km; untreated: 0.4–0.5). Six of 12 clearcuts (18–89 ha), harvested 4.5–8.5 years previously, were herbicide-treated in August 1991. Six of 11 different clearcuts (21–73 ha) were glyphosate-treated 7–10 years before sampling. Treated plots in this second group averaged 19 years post-felling and, untreated plots, 16 years. Across all 23 plots, groups of moose foraging tracks and all tracks, moose beds and faecal pellet clumps were counted 5–7 times/year in January–March of 1992 and 1993, along 2-m-wide transects, 3–7 days after snowfall.
A replicated, controlled study in 1991–1996 of a coniferous forest in Québec, Canada (2) found that, up to nine years after clearcutting, snowshoe hares Lepus americanus were not more numerous in replanted areas where competing vegetation had been removed than in naturally regenerating clearcuts. Data were not fully reported, nor were results of statistical analyses. However, hares seldom used removal plots. Only 5% of vegetation removal plots contained hare faecal pellets during any one survey and no preference for removal plots over those regenerating naturally was identified. Twenty-five sites (6–9 ha) were studied. Ten were clearcut in 1987, replanted in spring 1990, and competing vegetation removed in August 1992. In five sites vegetation was removed using brushsaws, and five using herbicide solution. Fifteen naturally regenerated sites, clearcut between 1987 and 1989, were controls. Hare faecal pellets were counted and cleared in 1 × 5-m plots, in June and September, 1991–1996.
A replicated, site comparison study in 2001–2002 of boreal forest stands in Ontario, Canada (3) found that stands subject to herbicide treatment and tree planting after logging were used more by American martens Martes americana than were naturally regenerating stands. The effects of herbicide and planting were not separated in the study. Radio-tracked martens made greater use of herbicide-treated and planted stands than they did of naturally regenerating stands (data not presented). However, the live-capture rate of martens in herbicide-treated and planted stands (5.6 martens/100 trap nights) was not significantly different to that in regenerating stands (1.9 martens/100 trap nights). Stands were all 35–45 years old and located in a 600-km2 forestry area. Forest stands were either herbicide-treated and planted following logging or were left to regenerate naturally after logging. Martens were live-trapped in 2003–2007, and monitored subsequently by radio-tracking.
(1) Eschholz W.E., Servello F.A., Griffith B., Raymond K.S. & Krohn W.B. (1996) Winter use of glyphosate-treated clearcuts by moose in Maine. The Journal of Wildlife Management, 60, 764–769.
(2) de Bellefeuille S., Bélanger L., Huot J. & Cimon A. (2001) Clearcutting and regeneration practices in Quebec boreal balsam fir forest: effects on snowshoe hare. Canadian Journal of Forest Research, 31, 41–51, https://doi.org/10.1139/x00-140
(3) Thompson I.D., Baker J.A., Jastrebski C., Dacosta J., Fryxell J. & Corbett D. (2008) Effects of post-harvest silviculture on use of boreal forest stands by amphibians and marten in Ontario. Forestry Chronicle, 84, 741–747, https://doi.org/10.5558/tfc84741-5
6.22. Retain understorey vegetation within plantations
https://www.conservationevidence.com/actions/2645
- One study evaluated the effects on mammals of retaining understorey vegetation within plantations. This study was in Chile1.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A replicated, controlled, before-and-after study in Chile1 found that areas with retained understorey vegetation had more species of medium-sized mammal, compared to areas cleared of understorey vegetation.
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (1 STUDY)
- Use (1 study): A replicated, controlled, before-and-after study in Chile1 found that areas with retained understorey vegetation had more visits from medium-sized mammals, compared to areas cleared of understorey vegetation.
Background
Understorey vegetation may compete for resources with planted trees, especially when trees are young, and is, therefore, sometimes removed as part of commercial forest management. However, retaining understorey vegetation has the potential to support native mammals (e.g. Carrilho et al. 2017) and may form part of a suite of actions that could attract premium payments for timber products marketed as being biodiversity-friendly.
Carrilho, M., Teixeira, D., Santos-Reis, M., & Rosalino, L. M. (2017). Small mammal abundance in Mediterranean Eucalyptus plantations: how shrub cover can really make a difference. Forest Ecology and Management, 391, 256–263, https://doi.org/10.1016/j.foreco.2017.01.032
A replicated, controlled, before-and-after study in 2009–2012 of a Monterey pine Pinus radiata plantation in central Chile (1) found that retaining understorey vegetation resulted in there being a greater number and higher visit rate of medium-sized mammal species, compared to areas cleared of understorey vegetation. Before clearance, the same four species were recorded both in plots designated to be uncleared and cleared; Leopardus guigna, culpeo Pseudalopex culpaeus, Molina’s hog-nosed skunk Conepatus chinga and southern pudu Pudu puda. After understorey clearance, all four species remained in uncleared plots but just southern pudu occurred in cleared plots. There were also fewer visits to cleared plots after understorey removal (visit rates presented as response ratios). Thirteen plots (≥300 m apart) were monitored using camera traps for four to five nights, monthly, from October 2009 to July 2012. In February 2011, understorey vegetation was removed from 1,600 m2 around cameras in five plots. Regrowth was controlled in February 2012.
(1) Simonetti J.A., Grez A.A. & Estades C.F. (2013) Providing habitat for native mammals through understory enhancement in forestry plantations. Conservation Biology, 27, 1117–1121, https://doi.org/10.1111/cobi.12129
6.23. Leave standing deadwood/snags in forests
https://www.conservationevidence.com/actions/2646
- One study evaluated the effects on mammals of leaving standing deadwood or snags in forests. This study was in the USA1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Abundance (1 study): A replicated, controlled study in the USA1 found that increasing the quantity of standing deadwood in forests increased the abundance of one of three shrew species, compared to removing deadwood.
BEHAVIOUR (0 STUDIES)
Background
Snags or standing dead trees and other dead wood can provide habitat or resources for some species within forest. Retaining or increasing provision of these features may benefit some forest mammal species.
A replicated, controlled study in 2007–2008 of three stands of loblolly pine Pinus taeda in South Carolina, USA (1) found that increasing the amount of forest standing deadwood increased the abundance of one of three shrew species compared to removing dead wood but not compared to in unmanipulated plots. More southeastern shrews Sorex longirostris were caught in plots with increased standing deadwood quantities (0.046 shrews/m of drift fence) than in plots cleared of fallen debris (0.013). Neither treatment differed significantly from the quantity in unmanipulated plots (0.026). There were no significant differences between treatments for southern short-tailed shrew Blarina carolinensis (standing deadwood: 0.069 shrews/m of drift fence; debris cleared: 0.051; unmanipulated: 0.058) or North American least shrew Cryptotis parva (standing deadwood: 0.004 shrews/m of drift fence; debris cleared: 0.014; unmanipulated: 0.015). Three plots, each 9.3 ha, were located in each of three loblolly pine stands, planted in 1950–1953. In each stand, standing deadwood quantities were increased tenfold in one plot in 2001, by ringbarking and injecting herbicide into trees, in another plot woody debris ≥10 cm across and ≥60-cm long was removed annually from 1996 and one plot was unmanipulated. Shrews were sampled across plots for 14 days, on seven occasions, from January 2007 to August 2008. Shrews were caught in 19-l plastic buckets, connected by drift fencing.
(1) Davis J.C., Castleberry S.B. & Kilgo J.C. (2010) Influence of coarse woody debris on the soricid community in southeastern Coastal Plain pine stands. Journal of Mammalogy, 91, 993–999, https://doi.org/10.1644/09-mamm-a-170.1
6.24. Leave coarse woody debris in forests
https://www.conservationevidence.com/actions/2647
- Three studies evaluated the effects on mammals of leaving coarse woody debris in forests. One study was in Canada1, one was in the USA2 and one was in Malaysia3.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A replicated, site comparison study, in Malaysia3 found more small mammal species groups in felled forest areas with woody debris than without.
POPULATION RESPONSE (3 STUDIES)
- Abundance (3 studies): One out of three replicated studies (two controlled, one site comparison, one before-and-after) in Canada1, the USA2 and Malaysia3 found that retaining or adding coarse woody debris did not increase numbers or frequency of records of small mammals1,3. The other study found that two of three shrew species were more numerous in areas with increased volumes of coarse woody debris than areas without coarse woody debris2.
BEHAVIOUR (0 STUDIES)
Background
Coarse woody debris consists of fallen dead trees and cut branches that are left after tree harvesting. Coarse woody debris increases the structural diversity at the forest floor. Sometimes, debris may be removed as part of forestry operations, such as for use as biofuel. However, retained coarse woody debris may provide resources on the forest floor that benefit woodland species.
This intervention covers studies where coarse woody debris is left evenly distributed. See also Gather coarse woody debris into piles after felling.
A replicated, controlled, before-and-after study in 1993–1996 of a boreal forest area in Alberta, Canada (1) found that retaining woody debris following harvesting did not enhance numbers of three small mammal species, relative to those in cleared areas. This was the case for estimated annual peak populations of red-backed vole Clethrionomys gapperi (debris: 53–91 voles/plot; no debris: 91–99 voles/plot), deer mouse Peromyscus maniculatus (debris: 71–115 mice/plot; no debris: 79–151 mice/plot) and meadow vole Microtus pennsylvanicus (debris: 36–118 voles/plot; no debris: 7–146 voles/plot). In a 6 × 6-km study area, trees across four plots were clearfelled during winter 1993–1994. In two plots, woody brash was spread by bulldozer to form a strip, approximately 50 m wide and 0.5 m deep, generally along block centres. Woody debris was removed entirely from the other two plots. Small mammals were surveyed using 60 or 120 Longworth live traps/6 ha block. Traps were operated for three nights and two days, at fortnightly or longer intervals, from May or June to August or September in 1993–1996.
A replicated, controlled study in 2007–2008 of three stands of loblolly pine Pinus taeda in South Carolina, USA (2) found that increasing coarse wood debris quantity increased the abundance of two of three shrew species compared to removing debris, but not compared to leaving debris as it fell. More southeastern shrews Sorex longirostris were caught in plots with increased coarse woody debris quantities (0.057 shrews/m of drift fence) than in plots cleared of fallen debris (0.013). Numbers in neither treatment differed significantly from those in unmanipulated plots (0.026). The same pattern was seen for southern short-tailed shrew Blarina carolinensis (increased debris: 0.105 shrews/m of drift fence; debris cleared: 0.051; unmanipulated: 0.058). However, there were no differences between treatments for North American least shrew Cryptotis parva (increased debris: 0.012 shrews/m of drift fence; debris cleared: 0.014; unmanipulated: 0.015). Three plots, each 9.3 ha, were located in each of three loblolly pine stands planted in 1950–1953. In each stand, woody debris quantities were increased fivefold in one plot in 2001 by felling trees, decreased in one plot by annually removing woody debris ≥10 cm across and ≥60 cm long from 1996 and left as it fell in one plot. Shrews were sampled across plots for 14 days, during seven seasons, from January 2007 to August 2008. Shrews were caught in 19-l plastic buckets connected by drift fencing.
A replicated, site comparison study in 2013 of a tropical forest in Malaysia (3) found more small mammal species groups, but not individual small mammals, where woody debris was left after selective logging than in areas lacking woody debris. On average, six small mammal species groups were recorded at sites with debris compared to four at sites without. No significant difference was detected for average numbers of small mammal recorded at sites with debris (43) compared to sites without (39). Sites were compared with respect to tree density, canopy openness, understorey vegetation cover, distance to road and slope and no differences in these measures were detected between sites with and without debris. Trees were selectively logged, within a 200-ha area, in 2010–2011. Single camera traps were set, around two years later, for 10 days each at 17 locations with logging woody debris and 17 without. Camera locations were ≥50 m from logging roads and were baited.
(1) Moses R.A. & Boutin S. (2001) The influence of clearcut logging and residual leave material on small mammal populations in aspen-dominated boreal mixed-woods. Canadian Journal of Forest Research, 31, 483–495, https://doi.org/10.1139/x00-186
(2) Davis J.C., Castleberry S.B. & Kilgo J.C. (2010) Influence of coarse woody debris on the soricid community in southeastern Coastal Plain pine stands. Journal of Mammalogy, 91, 993–999, https://doi.org/10.1644/09-mamm-a-170.1
(3) Yamada T., Yoshida S., Hosaka T. & Okuda T. (2016) Logging residues conserve small mammalian diversity in a Malaysian production forest. Biological Conservation, 194, 100–104, https://doi.org/10.1016/j.biocon.2015.12.004
6.25. Gather coarse woody debris into piles after felling
https://www.conservationevidence.com/actions/2653
- Two studies evaluated the effects on mammals of gathering coarse woody debris into piles after felling. Both studies were in Canada1,2.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A randomized, replicated, controlled study in Canada2 found higher mammal species richness where coarse woody debris was gathered into piles.
POPULATION RESPONSE (2 STUDIES)
- Abundance (2 studies): One of two randomized, replicated, controlled studies in Canada1,2 found higher counts of San Bernardino long-tailed voles where coarse woody debris was gathered into piles1. The other study found higher small mammal abundance at one of three plots where debris was gathered into piles2.
BEHAVIOUR (0 STUDIES)
Background
Coarse woody debris consists of fallen dead trees and cut branches that are left during tree harvesting. Gathering coarse woody debris into piles, either at a single point or as a line of debris across the forest floor, can increase structural diversity on a forest scale relative to evenly spreading the material.
A randomized, replicated, controlled study in 2006–2009, of a lodgepole pine Pinus contorta-dominated forest in British Colombia, Canada (1) found that gathering coarse woody debris from tree harvest waste into piles resulted in higher counts of San Bernardino long-tailed voles Microtus longicaudus than where debris was uniformly dispersed. There were more voles in plots where woody debris was gathered into piles at single points (9 voles/ha) or piles comprising rows of debris (7 voles/ha) than in plots where it was dispersed evenly (1 vole/ha). Within plots where woody debris was gathered in piles, more were caught within the piles (11–16 voles/ha) than on open ground (3 voles/ha). Plots were largely clearfelled in October 2006. Course woody debris was gathered into piles or uniformly dispersed. There were three replicate plots of each treatment, 0.2–3.0 km apart. Voles were sampled over two nights, at 4-week intervals, in May–October of 2007, 2008, and 2009, using Longworth live traps in a grid of 49 points across 1 ha in each plot.
A randomized, replicated, controlled study in 2005–2010 of three forest sites in British Colombia, Canada (2) found that plots with piles of coarse woody debris had greater small mammal abundance than did plots where woody debris was evenly spread at one of the three sites and that species richness was higher with debris in piles across all sites or in one of three sites, depending on survey method used. More small mammals were trapped in plots with course woody debris in single piles (38/plot) or arranged in lines (37/plot) than with evenly dispersed woody debris (21/plot) at one site. There were no differences at the two other sites (piles: 18–27; dispersed: 14–23/plot). Species richness of trapped mammals followed a similar pattern at the site with an abundance difference, with more species in plots with woody debris piles (4.3–4.6/plot) than with dispersed woody debris (3.7/plot). There was no difference at the other two sites (piles: 3.3–3.9; dispersed: 3.1–3.6). However, snow-tracking surveys recorded more mammal species in plots with course woody debris piles (2.7–3.4/plot) than with dispersed woody debris (1.7/plot). Trees (dominated by lodgepole pine Pinus contorta) were harvested at three sites in 2005–2007. Each site had three randomly assigned replicates of course woody debris gathered into single piles (2–3 piles/ha, 1–3 m high), debris gathered into rows (1–3 m high) and evenly dispersed debris. Plots within a site averaged 0.6–0.8 km apart. Small mammals were live-trapped for three nights and two days, at 4–8-week intervals, in May–October of 2007–2009. Mammal tracks were surveyed, generally three days after snowfall, twice each winter, from 2007–2008 to 2009–2010.
(1) Sullivan T.P. & Sullivan D.D. (2012) Woody debris, voles, and trees: Influence of habitat structures (piles and windrows) on long-tailed vole populations and feeding damage. Forest Ecology and Management, 189–198, https://doi.org/10.1016/j.foreco.2011.09.001
(2) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2012) If we build habitat, will they come? Woody debris structures and conservation of forest mammals. Journal of Mammalogy, 93, 1456–1468, https://doi.org/10.1644/11-mamm-a-250.1
6.26. Retain riparian buffer strips during timber harvest
https://www.conservationevidence.com/actions/2652
- We found no studies that evaluated the effects on mammals of retaining riparian buffer strips during timber harvesting.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Hannon S.J., Paszkowski C.A., Boutin S., DeGroot J., Macdonald S.E., Wheatley M. & Eaton B.R. (2002) Abundance and species composition of amphibians, small mammals, and songbirds in riparian forest buffer strips of varying widths in the boreal mixed-wood of Alberta. Canadian Journal of Forest Research, 32, 1784–1800, https://doi.org/10.1139/x02-092
6.27. Retain wildlife corridors in logged areas
https://www.conservationevidence.com/actions/2651
- Two studies evaluated the effects on mammals of retaining wildlife corridors in logged areas. One study was in Australia1 and one was in Canada2.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (2 STUDIES)
- Use (2 studies): A replicated study in Australia1 found that corridors of trees, retained after harvesting, supported seven species of arboreal marsupial. A replicated, controlled study in Canada2 found that lines of woody debris through clearcut areas that were connected to adjacent forest were not used more by red-backed voles than were isolated lines of woody debris.
Background
Corridors are areas of habitat that are contiguous or isolated (i.e. linkages or stepping stones) that enable species to disperse and migrate through the landscape. In a managed forest environment, corridors may enable recolonization of isolated forest blocks. This intervention includes corridors of natural unharvested vegetation and of cover provided by arrangement of felling debris.
A replicated study (year not stated) of forest at 49 sites in Victoria, Australia (1) found that linear corridors of unharvested trees retained after tree harvesting operations supported seven species of arboreal marsupial. From 402 tree hollows surveyed, 69 arboreal marsupials were recorded, at 54 trees. Greater glider Petauroides volans and mountain brushtail possum Trichosurus caninus were the most frequently recorded species, accounting for 78% of observations. Sites were chosen where forest had regrown for around 50 years, following wildfires in 1939, and then been felled years <4 years before mammal observations, but leaving a linear strip. Strips were 125–762 m long and had average widths of 30–264 m. Forty-three strips comprised Eucalyptus regnans stands and six were of Eucalyptus delegatensis. Strips had 1–29 trees with hollows. Marsupial occupation of tree hollows was determined by direct observations.
A replicated, controlled study in 2010–2012 of forest at three sites in British Colombia, Canada (2) found that following tree harvesting, rows of woody debris connected to adjacent forest were not used more by red-backed voles Myodes gapperi than were isolated rows of woody debris. The average number of voles/trapping session in rows of woody debris attached to forest (9.0) did not differ from the number in those that were isolated (9.3). However, both had more voles than did unharvested forest (4.4). Seventeen plots were spread across three sites of 42–47 ha extent. Eight plots contained rows of woody debris attached to forest edge, six had isolated woody debris rows in clearcut areas and three were unharvested mature or old-growth forest. Plots averaged 0.23–0.40 km apart. Rows of woody debris averaged 136–344 m long, 1–3 m high and 6–9 m diameter or width. Felling and establishment of rows of woody debris occurred in autumn 2009. Voles were sampled using Longworth live traps, at 4-week intervals (two sites) or 4–8-week intervals (one site), from May to October 2010–2012. Traps were set for one day and two nights each time.
(1) Lindenmayer D.B., Cunningham R.B., & Donnelly C.F. (1993) The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, south-east Australia, iv. the presence and abundance of arboreal marsupials in retained linear habitats (wildlife corridors) within logged forest. Biological Conservation, 66, 207–221.
(2) Sullivan T.P. & Sullivan D.S. (2014) Responses of red-backed voles (Myodes gapperi) to windrows of woody debris along forest–clearcut edges. Wildlife Research, 41, 212–221, https://doi.org/10.1071/wr14050
6.28. Thin trees within forest
https://www.conservationevidence.com/actions/2650
- Twelve studies evaluated the effects on mammals of thinning trees within forests. Six studies were in Canada2,4,8–11 and six were in the USA1,3,5,6,7,12.
COMMUNITY RESPONSE (2 STUDIES)
- Species richness (2 studies): A replicated, site comparison study in the USA1 found that in thinned tree forest stands, there was similar mammal species richness compared to in unthinned stands. A replicated, controlled study in Canada8 found that thinning of regenerating lodgepole pine did not result in greater small mammal species richness 12–14 years later.
POPULATION RESPONSE (8 STUDIES)
- Abundance (8 studies): Two of eight replicated or replicated and controlled, site comparison studies, in the USA1,3,5,6,7,12 and Canada4,8, found that thinning trees within forests lead to higher numbers of small mammals1,5,7. Two studies showed increases for some, but not all, small mammal species3,6 with a further study showing an increase for one of two squirrel species in response to at least some forest thinning treatments4. The other two studies showed no increases in abundances of small mammals8 or northern flying squirrels12 between 12 and 14 years after thinning.
BEHAVIOUR (4 STUDIES)
- Use (4 studies): Three of four controlled and comparison studies (three also replicated, one randomized) in Canada2,9,10,11 found that thinning trees within forests did not lead to greater use of areas by mule deer9,10,11, moose9,10,11 or snowshoe hares10,11. The other study found that a thinned area was used more by white-tailed deer than was unthinned forest2.
Background
Thinning is a forestry operation that involves removing some trees in order to allow remaining trees to grow faster, or straighter or otherwise to produce better quality timber. It may especially be applied in young forest, a few years after onset of regeneration or planting. Thinning increases light that reaches the forest floor, potentially adding to habitat diversity, and may enable remaining trees to produce higher quality forage for herbivores.
The evidence summarised for this intervention includes one case where trees were selectively thinned to increase overwinter browse availability for deer and one where combinations of thinning and felling of groups of trees were combined. See also Use thinning of forest instead of clearcutting.
A replicated, site comparison study in 1990–1991 of aspen Populus tremuloides forest at four sites in Minnesota, USA (1) found that in thinned tree stands, there was a greater abundance of small mammals, but a similar species richness compared to in unthinned stands. The average yearly site abundance of small mammals was greater in thinned stands (12–29 individuals/grid) than in unthinned stands (9–19 individuals/grid). Species richness did not differ between stand treatments (thinned: 2.8–5.3 species/grid; unthinned: 3.0–5.7 species/grid). Aspen stands at four sites had been growing for 9–11 years at time of thinning. Two had been thinned one year prior to sampling, one seven years previously and one 11 years previously. Unthinned stands were also surveyed at each site. Stands were 6–74 ha in extent. Small mammals were surveyed using snap traps, over two nights and one day, in July–September 1990 and 1991. Stands had 2–7 grids, of 64 traps each.
A site comparison study in 1996 of forest in Quebec, Canada (2) found that, following tree thinning through a partial forest cut aimed at increasing browse availability, white-tailed deer Odocoileus virginianus made proportionally greater use of the cut area than of the forest as a whole. Deer use of the cut area (estimated at 15,170 deer-days/km2) was higher than in the forest as a whole (estimated 2,808 deer-days/km2). However, deer did not move home ranges and only animals whose ranges overlapped the cut area used it. A partial forest cut, across 43 ha, was made in January–February 1996. This thinned the forest by removing approximately 40% of deciduous tree stems (with conifers and understorey trees retained). Deer use of the cut area was determined by counting pellet groups, on 27 and 28 April 1996, in eighty-four 2 × 40-m plots. This was compared with estimated pellet density in the whole forest area (total 25 km2) that was based on pellet production from an estimate of the overall deer population. Habitat selections of 30 individual deer were monitored by radiotracking, in January–April 1996.
A replicated, controlled, before-and-after study in 1994–1996 of four coniferous forest sites and a replicated, site comparison study in 1995–1996 of eight coniferous forest sites, all in Oregon, USA (3) found that thinning trees increased abundances of some small mammal species. Out of 12 species, abundances of three, deer mouse Peromyscus maniculatus, creeping vole Microtus oregoni and white-footed vole Arborimus albipes, increased in thinned plots during the two years post-thinning relative to in unthinned plots. Pacific jumping mouse Zapus trinotatus increased in thinned plots relative to in unthinned plots between the first and second years post-thinning. Seven species had similar abundances in each treatment. Western red-backed vole Clethrionomys californicus was less common in thinned than in unthinned plots. Capture rates did not significantly differ between plots before thinning. See paper for data. Of nine species, five, Pacific shrew Sorex pacificus, Trowbridge’s shrew Sorex trowbridgii, vagrant shrew Sorex vagrans, creeping vole and Pacific jumping mouse, were more abundant in plots thinned 7–24 years previously than in unthinned plots. See paper for data. Four sites, each with three 35–45-year-old Douglas-fir stands (26–40 ha/stand) were studied. Two stands/site were thinned in 1994–1995 (to averages of 193–267 trees/ha) and one was unthinned (average 500 trees/ha). Also, at eight pairs of stands, 52–100 years old and <1 mile apart, one stand (10–28 ha) had been thinned 7–24 years before surveying and one (20–73 ha) was unthinned. Small mammals were surveyed within the controlled study using pitfall traps for six weeks/year in 1994 (before thinning) and in 1995 and 1996 (after thinning). In the site comparison study, pitfall traps were operated for 40 consecutive days in each 1995 and 1996.
A replicated, controlled study in 2000–2002 of three coniferous forest sites in British Columbia, Canada (4) found thinning of lodgepole pine Pinus contorta stands resulted in higher numbers of northern flying squirrels Glaucomys sabrinus when resultant tree density was high, whilst thinning did not affect abundances of red squirrels Tamiasciurus hudsonicus. Average northern flying squirrel abundance was highest in thinned stands where remaining trees were at high density (4.6 squirrels/stand), intermediate in medium density stands (3.3/stand) and lowest in low density (1.3/stand) and unthinned (1.8/stand) stands. Red squirrel abundance did not differ between treatments (high density: 10.8/stand; medium density: 9.7/stand; low density: 13.5/stand; unthinned: 11.3/stand). In each of three sites, four forest stands, regenerating following felling and/or wildfire in 1960–1972, were studied. In 1988–1989, one stand each in each site was thinned to approximately 500 (low), 1,000 (medium), and 2,000 (high) stems/ha and one was unthinned (with 4,700–6,000 stems/ha in 1988). Squirrels were surveyed using Tomahawk live traps, at 4-week intervals, from May–October 2000 and 2001 and at 8-week intervals in 2002. One trapping grid (9 ha, 50 traps) was located in each stand.
A randomized, replicated, controlled, before-and-after study in 1994–2001 in a pine and oak forest area in Missouri, USA (5) found that thinning and partial harvesting of trees led to a higher abundance of Peromyscus mice spp. Two to five years after harvesting, the annual average number of mice caught in uneven-aged harvesting compartments, where single trees and small groups were felled (8.5–27.0 mice) and even-aged harvesting compartments, involving limited clearcutting and thinning (11.4–31.5 mice) were higher than in uncut compartments (5.9–10.0 mice). Catch data from two Peromyscus spp. were combined. Mice were live-trapped, in two blocks of 144 traps each, in nine compartments (312–514 ha), over six nights each year in April or May of 1994–1995 and 1998–2001. Compartments were grouped in three replicate blocks. Uneven-aged harvesting (three compartments) involved cutting single trees and small groups. Even-aged harvesting (three compartments) involved clearcutting and thinning 10–15 % of trees. Three compartments were uncut. Harvesting was carried out in 1996. Biomass removal was similar between harvesting treatments.
A replicated, site comparison study in 2000–2001 of coniferous forest across seven townships in Maine, USA (6) found that thinned regrowing forest stands had more red-backed voles Clethrionomys gapperi and masked shrews Sorex cinereus, but not deer mouse Peromyscus maniculatus or short-tailed shrew Blarina brevicauda than did unthinned stands. More red-backed voles were caught in thinned (9.1/survey) than in unthinned (3.8/survey) stands. The same pattern held for masked shrew (6.8 vs 1.2). No significant abundance differences were detected for deer mouse (3.6 vs 4.4) or short-tailed shrew (6.0 vs 4.4). Twenty-four stands were felled in 1967–1983, herbicide-treated in 1977–1988 and thinned in 1984–1999. Thirteen stands were felled in 1974–1982 and herbicide-treated in 1982–1988 but not thinned. Small mammals were surveyed at 64 live-trapping stations/stand for six consecutive 24-h periods during June–August 2000 and again in 2001.
A replicated, controlled, before-and-after study in 1991–1997 of two second-growth forests in Arkansas and Oklahoma, USA (7) found that thinning trees increased small mammal abundance relative to unthinned stands, but not to clearcut stands. Before management, average small mammal abundances were similar between stands planned for different treatments (thinning: 2.4 small mammals/100 trap nights; no thinning: 2.5; clearcut: 0.9). After management, more small mammals were caught in thinned stands (9.3/100 trap nights) than in unthinned stands (1.7) but a similar number was caught in clearcut stands (10.7). In each of four blocks of second-growth forest (59–69 years old at start of study), one stand was thinned, retaining 49–99 of the largest trees/ha, one was not thinned and one was clearcut. Tree removal was conducted in summer 1993. Stand extent was 13–28 ha. Small mammals were surveyed using an average of 67 Sherman live traps/stand, pre-management in 1991 and 1992, and post-management in 1995, 1997 and 1999. Traps were operated for seven consecutive nights during winter (December–January).
A replicated, controlled study in 2000–2002 of three coniferous forests in British Columbia, Canada (8) found that thinning of regenerating lodgepole pine Pinus contorta stands did not result in higher small mammal abundance or species richness 12–14 years later. Small mammal abundance varied between years but not between treatments (low remaining tree density: 13–26 individuals/stand; medium density: 11–23 individuals/stand; high density: 15–27 individuals/stand; unthinned: 10–26 individuals/stand). Similarly, species richness did not differ between treatments (low tree density: 2.3–4.3 species/stand; medium density: 3.7–3.9 species/stand; high density: 3.0–3.4 species/stand; unthinned: 2.5–3.7 species/stand). In each of three sites, four forest stands, regenerating following felling and/or wildfire in 1960–1972, were studied. In 1988–1989, one stand each in each site was thinned to approximately 500 (low), 1,000 (medium), and 2,000 (high) stems/ha and one was unthinned (with 4,700–6,000 stems/ha in 1988). Small mammals were live-trapped, over two nights and one day, at 4-week intervals, from May–October of 2000, 2001, and 2002. One trapping grid (1 ha, 49 trap stations) was located in each stand.
A replicated, site comparison study in 1999–2003 of two pine forest sites in British Columbia, Canada (9) found that thinning lodgepole pine Pinus contorta stands did not lead to greater use by mule deer Odocoileus hemionus or moose Alces alces. The average number of mule deer faecal pellet groups did not differ between thinned and unthinned stands in summer (thinned stands: 219/ha; unthinned stands: 73/ha) or winter (thinned: 378/ha; unthinned: 190/ha). Similarly, there was no significant difference between stands in the quantity of moose faecal pellet groups in summer (thinned: 7/ha; unthinnged: 7/ha) or winter (thinned: 16/ha; unthinned: 30 pellet groups/ha). Across the two sites, three forest stands in total were thinned in 1993 (to 1,000 stems/ha) and three were left unthinned. Stands had been clearcut in 1978–1982 and lodgepole pine had regenerated naturally. Faecal pellet groups were counted over a two-week period, five times in May and four times in October, in 55–145 plots/stands (plots were circles of 1.26 m radius), in 1999–2003.
A randomized, replicated, controlled study in 2000–2004 of five second-growth lodgepole pine Pinus contorta forests in British Colombia, Canada (10) found that in thinned stands, the abundances of snowshoe hare Lepus americanus, mule deer Odocoileus hemionus and moose Alces alces were not greater than in unthinned stands. Faecal pellet counts for snowshoe hares were not significantly different between low-density thinned plots (70,000 pellets/ha), medium-density thinned plots (60,000 pellets/ha), high-density thinned plots (38,000 pellets/ha) or unthinned plots (13,000 pellets/ha). Similarly, despite large count variations, no significant differences between treatments were detected for mule deer (low: 259 pellet clumps/ha; medium: 79; high: 33; unthinned: 13) or moose (low: 365 pellet clumps/ha; medium: 133; high: 188; unthinned: 93). In each of three areas, four stands (17–27 years old) were studied. One stand each was thinned to low (approximately 500 stems/ha), medium (1,000 stems/ha) and high (2,000 stems/ha) tree density in 1988–1989. One was unthinned (4,700–6,000 stems/ha at time of thinning). Treatments were assigned randomly within study areas. Mammal faecal pellets and clumps were surveyed in one hundred 5-m2 plots in each stand. Plots were cleared of pellets in early October 2000. Pellets were counted in spring 2004.
A replicated, controlled study in 2003–2008 of four lodgepole pine Pinus contorta forests in British Colombia, Canada (11) found that thinning did not increase forest stand use by snowshoe hares Lepus americanus, mule deer Odocoileus hemionus or moose Alces alces, relative to unthinned stands, 15–20 years after thinning. Hare faecal pellet density did not differ significantly between low (26,000 pellets/ha), medium (25,000 pellets/ha) or high (49,000 pellets/ha) density thinning or unthinned forest (106,000 pellets/ha). Similarly, there were no significant differences between treatments for mule deer (low: 495 pellet-groups/ha; medium: 500; high: 447; unthinned: 195) or moose (low: 190 pellet-groups/ha; medium: 88; high: 131; unthinned: 71). Naturally regenerated young lodgepole pine stands were studied at four sites. Stands were thinned, in 1988–1993, to target densities of 500 (low), 1,000 (medium) and 2,000 (high) stems/ha. Unthinned stands had >3,000 stems/ha. Mammal faecal pellets and pellet-groups were surveyed in 5-m2 plots (55–145 plots/stand). Plots were cleared of pellets in autumn 2003. New pellets and pellet-groups were counted in spring 2008.
A replicated, controlled study in 2007–2008 of a Douglas-fir Pseudotsuga menziesii forest in Oregon, USA (12) found that, 11–13 years after thinning, northern flying squirrels Glaucomys sabrinus were not more numerous in thinned than in unthinned stands. Flying squirrel density was lower in thinned (0.4 squirrels/ha) than unthinned (2.0/ha) stands. Among thinned stands, there were more flying squirrels in those that were lightly thinned with gaps (0.5/ha) than in heavily thinned stands (0.2/ha). The numbers in lightly thinned stands without gaps (0.4/ha) did not differ significantly from that in lightly thinned stands with gaps. Treatments were applied to 16 stands (15–53 ha), in four blocks (2.5–21 km apart), of 55–65-year-old forest, in 1994–1997. In each block, treatments were heavy thinning (to 125–137 trees/ha), light thinning (250–275 trees/ha), light thinning with gaps (as light thinning but also with 20% of the stand harvested leaving 0.2-ha gaps) and unthinned. Flying squirrels were surveyed using 100 traps/stand for four nights and three days, between late September and late November, in 2007 and 2008.
(1) Christian D.P., Reuvers-House M., Hanowski J.M., Niemi G.J., Blake J.G. & Berguson W.E. (1996) Effects of mechanical strip thinning of aspen on small mammals and breeding birds in northern Minnesota, U.S.A. Canadian Journal of Forest Research, 26, 1284–1294.
(2) St-Louis A., Ouellet J.-P, Crête M. Maltais J. & Huot J. (2000) Effects of partial cutting in winter on white-tailed deer. Canadian Journal of Forest Research, 30, 655–661.
(3) Suzuki N. & Hayes J.P. (2003) Effects of thinning on small mammals in Oregon coastal forests. The Journal of Wildlife Management, 67, 352–371, https://doi.org/10.2307/3802777
(4) Ransome D.B., Lindgren P.M.F., Sullivan D.S. & Sullivan T.P. (2004) Long-term responses of ecosystem components to stand thinning in young lodgepole pine forest. I. Population dynamics of northern flying squirrels and red squirrels. Forest Ecology and Management, 202, 355–367, https://doi.org/10.1016/j.foreco.2004.08.002
(5) Fantz D.K. & Renken R.B. (2005) Short-term landscape-scale effects of forest management on Peromyscus spp. mice within Missouri Ozark forests. Wildlife Society Bulletin, 33, 293–301, https://doi.org/10.2193/0091-7648(2005)33[293:sleofm]2.0.co;2
(6) Homyack J.A., Harrison D.J. & Krohn WB. (2005) Long-term effects of precommercial thinning on small mammals in northern Maine. Forest Ecology and Management, 205, 43–57, https://doi.org/10.1016/j.foreco.2004.10.005
(7) Perry R.W. & Thill R.E. (2005) Small-mammal responses to pine regeneration treatments in the Ouachita Mountains of Arkansas and Oklahoma, USA. Forest Ecology and Management, 219, 81–94, https://doi.org/10.1016/j.foreco.2004.10.005
(8) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2005) Long-term responses of ecosystem components to stand thinning in young lodgepole pine forest II. Diversity and population dynamics of forest floor small mammals. Forest Ecology and Management, 205, 1–14.
(9) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2006) Influence of repeated fertilization on forest ecosystems: relative habitat use by mule deer and moose. Canadian Journal of Forest Research, 36, 1395–1406, https://doi.org/10.1139/x06-033
(10) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2007) Long-term responses of ecosystem components to stand thinning in young lodgepole pine forest: IV. Relative habitat use by mammalian herbivores. Forest Ecology and Management, 240, 32–41.
(11) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2010) Long-term responses of mammalian herbivores to stand thinning and fertilization in young lodgepole pine (Pinus contorta var. latifolia) forest. Canadian Journal of Forest Research, 40, 2302–2312, https://doi.org/10.1139/x10-173
(12) Manning T., Hagar J.C. & McComb B.C. (2012) Thinning of young Douglas-fir forests decreases density of northern flying squirrels in the Oregon Cascades. Forest Ecology and Management, 264, 115–124, https://doi.org/10.1016/j.foreco.2011.09.043
6.29. Apply fertilizer to trees
https://www.conservationevidence.com/actions/2649
- Three studies evaluated the effects on mammals of applying fertilizer to trees. All three studies were in Canada1,2,3.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (3 STUDIES)
- Use (3 studies): One of three replicated studies (including one controlled study and two site comparison studies), in Canada1,2,3, found that thinned forest stands to which fertilizer was applied were used more by snowshoe hares in winter but not in summer over the short-term2. The other studies found that forest stands to which fertilizer was applied were not more used by snowshoe hares in the longer term3 or by mule deer or moose1,3.
Background
Chemical fertilizers (nitrogen, phosphorus and potassium) are frequently applied to newly planted or regenerating trees. They increase soil fertility and may, therefore, enhance tree growth and nutritional content of foliage available to browsing herbivores. This could increase use of such areas by herbivores, leading to enhanced survival or abundance of these species.
A replicated, site comparison study in 1999–2003, in two pine forest sites in British Columbia, Canada (1, same experimental set-up as 2 and 3) found that applying fertilizer to thinned stands of lodgepole pines Pinus contorta did not increase their use by mule deer Odocoileus hemionus or moose Alces alces. Mule deer use of stands did not differ significantly between fertilized and unfertilized stands in summer (fertilized: 185–700 faecal pellet groups/ha; unfertilized: 5–276) or winter (fertilized: 392–472 faecal pellet groups/ha; unfertilized: 111–261). Similarly, for moose, there was no significant difference in stand use in summer (fertilized: 13–87 faecal pellet groups/ha; unfertilized: 3–31) or winter (fertilized: 29–90 faecal pellet groups/ha; unfertilized: 21–66). Across the two sites, six forest stands in total were felled in 1978–1982 and lodgepole pine then regenerated naturally. The stands were thinned in 1993 (to 1,000 stems/ha). Three stands were then fertilized six times in 1994–2003. Faecal pellet groups were counted over two-week periods, five times in May and four times in October, in 1999–2003, in 55–145 plots/stands (plots were circles of 1.3 m radius).
A replicated, controlled study, in 1999–2003, of three lodgepole pine Pinus contorta forests in British Columbia, Canada (2, same experimental set-up as 1 and 3) found that adding fertilizer to thinned forest stands increased their use by snowshoe hares Lepus americanus in winter but not in summer. In winter, the average density of hare faecal pellets across fertilized stands (7,000–62,000/ha) was higher than that across unfertilized stands (1,400–28,000/ha). In summer, there was no significant difference in the density of hare faecal pellets between fertilized stands (800–21,000/ha) and unfertilized stands (600–11,000/ha). Within each of the three sites, blocks of commercially grown lodgepole pines were thinned to 2,000, 1,000, 500 and 250 stems/ha in 1993. Half of each stand was fertilized five times in 1994–2003. Hare faecal pellets on 5-m2 permanent plots were counted in summer (May–September) and winter (October–April) 1999–2003.
A replicated, site comparison study in 2003–2008 of two lodgepole pine Pinus contorta forests in British Colombia, Canada (3; same experimental set-up as 1 and 2) found that repeated fertilization of thinned forest stands did not increase their use by snowshoe hares Lepus americanus, mule deer Odocoileus hemionus or moose Alces alces. Hare faecal pellet density and mule deer and moose pellet-group density did not differ between fertilized and unfertilized stands (data not presented). Naturally regenerated young lodgepole pine stands were studied at two sites. At each site, two stands were thinned, in 1993, to each of 2,000, 1,000, 500 and 250 stems/ha. Treatment stands were fertilized five times, in 1994–2003, using fertilizer blends which included 100–200 kg nitrogen/ha. Control stands were not fertilized. Mammal faecal pellets and pellet-groups were surveyed in 5-m2 plots (55–145 plots/stand). Plots were cleared of pellets in autumn 2003. New pellets and pellet-groups were counted in spring 2008.
(1) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome DB (2006) Influence of repeated fertilization on forest ecosystems: relative habitat use by mule deer and moose. Canadian Journal of Forest Research, 36, 1395–1406, https://doi.org/10.1139/x06-033
(2) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2006) Influence of repeated fertilization on forest ecosystems: relative habitat use by snowshoe hares (Lepus americanus). Canadian Journal of Forest Research, 36, 2080–2089, https://doi.org/10.1139/x06-093
(3) Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2010) Long-term responses of mammalian herbivores to stand thinning and fertilization in young lodgepole pine (Pinus contorta var. latifolia) forest. Canadian Journal of Forest Research, 40, 2302–2312, https://doi.org/10.1139/x10-173
6.30. Fell trees in groups, leaving surrounding forest unharvested
https://www.conservationevidence.com/actions/2648
- Three studies evaluated the effects on mammals of felling trees in groups, leaving surrounding forest unharvested. Two studies were in Canada1,2 and one was in the UK3.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (3 STUDIES)
- Abundance (2 studies): One of two replicated studies (including one controlled study and one site comparison study), in Canada1,2, found that felling groups of trees within otherwise undisturbed stands increased the abundance of one of four small mammal species relative to clearcutting. The other study found that none of four small mammal species monitored showed abundance increases.
- Survival (1 study): A study in the UK3 found that when trees were felled in large groups with surrounding forest unaffected, there was less damage to artificial hazel dormouse nests than when trees were felled in small groups or thinned throughout.
BEHAVIOUR (0 STUDIES)
Background
When timber harvesting or woodland management operations take place, trees may be clearfelled across a large area, thinned throughout the woodland or cut in patches, leaving surrounding forest unharvested. Felling in groups will produce a lower timber harvest than clearfelling but will leave more forest unaffected, which may help to sustain populations of some species. It will also affect less of the woodland area overall than does thinning of trees or selecting individual trees scattered throughout the forest to fell.
A replicated, controlled study in 1994–1997 of Douglas-fir Pseudotsuga menziesii forest in British Colombia, Canada (1) found that felling groups of trees within otherwise undisturbed stands increased southern red-backed vole Myodes gapperi abundance in some years relative to clearcutting but did not increase abundances of three other small mammal species. There were more southern red-backed voles in the third and fourth year after felling in group cut stands (7–14/stand) than in clearcuts (0.3–0.7/stand) but similar numbers between treatments in the first two years (group cut: 27–51/stand; clearcut: 13–34/stand). There were no differences between treatments for deer mouse Peromyscus maniculatus (group cut: 2–13/stand; clearcut: 6–21) or northwestern chipmunk Tamias amoenus (group cut: 1–8/stand; clearcut: 0.3–6/stand). There were fewer meadow voles Microtus pennsylvanicus in 20% group cut stands (1–3/stand) than in 50% group cut stands (0.8–4/stand) or clearcut stands (3–14/stand). Forest stands (20–25 ha) were partially harvested in winter 1993/94. Two each had 20% volume removed by cutting patches of 0.1–1.6 ha and 50% volume removed by cutting patches of 0.1–1.6 ha. Abundances across these stands were compared with that in two clearcuts of 1.6 ha. Small mammals were sampled by live-trapping at 2–4-week intervals, from May–October in 1994, 1995, and 1996 and from April–May 1997.
A replicated, site comparison study in 2006 in four forest sites in British Columbia, Canada (2) found that harvesting trees in 1 ha blocks did not result in higher small mammal abundance compared to clearcutting large areas. The average number of red-backed voles Myodes gapperi caught in 1-ha cuts (19.0 individuals) was not significantly different to that caught in clearcuts (8.4 individuals). Numbers caught also did not differ significantly between felling types for dusky shrew Sorex monticolus (1-ha cuts: 34.0 individuals; clearcuts: 44.3 individuals), deer mouse Peromyscus maniculatus (1-ha cuts: 9.6 individuals; clearcuts: 11.6 individuals) or common shrew Sorex cinereus (1-ha cuts: 7.3; clearcuts: 7.0). A 1-ha area was harvested in each of four sites. These were compared with two large (>30 ha) clearcut areas. Trees were harvested in 1992–1993. Small mammals were live-trapped every three weeks in June–October 2006 (five sessions). Traps were operated for two nights and, if daytime temperatures were ≤25°C, the intervening day.
A study in 2003 of a forest in Worcestershire, UK (3) found that, when trees were felled in large groups with surrounding forest unaffected, there was less damage to artificial hazel dormouse Muscardinus avellanarius nests than when trees were felled in small groups or thinned throughout. A lower proportion of artificial nests was damaged during large group felling (31%) than small group felling (62–66%) or thinning (73%). Non-native Corsican pines Pinus nigra were cleared from one third of the area of each of four plots (3 ha each) in a forest undergoing restoration to ancient woodland vegetation. Plot treatments, executed in late autumn/winter 2003, were clearance of small groups (12–14 trees) using chainsaws, clearance of small groups using a mechanised harvester, thinning throughout using a harvester and large group fells (c.0.4 ha each) using a harvester. Artificial dormouse nests comprised spheres of florists’ ‘oasis’ (7–10 cm diameter) on the ground mimicking natural nests.
(1) Klenner W. & Sullivan T.P. (2009) Partial and clearcut harvesting of dry Douglas-fir forests: Implications for small mammal communities. Forest Ecology and Management, 257, 1078–1086, https://doi.org/10.1016/j.foreco.2008.11.012
(2) Ransome D.B., Lindgren P.M.F., Waterhouse M.J., Armleder H.M. & Sullivan T.P. (2009) Small-mammal response to group-selection silvicultural systems in Engelmann spruce — subalpine fir forests 14 years postharvest. Canadian Journal of Forest Research, 39, 1698–1708, https://doi.org/10.1139/x09-095
(3) Trout R.C., Brooks S.E., Rudlin P. & Neil J. (2012) The effects of restoring a conifer plantation on an Ancient Woodland Site (PAWS) in the UK on the habitat and local population of the hazel dormouse (Muscardinus avellanarius). European Journal of Wildlife Research, 58, 635–643, https://doi.org/10.1007/s10344-012-0611-9
6.31. Coppice trees
https://www.conservationevidence.com/actions/2635
- We found no studies that evaluated the effects of coppicing trees on mammals.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Coppicing is a management practice typical of Eurasian northern temperate zone deciduous woodlands and wood pastures, in which stems of tree species, such as hazel Corylus avellana and sweet chestnut Castanea sativa, are cut near ground level once every few years, often in defined coppice compartments. These then regrow from the cut ‘stool’ giving a sustainable yield of woody material harvested on a rotational basis. Coppicing maintains a mosaic of woodland areas with differing amounts of daylight reaching the forest floor and, therefore, promotes a variety of ground vegetation conditions. This may benefit mammals that require either open canopy woodland or a mix of open and more closed woodland in close proximity. Coppicing has declined over the last century and some former coppice woodlands are no longer actively managed.
6.32. Allow forest to regenerate naturally following logging
https://www.conservationevidence.com/actions/2634
- One study evaluated the effects on mammals of allowing forest to regenerate naturally following logging. This study was in Canada1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (1 STUDY)
- Abundance (1 study): A replicated, site comparison study in Canada1 found that, natural forest regeneration increased moose numbers relative to more intensive management in the short-to medium-term but not in the longer term.
BEHAVIOUR (0 STUDIES)
Background
After logging of forests, cut areas may be left to regenerate naturally or may be subject to management aimed at accelerating tree planting. Allowing natural regeneration may facilitate formation of more natural vegetation which could improve habitat and resource availability for mammals.
A replicated, site comparison study, in 2008–2009, on three large adjacent coniferous forest sites in Ontario, Canada (1) found that, following clearcutting, large-scale natural forest regeneration increased moose Alces alces numbers relative to more intensive silvicultural practices (mechanical ground preparation, replanting and herbicide application) 10 years after felling but not 30 years after felling. The number of moose faecal pellet clumps was positively correlated with the extent of naturally regenerating forest that was felled 10 years previously in areas of 10, 20 and 40 km2 around the stand, but not with the extent subject to more intensive silviculture, nor with the extent felled 30 years previously and subject to either management practice (data not presented). Ten forest stands were felled 10 years previously (five regenerating naturally and five subject to intensive silviculture) and ten were felled 30 years previously (five regenerating naturally and five subject to intensive silviculture). Moose faecal pellet clumps were counted within five circles of 5.65 m radius in each stand between July and early September of 2008 or 2009.
(1) Baon J.J., McLaren B.E. & Malcolm J.R. (2011) Influence of post-harvest silviculture on understory vegetation: Implications for forage in a multi-ungulate system. Forest Ecology and Management, 262, 1704–1712, https://doi.org/10.1016/j.foreco.2011.07.022
6.33. Harvest timber outside mammal reproduction period
https://www.conservationevidence.com/actions/2633
- We found no studies that evaluated the effects of harvesting timber outside the mammal reproduction period.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Tree-felling poses risks to woodland-dwelling mammals. For species with young in a nest or den, tree felling could cause death of these young through injury or abandonment. Planning timber harvesting for times outside the period when young are at their most vulnerable may reduce such direct casualties of felling operations.
6.34. Control firewood collection in remnant native forest and woodland
https://www.conservationevidence.com/actions/2632
- We found no studies that evaluated the effects on mammals of controlling firewood collection in remnant native forest and woodland.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
Firewood is an important fuel for heating and cooking in some homes and communities. However, wood that may be collected as firewood, such as from fallen trees, may provide an important element of the habitat for some forest floor species. This is most likely to be the case in forests that have been least affected by management. Thus, collection of firewood may be controlled in remnant native forests and woodland to benefit woodland biodiversity, including mammals.
6.35. Plant trees following clearfelling
https://www.conservationevidence.com/actions/2631
- One study evaluated the effects on mammals of planting trees following clearfelling. This study was in Canada1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (1 STUDY)
- Use (1 study): A replicated, site comparison study in Canada1 found that forest stands subject to tree planting and herbicide treatment after logging were used more by American martens compared to naturally regenerating stands.
A replicated, site comparison study in 2001–2002 of boreal forest stands in Ontario, Canada (1) found that forest stands subject to tree planting and herbicide treatment after logging were used more by American martens Martes americana than were naturally regenerating stands. The effects of planting and herbicide use were not separated in the study. Radio-tracked martens made greater use of planted and herbicide-treated stands than they did of naturally regenerating stands (data not presented). However, the live-capture rate of martens in planted and herbicide-treated stands (5.6 martens/100 trap nights) was not significantly different to that in regenerating stands (1.9 martens/100 trap nights). Stands were 35–45 years old and located in a 600-km2 forestry area. Forest stands were either regenerating naturally following logging or planted following logging and treated with herbicide. Martens were live-trapped in 2003–2007, and monitored subsequently by radio-tracking.
(1) Thompson I.D., Baker J.A., Jastrebski C., Dacosta J., Fryxell J. & Corbett D. (2008) Effects of post-harvest silviculture on use of boreal forest stands by amphibians and marten in Ontario. Forestry Chronicle, 84, 741–747, https://doi.org/10.5558/tfc84741-5
6.36. Use tree tubes/small fences/cages to protect individual trees
https://www.conservationevidence.com/actions/2630
- We found no studies that evaluated the effects of using tree tubes, small fences or cages to protect individual trees from mammals.
‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.
Background
A range of mammals, including rodents and ungulates, can cause substantial damage to trees, especially young trees, through browsing activities on foliage and by stripping bark from trees. As well as damage to natural habitats, this can cause financial losses to the forestry industry (Huitu et al. 2009). In an attempt to reduce such conflict, trees may be protected from attack using a range of barriers to prevent mammals from accessing them. If successful, this could reduce incentives for carrying out lethal control on these mammals.
Huitu O., Kiljunen N., Korpimäki E., Koskela E., Mappes T., Pietiäinen H., Pöysä H. & Henttonen H. (2009) Density-dependent vole damage in silviculture and associated economic losses at a nationwide scale. Forest Ecology and Management, 258, 1219–1224, https://doi.org/10.1016/j.foreco.2009.06.013
6.37. Provide supplementary feed to reduce tree damage
https://www.conservationevidence.com/actions/2629
- One study evaluated the effects of providing supplementary feed on the magnitude of tree damage caused by mammals. This study was in USA1.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (0 STUDIES)
OTHER (1 STUDY)
- Human-wildlife conflict (1 study): A replicated, randomized, paired sites, controlled, before-and-after study in USA1 found that supplementary feeding reduced tree damage by black bears.
A replicated, randomized, paired sites, controlled, before-and-after study in 1999–2002 in 14 coniferous forest sites in Washington, USA (1) found that supplementary feeding reduced tree damage caused by black bears Ursus americanus. The number of trees damaged by bears in sites where supplementary feeding was used was lower (3–10 trees/year) than in sites where no supplementary feeding was used (15–26 trees/year). When supplementary feeding was stopped at one site, the number of trees damaged by bears increased from 6 to 40/year. In March 1999, in fourteen 16–20-ha sites, bear-damaged trees were marked with paint. Sites with similar amounts of damage were paired. In April 1999, one site/pair was randomly chosen to have two plastic drums containing food pellets placed in it, while the other site had no supplementary food provided. Plastic drums were refilled weekly in April–July with 100 kg of pellets. In the first year, at sites where supplementary feed was provided, beaver Castor canadensis carcasses were hung from trees to attract bears. In July 2000, supplementary feeding was stopped at two of the seven sites (results not presented for the second site due to the feeding station not being maintained prior to this). Sites were surveyed for bear damage to trees in July of 1999–2002.
(1) Ziegltrum G. I. (2004) Efficacy of black bear supplemental feeding to reduce conifer damage in western Washington. The Journal of Wildlife Management, 68, 470–474, https://doi.org/10.2193/0022-541x(2004)068[0470:eobbsf]2.0.co;2