Install non-electric fencing to exclude predators or herbivores and reduce human-wildlife conflict
Overall effectiveness category Beneficial
Number of studies: 8
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Background information and definitions
Wild mammals can compete with domestic herbivores for food, can predate domestic herbivores or can damage crops. Human-wildlife conflict can be reduced if wild mammals can be effectively excluded from fields or other areas of crops or livestock. Non-electric fences are extensively used and can reduce the risk of wild mammal incursions into such sites. If successful, this could reduce incentives for carrying out lethal control of such mammals. Non-electric fences may be more suited to more extensive farming situations than are electric fences, as they may require less maintenance. This intervention also includes fortification of bomas (traditional livestock enclosures constructed by pastoralists) using conventional fencing materials such as fence wires.
Supporting evidence from individual studies
A replicated, before-and-after, site comparison study in 1972–1977 in two pasture ranches in Oregon, USA (deCalesta & Cropsey 1978) found that following erection of a fence to protect sheep, the number killed by coyotes Canis latrans was reduced to zero. Results were not tested for statistical significance. Over one year after fencing, no sheep were lost to coyotes in two fenced pastures. During the five years before fences were installed, 2% of sheep/pasture/year were killed by coyotes across one ranch and 24% across the other. On unfenced pastures on one of the ranch 1% of sheep were lost to coyotes in the year that the fenced pasture was monitored with 10% lost to coyotes on unfenced pastures on the other ranch. Two 5-ha pastures were fenced in November–December 1976. Fences were 1.8 m tall, made of wire, had a 41-cm overhang at a 60° angle from the fenced poles and an apron of old fence wire extending 61 cm out from the bottom, to inhibit digging under the fence. Ranchers monitored sheep kills by coyotes.Study and other actions tested
A replicated, controlled study in 1975–1976 in a captive facility in Oregon, USA (Thompson 1979) found that a high woven wire fence with small mesh, an overhang and an wire apron projecting out from the fence base (to deter burrowing) was the most effective of 34 fence designs at deterring crossings by coyotes Canis latrans. Fence performance varied from 0 to 71% of coyotes failing to cross fences. The best-performing non-electric fence prevented more crossings (14 of 15 trials) than did the best-performing electric fence (11 of 15 trials) or a standard sheep fence (6 of 15 trials). One of two coyotes, which had already crossed a standard sheep fence, crossed the best-performing fence during each of two tests whilst the other failed to cross it during four tests. Best-performing fence measurements were not stated explicitly but the paper recommends fences are ≥168 cm high, with mesh ≤15.2 × 10.2 cm and with an overhang and apron of ≥38 cm. Initial tests involved 10 coyotes, conditioned to walk a route, with 34 fence designs sequentially installed on the route. Subsequent trials, with five new coyotes, tested their ability to cross fences to reach a tethered rabbit. In final trials, coyotes that crossed a standard sheep fence and killed a tethered rabbit were tested using the best-performing fence design. Coyotes were wild caught. Trials were conducted from April 1975 to March 1976.Study and other actions tested
A replicated, controlled study in 1997 of four grassland fields and one cultivated field in central Germany (Wölfel 1981) found that fencing with phosphorescent tape was more effective than fencing with normal yellow tape for deterring red deer Cervus elaphus and roe deer Capreolus capreolus, but had no effect on crossings by wild boar Sus scrofa or brown hare Lepus europaeus. At four grazing sites, areas surrounded by phosphorescent tape were avoided by red deer for four months and by roe deer for three weeks. Red deer entered areas fenced with yellow non-phosphorescent tape after one week and roe deer after one day. All deer species kept out of an area of willow fenced with phosphorescent strips for three weeks. After that, roe deer (but not red deer) tracks were found within the area. Wild boar and brown hare movements were not affected by tapes. PVC tape (4 cm wide) was attached 1 m high on 1.3-m iron posts. Four game grazing fields each had two 300-m2 areas fenced off using phosphorescent strips and two with non-phosphorescent tape. After two months, all four areas were mown and the type of fencing was swapped. Mammal presence was assessed from droppings and tracks.Study and other actions tested
A replicated, before-and-after, site comparison study in 1980–1983 on 23 arable sites in southern UK (McKillop & Wilson 1987) found that wire netting fences reduced European rabbit Oryctolagus cuniculus numbers on crops. Rabbit numbers on plots protected by fences with a buried fence base were lower 0–4 weeks after erection (7 rabbits/count) and 5–20 weeks after erection (7 rabbits/count) than before erection (41 rabbits/count). Numbers were also lower on plots protected by fences with the base folded horizontally along the ground 0–4 weeks after erection (11 rabbits/count) and 5–20 weeks after erection (7 rabbits/count) than they were before erection (45 rabbits/count). Rabbit numbers in unfenced plots remained constant throughout (0–4 weeks after erection: 16 rabbits/count; 5–20 weeks after erection: 13 rabbits/count; before erection: 14 rabbits/count). Fences (0.9 m high) were erected along one side of winter barley fields. Fences had bases buried 150 mm deep and then projecting horizontally underground for 150 mm (six sites), or laid out horizontally for 150 mm at ground level (seven sites). Ten unfenced sites were also monitored. Adult rabbits were counted using spotlights and binoculars in November–April between 1980 and 1983.Study and other actions tested
A controlled study in 2008 at three vineyards in Córdoba province, Spain (Barrio et al. 2010) found that fencing reduced damage by European rabbits Oryctolagus cuniculus to common grape vines Vitis vinifera and resulted in greater grape vine yields. Grape vines within fenced plots had a lower percentage of buds and shoots removed by rabbits (0.5%) and greater yields (7 kg/vine) than unfenced plots (21%; 4.7 kg/vine). Each of three vineyard sites had a fenced plot and an unfenced plot. Fences were checked weekly. No details are provided about the fencing design. The proportion of buds and shoots removed by rabbits on 15–20 vines/plot was recorded throughout the growing season in 2008. Grape vine yields were estimated during harvest from the number and size of grape clusters on each vine.Study and other actions tested
A replicated, before-and-after study in 2008–2009 of 19 households in Tibetan Autonomous Region, China (Papworth et al. 2014) found that households fenced to exclude predators experienced fewer visits and lower rates of livestock predation by Tibetan brown bears Ursus arctos pruinosus. Results were not tested for statistical significance. In the year after fence installation, there were fewer bear visits (2.4/household) than in the year before (5.3/household). In the year after fence installation, fewer livestock were lost to bears (0.2/household) than in the year before (11.6/household). Fourteen fences were constructed around 19 households (some fences enclosed >1 household) and associated livestock in 2008. Fences were constructed of wire mesh (with mesh diagonal dimensions of ≤30 cm) and barbed wire, set on a steel frame. Each fence enclosed 120–1,000 sheep and goats. Bear visits and predation events were recorded by householders.Study and other actions tested
A replicated, before-and-after, site comparison study, in 2003–2013 around two villages and associated pasture in Tanzania (Lichtenfeld et al. 2015) found that fortifying bomas with trees and chain link fencing resulted in reduced predation of livestock by large mammalian predators. There was a lower rate of attacks by large predators on livestock in bomas after fortification (0.001 attacks/boma/month) than before (0.012 attacks/boma/month). Including bomas that remained unfortified throughout the study, the attack rate was lower overall on fortified bomas (0.001 attacks/boma/month) than on unfortified bomas (0.009 attacks/boma/month). Between 2008 and 2013, 62 of 146 traditional bomas (built mainly from thorny branches) were fortified with “living walls” (which combined fast-growing, thorny trees Commiphora sp. as fence posts at 0.5-m intervals, connected with chain link fencing). The average cost of the chain link was US$500/boma. Bomas were monitored for predator attacks from September 2003 to August 2013 (excluding January–February of 2006 and 2010).Study and other actions tested
A replicated, site comparison study in 2013–2015 of 308 savanna households in Narok County, Kenya (Sutton et al. 2017) found that fewer livestock were lost to mammalian predators from fortified fenced areas than from traditional thorn-bush-fenced areas. Households holding their livestock in fortified fences lost fewer on average to predators (0.35 animal/month) than did households with livestock in traditional fenced areas (0.96 animals/month). The proportion of households not losing any livestock to mammalian predators over a year was higher for those using fortified fences (67%) than for those using traditional fences (15%). Mammalian predators included lions Panthera leo, leopards Panthera pardus, wild dogs Lycaon pictus, spotted hyenas Crocuta crocuta, honey badgers Mellivora capensis, cheetahs Acinonyx jubatus and baboons Papio sp. The study was based on 375 interviews, carried out from April 2013 to July 2015, with 308 Maasai households that housed livestock in fenced areas (bomas). Including some that were upgraded during the study, 179 households used fences fortified with posts, chain link wire and galvanized wire and 164 households used traditional fences made of thorny plants and branches during some or all of the period.Study and other actions tested
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This Action forms part of the Action Synopsis:Terrestrial Mammal Conservation
Terrestrial Mammal Conservation - Published 2020
Terrestrial Mammal Conservation