Evaluating Responses by Sympatric Ungulates to Fence Modifications Across the Northern Great Plains

Abstract

Across North America, incentive programs have assisted landholders with the construction of fences, often considered “wildlife friendly,” to assist in grazing management, which has resulted in a proliferation of fencing on the landscape. Many suggested “wildlife‐friendly” fence modifications have not been evaluated for their effectiveness on the targeted species or evaluated to assess consequences for nontarget species. We evaluated the effects of 2 modifications aimed to increase fence visibility (sage‐grouse [SAGR] reflectors and white polyvinyl chloride [PVC]) on the fence‐crossing behavior of 3 sympatric ungulates in the Northern Great Plains. We used trail cameras from 2016 to 2018 to capture images of pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus), and white‐tailed deer (O. virginianus) at sites before and after fence sections were modified and compared crossing success by the 3 ungulates with that achieved at unchanged control sites. We used generalized linear modeling and a time‐to‐event approach to test the effect of fence modifications on ungulate crossing behavior. Our results showed that both SAGR reflectors and white PVC pipe did not impede fence‐crossing behaviors for either pronghorn or deer, nor was there a time lag in use of sites observed after modifications were deployed. Though we did not alter the height of the bottom wire, there was enough variability in bottom wire height between sites that our results indicate a greater probability of successful crossing by all 3 ungulates as bottom wire height increased. We recommend implementation of both SAGR reflectors and white PVC pipe because our results demonstrate no substantial unintended consequences on the crossing behavior of pronghorn and deer. © 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Designing a fence that enables free passage of wildlife while containing reintroduced bison: a multispecies evaluation

“…Significant age-sex effects were few and inconsistent, suggesting fences did not exert a disproportionate influence on antlered male ungulates compared to their conspecific counterparts. These results differ from studies elsewhere in western North America which found reduced crossing success for adult males compared with adult females in mule and whitetailed deer (Burkholder et al 2018, Jones et al 2020. We did record a slightly reduced crossing likelihood of antlered male elk compared to adult females of the full height (5-wire and 3-rail) fences.…”

“…The cumulative effects of other biotic and abiotic variables on the landscape could be further examined to isolate how they impede or facilitate movement at this scale (Spear et al 2010, Bartzke et al 2015, Seidler et al 2015. Moreover, as wildlife continue to interact with the fences they will grow conditioned to their presence and learn to negotiate them more easily on subsequent encounters (Jones et al 2018(Jones et al , 2020. Additional research is required to quantify this rate of 'learning' following fence installation.…”

“…Wires were spaced 25-30 cm apart, and rails 30-50 cm apart. Such ground-to-bottom-wire height, as well as distance between wires, has been shown to be optimal to reduce ungulate entanglement (Burkholder et al 2018, Jones et al 2020. The 2-wire design is a dynamic modification of the 5-wire fence where the top three wires, and bottom two wires, are pinched together (staple latch method in Paige 2015).…”

“…For each event, we recorded whether an animal crossed the fence, and if so, whether it was under, over or through the fence. Following classification, we deleted duplicate records from overlapping camera fields of view and pooled data from all four study fences to maximize sample size, similar to other studies (Jones et al 2020). We analysed the effect of fence design on bighorn sheep Ovis canadensis, elk Cervus canadensis, mule deer Odocoileus hemionus, white-tailed deer Odocoileus virginianus and carnivores.…”

Species and demographic responses to wildlife‐friendly fencing on ungulate crossing success and behavior

“…While there are a variety of crossing structures designed to assist wildlife movement, such as wildlife bridges and underpasses, one measure that has gained recent attention is the replacement of traditional barbed‐wire fencing with wildlife‐friendly fencing. One of the key design changes to standard fencing to make it wildlife‐friendlier is the use of a raised, smooth bottom wire; this is based on accumulated evidence that this design change improves the permeability of the barrier, with lower aversion and increased crossing rates compared to barbed‐wire fencing (Figure 1) (Jones et al, 2020; Karhu & Anderson, 2003). Other modifications include visible markers, reducing the height of the top wire and using seasonal electric fencing (Paige, 2012).…”