Effects of fences on roadway crossings and home range distribution of white-tailed deer
Gulsby, William Donald
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Although many deer-vehicle collision (DVC) mitigation devices have been developed and tested, only fencing has proven effective. Because a 2.4-m woven-wire fence and a prototype outrigger fence (i.e., 0.6-m outriggers attached to a 1.2-m wire fence angled at 45º) were 100% effective at preventing crossings by captive white-tailed deer (Odocoileus virginianus), we evaluated the efficacy of these designs at preventing crossings by free-ranging deer. From January to April 2009, we fitted 14 adult does with GPS collars, programmed to collect ≥ 24 locations/day. In June 2009, we constructed a 3.2-km fence treatment that included a 1.6-km section of 2.4-m vertical-wire fence and a 1.6-km section of the outrigger fence. We retrieved collars between January and March 2010. We compared home ranges, core areas, fence crossings, and fence circumventions among deer that encountered the outrigger and 2.4-m fences as well as for deer that did not encounter the fence (i.e., controls), before and after fence construction. Although home ranges and core areas changed among seasons, we found no effect of fencing. Deer with pre-treatment home ranges that approached or encompassed the end of the fence maintained a high degree of site fidelity by circumventing the fences. Fence crossings, however, were reduced by 98% and 90% for the 2.4-m and outrigger treatment groups, respectively. Although we recorded fewer crossings of the 2.4-m fence, the prototype outrigger fence may be a viable option for reducing DVCs because of its affordability and potential as a one-way barrier. More importantly, we believe this study highlights the importance of using localized data on deer home range sizes to determine the minimum length of fencing necessary to prevent circumvention in high-risk areas.