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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

An Evaluation of Pronghorn (Antilocapra Americana) Permeability Associated with Transportation Right-Of-Way Fence Characteristics in Northern Arizona

Previous studies have documented that fenced roads can be substantial barriers to pronghorn movements. In order to evaluate the effects of fenced roads and specific fence characteristics on pronghorn connectivity, the authors outfitted 37 pronghorn with GPS collars between January 2007 and December 2008, generating 121,000 locations prior to right-of-way (ROW) fence treatments. Select sections of pasture fence within the target area were improved to meet pronghorn-friendly guideline specifications (3 barbed strands with a smooth raised bottom wire and “goat-bar” crossings). The ROW fence was removed from the 3.4-km portion of US 89 that passes through Wupatki National Monument, which is closed to livestock grazing. Another 0.5-km stretch of fence was moved away from the road. Large sections of fence remained untreated. The authors outfitted another 17 pronghorn with GPS collars between November 2008 and December 2010, generating an additional 58,500 locations to collect post-treatment movement data. To create a time-sensitive dataset of fence classes, fences within the study area were inventoried and classified according to characteristics (height, wire type, condition, etc.) and time/type of modifications. The authors tabulated pronghorn crossing rates and evaluated permeability by comparing ratios of crossing rates to availability for each fence class, including a no-fence control line. Temporal patterns of fence-crossing hotspots were evaluated with a focus on areas that underwent mitigation modifications during the study. Pronghorn were found to cross the no-fence control lines twice as often as actual fences, suggesting that the fences were indeed a barrier to pronghorn movements. There was a significantly higher proportion of crossings in fence sections with a bottom wire height of 16” or higher. There was an increase in crossings of the highway after ROW fencing was removed. There were significantly more crossings than expected at sections of set-back ROW fence that were 200m to 400m from the highway, lending empirical support to the hypothesis that staging areas between fences and low-traffic highways facilitate road crossings. These findings indicate that fences with at least 16” of clearance under the bottom wire, that are pulled back from the roadside, or that are removed altogether, where possible, could repair connectivity in the northern Arizona pronghorn meta-population over the short-term. The results of this study have led to a cooperative effort to implement these temporary mitigations in key areas. As traffic levels increase toward projected volumes, long-term solutions such as overpasses and/or raised viaduct underpasses must be implemented in order to maintain an intact landscape.

  • Summary URL:
  • Supplemental Notes:
    • Abstract used with permission from the International Conference on Ecology and Transportation, organized by the Center for Transportation and the Environment, Institute for Transportation Research and Education, North Carolina State University.
  • Corporate Authors:

    North Carolina State University, Raleigh

    Center for Transportation and the Environment
    Raleigh, NC  United States  27695-8601
  • Authors:
    • Sprague, Scott
    • Gagnon, Jeff
    • Boe, Sue
    • Loberger, Chad
    • Schweinsburg, Ray
  • Conference:
  • Publication Date: 2013

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 10p
  • Monograph Title: Proceedings of the 2013 International Conference on Ecology and Transportation (ICOET 2013)

Subject/Index Terms

Filing Info

  • Accession Number: 01557942
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 27 2015 10:30AM