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Monitoring Wildlife Road Mortalities during Construction of Wildlife Crossings Structures in Cameron County, Texas: Preliminary Results

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  • Monitoring Wildlife Road Mortalities during Construction of Wildlife Crossings Structures in Cameron County, Texas: Preliminary Results
Zachary M. Wardle, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville
Thomas J. Yamashita, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville
Daniel G. Scognamillo, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville
Michael E. Tewes, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville
John H. Young Jr, Texas Department of Transportation
Jason V. Lombardi, Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville
Mitigation / restoration
Multi-Media Session 1

Vehicle collisions along roads are an important source of mortality for many wildlife species. To reduce wildlife-vehicle collisions, mitigation structures can be constructed to prevent wildlife from accessing the roadway and provide safe passage for crossing animals. An important step in assessing the effectiveness of mitigation efforts is to monitor changes in the number and spatial distribution of wildlife road mortalities after mitigation structures are built. In South Texas, the Texas Department of Transportation has been constructing wildlife mitigation structures, such as wildlife crossings and exclusionary fencing, as part of highway improvement projects to reduce the threat of roads to the endangered ocelot (Leopardus pardalis). One road undergoing improvement is Farm-to-Market (FM) 1847 in Cameron County, where construction of five wildlife crossings and short sections of fencing is ongoing and expected to be completed in 2022. We began weekly wildlife road mortality surveys on FM 1847 in May 2020 and will continue monitoring for five years after construction has concluded. We present preliminary results from monitoring wildlife road mortalities on FM 1847. Thus far, we have documented 187 wildlife road mortalities, which include 48 Virginia opossums (Didelphis virginiana), 13 eastern cottontails (Sylvilagus floridanus), nine nine-banded armadillos (Dasypus novemcinctus), eight domestic cats (Felis catus), and seven domestic dogs (Canis familiaris). Mammals have been the most common type of mortality, followed by birds and herpetofauna. The majority of mortalities have occurred outside of the mitigation area and with greater frequency in areas of increased urbanization compared to more rural areas. These results will help provide a baseline for assessing effectiveness of the future wildlife mitigation structures on FM 1847.

Wildlife Road Mortality
wildlife crossing structures
road mitigation

Header image courtesy of Martin Gradjean -- Air Traffic Network

ICOET 2025 — International Conference On Ecology and Transportation