Fig 1.
Location of wildlife exits along the section of State Highway 100.
The Texas Department of Transportation constructed ten wildlife exits along 11.9 km section of fenced roadway starting from Laguna Vista to Los Fresnos in South Texas. The wildlife exits were installed to allow wildlife to escape the right-of-way and prevent wildlife vehicle collisions.
Fig 2.
Three wildlife exit (WE) designs installed along the fenced roadway of State Highway 100, Cameron County, Texas between 2019 to 2024.
(A) Design A was installed in 2019 to allow small-medium sized wild animals to escape from the right-of-way. This design didn’t have any barriers or doors that allowed wildlife to easily access the roadway. (B, C) Design B installed in 2022 as a replacement for Design A to prevent wildlife from accessing the roadway where raised berms were installed at all 10 WE sites with six sites having a one-way door and the remaining four without a door. (D, E) Design C installed in 2023 where all raised berms were removed, keeping door and structural features same as in Design B. All measurements are in cm.
Fig 3.
Illustration of camera trap position at wildlife exit sites along State Highway 100, Cameron County, Texas.
Two cameras were positioned at the habitat side of the fenced roadway (a trip-triggered camera captures 30-second video and a motion-trigger camera captures three images per trigger, and one motion-triggered camera at the right-of-way with three photo outputs per trigger. All three cameras were faced toward the entrance of the wildlife exit to capture the interactions of wildlife with the structure.
Fig 4.
Wildlife interaction categorization at wildlife exit on State Highway 100, Cameron County Texas.
Class A: Interactions of individuals making successful crossings from habitat to road (H-R) or road to habitat (R-H). Class B: Interactions where entry/exit occurs on the same side of the chain-link fence (Habitat: H, Road: R) and Class P: Interactions where individuals move parallel to the fence either in road (R) or habitat (H) without crossing the wildlife exit.
Table 1.
Mean approaches of mammalian species from the roadside of the fence. The data involved four mammalian species at ten WE sites, analyzed across three WE designs (Design A, B, and C). Approaches were calculated based on the sites with “Door” and “No Door” categories along with interactions classified into “Approach” (Class A and B, direction R-H and R) and “No Approach” (Class P, direction R).
Table 2.
Mean approaches of mammalian species from the habitat side of the fence. The data involved four mammalian species at ten WE sites, analyzed across three WE designs (Design A, B, and C). Approaches were calculated based on the sites with “Door” and “No Door” categories along with interactions classified into “Approach” (Class A and B, direction H-R and H) and “No Approach” (Class P, direction H).
Fig 5.
The mean approaches of four meso-carnivores (bobcat, coyote, northern raccoon, and striped skunk) at the wildlife exits along the State Highway 100, Cameron County, Texas, analyzed from the roadside of the fence based on design and door types.
The approaches were categorized into six groups (Design A: Future Door and Design A: No Future Door; Design B: Door and Design B: No Door; Design C: Door and Design C: No Door). It was determined based on approach interactions (Class A and B) with directions from road to habitat (R-H) and road (R). Letters indicate pair-wise comparisons with significant values (P < 0.05) with bar indicating a standard error (SE).
Fig 6.
Mean approaches of four meso-carnivore species (bobcat, coyote, northern raccoon, and striped skunk) at wildlife exits on State Highway 100 in Cameron County, Texas, analyzed based on three wildlife exit design types (Design A, B, and C) with bar indicating as standard error (SE).
Figure A illustrates the mean approaches of species on the “Road” side and Figure B shows the mean approaches from the “Habitat” side of the fence. Interactions classified as Class A and B were considered “Approach” while interactions from Class P as “No Approach”.
Fig 7.
The mean approaches of four meso-carnivores (bobcat, coyote, northern raccoon, and striped skunk) at the wildlife exits along the State Highway 100, Cameron County, Texas, analyzed from the habitat side of the fence based on design and door types.
The approaches were categorized into six groups: Design A: Future Door; Design A: No Future Door; Design B: Door; Design B: No Door; Design C: Door; Design C: No Door). It was determined based on approach interactions (Class: A and B) with directions from habitat to road (H-R) and habitat (H). Letters indicate pair-wise comparisons with significant values (P < 0.05) and bars indicating standard error (SE).