At Phil Hardberger Park in San Antonio, timelapse data shows images of a pack of coyotes wrestling playfully, a family of bobcats walking together and a raccoon standing up on two feet.
The animals caught on video are part of a scientific study helping prove whether wildlife is using the 189-foot Robert L.B. Tobin Land Bridge to cross over the urbanized Wurzbach Parkway.
Wildlife at the Tobin Land Bridge is being studied because the bridge was built with the intention to serve not only as a pedestrian bridge, but also as a green corridor for animals to travel safely, opening up green space for wildlife populations to build genetic diversity and decreasing wildlife-vehicle collisions in the area.
Data has been collected through timelapse cameras‘ data processing since April 2021, in a study funded by the city’s Parks and Recreation department and the Phil Hardberger Park Conservancy.
The city’s Parks and Recreation Board heard the first update on the progress of the five-year wildlife study Monday night.
So far, data recorded an hour before sunset through an hour after sunrise shows that vegetation has filled in “like a jungle,” San Antonio Parks and Recreation Parks Naturalist Casey Cowan said. There are now 16 species regularly traveling in the area, including axis deer, bobcat, fox, coyotes, squirrels, armadillos, raccoons, hawks, skunks, opossums and rodents, to name a few.
While the study is in year two, data already shows that deer benefit from the land bridge the most, while other species often cross using the culverts within the park, Cowan said.
“Anecdotally, I can tell you that animals are crossing the bridge, because I’ve literally watched deer go from one side to the other,” she said. “But the whole point of the study is to have statistical significance and say that for sure this is happening.”
Having less green space causes isolation among populations of animals, leading to interbreeding and competition between them Cowan said, but the study is proving the bridge creates a way for animals to cross freely.
“You may have a decline in those populations due to genetic loss and mutations that can happen,” she added.
Since the study began, more timelapse cameras have been added at the park to study different areas, and are programmed for certain hours instead of running 24 hours a day.
“What we’re interested in learning is if the bridge is being used in totality by wildlife, or are they going up to the bridge and then returning to where they came [from],” Cowan said. “Is it just like an approach of using resources and then going back?”
Until enough data is compiled, those questions won’t be answered definitively. The study is expected to go into 2024, but enough data may be collected before then, Cowan said.
At one point, the Tobin Land Bridge was one of only two mixed-use — meaning open to people and animals — bridges in the world, but it is becoming more popular, Cowan said.
“I think ours is unique though because ours was carefully designed to be a mixed-use land bridge,” she said. “We have a specific corridor for wildlife and then we have a specific corridor for humans. … There’s two distinct sides to it.”
