Wildlife corridor

Dr. Fraser Shilling presented the followng map during a recent Open Space Advisory Committee meeting on June 19. Captured here are various wildlife vehicle conflict areas in the Bay Area, including portions of the Tri-Valley. (Graphic - Dr. Frasser Shilling)

According to Dr. Fraser Shilling, “Failure to protect and restore wildlife movement will result in continued population declines, extinction of some species locally and wildlife-vehicle collisions, endangering public safety.”

Shilling, a professor and U.C. Davis Road Ecology Center co-director, presented a wildlife corridor study status update during the June 19 Altamont Landfill and Resource Recovery Facility Open Space Advisory Committee meeting. He shared images captured by the

various cameras placed in land divided by local highways. The cameras are one tool utilized to gain a stronger understanding of species’ activities — important data needed for assessing a corridor for enhanced connectivity.

“Wildlife connectivity refers to an ecological attribute required for ecosystems to function,” Shilling said. “If you don’t have it, the whole ecosystem can deteriorate.”

Shilling’s presentation outlined the issues facing this connectivity to include rapid development, resulting in highways forming barriers to wildlife movement while also posing a threat to driver safety, as animals cross roads. The specific problem areas concern interstates 580, 680 and State Route 84, which create barriers to wildlife moving through the Diablo range and East Bay hills.

There were three main project progress updates to report. The group connected with landowners to establish cameras on private land. It obtained permission to access Contra Costa Water District lands at the east end of 580. And it deployed new cameras to parcels on the north and south of 580.

In addition to some curious cows, who also liked to use the camera posts to scratch themselves, the cameras have been able to capture at least 20 pictures of wild animals, Shilling reported. Mainly, they congregate near water, but one mechanism to lure wildlife into the frame is a concoction of animal parts that has a particularly strong scent. Through this, they’ve managed to collect data on bobcats and coyotes.

The ongoing study is part of a program that launched in 2018 in a partnership between the Alameda County Resource Conservation District and the Road Ecology Center at UC Davis. Scientists have been gathering data to determine the population sizes, ranges and obstacles with regard to connecting with one another. An issue that arises when populations are cut off from one another is a lack of diversity within the gene pool.

“Road-induced genetic divergence among populations or among segments of a population has been documented for many vertebrate species,” indicates the Road Ecology Center’s website page covering the impact highways have on gene flow to ground-dwelling mammals. “Despite many studies of road-crossing effectiveness by wildlife, individual animal crossing of roads may not be sufficient to guarantee the persistence of an entire population, because a species-specific minimum number of individual movements is required to assure gene flow.”

The project combines wildlife observations with models for creating connectivity. In reviewing coyote populations, for example, teams collect genetic samples from animals on either side of State Route 50, and interstates 80, 580 and 680. Genetic samples can be collected directly from the animal in the form of blood, skin or hair/fur, or indirectly from its feces, or scat.

During the meeting public speaker, Peter Rosch, asked if the public would have access to the data collected from the studies. Shilling said that footage collected on private land might be held from public publication. However, all images are saved in a web-based system, and teams are reviewing long-term plans for data storage.

Describing the data that leads to wildlife connectivity, Shilling said the term “corridor” refers to the constructed wildlife bridges or tunnels across roads and highways.

“Wildlife doesn't naturally follow narrow ‘corridors’ on the landscape. This idea and its cousin ‘linkages’ were created by conservation planners looking for the minimum parts of the landscape that wildlife need to move around,” Shilling explained. “Wildlife are opportunistic, moving wherever they need to in order to eat, mate and disperse. So I focus on that point where they collide with a road/highway and give them a way across — a corridor.”