The study, published in the journal "Conservation Biology," focused on three populations of desert bighorn sheep in the Peninsular Ranges of Southern California. These populations are isolated from each other by Interstate 15 and Interstate 8, which fragment their habitat and make it difficult for them to move freely.
To identify the best locations for wildlife crossings, the researchers used GPS tracking data from 64 desert bighorn sheep to understand their movement patterns and habitat use. They then used computer simulations to model how different crossing structures, such as bridges and culverts, would affect the sheep's ability to cross the freeways.
The results showed that the optimal locations for wildlife crossings were areas where the sheep had high levels of activity and where the freeway had low traffic volumes. The researchers also found that bridges were more effective than culverts at facilitating sheep crossings.
"Our study provides important information that can be used to design and implement effective wildlife crossings for desert bighorn sheep in Southern California," said Dr. Fraser Shilling, lead author of the study and a postdoctoral researcher at UC Davis. "These crossings will help to improve the sheep's ability to move freely between different parts of their habitat, which is essential for their long-term survival."
The researchers hope that their findings will be used by transportation agencies and land managers to improve the safety of desert bighorn sheep and other wildlife along California's freeways.
In addition to desert bighorn sheep, the wildlife crossings could also benefit other species, such as mountain lions, coyotes, and bobcats. By providing safe passage for these animals, the crossings will help to maintain the biodiversity and ecological integrity of the Peninsular Ranges.
