UC Davis Tags California Roadkill 'Hotspots'

A new report on wildlife roadkill in California tags the San Francisco Bay Area and an area near Sacramento as two of the deadliest traffic spots for wildlife. 

The University of California-Davis Road Ecology Center prepared the map of wildlife roadkill hotspots in California. It also created a website, the California Roadkill Observation System, where people can report their observations of roadkill. There is also a website with an interactive map.

Center co-director Fraser Shilling said researchers used 29,000 roadkill reports from volunteers over five years. He said roads are the third-biggest cause of death for wildlife.

The report calls San Francisco Bay Area freeways a "ring of death" for animals because of busy roads running alongside marshes.

In the Sacramento area, where Interstates 80 and 5 run across bypasses along the Pacific Flyway migratory bird route, marshy areas attract birds during migration and result in high rates of roadkill. 

The report said birds are among the most common wildlife group types killed by road collisions.

"For instance, there is a high rate of barn owl roadkill where I-5 runs through agricultural lands of the Central Valley," according to the report. "Without trees or other elevated structures by the highways, the owls swoop down for prey without considering the trucks and other vehicles coming toward them."

California Drought Could Be Increasing Roadkill

Fraser recommends planting vegetation in those highway areas, such as oleander and ice plant, nonnative species that repel rather than attract wildlife to the roadsides.

"You have a sterile, dangerous place - the roadway,” Fraser said. “You don’t want to attract animals there.” 

In Southern California, Fraser said many areas along State Route 94 in San Diego County have high rates of collisions where the highway runs through wildlife habitat. He said Caltrans is planning to build five new wildlife-crossing structures in that area.

Fraser said the state needs to dramatically speed up building of wildlife crossings. 

The report said the drought may be increasing the number of roadkill, as animals seem to be putting themselves at greater risk to find food and water sources, crossing roads they may not have in the past.

“These data help identify places where immediate action is warranted,” said Shilling, who is a research scientist with the UC Davis Department of Environmental Science and Policy.