Interesting study from the Sacramento Bee about California’s roadway accidents with wildlife:
Using observations of reported traffic incidents and carcasses, the total cost of reported large wildlife-vehicle collisions in California in the last five years is estimated to be at least $1 billion, according to a new report.
When including crashes with mule deer that are claimed by insurance companies but unreported to police, the estimated cost could be as high as $2 billion, according to a 2021 report by the Road Ecology Center at the University of California, Davis.
“What we’re actually showing is the state highways.. so if we had someway of finding all of the collisions that occur on on other roads, obviously its going to be more,” said lead author Fraser Shilling, director of the Road Ecology Center. “Highways are not just the only places this occurs.
Here’s a link to the full UC Davis report with some more details:
Like most species at the top of the food web, mountain lions are especially vulnerable to WVC because they move around a lot and cross roads and highways. Mountain lions are important ecologically because they are the only large, widespread predator in most California ecosystems. They are also important socially, with great interest in their well-being in Southern California and Bay Area urban regions. Black bears are similarly critical species in most CA ecosystems, ranging widely to forage and therefore regularly crossing roads.
A critical problem for mountain lions and black bears in California is that there is no formal program, system or requirement to report when they are killed on roads, which happens frequently. As such, we only know the minimum killed each year on roads, when they are reported to CROS or by CHP, and have no way of knowing the actual WVC impact to these important and charismatic species. Between 2016 and 2020, inclusive, 302 mountain lions and 557 black bears were reported killed on roads by a combination of CROS volunteers, CHP, CDFW, and biologists in Southern California (Figure 6). These were incidental reports and do not represent all mountain lions and black bears killed on CA’s roads and highways. …
One of the more common questions for studies like this is “where is the worst place in California for WVC.” One way to answer that is using the cost of WVC to society. The highway with the consistently highest rate and cost of WVC in any given year in the last 5 has been I-280 on the San Francisco Peninsula, between San Bruno and Cupertino (Figure 5). Five of the top-20 highest cost, 1-mile segments of highway in CA are on I-280. The total annual cost from WVC on 31 miles of I-280 is $5.8 million, or $187,897/mile-year.