Squirrel Population Declines in San Bernardino Mountains

State officials this week identified what's behind the death of squirrels in the San Bernardino Mountains: mange.Mountain area residents this year have noticed fewer western gray squirrels, prompting concern and complaints directed towards the Department of Fish and Game.

Mange is a skin disease caused by mites that can sickens and kills. This specific mange has been preliminarily identified as Notoedres centrifera, which affects rodents, not humans, dogs or cats. Other species of mange, carried by coyotes, raccoons and bobcats, can infect pets and sometimes people.

The direct reason for the outbreak is unknown, but its spread around the mountain range communities has been attributed to a high population density. "Gray squirrels were at higher numbers than natural foods would support, because artificial feeding is prevalent in the mountain communities," explained DFG Wildlife Biologist Jeff Villepique. "The inevitable consequence when you combine an artificially high population with animals gathering at food sources is the eventual spread of disease."

Deaths of squirrels in past years have also been caused by West Nile Virus, but none have tested positive this year. Residents are encouraged to report dead birds or squirrels by calling (877) 968-2473 (877-WNV-BIRD) or submitting a report online.

The Back Forty is an environmental blog that reports on news through the lens of open space, land use and natural resources.