Twenty-five species of bats occur in California.  Most cause no problems, are nocturnal, and rarely seen. However, some species will utilize houses and other man-made structures for roosts or nests. This can lead to an accumulation of droppings, and in certain instances the possibility of rabies transmission to humans.

Raccoons are nocturnal animals with brown fur, distinctive black mask-like markings on their faces, and ringed tails. They are usually about the size of a cat, but may be larger when well-fed on garbage. If they are used to being fed, raccoons can lose their fear of humans and become aggressive. Since they can carry rabies, it’s important that you never feed or approach a raccoon.

Opossums (Didelphis virginiana) are not rodents, but they are often confused as rodents. (They are marsupials – like kangaroos!) Opossums are grey, brown and white with a sharp pointed face and a long, scaled tail. Adult opossums are 2-3 feet long with the tail included and can weigh up to 15 lbs. If you have seen or heard of “a rat as big as a cat,” it was most likely an opossum.

There are many different kinds of rodents in San Mateo County but the most common nuisance rodents are house mice, roof rats, and Norway rats.

Skunks are small black and white animals. They are not usually aggressive, but when threatened may spray a very unpleasant-smelling substance. Skunks often do a ‘hand stand’ on their front paws with their tail and body in the air before spraying. If you see a skunk in this position, you should retreat quietly and slowly to avoid being sprayed.

Several members of the corvid family are common throughout San Mateo County, these include the American crow (Corvus brachyrhynchos) and the common raven (Corvus corax). Crows and ravens are both large birds with shiny black feathers. However, with close observation they can be easily distinguished.

Deer are welcome visitors for many property owners, but may sometimes cause damage to gardens and other landscaping.

The District does not control coyotes. For information about how to stay safe around these native wildlife, visit the California Department of Fish and Wildlife's (CDFW) webpage about coyotes. You can also view these short videos made by the City of Foster City with CDFW advice.

Mountain lions are sometimes seen in rural and suburban areas of San Mateo County. More information on preventing problems with mountain lions is available from the California Department of Fish and Wildlife.