Roof rats are also called black rats, ship rats, or house rats.

Norway rats are also called brown rats, sewer rats, or street rats.

House mice (Mus musculus) are brown to black with a lighter, but not white, underbelly. They are smaller than rats (2 to 3.5 inch long body with 3 to 4 inch long tail) but similar in appearance. Young rats are sometimes mistaken for mice. House mice are seen both indoors and in agricultural areas.

The western deer mouse (Peromyscus maniculatus) is native to California and distributed throughout wooded areas from Alaska down to central Mexico.

Dusky-footed wood rats (Neotoma fuscipes) are native to San Mateo County and frequently live in wooded areas near creeks and streams. They make large, elaborate nests, called woodrat houses, of twigs and leaves that can be over three feet high. These houses can be on the ground or in the trees and provide shelter for other species including native mice, lizards, and an incredible variety of…

There are multiple species of squirrels common throughout San Mateo County, but only the ones that live up in trees are called “tree squirrels” (squirrels that live underground are called ground squirrels).

The California ground squirrel (Otospermophilus beecheyi) is native to the United States from western Washington to Baja California.

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.

Gophers, moles, and voles