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Native Rodents of Orange County: Part 2

Updated: Mar 18, 2022

Rodents play a key role in the natural ecosystem. Hence, it is important to protect and conserve these species and their habitats. We also have to understand that rodents are not pests but instead, they are important in seed and spore dispersal, pollination, seed predation, energy and nutrient cycle, modification of plant succession, and species composition. Orange County (OC) habitats are heavily dependent on rodents.

Western gray squirrel eating to regain its energy. Photo by Joseph V Higbee

Next in our native rodents of OC spotlight series is the Western gray squirrel. The Western gray squirrel, Sciurus griseus, is also known as the California gray squirrel, silver-gray squirrel, and Oregon gray squirrel. It is an arboreal rodent found along the western coast of the United States and Mexico. The conservation status of the squirrel is the least concern; however, in some landscapes, it has lost habitat or experienced local extinction (extirpation) due to competition with other squirrel species and other pressure on their population.

The western gray squirrel is the largest native tree squirrel in the western coastal United States. Weights vary from about 0.77 to 2.20 pounds, and length (including tail) from 17 to 24 inches. It undergoes a complete head-to-tail molt in the spring and a rump-to-head molt in the fall. Tail hair is replaced only in the spring. Nesting mothers will use their tail hair to line birthing nests. The squirrels feed on berries, nuts, a variety of seeds, and the eggs of small birds.

The squirrels reach sexual maturity at 10 to 11 months, and will begin breeding at approximately one year of age. They mate over an extended period ranging from December through June. Young are born after about a 44-day gestation period. Juveniles emerge from nests between March and mid-August.

The western gray squirrel observing its surroundings to see if there are any dangers. Photo from Wikipedia

The western gray squirrel has many predators, including red-tailed hawks, great-horned owls, eagles, bobcats, coyotes, cougars, domestic cats, and dogs. However, the predation does not control the squirrel's population density. Although they can be found in the foothills or mountain areas of OC, they are not as common due to habitat loss, as well as competition from introduced species such as the eastern squirrel.

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