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Terrestrial Mammals of the Piedras Blancas Rookery California Ground Squirrel (Otospermophilus beecheyi)
The California ground squirrel is a common and easily observed ground squirrel of the western United States and the Baja peninsula. The squirrel's upper parts are mottled, the fur containing a mixture of gray, light brown and dusky hairs; the underside is lighter, buff or grayish yellow. The fur around the eyes is whitish, while that around the ears is black. Head and body are about 12” long and the tail an additional 6”. California Ground Squirrels live in burrows. Hillsides or low earth banks are preferred sites because the burrows can be excavated horizontally, although many burrows are dug down vertically several feet to assure protection. Burrows, which are about four or five inches in diameter, may vary in length from five feet to more than thirty-five feet and may be used by many generations of ground squirrels. California ground squirrels are often regarded as a pest in the rookery because their burrows undermine the bluff. In the moderate climate of the rookery California ground squirrels are active year round. They eat a variety of seeds, fruits, acorns, roots, mushrooms, and insects such as grasshoppers, crickets, and caterpillars. They have been observed nibbling on the dried carcasses of seal pups.
The breeding season is from February to April. The average litter is 5-6 babies, after a month-long gestation period. California ground squirrels are ever vigilant and ready to sound an alarm if danger is perceived. If frightened, a squirrel often makes long leaps and emits a sharp, metallic alarm cry several times in rapid succession. Rattlesnakes frequently prey on California ground squirrels. When facing a rattlesnake, a ground squirrel may rush blood to its tail and fan it to make their heat signature bigger—-too big to eat. Eagles, raccoons, foxes, and weasels also prey on ground squirrels. California ground squirrels may live as long as six years. But three or four years is probably their life span in the wild.
Brush Rabbit (Sylvilagus bachmani)
The brush rabbit is smaller than many of the other cottontails, and unlike most of them, the under side of its tail is grey rather than white. The upper side of the brush rabbit's fur varies from light brown to gray, while the underside is usually white. Adult rabbits measure anywhere from 10–14 inches long and rarely weigh over two pounds. The brush rabbit inhabits dense, brushy cover, most commonly in chaparral vegetation. It forms networks of runways through the vegetation. The brush rabbit does not dig its own burrow or den, but uses brush piles or the burrow of other species. The brush rabbit feeds mainly on grasses and herbaceous plants, especially green clover, though it will also take berries and browse from bushes. Its predators include the cougar, the coyote, foxes, the bobcat, weasels, and various raptors and snakes. Its survival strategies include remaining immobile when in brushy areas, and zigzag running when found, or in open spaces.
Coyote (Canis latrans)
The coyote’s name translates from the Aztec word for trickster. It is a cunning hunter that can occasionally be seen in the dunes above the rookery. To date, there is no evidence of a coyote being anything more than curious among the e-seals. However, it is believed that eseals first chose island habitats to avoid predation by the larger populations of coyotes, bears, and mountain lions that roamed the coastline long ago. The coyote’s coloring varies from grayish-brown to yellowish-gray on the upper body with buff or white coloring on the throat and belly. The back has tawny-colored underfur and long, blacktipped guard hairs that form a black dorsal stripe and a dark cross on the shoulder area. The ears are proportionately large in relation to the head, while the feet are relatively small in relation to the rest of the body Coyotes typically grow to 30–34 inches in length, not counting a tail of 12–16 inches. They stand 23–26 inches at the shoulder and weigh from 15–46 pounds. During pursuit, a coyote may reach speeds up to 43 mph making it one of the fastest terrestrial mammals in North America, and can jump a distance of over 13 ft. The gestation period lasts from 60 to 63 days. Litter size ranges from 1 to 19 pups; the average is six. 50 to 70 percent of pups do not survive to adulthood.
