San Joaquin antelope squirrel | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Sciuridae |
Genus: | Ammospermophilus |
Species: | A. nelsoni |
Binomial name | |
Ammospermophilus nelsoni (Merriam, 1893) |
The San Joaquin antelope squirrel or Nelson's antelope squirrel (Ammospermophilus nelsoni), is a species of antelope squirrel, in the San Joaquin Valley of the U.S. state of California.
The San Joaquin antelope squirrel is found in the San Joaquin Valley, including slopes and ridge tops along the western edge of the valley. It is endemic to the region, and is found in a much smaller range today than it originally inhabited. Since the San Joaquin Valley fell under heavy agricultural cultivation, habitat loss combined with rodenticide use has reduced the squirrels numbers enough that it is now listed as a threatened species.
Most of today's remaining San Joaquin antelope squirrels can be found in the Carrizo Plain, where their original habitat remains undisturbed. The squirrels live in small underground familial colonies on sandy, easily excavated grasslands in isolated locations in San Luis Obispo and Kern Counties. Common vegetation associated with the squirrel includes Atriplex and Ephedra, and some junipers. The binomial of this species commemorates the American naturalist Edward William Nelson.
The San Joaquin antelope squirrel is dull yellowish-brown or buffy-clay in color on upper body and outer surfaces of the legs with a white belly and a white streak down each side of its body in the fashion of other antelope squirrels. The underside of the tail is a buffy white with black edges. Males are approximately 9.8 inches and females are approximately 9.4 inches in length.
Studies by Hawbecker provide abundant information on breeding and the life cycle of Nelson's antelope squirrel. They breed in late winter to early spring and have nearly all their young in March. Once pregnant, gestation lasts a little less than a month. The young do not emerge from their dens until approximately the first week of April. Nelson's antelope squirrel has only one breeding season, which is timed appropriately so that the young are born during the time of year when green vegetation is the most abundant.