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Thursday, November 27, 2014

Shadow Tails

Fox Squirrel, Sciurus niger

The word ‘squirrel’ comes from the Greek ‘sciourus’, meaning ‘shadow tail’, and refers to the bushy appendage possessed by most all squirrel species.  They are members of the rodent family, and Texas is home to 10 species of squirrels with 4 of them common in the Austin area.

Along with their bushy tails, squirrels are generally slender animals with large eyes and soft fur. Their front limbs are shorter than their hind limbs, with 4 or 5 toes on each foot.  Their front feet include a usually underdeveloped thumb, and all toes have sharp claws for climbing trees and quickly clamoring over uneven terrain. Squirrels are strongly vegetarian, and feed mostly on a wide variety of seeds, nuts, fruits, buds, bark, and leaves.  Their vision is sharp and they have ‘vibrissae’ or specialized hairs on their head and limbs, which afford them an excellent sense of touch.   

The most common tree squirrels in Central Texas are the Eastern Fox Squirrel (Sciurus niger) and the Eastern Gray Squirrel (Sciurus carolinensis). A large squirrel with rusty or reddish underparts and grayish or brownish upperparts, the Fox Squirrel prefers open woodlands of mixed trees and riparian areas along rivers and streams, and makes its dens in hollow trees or nests made of leaves.  Their diet is largely made up of acorns which are buried in winter and relocated through their keen sense of smell. Mating occurs in January/February, and again in May/June, with offspring born in March and July.  

The Gray Squirrel is a medium-sized squirrel with grayish upperparts with white-tipped hairs, white underparts, and a white spot at the base of its ears in winter.  Gray Squirrels live in dense live oak stands and bottomland areas, with the Austin area in the westernmost part of their range.  There are usually two openings to their nests, which are otherwise similar to the Fox Squirrel, as is their diet and breeding cycle.  Destruction of bottomland habitat from logging, overgrazing by livestock, and development are the main reasons why gray squirrels are only locally common, and declining in many areas.      

Rock Squirrel, Spermophilus variegatus

Our most frequently seen ground squirrels include the Rock Squirrel (Spermophilus variegatus) and the Mexican Ground Squirrel (Spermophilus mexicanus).  A rather large, stout squirrel with a blackish head and upper back and a mottled grayish-brown rump and tail, the Rock Squirrel is nearly always found in rocky canyons, cliffs, and rock piles, where they make their dens.  While they can climb trees, they prefer to be ground dwellers, where they forage for acorns, nuts, insects, and berries.  In Central Texas, these squirrels hibernate beginning in November, and emerge in late February or March to begin breeding.

Mexican Ground Squirrel, Spermophilus mexicanus

The western edge of Austin is the easternmost range for the Mexican Ground Squirrel, a rather small squirrel with about nine rows of squarish white spots on its back and a moderately bushy tail. They prefer brushy or grassy areas, including mowed lawns and overgrazed pastures and live in burrows dug into the soil.  They eat chiefly green vegetation and insects, but are one of the few squirrel species that will eat meat.  Breeding begins in late March or early April, with a brood chamber built into a side tunnel in the deepest part of their burrow. 

Anyone who has seen a squirrel running along a tree limb or across an open road with its bushy tail undulating and waving behind it, or spotted a squirrel sitting with its tail curled over its back while it eats or surveys its surroundings, can appreciate why their name means shadow tail!