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Arizona Gray Squirrel
Sciurus arizonensis occupies mountain ranges in central Arizona,
western New Mexico, and Sonora, Mexico, along the U.S. border. In
Arizona, S. arizonensis occurs in dense, mixed-broadleaf communities
of riparian-deciduous forest. Usually, the species is restricted to
elevations of 1,500 to 1,900 meters above sea level. Favored
habitats are groves of old cavity-prone Arizona sycamores and other
large deciduous trees. In New Mexico, the squirrel is confined to
deep canyons with water, where black walnuts and acorns are
abundant. In Mexico, the squirrel occupies riparian forests at lower
elevations than does its Arizona cousin.
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Arizona Gray Squirrel
Known commonly as the Arizona gray squirrel, Sciurus arizonensis is
gray in color throughout most of its upper body. Patches of yellow
are sometimes present behind the ears. The tail is black dorsally
and yellow to brown ventrally. The two sides of the tail are
separated by white edging, and the underparts of the squirrel also
are white. The squirrel's gray pelage darkens during the winter, and
its underparts and feet are often stained from walnut juice. Total
body length for the species, including the tail, averages 21 inches.
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Reproduction
The onset of breeding activity in the Arizona gray squirrel is
correlated with flower emergence and the inclusion of flower parts
in the diet. It is theorized that the flower parts contain vitamin A
and other vitamins that stimulate reproductive activity. Estrus
occurs in females in April and early May. Mating chases also occur
during this time, with several males pursuing a single female. Not
all females breed each year. Gestation usually lasts about two
months, and the litter size ranges from two to four offspring.
Behavior
The Arizona gray squirrel often runs on the ground and jumps from
branch to branch in trees. Depending on its feeding habits and the
time of year, the squirrel may be secretive or easily observed.
During the breeding season, when females are pregnant or nursing
young, S. arizonensis is hard to locate. At other times of the year,
it is conspicuous. When it wants to avoid detection, the squirrel
may stand perfectly still for long periods of time. The Arizona gray
squirrel is essentially a silent animal. Its only vocalizations are
chucking and barking alarm calls, which the animal ventures only
when safely perched in a tree. The species is generally not afraid
of humans or dogs, but it will vocalize warnings if it detects the
presence of spotted skunks, snakes of various kinds, or housecats.
In Arizona, the squirrel builds conspicuous leaf nests in the crotch
between a tree's trunk and a major branch. Each squirrel may have
several leaf nests or none at all. During the winter, several adults
may occupy a nest.
Food Habits
Sciurus arizonensis may feed on a wide variety of vegetable
material, including nuts, fruits, bark, berries, flowers, and fungi.
The actual breadth of the diet depends on the availability of food
sources and the particular geographic range of the animal. In New
Mexico, S. arizonensis feeds almost exclusively on walnuts,
supplemented by roots. In Arizona and Mexico, the gray squirrel eats
walnuts, but also acorns, juniper berries, hackberries, pine seeds,
and fungi. The diet of these squirrels is more varied on a seasonal
basis as well. In late summer and early autumn, the Arizona- and
Mexico-based squirrels take in insects and other animal matter.
Walnuts are a staple for S. arizonensis regardless of geographic
range, and several individuals often harvest these nuts in the same
tree. Another dietary habit shared by all members of the species is
the consumption of flower parts in late winter and early spring.
This seasonal food source is thought to be linked to reproductive
activity. In captivity they should be offered a complete diet of
rodent lab blocks, and rat or mouse
mix, with bits of fruit or veggies regularly. Cheerios or wheat
bread are great treats, in small quantities. Do NOT feed chocolate,
fried foods, salted foods, candy or junk food! They may enjoy
crickets and mealworms if they are captive bred, never feed wild
insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium
during nursing and growth due to demands on their systems at those
times, but take care not to overdo it. Water bottles should be used
to proved constant, clean water. Ceramic or stoneware food dishes
work well for keeping seeds or fresh foods off the floor, and a wire
mesh hopper that allows them to eat the lab blocks through without
extra waste.
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