Squirrels of the World

Sciurus arizonensis 43

nuts, and fruits, as well as on mushrooms; animal matter
(insects, bird eggs, and nestlings) is occasionally eaten.
Seeds with low perishability can be larder-hoarded within
tree cavities or scatter-hoarded on the ground in shallow
storage locations. The vocalization is a high-pitched metal-
lic-sounding “chit-chit-chit,” used in response to potential
predators. Wild and domestic felids, canids, mustelids, and
raptors are known to prey upon these squirrels. Their pelts
are harvested for fur clothing and ornamentation; however,
the quality of S. anomalus pelt s is v iewed a s considerably less
than that of S. vulgaris. Caucasian squirrels are hunted for
food in much of their range and are considered pests in
some regions with nut and fruit orchards. Young squirrels
are sold as pets. Habitat loss due to timber harvesting and
the conversion of forests to agriculture remains a threat.

general references: Albayrak and Arslan 2006; Amr
2000; Demirsoy et al. 2006; Gavish 1993; D. L. Harrison and
Bates 1991; Qumsiyeh 1996.

Sciurus arizonensis (Coues, 1867)

Arizona Gray Squirrel

description: S. arizonensis has a silvery gray dorsum, oc-
casionally with a faint medial brownish band; a white to
cream venter; and a gray tail frosted with white. A cream to
white eye ring is prominent.

size: Female—HB 259.1 mm; T 254.5 mm; Mass 667 g.

Male—HB 248.2 mm; T 245.8 mm; Mass 736 g.

distribution: This species is found in Arizona and ex-

treme western New Mexico (USA) south into Sonora

(México).

geographic variation: There is disagreement as to

whether S. arizonensis is monotypic or whether three sub-

species should be recognized. Currently, this species is con-

sidered to be monotypic.

conservation: IUCN status—data defi cient. Population

trend—no information. It is considered to be threatened in

México.

habitat: Arizona gray squirrels are found in forests, rang-

ing from low-elevation Madrean forests with a mixture of

pine (Pinus) and oak (Quercus) to higher-elevation mixed co-

nifer forests. Riparian areas with large cottonwoods (Popu-

lus) and sycamores (Platanus) also harbor high densities of

Arizona gray squirrels.

natural history: This species is diurnal. The ecology of

Arizona gray squirrels is poorly known, despite their origi-

nal description more than 140 years ago. S. arizonensis dem-

onstrates a seasonal reproductive pattern. There is a short

day-long estrus in spring (February–May), when multiple

males pursue females, followed by the birth of a single litter

of two to four young (mean = 3.1) in late spring or summer.

Males possess scrotal testes from winter through summer.

The testes are withdrawn into the abdominal cavity during

Sciurus arizonensis. Photo courtesy Nichole Cudworth.