Eastern fox squirrel

Sciurus niger

TAXONOMY

Sciurus niger Linnaeus, 1758, South Carolina, United States.

OTHER COMMON NAMES

English: Cat squirrel, stump-eared squirrel.

PHYSICAL CHARACTERISTICS

Head and body length 10-14.5 in (260-370 mm), tail 7-13 in (180-330 mm); weight 17.5-49.5 oz (500-1,400 g). Coat color variable.

DISTRIBUTION

Eastern and central United states reaching southern Canada in the north. Introduced to Ontario in Canada and New Mexico, Texas, California, Oregon, Colorado, Idaho, and North Dakota within the United States.

HABITAT

Forests, woodlands, urban areas, and agricultural landscapes. BEHAVIOR

Diurnal activity pattern, period of greatest activity in winter is in the early morning. Social system characterized by dominance hierarchy. Main factors influencing dominance status of individuals are their sex and age. Fox squirrels will forage in open fields near woodland. The behavior of caching seeds in grassland thought to be important in seed dispersal and habitat succession.

FEEDING ECOLOGY AND DIET

Tree seeds and nuts as well as buds and flowers of trees.

REPRODUCTIVE BIOLOGY

Polygamous. Reproductively active from mid-December onwards. Similar to gray squirrels, there are two breeding peaks within a year but not all females produce two litters. Mean litter size ranges from 2-3.5 young.

PHYSICAL CHARACTERISTICS

Head and body length 10-12.5 in (260-320 mm), tail (190-260 mm); weight 16-29 oz (450-820 g). Peppered gray upper fur, underside white. White conspicuous eye ring. Tail is gray fringed in white. Ear tufts or tassels can reach up to 1.5 in (40 mm) in February and March, very reduced or absent during the summer. Some populations in New Mexico and Colorado have a high incidence of melanism. Kaibab race characterized by dark gray to black belly and white tail.

DISTRIBUTION

Northern Mexico, Arizona, New Mexico, Utah, Colorado, and Wyoming.

HABITAT

Ponderosa and yellow pine forests, mixed conifer forests.

BEHAVIOR

Diurnal activity pattern. Home range size reported to vary seasonally linked to the availability of resources, with male home ranges larger than female ranges.

FEEDING ECOLOGY AND DIET

Ponderosa pine seeds, bark, buds, and flowers. Other food items include insects, acorns, mistletoe berries, and fungi. Fungi are an important food source in the summer and Abert squirrels may be important spore dispersal agents.

REPRODUCTIVE BIOLOGY

Polygamous. Gestation approximately 40 days, mean litter size 3.4 young.

CONSERVATION STATUS

There have been suggestions that existing logging and forest management practices may impact negatively on some populations.

SIGNIFICANCE TO HUMANS None known. ♦

CONSERVATION STATUS

Delmarva Peninsula fox squirrel, 5. n. cinereus, considered endangered. Logging and changes to habitat composition have been suggested as causes for decline. The Big Cypress fox squirrel, 5. n. avicennia, in Florida is locally regarded as threatened.

SIGNIFICANCE TO HUMANS Hunted for food and sport. ♦

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