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2. General Body Adaptations

Sciurus niger photo courtsey of Mark Cassino

Challenges Faced by Tree Squirrels

GRAVITY

LOCOMOTION

FOOD COLLECTION AND STORAGE

PREDATORS

TEMPERATURE REGULATION

Gravity is thwarted by body shape and size, strong forelimbs and large claws: the same structures facilitate Locomotion.

-- adult tree squirrels may weigh as little as 45 grams, even 1000 gram squirrels are easily supported by thicker twigs

-- the shape of the squirrel is important. long slender bodies spread weight across a limb. (Halloran 1999) (other arboreal animals using this strategy are chamelian lizards, snakes and preying mantises)

-- the tail adds balance; held out when jumping, the tail is curved over the back when the squirrel is sitting

-- forelimbs with strong muscles cling to trees and large hind feet and leg muscles propel the squirrel to jump to other branches. (Halloran 1999)

-- thick, strong claws also hold the animal tight to the branch

Food collection and storage patterns are similar in S. carolinensis and S. niger. Collection is apparently related to cover/ predator risk of the environment. Temperature regulation mainly deals with heat conservation especially in the nest.

-- S. carolinensis sometimes carry food away and at other times consume it immediatley. studies reveal that the tendency to carry a food item decreases with distance from cover, or travel time, and increases with the item size or handling time. Predator risk increases with increased distance from cover. Distant food patches may not be foraged if sparsely covered. (Lima, Valone and Caraco 1985)

-- Both S. carolinensis and S. niger are non-territorial and interspecies home ranges may overlap without conflict.

-- Both S. carolinensis and S. niger increase energetic collection by 32% in the autumn to prepare for winter. (Halloran 1999)

-- G. volans home ranges have been estimated to be slightly different for males and females, including approximately 2.45 ha for the former and 1.95 for the latter. Vertical structure of the vegetation is believed to ba a major factor in distance from dens both sexes travel.(Bendel and Gates 1987)

--Each of the three species has a summer and a winter coat of fur, molting in May and again in September for increased winter insulation. Nests contain atleast two individuals whose contracted warmth is shared.(Halloran 1999)