Tree squirrels do not hibernate and do not form colonies. Most species are solitary, but some African species such as Heliosciurus rufobrachium or Funisciurus anerythrus are known to move in pairs or small groups. Tree squirrels use olfactory, vocal, and visual signals to communicate. Chemical signals are important in rodent communication and tree squirrels have a number of scent glands in the facial area around the mouth and cheeks. "Cheek-rubbing" is sometimes linked to biting of the substrate, and urine is used to mark the base of specific trees and the underside of branches. Anal dragging is also reported for some species in which anal glands and perhaps fecal materiel are used to produce a signal. Little is known about the different functions of marking in relation to orientation or inter-individual communication or even the potential for disease transmission.

Vocalizations of squirrels can be linked to several behavioral contexts. These include contact seeking or distress of young, alarm calls, calls associated with mating, and aggressive sounds. In contrast to forest species, estrus females in savanna species such as Paraxerus cepapi or Funisciurus congicus use vocal calls rather than olfactory clues to attract males. Some rainforest species have been reported to lower the frequency and to increase the length of calls as an adaptation to the dense vegetation around them.

Squirrels also make use of their fluffy tails, and tail waving and shivering is sometimes observed when males approach

The eastern gray squirrel (Sciurus carolinensis) can be either gray or black. (Photo by M. H. Sharp/Photo Researchers, Inc. Reproduced by permission.)
The striped tree squirrel (Funisciurus congicus) is endemic to Nambia and Angola. (Photo by Nigel J. Dennis/Photo Researchers, Inc. Reproduced by permission.)

females during mating. Tail flicking as well as foot stamping, linked to aggressive postures such as piloerection (hair-erection), are seen during agonistic encounters.

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