Unicolor Woolly Lemur (Avahi unicolor)

The lower second and third molars of males are larger than females and the skulls of males are slightly wider than females (Gingerich and Ryan, 1979), but for the most part this species is not sexually dimorphic. The lower incisors have been modified in this species to form a toothcomb that is used in grooming (Gingerich and Ryan, 1979). The upper incisors are reduced as compared to anthropoid primates (Gingerich and Ryan, 1979). The dental formula for this species is 2:1:2:3 on the upper jaw and 2:0:2:3 on the lower jaw (Ankel-Simons, 2000). The head and body has a light sandbrown-gray coloration (Thalmann and Geissmann, 2000). The tail of the unicolor avahi is a dark gray-grown or reddish-brown, with the tail base being a pale brown-gray or a cream color (Thalmann and Geissmann, 2000). The back may be slightly darker than the head and rest of body in the scapular area (Thalmann and Geissmann, 2000). The inner dorsal surface of the lower limbs is whitish in coloration (Thalmann and Geissmann, 2000). The chest, belly, and the inner surface of the upper arms are very light gray or mouse gray in color and the fur is thin and downy (Thalmann and Geissmann, 2000). The eyes of this species are maroon having black hairless eyelids (Thalmann and Geissmann, 2000). The snout of the unicolor avahi is black and hairless (Thalmann and Geissmann, 2000).

The unicolor avahi is found on the island of Madagascar. This species may be restricted to the Sambirano region (Thalmann and Geissmann, 2000). The southern limit for this species may be the Andranomalaza or Maevarano River (Thalmann and Geissmann, 2000). The northern limit may be the Sambirano River (Thalmann and Geissmann, 2000). This species is found on the western slope of the Manongarivo Special Reserve (Thalmann and Geissmann, 2000). This species lives in the evergreen humid formation type forests (Thalmann and Geissmann, 2000).

This is primarily a folivorous species.

The avahi is a vertical leaper. When leaping this species has a preference to take-off from horizontal supports (Warren, 1997). This species does not use the foot for propulsion when leaping (Demes et al., 1996). During leaping there is a wide range of movements at the hip joint (Demes et al., 1996). When this species descends slowly quadrupedally or downward leaps from trunk to trunk (Walker, 1979). If this species is on the ground it moves by bipedal hopping (Walker, 1979).

The basic group is composed of a breeding pair and their offspring.

infant call: This call is composed of plaintive whistlelike noises which are used to attract the attention of the mother by the infant (Petter and Charles-Dominique, 1979).

distant communication call: This call is composed of high-pitched whistles that are modulated and prolonged (Petter and Charles-Dominique, 1979). This call elicits the same call by the receiver (Petter and Charles-Dominique, 1979). This call serves to communicate territorial demarcation (Petter and Charles-Dominique, 1979).

alarm call: This call starts out as a faint discreet grunting sound followed by a weak snorting sound when an individual is mildly disturbed, but may be transformed into a cooing call (Petter and Charles-Dominique, 1979). If an individual is highly disturbed the call transforms into a loud trembling call in which the pitch rises in a rapid manner to end on a powerful high-pitched note (Petter and Charles-Dominique, 1979). This sounds like "Ava Hy", hence the name for this species (Petter and Charles-Dominique, 1979).

cohesion call: This is a sudden, high-pitched call that is emitted by an individual when separated from another by a distance of 50 meters following an alarm situation (Petter and Charles-Dominique, 1979).

contact-rejection call: This call is composed of aggressive grunting sounds when an individual is attempting to be grasped and when grasped is transformed into a resonant snorting sound (Petter and Charles-Dominique, 1979).

Both sexes have specialized scent glands on the necks used in olfactory communication.



The avahi gives birth to a single offspring (Fleagle, 1988).

Demes, B., Jungers, W.L., Fleagle, J.G., Wunderlich, R.E., Richmond, B.G., and Lemelin, P. 1996. Body size and leaping kinematics in Malagasy vertical clingers and leapers. Journal of Human Evolution. Vol. 31, 367-388.

Fleagle, J. G. 1988. Primate Adaptation and Evolution. Academic Press.

Gingerich, P.D. and Ryan, A.S. 1979. Dental and cranial variation in living Indriidae. Primates. Vol. 20(1), 141-159.

Petter, J.J. and Charles-Dominique, P. 1979. Vocal communication in prosimians. In The Study of Prosimian Behavior. eds. G.A. Doyle and R.D. Martin. Academic Press: New York.

Thalmann, U. and Geissmann, T. 2000. Distribution and geographic variation in the western woolly lemur (Avahi occidentalis) with description of a new species (A. unicolor). International Journal of Primatology. Vol. 21(6), 915-941.

Walker, A. 1979. Prosimian locomotor behavior. In The Study of Prosimian Behavior. eds. G.A. Doyle and R.D. Martin. Academic Press: New York.

Warren, R.D. 1997. Habitat use and support preference of two free-ranging salutatory lemurs (Lepilemur edwardsi and Avahi occidentalis). Journal of Zoology. Vol. 241, 325-341.

Last Updated: March 22, 2007.
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