Ecological and behavioral studies of M. coquereli have been conducted in the Beroboka, Kirindy, and Marosalaza forests just north of Morondava (Petter et al., 1971; Pagès, 1978, 1980; Kappeler, 1997). Population densities reported from Marosalaza range from 30 individuals/km2 (Hladik et al., 1980) to 50 individuals/km2 (Petter et al., 1971) but, in the latter study, reached as high as 210 individuals/km2 in forests running along rivers. Ausilio and Raveloarinoro (1993) recorded densities of 100 individuals/km2 in the forests of Tsimembo, while Kappeler (1997) recorded 120 individuals/km2 in Kirindy. However, the latter population underwent an inexplicable decline after remaining steady for several years (Markolf et al., 2008b).Home ranges of 1 to 4 ha overlap extensively and all individuals studied seem to make heavy use of smaller core areas, which they defend aggressively (Pagès, 1978, 1980; Kappeler, 1997). Male ranges tend to overlap those of several females as well as those of other males. In the Kirindy Forest, their ranges more than quadruple in the mating season (Kappeler, 1997, 2003). Males interact positively (grooming, contact calling) with females when they make contact, and pairs travel together for short periods even during the dry season. Coquerel’s giant mouse lemur is typically solitary when foraging, and does not nest communally. It spends its daytime hours in a spherical nest of up to 50 cm in diameter (Kappeler, 2003), usually placed 2–10 m high in the fork of a large branch or among dense lianas (to discourage predators), and constructed of interlaced lianas, branches, leaves, and twigs chewed off from nearby trees (Petter et al., 1971; Pagès, 1980; Sarikaya and Kappeler, 1997). Pagès (1980) and Kappeler (1997) found only females and their offspring sharing nests. Each individual uses as many as 10 or 12 nests, changing its sleeping site every few days (Kappeler, 2003). Individuals leave the nest around dusk, at which time they begin feeding or self- grooming, or continue resting. Travel and foraging usually occur at heights of 5 to 10 m, though M. coquereli does come to the ground on occasion (Kappeler, 2003). During the latter half of the night they are more likely to be involved in social activities (Pagès, 1978, 1980). While they are likely to return to the nest for the second half of the night during the cold winter, they remain active year round and do not enter into a state of torpor. Some may make “loud calls,” usually at the beginning of their nightly activity, and they make soft hon calls while moving about (Kappeler, 2003). Individuals scent-mark objects using saliva, urine or anogenital secretions (Petter and van der Sloot, 2000). Coquerel’s giant mouse lemur is omnivorous, feeding on fruits, flowers, buds, gums, insects, insect excretions, and spiders, frogs, chameleons, and small birds (Pagès, 1980). It may even prey on smaller Microcebus species (Goodman, 2003). Another seemingly important food source during the dry season (June–July) are the excretions of cochineal and homopteran larvae (Pagès, 1980). Based on the results of comparative studies, reproductive activity of M. coquereli in the Kirindy Forest begins in November (Pagès, 1978, 1980; Kappeler, 2003). Gestation lasts about three months (Petter-Rousseaux, 1980) and two infants (occasionally one) leave the nest after about three weeks. The young are carried in their mother’s mouth for several weeks and are left in vegetation while she forages (Stanger et al., 1995; Kappeler, 1998). After three months infants forage alone, but maintain vocal contact with the mother (Pagès, 1980, 1983).