Collared brown lemurs are medium-sized primates and one of twelve species of the Brown lemur. Males and females in this species look different. Males are brownish-gray on top being paler gray underneath. Their muzzle, face and crown are dark gray to black; the eyebrow patches are creamy to gray-colored and vary between individuals. Cheeks are creamy to rufous-brown and beard is thick and bushy. The tails are dark gray with a dark stripe along the spine. Females are browner and more rufous than the males on top being pale creamy-gray underneath. Tails have same color as the dorsal coat. Their face is gray, with faint gray stripe extending over crown. Cheeks are rufous-brown, but less prominent than in males. Both males and females have orange-red eyes color.
Collared brown lemurs are found in southeastern Madagascar. They occur west to the Kalambatritra and in the south from Tôlanaro north to the Mananara River. They can be found in the Mandena Conservation Zone, Sainte Luce Reserve, and Andohahela National Park. These animals live in tropical moist lowland, montane forests and littoral forests.
Collared brown lemurs are cathemeral which means that they are active both day and night throughout the year. These animals live in social groups that are multi-male/multi-female, with groups ranging in size from two to seventeen individuals. Like most species of lemur, Collared brown lemurs are arboreal. They move quadrupedally and occasionally leap from tree to tree.
Little is known about the mating behaviour of Collared brown lemurs. However, as these animals live in multi-male/multi-female social groups it is suggested that they may exhibit either polygynous (one male mates with multiple females) or polygynandrous (promiscuous) (both males and females have multiple mates) mating systems. Females give birth to one offspring between October and December after the gestation period that lasts around 120 days. It is known that young Collared brown lemurs become reproductively mature at 1-2 years of age.
The biggest threat to these animals is habitat loss from slash-and-burn agriculture and charcoal production. Collared brown lemurs are also hunted for food and captured for the local pet trade. Additionally, ilmenite mining threatens populations of this species in littoral forests.
The IUCN Red List and other sources don’t provide the number of the Collared brown lemur total population size. Currently, this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.
In their environment, Collared brown lemurs act as seed dispersers. These animals are especially critical for the dispersal of large-seeded fruiting trees within their range. Collared brown lemurs may be the last remaining seed dispersers for these tree species due to the extinction of larger frugivorous birds and subfossil lemurs.