The red-collared brown lemur is a lemur species found only in southeastern Madagascar. It inhabits humid forests from lowland to montane areas, moving on all fours through the trees and sometimes foraging close to the ground. It has reddish-brown fur and a long tail, and males and females differ in facial coloration and coat. In particular, males show conspicuous reddish-brown fur from the cheeks to the chin that appears like a collar, which is the origin of its name. It can be active during day or night and lives in groups of a few to a dozen or so individuals. Its diet is primarily fruit, but depending on the season it also consumes flowers, young leaves, and insects. In addition to habitat loss and fragmentation from slash-and-burn agriculture, charcoal production, and timber use, hunting and capture for the pet trade pose threats; the IUCN Red List assesses it as Endangered (EN).