The collared brown lemur (Eulemur collaris), also known as the red-collared brown lemur or red-collared lemur, is a medium-sized lemur and in one of twelve species of brown lemur. It is only found in south-eastern Madagascar. Like most species of lemur, it is arboreal, moving quadrupedally and occasionally leaping from tree to tree. Like other brown lemurs, this species is active during the day and the night, lives in social groups, primarily eats fruit, exhibits sexual dichromatism, and does not demonstrate female dominance. The species is listed as endangered and is threatened primarily by habitat loss.