Black lion tamarin (Leontopithecus chrysopygus). A small arboreal monkey native to the coastal forests of Brazil. Head-body length is about 30 cm, weight 300–700 g, and tail length about 30–40 cm. Diurnal, it eats fruit and insects and seldom descends to the ground. Groups consist of 4–8 individuals and may include multiple males and females, but only a limited number of females breed. Females commonly give birth to twins, and males participate in parental care, carrying young on their backs. Populations have declined sharply due to habitat fragmentation, and the species is classified as Endangered (IUCN Category I B).