The Brown-headed spider monkey (Ateles fusciceps) is a New World monkey that lives primarily in the upper canopy of tropical rainforests in Colombia, Ecuador, and Panama. Ripe fruit makes up the majority of its diet, and it plays an important role in forest regeneration as a seed disperser. It has a reduced thumb and a long prehensile tail which it uses to move through the trees. Although groups number 20–30 individuals, they usually travel in smaller subgroups. Gestation lasts 7–8 months. Due to habitat destruction and hunting, it is listed as Critically Endangered (IUCN Category: CR/IUCN 1A).