The white-eared titi monkey (Plecturocebus donacophilus) also known as the Bolivian titi or Bolivian gray titi, is a species of titi monkey, a type of New World monkey, from eastern Bolivia and an area of western Brazil. The species has a range that extends east from the Manique River in Beni Department, Bolivia to southern Rondônia in Brazil. The southern end of its range includes forests around the city of Santa Cruz de la Sierra. It is a medium-sized monkey with a grey back, orange underside and distinctive white ear tufts. It has an omnivorous diet, eating fruits, other plant materials and invertebrates. It is predated upon primarily by raptors, though felids and other monkey species have been known to attack the species. It is a monogamous species and lives in small groups of two to seven members consisting of the pair and their offspring. The family group has a home range of and the adults have a complex vocal repertoire to maintain their territory. It is also known for its characteristic twining of tails when groups are sitting together. White-eared titis can live for more than 25 years in captivity. The white-eared titi population has a declining trend. The decline is believed to be mainly caused by human-induced habitat loss and degradation. Despite this, the International Union for Conservation of Nature (IUCN) classified the species as being of least concern in 2008 as it has shown adaptability to habitat disturbance and is found over a wide range. Taxonomy The white-eared titi belongs to the New World monkey family Pitheciidae, which contains the titis, saki monkeys (Pithecia), bearded sakis (Chiropotes), and uakaris (Cacajao). It is a member of the subfamily Callicebinae. It was first described as Callicebus donacophilus in 1836, but was reassessed based on molecular evidence and recombined as a species within the genus Plecturocebus. Within the new genus Plecturocebus, the white-eared titi is part of the P. donacophilus group with the Rio Beni titi (P. modestus), Rio Mayo titi (P. oenanthe), Olalla brothers' titi (P. olallae), white-coated titi (P. pallescens), and Urubamba brown titi, (P. urubambensis). The white-coated titi has sometimes been considered a subspecies of the white-eared titi, but they are treated as separate species in the latest edition of Mammal Species of the World. Physical description The white-eared titi is a medium-sized primate with grey to orange pelage. The species does not exhibit sexual dimorphism; the