male's head and body length averages while females average . The white-eared titi's fluffy tail is longer than the length of its head and body together. It typically has thick fur, with a dorsal side and limbs that vary in colour from grey agouti to orange agouti, with an orange underside and white ear tufts. Body weight ranges from around , with the female generally a little lighter. It has the dental formula , meaning that on each side of the jaw it has two incisors, one canine tooth, three premolars, and three molar teeth. The canine teeth are relatively short when compared with other New World monkeys. In captivity, the white-eared titi has been known to live for over 25 years. Behaviour The white-eared titi is cryptic, diurnal and known to live in small family groups. It is a monogamous species that is thought to mate for life and lives in groups that usually consist of two to seven members; an adult pair and up to five young. Multi-male groups have also been recorded. Offspring are carried by the male, and are always with them, except when feeding. Between the ages of two to four years, offspring will disperse from the natal group, with females leaving earlier than the males. There is a strong bond between the adult mating pair, they stay close and carry out activities together. Either member of the pair may follow the other and leadership changes through the day. Evidence of the strength of the pair bond is shown by grooming, huddling together with their tails twined, nuzzling, and gentle grasping. Titi monkeys are highly territorial and when confronted with another family group, both will respond with threatening behaviour, males showing increased agitation towards intruding males. When not close together, the pair show a significant amount of distress and agitation. Titi monkeys are well known for their vocal communication, and have a complex repertoire of calls. The calls can be divided into two categories: high-pitched quiet calls and low-pitched loud calls. Vocalisations are often combined and repeated to form sequences that are used to indicate distress, conflict, play, bonding, disturbance, and to strengthen territory. The high-pitched quiet calls are mostly used when the monkeys are disturbed, but may also be used before or after group calling, while foraging, or to find other members of the group. The loud low-pitched calls are mostly used in long