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Yellow-tailed woolly monkey
Oreonax flavicauda


O. flavicauda
Photo: Noga Shanee

In general, group size is usually between around 5 to 18 individuals, but groups as large as 30 have been reported (Leo Luna 1980; 1987; Aquino & Encarnación 1994; Butchart et al. 1995; Mittermeier et al. 1977; DeLuycker 2007; Shanee et al. 2007b; Cornejo et al. 2009). Larger groups could possibly be the result of insufficient habitat or seasonal aggregations of individuals (DeLuycker 2007). Groups are typically multi-male/multi-female, and usually contain more than one adult male (one of which appears to be dominant), and several adult females and subadults (Leo Luna 1980; 1987; Parker & Barkley 1981; Aquino & Encarnación 1994). The social organization is possibly fission-fusion (Cornejo 2008). Similarly to the other woolly monkeys (Lagothrix sp.), yellow-tailed woolly monkey groups will split into subgroups for up to several days at a time (Cornejo 2008). A single group had a home range of 0.69 km² (0.27 mi²) and a daily path of under one kilometer (<0.62 mi) (Cornejo 2008).


Very few data exist about reproduction and parental care in yellow-tailed woolly monkeys. They probably have a low birth rate similar to the genus Lagothrix (around 3 years) (Leo Luna 1980; DeLuycker 2007). They may reach sexual maturity when they are older than four years of age, but this has not been demonstrated (Leo Luna 1980).

Juvenile and infant yellow-tailed woolly monkeys do not have the characteristic yellow tail-hairs nor the genital tufts of adult individuals (Thomas 1926; Leo Luna 1982b cited in DeLuycker 2007; DeLuycker 2007).

Males have been seen carrying infants ventrally, while a female was seen carrying a young juvenile on her back (Parker & Barkley 1981; Butchart et al. 1995).


When excited, a bark is emitted and can be heard for some distance (Leo Luna 1980). Alarm calls are emitted in response to potential predators, including raptors (DeLuycker 2007). Adults have been heard calling for prolonged periods of time (ca. 30 mins) (DeLuycker 2007).

When confronted with a threat, male yellow-tailed woolly monkeys will confront the threat with a display which includes showing of the genitals, hip shaking, shaking and throwing tree branches, and occasionally urination and defecation (Leo Luna 1980; 1982a; Butchart et al. 1995; DeLuycker 2007). "Simulated attacks" are also directed at threats sometimes, where the woolly monkey will run and quickly leap into supports above the threat (Leo Luna 1982a).

Content last modified: September 30, 2010

Written by Kurt Gron.

Cite this page as:
Gron KJ. 2010 September 30. Primate Factsheets: Yellow-tailed woolly monkey (Oreonax flavicauda) Behavior . <>. Accessed 2020 July 6.