Identification

Measurements: Head and body length is estimated to be approximately 40-55cm for females and 50-65cm for males, with the average tail length estimated between 50-65cm (Kingdon, 1997). Female owl-faced monkeys are estimated to be 4.5-6kg, and males approximately 7-10kg (Kingdon, 1997).

Adult owl-faced monkeys are olive-gray and black colored monkeys. Their thick coat is typically blackest or darkest along their underbelly, the underside of their hindlimbs and their arms. Their backs have a olive-gray tint. The most distinguishing feature of the adult owl-faced monkey is its facial pattern. The face is divided by a horizontal yellow-cream to white colored stripe across their brow and a white stripe that exists from the brow to the lip area. The two stripes form (what has been described as) a "T" shaped facial marking.

Neonates have at first a yellowish brown coat, and later, a thin black ring of fur around its face. The neonate coat gradually changes to adult coloring (Rowe, 1996 and Kingdon, 1997). Owl-faced monkey fur is fine, dense and long.

Both male and female adult owl-faced monkeys have bare, blue-skinned buttocks and genital regions, the male genitalia area being commonly brighter. Adult males have a blue scrotum and reddish-pink penis. The genitalia of maturing adolescent owl-faced monkeys, particularly adolescent males, do not have as large or as brightly colored scrotums as the adult males. In captivity scrotum size and genitalia coloration is associated with the degree of sexual maturity of the owl-faced monkey, though it has not been well documented. A study conducted by Dobroruka (1966) upon a closely related species to owl-faced monkey, C. neglectus, or De Brazza's Monkey, reported a correlation between aggressive behavior and adult coloring. The study proposes that group dynamics have a significant effect upon the hormonal control in maturation (Dobroruka, 1966).

Owl-faced monkeys are dimorphic, the male being typically larger than the female. Beaver College researcher Spearman (1997) reported four distinctly different vocalizations of owl-faced monkeys in captivity; the boom call, the cough/chit/click vocal, the female's screech and male's grinding vocalizations during copulation. The species is often also described as being exceptionally "wary," or very cautious (Kingdon, 1997).