Cercopithecus hamlyni, Pocock, 1907

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 550-755 : 687

69.

Owl-faced Monkey

Cercopithecus hamlyni

French: Cercopitheque de Hamlyn / German: Eulenkopfmeerkatze / Spanish: Cercopiteco de Hamlyn

Other common names: Hamlyn’s Guenon, Hamlyn’s Monkey, Owl-faced Guenon; Mount Kahuzi Owl-faced Monkey (kahuziensis), Nose-stripe Owl-faced Monkey (hamlyni)

Taxonomy. Cercopithecus hamlyni Pocock, 1907 ,

Democratic Republic of the Congo, Ituri Forest.

C. hamlyni is placed in its own species group. Lowland and highland forms of C. hamlyni differ in cranial morphology and are classified as subspecies: hamlyni and kahuziensis. In their 2003 review of the taxonomy of the African primates, P. Grubb and colleagues acknowledged doubts expressed by J. Hart concerning the validity of kahuziensis and indicated the need for further study. Two subspecies recognized.

Subspecies and Distribution.

C.h.hamlyniPocock,1907—EDRCongo,fromthelowlandsoftheRiverLualabaEtoIturiForestandtheAlbertineRiftinWRwanda(NyungweForestNationalPark),andextendingNtotheLindi-Nepokosystem,andStothelimitoftherainforest(poorlydefined);possiblyfoundinSUgandaandNBurundi.

C. h. kahuziensis Colyn & Rahm, 1987 — E DR Congo, Mt. Kahuzi in the Albertine Rift Mts.

Descriptive notes. Head-body 55 cm, tail 57 cm (males; no measurements for females); weight 5-5 kg (males) and 3.1-3.7 kg (females). Males are larger than females. The Owl-faced Monkey has dark and dense grizzled gray pelage that is elongated to form a hood over its crown and cheeks. Hairs are gray at the base, with four or five alternating light/dark band pairs. Scrotum is blue. The “Nose-stripe Owl-faced Monkey” (C. h. hamlyni ) has a narrow white stripe running down its nose from the interocular region to the border of the upper lip, which with a white brow band forms the characteristic “T” of white on its face. Its body is olive-green to yellow-gray, varying in tone. There are silver-gray hairs on backs of thighs, perianal region, and base oftail. Its underside, limbs, and distal half of tail are black. The “Mount Kahuzi Owl-faced Monkey” (C. h. kahuziensis) has a darker body, an olive-green back, and entirely black facial hairs, except around eyes where they are a lighter grayish. It has no white nasal or brow band. Its tail is shorter than its head-body length.

Habitat. The Nose-stripe Owl-faced Monkeylives in a variety of forest habitats including lowland and mid-montane moist forest and secondary growth forest. It has been reported in open canopy forest with a dense understory. The Mount Kahuzi Owl-faced Monkey occurs in montane bamboo forest. Owl-faced Monkeys occur at elevations of 600-3300 m; the Mount Kahuzi Owl-faced Monkey occurs above 3000 m in both Tshiberimu and Kahuzi.

Food and Feeding. Owl-faced Monkeys eatfruit, seeds, young and mature leaves, flowers, bark, lichen, and insects. In higher elevation habitats, Mount Kahuzi Owl-faced Monkeys eat leaves and shoots of bamboo and leaves, shoots, pith, and stems of wild celery ( Peucedanum , Apiaceae ) and Vernonia (Asteraceae) . They also eat fruits such as blackberries ( Rubus , Rosaceae ), and those of Podocarpus (Podocarpaceae) , Myrica (Myricaceae) , Schefflerea ( Araliaceae ), Dombeya (Malvaceae) , and Cassipourea (Rhizophoraceae) .

Breeding. In captivity, neonatal Owl-faced Monkeys weigh 280 g. The time from birth to weaning is ¢.8-5 months. The infant first begins to climb at two weeks. Only the mother cares for the young. There is an apparent birth season in June-October in at least part of its distribution. Life span in captivity is twelve years.

Activity patterns. Owl-faced Monkeys are diurnal and semi-terrestrial. They spend more than 60% of their time on the ground and show a preference for lower levels of the forest canopy at heights of less than 10 m. Locomotion is quadrupedal. Climbing was reported for 30% of the time, with vertical clinging and leaping reported at 10%.

Movements, Home range and Social organization. Owl-faced Monkeys live in maledominated, unimale-multifemale or multimale-multifemale social groups. Monogamy is facultative. Group sizes are 2-22 individuals. Solitary individuals are frequently observed.

Status and Conservation. CITES Appendix II. Classified as Vulnerable on The IUCN Red List, but the two subspecies have not been assessed. The Owl-faced Monkey is listed as Class B in the African Convention on the Conservation of Nature and Natural Resources. It has undergone declines in the past and continues to fall in numbers. Bamboo is often harvested in the montane forests where it occurs. It is rare in DR Congo and Rwanda but relatively abundant in Mount Kahuzi-Biéga National Park. Its entire distribution is in a region of intense conflict, where civil war has exacerbated identified threats. Declines will probably continue in the face of the ongoing political climate of the region, resulting in an overall population reduction of more than 30% over 30 years (three generations).

Bibliography. Colyn (1988), Colyn & Rahm (1987), Gautier-Hion & Gautier (1978), Gautier-Hion et al. (1999), Goodwin & Kaplin (2011), Groves (2001, 2005b), Grubb et al. (2003), Hall et al. (2002/2003), Hart & Butynski (2008), Hill (1966), Kingdon (1997), Rahm (1970), Thomas (1991), Williams (2000).

Figures

69. Owl-faced Monkey (Cercopithecus hamlyni), 70. Lesula (Cercopithecus lomamiensis), 71. Spot-nosed Monkey (Cercopithecus petaurista), 72. Red-bellied Monkey (Cercopithecus erythrogaster), 73. Sclater’s Monkey (Cercopithecus sclateri), 74. Red-eared Monkey (Cercopithecus erythrotis), 75. Mustached Monkey (Cercopithecus cephus), 76. Red-tailed Monkey (Cercopithecus ascanius)

Subspecies and Distribution. C.h.hamlyniPocock,1907—EDRCongo,fromthelowlandsoftheRiverLualabaEtoIturiForestandtheAlbertineRiftinWRwanda(NyungweForestNationalPark),andextendingNtotheLindi-Nepokosystem,andStothelimitoftherainforest(poorlydefined);possiblyfoundinSUgandaandNBurundi. C. h. kahuziensis Colyn & Rahm, 1987 — E DR Congo, Mt. Kahuzi in the Albertine Rift Mts.