PrimatesId code: amd068
(Eng) Owl-faced or Hamlyn's guenon
(Fre) Cercopithèque à tête de hibou
Two subspecies have been described: C. h. hamlyni and C. h. kahuziensis (Lernould, 1988).
IUCN threat category
Lower Risk, near threatened (LR: nt) as C. hamlyni, but Vulnerable (VU: criteria A2c) as C. h. kahuziensis (Kahuzi Owl-faced monkey) in former Zaire and possibly in Rwanda.
No specific studies on the species’ ecology have been carried out. Data on its occurrence are available for part of former Zaire (Colyn, 1987; 1988; Rahm & Christiaensen, 1966) and Rwanda (Monfort, 1992). An overall view of the species’ distribution is given by Lernould (1988). The authors mentioned above also report on the ecology of the species, particularly its habitat. General information on the biology of the species is found in Kingdon (1997) and Stuart & Stuart (1997). Status, threats, and distribution are discussed in Lee et al. (1988).
Known extent of occurrence
The distribution map was obtained from Lernould (1988) and Colyn (1988); its boundaries were adjusted using the river network and Colyn (1987, 1988) and Kingdon (1997). Fig. 2.3.12.a shows the current range of this species in East former Zaire (Ituri and Kivu districts), Uganda (Lee et al., 1988) and Rwanda, with the Lukuga River bounding the southern limit, the Zaire-Lualaba the western one (Colyn, 1987) and the Ituri-Epulu Rivers probably delimiting the northern one.
Categorical-discrete (CD) distribution model
Lowland forest are likely to have been recently colonised; the primary habitat type is dense montane forest (Kingdon, 1997; Lee et al., 1988; Rahm & Christiaensen, 1966).
Based on these environmental preferences, the following scores were assigned (Fig. 2.3.12.b) (Tab. 2.3.12.a):
Tab 2.3.12.a: Cumulative size (km2) of areas pertaining to each environmental suitability class within the Extent of Occurrence.
Tab 2.3.12.b: Area of Occupancy fragmentation indexes.
Probabilistic-continuous (PC) distribution model
The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.12.c.
No occurrence of the species within the four sample areas.
Comments and conservation issues
The known EO of this species largely overlaps with that of Cercopithecus lhoesti but is much smaller. About a third of the known EO appears to be unsuitable, especially in the eastern and southern parts of the range. The AO appears to be only slightly fragmented (LPI = 94.64%) and interspersed with unsuitable areas on the eastern and southern edges (AWMSI = 8.32). About 5.6% of the total AO is included in existing protected areas.
Tab 2.3.12.c: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.
Colyn M.M. (1987). Les primates de la foret ombrophile de la Cuvette du Zaire: interprétations zoogéographique des modèles de distribution. Rev. Zool. Africaine: 101, 183-196.
Colyn M.M. (1988). Distribution of guenons in the Zaire-Lualaba-Lomani river system. In: Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York: pp 104-124.
Kingdon J. (1997). The Kingdon field guide to African Mammals. Academic Press, London and New York: Natural World.
Lee P.C., Thornback J., Bennet E.L. (1988). Threatened Primates of Africa. IUCN, Gland - Switzerland and Cambridge, UK.
Lernould J. (1988). Classification and geographical distribution of guenons: a review. In: Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York: pp 54-78.
Monfort A. (1992). Première liste commentée des mammifères du Rwanda. Rev. Zool. Africaine: 106 (2), 141-151.
Rahm U., Christiaensen A. (1966). Les mammiferès de l'Ile Idjwi (Lac Kivu, Congo). Les mammifères de la foret equatoriale de l'est du Congo. Ann. Mus. Roy. Afr. Cent.: n° 149.
Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers.