Primates Id code: amd067Cercopithecidae Cercopithecus erythrotis Waterhouse, 1838 (Eng) Red-eared guenon (Fre) Moustac à oreilles rousses Taxonomic notes Considered a subspecies of C. cephus by some authors, it has been regarded as a full species here in accordance with Wilson & Reeder (1993) and Oates (1996), but its classification needs to be clarified. According to Kingdon (1997) two subspecies may be recognised: C. e. camerunensis (between Cross/Benue and Sanaga Rivers), C. e. erythrotis (endemic to Bioko). C. sclateri, included in C. erythrotis by Lee et al. (1988), has been recognised as a distinct species (Wilson & Reeder, 1993; Oates, 1996). IUCN threat category Vulnerable (VU: criteria A1c) as C. erythrotis, but Endangered (EN: criteria B1+2abce) as C. e. erythrotis (Fernando Po red-eared monkey) on Bioko Island. Available information Literature available on the ecology of the species is quite poor. No specific studies on habitat use and requirements have been conducted, except for the one by Gonzalez-Kirchner (1996), who investigated habitat use, density, and interspecific relationships on Bioko Island. Some information on its feeding habits, habitat, and coexistence with other primates is found in Gartlan & Struhsaker (1979), who did research on the species in Cameroon. Data on the species’ distribution are found in Butynski & Koster (1994), Lernould (1988) and Oates (1988); the authors mentioned above also give some information on the ecology of the species, particularly its habitat. General information on its ecology and distribution is found in Kingdon (1997), Eisenberg et al. (1979) and Stuart & Stuart (1997). Status, threats and conservation issues are discussed in Lee et al. (1988) and Oates (1996). Known extent of occurrence 
C. erythrotis is present only in south and east Nigeria, North Cameroon and on Bioko Island, in Equatorial Guinea (Wilson & Reeder, 1993). The distribution range was obtained joining the mainland map from Gautier-Hion et al. (1988) with the Bioko map from Butynski & Koster (1994) and then adjusted using the river network and Kingdon (1997) (Fig. 2.3.11.a). Categorical-discrete (CD) distribution model This species prefers primary lowland forest; it is also found in secondary forest and seasonally flooded forest (Gonzalez-Kirchner, 1996; Kingdon, 1997; Lee et al., 1988; Butynski & Koster, 1994). Based on these environmental preferences, the following scores were assigned (Fig. 2.3.11.b) (Tab. 2.3.11.a):
Tab 2.3.11.a: Cumulative size (km2) of areas pertaining to each environmental suitability class within the Extent of Occurrence.
Tab 2.3.11.b: Area of Occupancy fragmentation indexes. Probabilistic-continuous (PC) distribution model The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 2.3.11.c. Validation
Tab 2.3.11.c: Categorical-discrete (CD) distribution model validation parameters. Comments and conservation issues Only half of the known EO is covered by primary forests which are the preferred vegetation types for this species. The total AO is small (70 000 km2) but overall fragmentation is limited: the two classes of suitability are very interspersed as shown by the small NP and high LPI for the total AO. Although the Index of Accordance (41.67%) suggests some caution in interpreting the CD model’s results, both models show that the unsuitable areas are widely scattered throughout the range and that their possible expansion would increase the fragmentation of the suitable areas. The parts of AO on Bioko are inevitably small and this prompted the threatened status of that population. About 7% of the total AO is included in existing protected areas.
Tab 2.3.11.d: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas. References Butynski T.M., Koster S.H. (1994). Distribution and conservation status of primates on Bioko Island, Equatorial Guinea. Biodiversity Conserv: 3(9), 893-909. Eisenberg J.F., Muckenhirn N., Rudran R. (1979). The relations between ecology and social structure in primates. [reprinted from Science (1972), 176: 863-874]. In: Sussman R.W. (Ed.). Primate Ecology. Problem-oriented field studies. Wiley, Chichester & New York. chap. 23: 455-484. Gartlan J.S., Struhsaker T.T. (1979). Polyspecific associations and niche separation of rain-forest anthropoids in Cameroon, West Africa. In: Sussman R.W. (Ed.). Primate Ecology. Problem-oriented field studies. Wiley, Chichester & New York: pp 155-164. Gautier-Hion A., Bourlière F., Gautier J., Kingdon J. (Eds) (1988). A Primate Radiation: Evolutionary Biology of the African Guenons. Cambridge University Press, New York. Gonzalez-Kirchner J.P. (1996). Notes on habitat use by the Russet-eared guenon (Cercopithecus erythrotis Waterhouse 1838) on Bioko Island, Equatorial Guinea. Tropical Zoology: 9, 297-304. 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. Oates J.F. (1988). The distribution of Cercopithecus monkeys in West African forests. 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 79-103. Oates J.F. (1996). African Primates Status Survey and Conservation Action plan. IUCN/SSC Primate Specialist Group. Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers. Wilson D.E., Reeder D.M. (Eds) (1993). Mammal Species of the World: A Taxonomic and Geographic Reference. Second edition. Smithsonian Institution Press, Washington D.C.
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