The American Zoo and Aquarium Association (AZA) currently sponsors 84 Species Survival Plans (SSPs), programs that manage captive populations of endangered and threatened animals. One SSP, however, was awarded to a species not yet officially listed-the De Brazza's monkey (Cercopithecus neglectus). Unlike many programs whose immediate goal is to prevent extinction, the De Brazza program is proactively working to prevent future need for drastic down-to-the-wire conservation.
The De Brazza's monkey is one of the most unusual species in a group of old world monkeys commonly known as guenons (Nowak 1991; Macdonald 1993). De Brazza's monkeys, also known as swamp monkeys, are primarily found in flooded forests and swamps throughout equatorial Africa. Though good swimmers, De Brazza's are considered arboreal, spending 70% of the time in the understory and 20% on the ground (Gautier-Hion 1988). Unlike other primates, De Brazza's rarely use group calls, and social alarm calls are absent (Maté et al. 1995). Not only are they the only species of guenon that does not respond to alarm calls of other monkey species, they actively avoid any contact with other animals. In rare encounters that do occur, they utilize predatory behaviors of silence and concealment (McGraw 1994). Only when fully threatened will males shake branches and bark to divert attention from the group (Gautier-Hion 1988).
Their diet is omnivorous, primarily consisting of fruits and seeds with supplements of leaves, arthropods, flowers and mushrooms (Staaden 1996). Once a food source has been located, they will visit the source repeatedly, resulting in not even a half-eaten fruit being left behind (Rowe 1996). On occasion, however, they will also eat small birds and mammals (personal observation).
Generally believed to be polygamous, there have been reports of monogamous behavior in certain troops. In the late 1970's, Gautier-Hion and Gautier (Gautier-Hion 1988) investigated a colony in Gabon, finding small, intimate groups of three to four members, consisting of a male, female, and their offspring-a social grouping indicative of monogamy. In contrast, troops in Kenya have been documented to number up to 16 members with a dominant male and several females-a social structure indicative of polygamy (Wahome 1993).
In addition, De Brazza's are strongly sexually dimorphic. On average, males reach 7.8. kg and females 4.5 kg (Nowak 1991). Males become sexually mature at 4 years of age but do not generally breed until 6-8 years. Females mature at 3 years and breed at 4-5 years. (Brennan 1989; Harvey 1985). There is generally a single offspring, although twins have rarely occurred. The gestation period lasts between 177 and 187 days with an interbirth interval of 12 months (Brennan, 1989).
As with most other species, human intrusion is the primary threat to the De Brazza's monkey's survival. Agricultural needs, hunting, logging and living space requirements for a growing human population have resulted in fragmentation of the De Brazza's limited primary habitats. In addition, low fertility rate and high infant mortality make it difficult for De Brazza's to respond to strong anthropogenic forces (Brennan 1989). Approximately 23% of females and 20% of males die before reaching one year of age (Staaden 1996).
Because of superior hiding tactics, population counts are difficult in the wild (Wolfheim 1983). Quris (1976) estimated an approximate population density of 28 De Brazza's monkeys per square kilometer in Gabon, and the CBSG IUCN/SSC Supplement to Global Captive Action Plan for Primates suggested over 100,000 C. neglectus in Africa (Discussion Edition, 15 September 1991). The World Conservation Union (IUCN) gives the De Brazza's monkey a conservation rank of 3 out of 6, with Degree of Threat rated as 1 (i.e. low risk of extinction at present time) and Taxonomic Distinctiveness rated as 2 (i.e. no more then one close relative). It is considered an Appendix II species as defined by the Convention on International Trade in Endangered Species (CITES), while the U.S. Fish and Wildlife Service has not listed this species (Staaden 1996).
Cooperative management of the North American captive population of De Brazza's Monkey began in 1996 with the publication of the first regional studbook. In December of that same year, the AZA approved a petition to manage this species under an SSP. In August 1997, the De Brazza's monkey management team met to determine specific breeding recommendations in an effort to slow the loss of genetic diversity that occurs naturally, over time, in populations of limited size.
As of June 1995, the International Species Information System (ISIS) listed 208 captive De Brazza's monkeys located at 58 institutions throughout the world. The known number of wild-born founders, however, is only 12. Unfortunately, there is a large number of unknown animals at various institutions that are probably wild-born, yet cannot be included as founders. Without the inclusion of these individuals, the captive population has a relatively low Founder Genome Equivalent (FGE) (3.910). If all unknowns were assumed to be wild-born, the FGE would jump dramatically to 21.869. In addition, the SSP committee has calculated an effective population size (Ne) of 31.5, and a mean inbreeding coefficient of 0.035. Using a breeding strategy based on mean kinship values, 15 pairings were recommended from the 85 animals considered for breeding. The group's goal was to maintain at least 90% genetic diversity for 100 years (Staaden 1996). Unfortunately, there has been minimal reproductive success in captivity. Unlike wild females, who have on average produced approximately 2.45 offspring each, the average female in captivity has produced only 1.69 offspring (Brennan 1989).
Relative to other big interest animals, such as gorilla, chimpanzee and elephant, little research has been conducted on the basic biology and husbandry of this animal. Areas of needed research include: 1) accurate assessment of the size of wild populations, 2) further investigation and differentiation of varying colonies of De Brazza's monkeys, 3) evaluation of nutritional requirements, and 4) determination of ways to increase reproductive success in captivity. The development of a De Brazza SSP, however, is an important step for increasing awareness and interest in these unique primates.
Literature cited
Brennan, E.J. 1989. Demographics of captive De Brazza's guenons. Zoo Biology 8:37-47.
CBSG IUCN/SSC Supplement to Global Captive Action Plan for Primates (Discussion Edition, 15 September 1991).
Fay, J.M. 1988. Forest monkey populations in the Central African Republic: The northern limits. A census in Manovo-Gounda-St. Floris National Park. Mammalia 52(1):57-65.
Gautier-Hion, A. 1988. Primate Radiation-Evolutionary Biology of the African Guenon. Cambridge University Press, New York.
Harvey, P.H. and T.H. Clutton-Brock. 1985. Life history variation in primates. Evolution 39:559-581.
Macdonald, D. 1993. The Encyclopedia of Mammals. Facts on File, New York.
Maté, C., C. Montserrat, M. Escobar. 1995. Preliminary observations on the ecology of forest Cercopithecidae in the Lokofe-Ikomaloki Region (Ikela, Zaire). Folia Primatol 64:196-200.
McGraw, S. 1994. Census, habitat preference, and polyspecific associations of six monkeys in the Lomako Forest, Zaire. American Journal of Primatology 34:295-307.
Nowak, R.M. 1991. Walker's Mammals of the World, 5th Edition, Vol. I. Johns Hopkins University Press, Baltimore.
Quris, P. 1976. Donnees comparative sur socio-ecologie de huit especes de Cercopithecidae vivant dans une meme zone de foret primitive periodiquement Inondee (Nord-Est du Gabon). Terre Vie 30:193-209.
Staaden, S. 1996. North American Regional Studbook for De Brazza's Monkey, Cercopithecus neglectus, First edition. North Carolina Zoological Park.
Wahome, J.M. 1993. The De Brazza's monkey: A species under siege in Kenya. Swara 16:33-34.
Wolfheim, J.H. 1983. Primates of the World: Distribution,
Abundance, and Conservation. University of Washington Press, Seattle.
Curtis Eng, D.V.M. is the Staff Veterinarian and Assistant Director of the Potawatomi Zoo in South Bend, Indiana. Dr. Eng is also a member of the De Brazza's monkey SSP committee.
Archives | Bulletin Board | Comments | Contribute to the ESU | ESU Staff | Home | Links | March/April 1998 Contents | Next Issue | Search by Keyword | Subscriptions