The diet of this diurnal species consists of fruits, seeds, herbaceous plants, insects and small vertebrate prey (8). Although spending much of their time on the ground during the day, groups will sleep in the canopy, 10 to 15 meters above the ground (9). Mean group size for this species is 17 individuals (8) (10), consisting of one male and multiple females, although solitary males are known to occur (6) (8). The sun-tailed monkey has a polygynous mating system (9), and adult males will actively defend their groups from other males trying to usurp them (11). Whilst males disperse from their natal group, females remain, and a dominance hierarchy exists amongst these females, which is subsequently inherited by their offspring (11). The sun-tailed monkey gives birth to a single offspring, and the age of first reproduction for females is about 4 years old (9).

The sun-tailed monkey was first described in 1986 (1). It is a close relative of L'Hoest's Monkey, (Cercopithecus lhoesti), and Preuss's monkey (C. preussi), and in many ways resembles these primates with their dark grey coats, white markings, and long tails (4) (5).

This species is endemic to central Gabon with a total range thought to be in the order of 11,000-12,000 km² (encompassing the Forêt des Abeilles). The species has been recorded west of the Offoué River within Lopé National Park, but not to the west of 11.50°E; the westerly limit remains unclear. The recorded eastern limit is the Ogooué R. The southern limit is also unclear, but it extends apparently to the foothills of the Massif du Chaillu (Gautier et al. 1992; Brugiere and Gautier 1999).

This species is endemic to Gabon, West Africa (4). It has a fragmented distribution area estimated at about 10,300 km², mainly centred in the Foret des Abeilles in central Gabon (6). This range is limited to the north and east by the Ogooue, Lolo and Bouenguidi rivers though it is not clear to what extent this primate occurs to the west and south of the Foret des Abeilles (6). More recent research suggests that this species occurs in the southern parts of the Lope National Park (5).

Habitat and Ecology

Systems

• Terrestrial

Inhabits hilly primary and secondary moist evergreen forest (1) (2). The sun-tailed monkey is a predominantly terrestrial primate (7).

Observations: Little is known about the longevity of these animals, but one specimen estimated to be 18 years old is alive in captivity (Richard Weigl 2005).

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 2000
  Vulnerable
• 1996
  Vulnerable
  (Baillie and Groombridge 1996)
• 1994
  Endangered
  (Groombridge 1994)
• 1990
  Vulnerable
  (IUCN 1990)
• 1988
  Vulnerable
  (IUCN Conservation Monitoring Centre 1988)
• 1988
  Vulnerable

Classified as Vulnerable (VU B1+2abcde, C1) on the IUCN Red List 2004 (1), and listed on Appendix II of CITES (3).

Population

Population Trend

Major Threats

This monkey has a restricted range and is therefore highly at risk from habitat loss and fragmentation (1). While the area of Lope is relatively well protected, the Foret des Abeilles has been opened up to timber exploitation (5). As the forests become accessible for logging, the wildlife becomes more susceptible to hunting by locals for meat. In addition, the sun-tailed monkey is semi-terrestrial and so is at risk from being trapped in ground snares (5).

Conservation Actions

The Gabonese government declared the sun-tailed monkey as a fully protected species in 1994 (5), and it is now considered a flagship species for conservation in Gabon (2). The future of this species rests with its protection within its range, and of its habitat. It will be important to determine this primate's distribution more precisely, and monitor the planned logging operation in the Foret des Abeilles and Lope closely (5).