Aspects of the ecological flexibility of the Tana mangabey (Cercocebus galeritus) in its fragmented habitat, Tana River, Kenya
Wieczkowski, Julie Ann
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This dissertation investigated the ecological flexibility of the Tana mangabey (Cercocebus galeritus) and its use of a fragmented habitat, within the context of its ecological flexibility. The Tana mangabey is one of the world’s most endangered primates, endemic to a 60-kilometer stretch of the lower Tana River in Kenya. The strength of this study is in its examination of both the mangabey’s diverse habitat and its behavior. The research had two major foci. One examined the ecological correlates of mangabey abundance, with the goal of recommending management strategies. The other extended the temporal investigation of the mangabeys’ ecological flexibility by studying one mangabey group that was also studied in 1974 and in 1988-89. Thirty-one study forests were selected throughout the mangabeys’ distribution. One hundred and seven vegetation belt transects were sampled and 307 mangabey surveys were conducted in these study forests. From August 2000 until July 2001, monthly 3-day samples were conducted on the mangabey group to collect behavioral, dietary, and ranging data. In addition, phenology was monitored monthly in 226 trees in 11 species across the three forests visited by that group. The Tana mangabey was found to be very general in its habitat needs; the mean number of mangabey groups per forest was positively associated with forest size, density of trees = 10 cm diameter at breast height, and basal area of the top 15 food species (in forests within the Tana River Primate National Reserve). Behavioral changes exhibited by the study group can be linked to the group’s increased size and diet differences. Although ecological explanations for dietary changes are limited, it was found that the mangabey does not consume ripe fruit in relation to availability. Instead, they concentrate on ripe fruit, ripe seed, unripe fruit, and/or unripe seed on a species-specific basis. Finally, the most important reason for the group’s expansion of its home range was the increased group size. Overall, the research supports the conclusion that the general habitat needs and ecological flexibility of the mangabey aid their survival in their highly diverse and fragmented habitat.