Seed dispersal effectiveness of samango monkey (Cercopithecus albogularis schwarzi)
The effectiveness of a seed disperser is dependent on the impact it has on plant fitness. For fruiting species, plant fitness is dependent on the behaviour of its mutualists in (a) reducing seed mortality and (b) increasing the likelihood of future reproduction. The main aim of this thesis was to assess how intergroup variability in the feeding and movement behaviour of a highly social frugivore, influences seed dispersal effectiveness (SDE) and plant fitness. I achieved this by deconstructing the different components of seed dispersal, the quality of dispersal and the quantity of dispersal and investigated how the behaviour of samango monkeys influenced each component. Germination experiments demonstrated that although removal of germination inhibiting fruit pulp through seed-spitting increased germination potential compared to the mechanical and scarification of seeds via seed-swallowing, plants may trade quality for quantity, as the SDE of samango monkeys was greater for swallowed seeds. Time budget analysis showed that intergroup variability in feeding behaviour led to differences in the quantity of seeds dispersed by each group Movement behaviour analysis showed that differences in habitat quality influenced the quality of dispersal. Gut passage time analysis provided a reliable estimate of a gut passage time window between 16.63 – 25.12 hrs. The findings of this study highlight intergroup variability in SDE of neighbouring groups of social foraging frugivores, which possibly arose through ecological constraints associated with group size (Janson & van Schaik 1988; Chapman & Chapman 2000b). Intergroup variability in SDE could have important consequences on the maintenance of forest systems and the recruitment in, and colonization of, secondary forest or open habitats. Variation in SDE within animal populations can have important implications for spatial demographics in plant communities, and this thesis highlights the importance of including intergroup variability seed dispersal models.
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