The ecology of an African savanna fruit bat community: resource partitioning and role in seed dispersal.

(Uploaded by Plazi for the Bat Literature Project) This study was undertaken to examine the structure of a fruit bat community, its seasonal variation in composition, the mechanisms of partitioning of fruit resources, and the role of the bats as seed dispersers in southern Guinea savanna in Africa. The community is structured on two levels. A group of four species remain resident in the savanna-forest mosaic zone year round and three species invade the community from the southern forest zone seasonally. Diets indicate that the resident species (Epomops buettikoferi, Hypsignathus monstrosus, Lissonycteris angolensis, and Mieropteropus pusillus) forage in three mutually exclusive zones and the diet overlaps between these species are low, except in the case of E. buettikoferi and M. pusillus. The latter two species overlap heavily-in both diet selection and in foraging zone, and evidence is presented showing them to be in severe competition when resources are limiting. They co-exist only in high fruit density patches. The migrant species (Eidolon helvum, Myonycteris torquata, and Nanonycteris veldkampi) invade the community at the onsert of the rains when the diversity of fruit resources increases over the dry season low. Each uses one of the three foraging zones and co-existence is mediated through: 1) the use of different fruit sizes and 2) overlap with the resident species only on fruits that are super-abundant. Dry season limitation of the resident species' populations appears to be important in permitting the invasion of this community. -The seed rain generated by bats and birds was measured with ground-based collecting sheets on transects through the savanna. Seed rains were impressively high, with each square metre receiving on the average 3.3 seed loads annually. Bats accounted for 95.7-98.2% of the measured rain. The bat dominance appears due to the higher proportion of time spent in flight compared with birds. •