Seed dispersal and reforestation by bats in South American rain forests

Background/Question/Methods

In the Neotropics, frugivorous bats (Chiroptera: Phyllostomidae) have been reported as the dispersal agents of at least 549 flowering plant species in 191 genera from 62 families. This number, however, accounts for only about 1% of species in the region, some of which may rely on additional seed dispersers besides bats. So, why have fruit bats become synonymous with tropical reforestation? Previous studies have shown both the large quantities of seeds consumed (a few hundred to 60,000 per night depending on the fruits eaten) and the relatively good quality of dispersal (flying away from parent plant, not damaging seeds, dropping seeds where they are likely to germinate) by bats at single locations, especially in dry forests and secondary wet forests. They also revealed that fruit bats eat a taxonomically non-random subset of fruits with different bat genera specializing on different plant genera, such as Carollia on the pioneer genus Piper and Artibeus on the late-secondary forest species of Ficus. The current study incorporates these findings, but takes a flora-level approach. We focus on all available fleshy-fruited plant species in the 140,250-ha rectangle of primary lowland moist forest in central French Guiana and determine which species rely on bats for seed dispersal. By comparing what plant species are available to what are selected by bats, we can develop a better understanding of the role that fruit bats play in the rain forest regeneration process in primary forests. 

Results/Conclusions

Of the 1,918 native species (133 families) of flowering plants in the study area, 981 have fleshy fruits attractive to animal dispersers and 111  of these were identified in the diets of the 32 obligate and opportunistic frugivorous bats known from central French Guiana. Bat-dispersed species, therefore, account for 6% of the whole flora and 11% of the fleshy-fruited flora. Counter to what has been seen at other locations, over half of the bat-dispersed species in our study area are considered climax species while 39% are pioneer species. Forty-five of the 111 bat-dispersed species have been found in the diets of other vertebrates, bats sharing 27 species with arboreal mammals, 6 with birds, and 12 with both arboreal mammals and birds. The results of this study emphasize the importance of Neotropical bats as seed-dispersers in primary forests, particularly of climax species, and support previous findings that promote their conservation.