Avian communities and vegetation structure in cacao and banana agroforests of Talamanca, Costa Rica

Background/Question/Methods

Identifying the structural elements of agroforests correlated to animal diversity will inform conservation efforts on private lands located in habitat buffers and corridors. We examined the relationships between vegetation structure and avian communities in four shaded agroforestry systems in Talamanca, Costa Rica: abandoned cacao, cacao, cacao with banana, and banana. During two field seasons, we identified 2,791 trees from approximately 59 species and 2,605 birds from 106 species. Indices of species abundance, richness, diversity, and evenness for each agroforestry system were contrasted using analysis of variance; a multidimensional scaling algorithm was used to compare community composition; and the relationships between vegetation parameters and avian communities were explored with regression analysis.  

Results/Conclusions

Canopy, understory, and groundcover vegetation as well as avian community composition differed between systems, while avian species diversity was similar. Agroforestry systems lacking banana had significantly more forest birds and fewer agricultural generalists than systems with banana. Understory- and ground-foraging birds were also more abundant in agroforests without bananas. Small (<15cm diameter) tree diversity and groundcover explained a substantial portion of the variation in avian community composition in one season (r²=0.48). Vegetation measures (e.g. groundcover, canopy height, and small tree diversity) also explained portions of the variation in the abundances of forest birds and understory- and ground-foraging birds. Results indicate that cacao agroforests should be positioned near remnant forest to maximize their conservation value for forest birds, while banana and cacao with banana agroforests should be adjacent to disturbed areas.