The role of cacao plantations in maintaining forest avian diversity in southeastern Costa Rica

摘要

We conducted 600 ten-minute, fixed-radius point counts in two climatically different seasons in forest, abandoned cacao (Theobroma cacao), and managed cacao habitat from September 1997 through April 1998 in the Talamanca lowlands of Costa Rica. A total of 1,464, 1,713, and 1,708 individual birds and 130, 131, and 144 total species were detected in forest, abandoned cacao, and managed cacao, respectively. Independent of season, cacao habitats had a significantly greater number of individuals and species per point than forest. Community similarity analyses based on guild categorizations revealed a significant degree of similarity among all habitats; however, habitat affinity analyses showed cacao habitats having significantly less forest specialists than forest. A multiple linear regression model for actively managed cacao habitat using habitat and landscape variables revealed density and diversity of canopy tree species to be significantly correlated with numbers of forest specialist species detected per point. Although nearest distance to forest was negatively correlated with the number of forest specialist species per point, it was not a significant variable in the model, possibly indicating the complex and unpredictable nature of bird movements within the complex habitat mosaic of Talamanca. The present forest bird community of the Talamanca lowlands is poor in forest specialist species relative to other forested Caribbean lowland sites. The broad patterns of avifaunal distribution illustrated by our results suggest, therefore, that although cacao plantations cannot substitute for forest, they provide habitat for a large number of species which depend to some degree on forests.