Distribution of the community of frugivorous birds along a successional gradient in a tropical dry forest in south-western Mexico

Abstract

Abstract:Few reports have described the relationship between the distribution of frugivorous birds and vegetation successional changes in dry forests. We assessed the abundance and behaviour of frugivorous birds in early, intermediate and mature dry forests in the Balsas river basin, Guerrero, Mexico. We selected nine dry-forest fragments, three fragments per stage, in these three stages of succession. We analysed the vegetation, estimated bird abundances in 10-min count periods, and recorded the way birds process fruits in circular plots (11–15 plots per fragment, 123 plots in total). Birds were classified as seed predators (15% of all individuals in this study), pulp consumers (15%) or legitimate dispersers (70%). Bird abundance was higher in mature forests in the dry season, while abundance and richness of legitimate dispersers and seed predators were positively related to vegetation complexity. Mature forests have a high vegetation complexity and a high cover ofBurseraspecies that produce fruit during the dry season. During the rains, abundance was higher in early-successional sites when the zoochorous plants produced fruit. Legitimate disperser migrants (i.e.Tyrannus vociferans, Myiarchus cinerascensandM. tyrannulus) were widespread, helping the establishment of zoochorous trees such asBurseraspp. in early-successional forests.