Avian Conservation and Ecology (Jun 2019)
Recovery of bird activity and species richness in an early-stage tropical forest restoration
Abstract
Bird habitat creation is often a goal of tropical forest restoration because bird-driven ecosystem services can accelerate forest recovery. However, resident tropical bird responses are not well characterized in the earliest years following restoration action. During a five-year study of the bird community in an experimental tropical forest restoration, we examined temporal trends in bird activity and diversity and the effects of habitat variables on the distribution of bird species within the site. Our site consisted of 16 replicate plots with 1, 2, 4, or 8 native tree species planted into former heavily-grazed pasture. Four years after tree planting, we observed a 3-fold increase in bird activity and 11-fold increase in species richness compared to preplanting. We also found changes in proportions of habitat guilds, with marked declines in open country birds and increases in birds associated with brushy, early secondary growth, and forest edge habitats. Number of bird species observed differed strongly between plots four years postplanting. Using a multispecies occurrence model under a Bayesian framework, we considered possible reasons for these differences related to plot content and context. Content features within plots ("content"), including number of tree species planted, canopy cover, tree species identity, and presence of legacy trees, did not explain differences in number of bird species observed, potentially because of small plot size relative to bird mobility. Neighborhood features ("context") of each plot did explain differences; more bird species were detected in plots with more adjacent woodland and farther from actively grazed pasture. Our results demonstrate that planting native tree species in highly degraded sites can generate rapid, positive responses from tropical bird communities. These responses are likely mediated by surrounding habitat matrix, which influences rates of bird community recovery. Considering site context can improve predictions of fine-scale distribution of bird activity and diversity within restoration sites.
