Negative trends in bird abundance are strongly correlated to rainfall decline in a Central American tropical forest

Abstract

Climate change is considered one of the main factors threatening biodiversity. Weather is of major importance for bird population dynamics, but the implications of climate change have only recently begun to be addressed, especially for tropical birds. For Northern Central America, climate change scenarios for 2050 predict a reduction in precipitation across the region, with decreases ranging from 4–19% of current rainfall. In this work, we addressed the relationship between temporal changes in precipitation amount and bird community dynamics in eastern tropical Guatemala, for a time period of 18 years (1993–2010). Data consisted of yearly captures and recaptures in four sites, located at elevations between 100–750 masl, and analyses were carried out for total captures and for six foraging guilds. Statistical analyses consisted of Poisson regressions, where estimated abundance (taking into account recapture probability) was modelled as a function of wet-season, dry-season, and annual rainfall, and temporal trend. We detected strong declines in total abundance and in the abundance of nectarivores, omnivores, frugivores, and, to a lesser degree, foliage insectivores. These declines were strongly associated with declines in rainfall amount, generally during the rainy season. A more comprehensive understanding of the effects of climate change on animal abundance in tropical ecosystems is strongly needed to propose conservation and management actions in these biodiverse ecosystems.