The biotic interactions hypothesis partially explains bird species turnover along a lowland Neotropical precipitation gradient

Aim: We evaluated the influence of climate in determining bird communities along precipitation gradients. We argue that mechanisms responsible for community turnover along precipitation gradients are similar to mechanisms operating along temperature and latitudinal gradients. We test the hypothesis that environmental conditions affect community composition in dry forests, whereas biotic interactions affect community composition in wet forests.

Location: Low-elevation forests along a precipitation gradient in Colombia where precipitation ranges from 700 – 4000 mm annually but elevation and temperature remain constant.

Time period: Present day

Major Taxa Studied: Tropical Forest Birds.

Methods: We performed 291 bird counts in nine study areas across the ~3000 mm precipitation range. In each locality we obtained climatic characteristics, and a phylogenetic, morphological and physiological proxy data set to test predictions about the evolutionary relationships and distribution o...