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 neither temperature or elevation change.

Time period

Present day

Major Taxa Studied

Tropical Forest Birds.

Methods

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