Effects of Vegetation Traits on Habitat Preferences of Frugivorous Birds in Atlantic Rain Forest

Abstract

ABSTRACTStructural and floristic components of vegetation and fruit production were examined to evaluate the relative importance of each vegetation aspect on patterns of habitat use and to determine whether differences in degree of frugivory would affect sensitivity of birds to vegetation components. Abundances of 12 bird species were quantified in four different habitat types in the Southeastern Atlantic rain forest of Brazil using captures with mist nets. Structural and floristic traits and fruit production were sampled within plots along the mist net lines. Best explanations for the variation in species abundance were obtained by different combinations of the vegetation components (generalized linear models, Akaike information criterion; R2 mean values = 0.48, Δ AICc= 0). Although each species had a particular preference for some vegetation variables, floristic components stood out in those relationships, generating models with a stronger explanatory capacity (R2 > 0.40) and higher levels of empirical support (Δ AICc= minimum values). The variation in bird sensitivities to the floristic component was associated with bird dependence on a fruit diet: there was a correlation between the explanatory capacity of models built with only floristic composition and a species' degree of frugivory (Spearman rank correlation, r= 0.66, P= 0.04), indicating that floristics had a higher effect in more frugivorous birds. For the other vegetation components, there was no clear pattern with statistical support. These results indicate that sensitivities of bird species to vegetation aspects are associated with their dependence on a fruit diet.