Abordagem com traços das espécies permite a identificação das relações das aves piscívoras com o ambiente.

Abstract

The identification of environmental filtering on species traits allows the prediction on community dynamics facing environmental disturbances. This study was performed at a floodplain in order to embrace a large range of spatial and temporal environmental gradients. Piscivorous birds were used as the model assemblage since they respond promptly to environmental changes and hence are considered indicator species that track habitat quality. RLQ analysis and fourth-corner approach were performed aiming to identify (i) environmental variables that might influence piscivorous bird abundances within their foraging habitat and (ii) trait combinations of piscivorous bird species that vary according to biotic and abiotic gradients. Three main avian groups were distinguished due to the influence of environmental filters over traits concerning foraging tactics and morphology: wading birds, pursuit swimmers and aerial piscivores. Wading birds are more abundant in shallower and larger lakes that have higher nutrient and dissolved oxygen concentrations, higher primary production but lower conductivity. Pursuit swimmers are more abundant in deeper and larger lakes that have lower nutrient concentration, lower primary production but higher conductivity and higher abundance of larger fish (15 30 cm). Aerial piscivores are more numerous in summer and in larger, deeper lakes that have higher conductivity but lower dissolved oxygen concentration. Thus, morphological and behavioral bird traits are of relevant importance on tracking spatial and temporal food resources variations. Moreover, environmental filters are the determinants of the structure of piscivorous birds assemblage in this floodplain.