Quantitative analysis of foraging habitat use by ciconiiformes in the upper Paraná river Floodplain, Brazil

ABSTRACT

The aim of this study was to analyze the seasonal variations in habitat selection and abundance of Ciconiiformes species in four foraging habitats (rivers, channels, connected and disconnected lagoons) on the upper Paraná River floodplain, Brazil, and to conduct the surveys of wading birds in 2002 and 2003. The largest number of species and highest abundances of most species were observed in the connected lagoons. Snowy Egrets (Egretta thula), Wood Storks (Mycteria americana), Roseate Spoonbills (Platalea ajaja), and Jabirus (Jabiru mycteria) frequently used connected lagoons (habitat with the highest fish abundance) and abandoned the areas during floods, suggesting that they were able to find high quality patches for foraging. Cocoi Herons (Ardea cocoi), Great Egrets (Ardea alba), and Rufescent Tiger-Herons (Tigrisoma lineatum) used habitats with lower fish abundance and did not totally abandon these areas during floods, suggesting they were not dependent on high quality patches. Differences in foraging techniques and social behavior explained the difference between the two groups. The results showed that opportunism did not totally explain the foraging habitat selection and in low water level seasons there were higher differences in foraging behavior among the species.