Notas sobre o comportamento alimentar do Anu branco, Guira Guira (GMELIN, 1788) (Cuculiformes, Aves)

Abstract

The feeding behaviour of a group of Guira cuckoos, Guira guira, freee in nature, was observed at the campus of FUEL, Londrina, PR. Feeding occurs all day with frequent interruptions when maintenance activities (sunning, preening, etc) take place. Feeding areas are open and have few trees. The type of food is mainly grasshoppers but some small vertebrates are also included. Feeding behaviour is a communal activity. The process includes the fallowing steps: lo. — Group previously perched at a high place not far from the feeding ground. 2o. - Progressive flights down to the ground; individuals frequently giving a caracteristic flight call. 3o. - On the ground the tecnique of capturing is similar to "disturb and chase". This activity is performed by birds in a group which facilitates the capture of escaping prey. The organization of the group walking on the ground is not rigid but presents a tendency to make paralel lines in the direction of locomotion. There is frequently a bird perched above the ground whose function could be to give alarm when terrestrial predators are present. Different mechanisms to keep the group together seem to exist. Among them, contrasting visual patterns, a large number of social calls and certain behavioural social patterns, appeared to be of importance. These are possible evidence for the adaptive value of their social structure.