COMPORTAMIENTO AGRESIVO ENTRE POLLUELOS DE Pelecanus occidentalis murphyi (AVES: PELECANIDAE) EN EL PARQUE NACIONAL NATURAL GORGONA: RELACIÓN CON ETAPAS TEMPRANAS DE DESARROLLO, TAMAÑO DE NIDADA Y ALIMENTACIÓN

Abstract

In many species of nidicolous birds the nestlings compete for food by fi ghting each other. In the Brown Pelican such behavior occasionally leads to fratricide, and is determinant for the chicks’ survival. In this research the role of age, brood size, amount of food, and feeding method in aggressive behavior was evaluated in nestlings of Pelecanus occidentalis murphyi. In Gorgonilla islet (NNP Gorgona), data were gathered from March to May 2011 on the aggressive behavior of 30 nests in the fi rst three stages of development. Non parametric tests and binary logistic regression were used for evaluation of the incidence of aggression. Nestlings in the third stage had almost ten times more probability of exhibiting aggressive behavior. Direct feeding events showed a greater incidence of aggression. Amount of food and brood size had no signifi cant effect in the incidence of aggression in nestlings. Logistic regression is recommended to integrate more variables in future investigations. This research aims to contribute to the understanding of the ecological constraints that operate on the behavior of P. o. murphyi during early development in the Gorgona NNP colony.