The Occurrence, Context and Functional Significance of Aggressive Begging Behaviours in Young American White Pelicans
Authors: Cash, Kevin J.; Evans, Roger M.
Source: Behaviour, Volume 102, Numbers 1-2, 1987 , pp. 119-128(10)
Abstract:Aggressive behaviours occurring in association with about 90% of all feedings developed in American white pelican chicks approximately three weeks old. These behaviours involved aggression directed toward self (Convulstion) and other young (Aggression). Observation of feedings revealed that: (1) when both Convulsion and Aggression occurred before or after a given feeding, convulsion bore a closer temporal relationship to the feed itself than did Aggression, (2) the frequency of both Aggression and Convulsion prior to feeding increased as the length of the begging bout increased, (3) the frequency of Convulsion and Aggression following feeding was not related to the duration of the feed but did depend on the amount fed (as measured by throat distension). Observations of identifiable parents and chicks revealed that most chicks receive a single feeding each day, each parent returning to the colony every two days. The frequency of multiple feeds given to the same chick on the same day or (by the presumed same parent) two days later was not related to the frequency of Aggression or Convulsion given after a feeding. The close association of these displays with feeding and low-intensity begging suggests that they function primarily as begging displays or, for Aggression, to drive other young away from the parent food source. Evidence suggesting that Convulsion may be a manifestation of parent-offspring conflict is discussed. Alternative proposed functions of Convulsion and Aggression are not supported by data collected in this study.
Document Type: Research article
Publication date: 1987-01-01