Variability of forage pecking in pigeons

Abstract

The pecking of birds has been classically considered a fixed action pattern that is little modified by varying internal and external circumstances. Although recent research has documented several instances of variability, the stereotypy of pecking by pigeons continues to be stressed. The present study illustrates the adaptability of the response employing an accelerometric/videographic technique. It is demonstrated that it is influenced by several experimental conditions mimicking natural contexts. The effects of admixture of non-nourishing grit, non-removability of food items, degree of deprivation, application of head loads and grain size, on the detailed course of pecking are described. A number of different, recurring types of pecking patterns were recognized but even within these the frequency, timing, extent, speed, and/or vigour of several component movements varied specifically in response to the various experimental treatments. Appreciable inter- and intraindividual variations still occur under identical conditions. In conjunction with additional evidence it is concluded that the pecking of pigeons exhibits a remarkable flexibility that conforms poorly with a fixed action pattern characterization. Accelerometry promises to be an efficient and economic aid in the analysis of the sensory, neural and motor mechanisms of avian pecking.