Stereotyped adjunctive pecking by caged pigeons

Abstract

The behavior of 77 pigeons maintained at 80% of their free-feeding weights in open-wire battery cages was monitored 16 times a day by observers for up to 285 days. Five distinct types of stereotyped behaviors were operationally defined. One of these behaviors, "spot pecking," clearly predominated. Forty-nine of the 77 pigeons were observed spotpecking on at least 25% of the days they were observed, and several pigeons emitted more than 50,000 spot pecks per day. This occurred in spite of the total absence of any explicit reinforcer. A series of three experiments demonstrated that the great majority of spot pecks occurred in the hours immediately after feeding, that only food-deprived birds spot pecked, and that the behavior of adjacent birds influenced the rate of acquisition of stereotypes. Difficulties with labeling spot pecking as superstitious, respondent, or mediating are discussed. It is suggested that spot pecking be classed as an "adjunctive" behavior. © 1980 Psychonomic Society, Inc.