Group size and disturbance effects on group vigilance in the Great Bustard Otis tarda in western China

Abstract

Capsule Great Bustards Otis tarda gained vigilance benefits from increasing group size: they showed a negative correlation between group size and the percentage of individuals scanning, and a positive correlation between group size and the percentage of time with at least one individual scanning. The relationship between vigilance and group size was independent of level of disturbance but individual vigilance was higher closer to a road. Higher group size and provision of continuous areas of high-quality habitat away from disturbance allows Great Bustards to reduce individual vigilance and so potentially increase investment in feeding time and their survival.