Intermediate flock sizes are best, allowing a balance between vigilance and feeding. The paper reports on a field experiment designed to investigate the initial detection of an aerial predator and the escape response by wild laughing doves Streptopelia senegalensis while feeding as members of flocks of different size. Results indicate that, within certain limits, a large flock has a higher probability of detecting an approaching predator than a small flock. Discussion centres on the gregarious habits of doves in hot arid country, focusing on flocking at water holes.