Randomness, chaos and confusion in the study of antipredator vigilance

The study of antipredator vigilance underwent a rapid and relatively recent synthesis 15–20 years ago. During the rise of behavioral ecology and sociobiology, researchers began to measure how often animals looked up from feeding. Subsequently, the field of vigilance crystallized quickly around a few striking results and an elegant theory. The convenient mathematical assumptions of this original theory continue to channel researchersʹ attentions today. Although data tend to match these assumptions — flock members scan independently, vigilance sequences are essentially unpredictable, and interscan intervals are highly variable — the assumptions themselves are difficult to justify. Some of our basic ideas about vigilance require detailed re-examination.