Duration of ‘peeks’ in ducks: how much time do Common Pochards Aythya ferina spend with an eye open while in a sleeping posture?

Abstract

Peeks’, or keeping an eye open, in wintering Common Pochard Aythya ferina, while in a sleeping posture, were relatively brief, typically (66% of observations) lasting less than one second. However, in 37% of individuals some peeks lasted 10 s or more. Contrary to our prediction of lower anti-predatory vigilance rates in larger groups, there was a positive relationship between peek duration and the numbers of neighbours in a flock.