Sleep-vigilance trade-off in Green-winged Teals (Anas crecca crecca)

Abstract

We observed the effect of several variables on the sleep-vigilance trade-off in Green-winged Teals (Anas crecca crecca) during winter in the Camargue, southern France. We investigated the relationship between flock size and peeking rate, using field observations and controlling for the effects of other variables with which vigilance previously has been reported to be correlated: sex, date, time of day, distance from shore, and predator presence. Vigilance while sleeping decreased with increasing flock size for females but not for males. The peeking rate was reduced at the end of the winter, when Green-winged Teals were facing important energy requirements. Exposure to a predator resulted in maintenance of a high peeking rate. We discuss these results in relation to predator detection, mate competition, and wintering strategy.