Sleep-vigilance trade-off in green-winged teals (Anas crecca crecca)

We observed the effect of several variables on the sleep-vigilance trade-off in Green-winged Teals (A,Anas crecca crecca) during winter in the Camargue, southern France. We investigated the relationship between nock size and peeking mtp 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 nock size for females but not for males. The pecking 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 discussed these results in relation to predator detection, mate competion, and wintering strategy.