Activity patterns, vocalizations, and site selection in nesting Blue-winged Teal

Abstract

Wet meadow sites represented more favourable microclimates for nesting Blue-winged Teal Anas discors than upland sites because of the denser vegetation, higher humidity, and less extreme temperatures. Behaviour of incubating females was examined to determine how they modify their behaviour to provide an optimal environment for developing eggs while meeting their own food requirements. Absences and movements on the nest were monitored and rate of egg heat loss during absences obtained. Absences were more common shortly after sunrise and after the high midday temperatures. Longer absences were correlated with higher ambient temperatures, but total time off the nest showed no clear relationship to mean daily ambient temperatures. More movement on the nest was also correlated with higher ambient temperatures, and with laying, early and late incubation, and hatching. Feeding was the most significant activity during absence of both laying and incubating females and the latter spent significantly more time feeding. Three different vocalizations at the nest were described during hatching: the 'maternal', the 'trill', and the 'alarm' call. Females vocalized infrequently during laying and incubation, but calling increased in response to the sounds and vocalizations from the hatching embryos, increasing dramatically at departure from the nest.