Behavioural responses to heat in captive native Australian birds

Abstract

Australian birds are under threat from climate change and heatwaves. We investigated whether captive native Australian birds adjusted their time budgets, microsite selections or used thermoregulatory behaviours on typical or extremely hot summer days. We observed eight species of birds at Adelaide Zoo and found that the proportion of time spent on stationary behaviours, feeding, in the sun and on the ground differed amongst species of birds, between mornings and afternoons and day type. Wing-venting was used more frequently during the hottest observation periods. The smallest birds in the study utilised wing-venting more than other species of birds, possibly because it is more important for them to conserve water. Psittaciform birds spent less time feeding and more time resting in cooler microsites during hot periods. Columbiform birds continued feeding and spent more time in the sun rather than resting in cooler microsites. Whitebrowed Woodswallows spent a significantly lower proportion of time on stationary behaviours and a higher proportion of time feeding compared to the other species. Our results suggest that columbiform birds may have an advantage during heatwaves as they can continue feeding through high ambient temperatures, provided there is adequate access to food and water.