Thermal and Behavioral Correlates of Nest Site Location in Black Noddies

Abstract

On Heron Island, Black Noddies Anous minutus select arboreal nest sites that range from fully shaded within dense stands of Pisonia grandis to sites that are exposed to the sun for most of the day in Argusia argentea at the forest edge. We monitored the temperature of wax-filled eggs and diurnal behaviour of incubating adults at each of these sites over a nine-day period. Nocturnal egg temperatures were no different at the two sites (32.4°C) but diurnal egg temperatures and adult body .temperatures were significantly hlgher in Argusia (35.7 and 41.9°C, respectively) than in Pisonia nests (34.1 and 39.5°C, respectively). The diurnal behaviour of incubating birds was directly affected by insolation as indicated by the postural ,adjustments, bouts of gaping or panting, and brief nest departures of birds following periods of exposure to the sun.