In order to assess the potential impact that artificial nest boxes may have on the occupation rate or physical condition of adults and chicks of little penguins (Eudyptula minor), we recorded temperature continuously for 37 days simultaneously inside 7 nest boxes and in surrounding bush. Temperature inside the boxes was always higher than that in the bush, the difference being greatest around noon. Solar radiation caused temperature inside the boxes to increase. Temperature differences between box interiors and exteriors were smaller on windy and dry days. To prevent hyperthermic conditions, we suggest improvements in the ventilation of nest boxes.