Nesting climate and behaviour of Cape Barren geese (Cereopsis novaehollandiae Latham)

Abstract

Embryonic development of birds is directly affected by nest temperature and humidity. Nest site selection may therefore have a large impact on reproductive success. Cape Barren geese (Cereopsis novaehollandiae) use a variety of nesting materials and sites that potentially create quite different environments for the eggs. We categorised nests according to their protective cover and monitored nest temperature, cooling rate, nest humidity, solar radiation level, female incubation constancy and reproductive success on Kangaroo Island, South Australia. Nest type was not correlated with clutch size or timing of incubation. Nest temperature and water vapour pressure were slightly lower in exposed nests (33.6–33.7°C, 2.60–2.94 kPa) than in more protected nests (34.7–35.0°C, 3.34–3.83 kPa), but incubation constancy and cooling rate during recesses did not differ between exposed and protected nests. Incubation constancy was 92.4% ± 4.2% (s.d.). Three to four recesses of 38 ± 10 min were undertaken, mainly between 08:00 and 16:30 hours. Total recess time, but not individual recess duration, was positively correlated with mean daily temperature, whereas rainfall had no effect on incubation constancy. Solar radiation input was generally stronger during recesses. Nests of Cape Barren geese were well insulated with large amounts of down; thus, nest type had minor influences on nest temperature and humidity and female behaviour. Hatching success was 88% overall, and did not depend on nest type.