Nest site attributes and nesting outcome in the vulnerable eastern Regent Parrot (Polytelis anthopeplus monarchoides)

The relationship between nest site characteristics and nest success is likely to be important in the conservation management of threatened cavity-nesting birds. The vulnerable eastern Regent Parrot (Polytelis anthopeplus monarchoides) is declining in South Australia, but there is little information on the behavioural ecology of its cavity-nesting habits. The aim of this study was to quantify parental nest visitation behaviour and measure nest site attributes in relation to nesting outcome. We collected data from 25 nests along the Murray River in South Australia, and analysed 608 h of video recording and 67 h of binocular observations. This study provides the first quantitative data on parental care behaviour of the eastern Regent Parrot. The results show (1) parent birds had ~0.5 visits per hour during incubation and ~2 visits per hour during feeding; (2) 16% of nesting cavities were abandoned, 24% usurped, 4% depredated (by lace monitor, Varanus varius), 4% unknown outcome; and (3) canopy cover was 58% at successful nests versus 34% at failed nests. Behavioural monitoring in the field should span at least two hours to capture parental activity at the nest, nesting success was correlated with canopy cover, and nesting failure was mostly explained by usurpation and abandonment.