Breeding biology of the White-winged Robin Peneothello sigillata, endemic to montane New Guinea

I studied the breeding biology of the high-elevation montane White-winged Robin Peneothello sigillata (Petroicidae) at Kumul Lodge, southern slope of Mt Hagen, Papua New Guinea, from 2 October to 17 November 2011. Three nests were watched for 18 hours during incubation; each had one egg. Female daylight incubation constancy (percentage of daylight hours spent in incubation) was 73%, the mean duration of incubation sessions was 3.35 minutes and mean absence from the nest was 1.33 minutes, the daily number of incubation sessions was 150 (12.5 per hour), feeding of the incubating female by the male at the nest was 4.6 times/hour, and the total number of nest visits by both male and female during incubation was 17.1/hour. The 100% egg-success in this species suggests that these incubation reproductive traits evolved more in response to food availability and perhaps food limitation than a high risk of nest predation. Nestling care by the female included brooding and the feeding of the young. Nestling care by males included delivering food to the female and feeding the nestling. Both the male and the female removed faecal sacs. Mean brooding constancy (percentage of time spent brooding) was 43.3% for the entire 17–21-day nestling period. Mean number of food-delivery trips by both the male and the female over the entire nestling period was 7.2/hour/nestling and the total number of nest visits by both the male and the female was 17.6/hour. Two nests were attended solely by the breeding pairs, and cooperative breeding, with one immature helper, occurred at one other nest. During the nestling stage, the high nest success, coupled with high nest visitation, suggests that the risk of nest predation is low. Peak nestling growth (to >90% of adult weight) occurred at 10–13 days of age. To elucidate the breeding strategy of the White-winged Robin, its reproductive traits are discussed and compared with those of other robins of New Guinea, tropical northern Australia, and temperate Australia and New Zealand.