Nesting Biology of the Golden Bowerbird Prionodura newtoniana Endemic to Australian Upland Tropical Rainforest

Abstract

Golden Bowerbirds Prionodura newtoniana nests (n = 86) were studied on the Paluma Range, north Queensland during 1978–89. Nesting began in late October; 93% of clutches were incubated during November–January and 64% of fledglings left the nest in January. Breeding failed in one season, apparently due to lack of food. Nests were deep, bulky, open cups typically built within a ‘roofed’ vertical crevice in a tree trunk (63%) or in a crevice-like site, mostly < 3 m above ground. Several nesting locations or specific nest sites were used more than once, sometimes by the same female. Nest sites averaged 97 m from a bower actively attended by an adult male. Nests took up to 25 days to construct and were laid in from 3-28 days after completion. Of 26 clutches, 65% were of two eggs and 35% of one (mean 1.7). At laying an egg was 13.6% of mean adult female weight. Only one female incubated, brooded and fed young at each nest. Eggs were incubated for 21-23 days in bouts averaging 18 min at 1.8 bouts per h. Nestling period was 17-20 days. During the first 13 days of nestling life, females spent 13% less time brooding two nestlings than one. A mean of 3.3 meals per h was provided for one nestling and 5.9 for two; of 408 identified meals, 68% were fruit and the rest animal, mainly insects. Nearly half the fruit meals were of four species of Elaeocarpaceae and > 45% of insect meals was cicadas; more fruit was fed to older nestlings. One to three days before nest departure mean nestling weight was 75% and mean wing length 52% that of adults. Fifty-six per cent of eggs hatched and 58% of nestlings fledged; 34% of eggs produced fledglings and overall nest success was 28%. Females produced 0.5 fledglings per year. We compare these data with those for three other bowerbird species.