THE BREEDING BEHAVIOUR AND BIOLOGY OF THE SHORT-BILLED FORM OF THE WHITE-TAILED BLACK COCKATOO CALYPTORHYNCHUS FUNEREUS

Authors

  • D. A. SAUNDERS

    1. Commonwealth Scientific and Industrial Research Organization Division of Wildlife Research Clayton Rd., Helena Valley, W/A 6056, Australia
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Summary

The breeding biology of the short-billed form of the White-tailed Black Cockatoo was studied at two main study areas, Coomallo Creek, an area with large tracts of uncleared lands, and Manmanning, an area of extensive clearing with little native vegetation remaining. The study was based on individually marked birds. The actions of females selecting and preparing their nest hollow ensured that other females were kept away from the area of that nest, resulting in nests being spaced out through the study areas.

Eggs were laid between July and November with birds at Manmanning starting about four weeks after those at Coomallo Creek. Clutch size was a maximum of two and incubation took 28–29 days. Hatching success was higher for two-egg clutches than for one-egg clutches. There were no differences between fledging success for one-egg or two-egg clutches at either area, but fledging success at Manmanning was lower than that of Coomallo Creek.

Rates of growth for weight and length of folded left wing were calculated for nestlings from both areas. These rates of growth were compared within areas between years and between areas within years. There were differences in rates of growth of nestlings from Coomallo Creek compared with those from Manmanning and these differences were related to shortages of food at Manmanning.

The annual survival of tagged adults was calculated at 61–69% and that of juveniles over the first 12 months after fledging at 15%. The survival figures for adults seemed too low and it is suggested that the wearing of wing-tags may place the individual at a selective disadvantage compared with an untagged individual.

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