Breeding and Movements of the Straw-necked Ibis in Australia

Abstract

Data on distribution and movements were obtained from the literature, an Australia-wide questionnaire and regular censuses at fifteen locations in eastern Australia from May 1969 to December 1972. Fifty-four breeding swamps were recorded, most in south-eastern Australia, Northern Territory and south-western Western Australia. Populations using these breeding areas may be largely discrete. Differences in time and regularity of breeding are probably caused by rainfall. Seasonal movements occurred between breeding areas and eastern coastal refuges in each year, but later and in smaller numbers in years of good rainfall inland than in poor ones. North-eastern Queensland seems to be an important refuge for Ibis breeding in northern Australia and south-eastern Queensland for those from south-eastern Australia, with relatively few sightings in intervening central coastal Queensland. Juveniles appear to disperse earlier and more widely than adults.

Local rainfall may stimulate Ibis to depart from refuges, most departures probably being pre-nuptial; rain also probably stimulates breeding. Though flooding is enough to do this at many swynps, at two in South Australia, not affected bv floods, increase in temperature is probably the proximate stimulus.