Seasonal abundance shifts by the Australian White Ibis Threskiornis molucca across parts of eastern Australia in 2007: a survey using questionnaires

摘要

The Australian White Ibis Threskiornis molucca has recently expanded its breeding range from inland wetlands into coastal areas of eastern Australia. Here it inhabits many urban environments and its high abundances require management. However, the lack of knowledge on large-scale abundances and movements of ibises prevents the development of appropriate management. This study investigates the abundances and distribution of ibises in New South Wales (NSW) and southern Queensland (Qld.) in two large-scale surveys - one during the non-breeding season (March-April) and the other during the early breeding season (June-July). Abundances increased significantly in coastal areas of NSW and southern Qld. during the breeding period, while they decreased in central and inland areas. The significantly higher abundances in bioregions with large coastal cities (e.g. Sydney,-Brisbane) in comparison to those with towns (e.g. Eden, Ballina) suggest that ibises favour large cities for breeding. Some urban areas (e.g. Gold Coast, Sunshine Coast) had high abundances of ibises during both surveys with no significant increases during the breeding season, which suggests ibises are predominantly sedentary there. The findings support the view that ibis populations on the east coast consist of sedentary and mobile subpopulations that enter city areas for breeding. This needs to be considered in their management.