Does available foraging area, location or colony character control the size of multispecies egret colonies?

摘要: Food supply is commonly regarded as ultimately controlling the size of bird colonies. Most studies examining this problem have been on seabirds, and all in Northern Hemisphere. To search more widely for evidence importance food a factor colonies, we investigated egret colonies Southern Hemisphere region. We examined relationship between colony area potential feeding habitat around each colony, compared with variables associated location physical characteristics colony. All (13 total) along 800 km coastline New South Wales, Australia, were studied. Colony ranged from 7 to than 2000 nests. There very few correlations number nests areas different types within 20 However, available saltmarshes proved be significant predictor great (Ardea alba), intermediate (A. intermedia) little egrets (Egretta garzetta). Saltmarshes may stable, long-term habitats these three native ‘aquatic feeders’, but not terrestrially cattle ibis). Nest numbers latter species related positively saltmarshes, negatively latitude, suggesting that nest exotic influenced by climate, proximate factors such colonial nesting also being important. Because numerical dominance egrets, followed same pattern egrets.