Patch Selection by Snowy Egrets

Abstract

Abstract Models of the Snowy Egret (Egretta thula), that use the tendency of wild birds to join foraging aggregations, were used in manipulative experiments to test the ability of wild individuals to use environmental and social information indicative of patch quality, including pool depth, prey accessibility, prey density, and prey exploitation, when choosing foraging patches. Snowy Egrets, but not some other aggregation species, preferred shallow ( 40 cm) pools, perhaps because they could wade throughout the shallow pools, disturbing fish prey and making them more accessible for capture. Snowy Egrets responded to an artificial increase in fish density by visiting prey-enhanced pools more than pools with most fish removed or unmanipulated pools. Snowy Egrets also responded to a decrease in prey density resulting from recent exploitation by aggregations by visiting these pools less than unmanipulated pools. These results indicate that, in addition to the presence of other individ...