Differential assessment of environmental information in a migratory and a nonmigratory passerine

Migratory birds stay in a particular area for only short periods and must rapidly acquire appropriate information about stopover sites. In contrast, resident birds can update their knowledge whenever necessary. In a novel environment migrants are thus predicted to assess relevant information faster than nonmigrants. We tested this prediction with two closely related species, the migratory garden warbler, Sylvia borin, and the resident Sardinian warbler, S. melanocephala momus. Each bird was allowed to explore two unfamiliar boxes, one of which contained food. Garden warblers found food significantly faster than Sardinian warblers. Garden warblers may have a wide-area exploration strategy to assess a novel room and Sardinian warblers may have a local-area exploration strategy. We conclude that a wide-area exploration strategy might be required for migrants to assess environmental information as rapidly as possible. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.