Cross-seasonal effects in the American Woodcock: conditions prior to fall migration relate to migration strategy and its implications for conservation

How post-breeding habitat quality and body composition of migratory birds carry over to influence fall migration strategies and residency merits consideration when creating cross-seasonal conservation plans, especially in breeding populations that are partial migrants. We assessed the influence of post-breeding habitat quality on departure body composition and fall migration patterns in a southern New England breeding population of American Woodcock (Scolopax minor). Woodcock that overwintered near breeding areas (n=5) had less fat upon capture in fall and used lower quality habitat during the fall than birds that eventually departed on migration (n=17). Woodcock that departed earlier were long-distance migrants that had inhabited higher-quality landscapes prior to migration, departed with less fat or similar fat stores, stopped over for shorter periods on migration, and arrived earlier on their more southerly wintering areas. In contrast, woodcock that departed later were short-distance migrants that had inhabited lower quality landscapes prior to migration yet stored similar or more fat upon departure, stopped over for longer periods on migration, and arrived relatively late to their more northerly wintering areas. These differences in migration strategies were evident under the same fall environmental conditions and did not appear related to individuals responding to their own condition as would be expected if they were class condition-based carry-over effects. As such, the southern New England breeding population of woodcock are best categorized as non-facultative partial migrants (i.e., includes residents, short-distance migrants, and long-distance migrants) that demonstrate weak connectivity between life stages; such populations are excellent for the study of the costs and benefits of migration. The stopover and wintering areas used by woodcock in the coastal mid-Atlantic deserve conservation and management attention in order to preserve critical habitat throughout their wintering range.