Strong migratory connectivity indicates Willets need subspecies-specific conservation strategies

By combining all available banding and tracking data, we found that Willets (Tringa semipalmata) have strong migratory connectivity between breeding and nonbreeding locations at the range-wide and subspecies levels, exposing the two subspecies to varying threats such as hunting for the eastern subspecies (T. s. semipalmata) and climatically-altered coastal habitats for both subspecies. We found that Western Willets (T. s. inornata) primarily used nonbreeding habitats along the Pacific Coast of the United States, although their reported nonbreeding range extends to the U.S. Atlantic and Gulf Coasts and the Pacific Coast of Central and South America. Eastern Willets wintered in Central and South America, which covers much of the subspecies' known nonbreeding range. By quantifying migratory connectivity within and between two subspecies, we could suggest subspecies-specific threats and potential limiting factors in the breeding and nonbreeding periods of the annual cycle of a declining migratory shorebird. Effective management of the species will likely require a range of conservation strategies across the diverse nonbreeding regions the two subspecies occupy within the United States, Central America, and South America. However, more data are needed from Willets breeding in mid-continent North America to understand the complete extent of overlap of the two subspecies throughout the annual cycle. The strong migratory connectivity documented here highlights the need to manage Willets by subspecies and protect a diversity of breeding and nonbreeding habitats, which will benefit the conservation of other shorebird species that overlap with Willets throughout the annual cycle.