Seasonal Patterns of Least Tern Distribution along the Atlantic Coasts of North, Central, and South America

Abstract. I describe seasonal changes in the distribution of Least Terns (Sternula antillarum) along the Atlantic and Caribbean coasts based on banding recoveries and data submitted to eBird and WikiAves. Human disturbance of nesting sites and habitat loss has caused declines in most populations, necessitating focused conservation activities. Yet little is known about where these birds occur away from their breeding colonies, or what survival threats they may face. Limited observations during the non-breeding season in the Caribbean and along the Atlantic coasts of Central and South America are typically assumed to be individuals from breeding colonies along the east and Gulf coasts of the U.S. and along the Missouri and Mississippi rivers and their tributaries. However, existence of nesting sites throughout the Caribbean, along the Atlantic coast of Central America, and along the north coast of South America indicate a more complicated distributional picture. Most of the limited band recoveries obtained south of the U.S. are of birds killed during hunting activities. Future research attention, especially including banding at South American, Central American, and Caribbean nesting sites, and efforts during October–April to locate and identify marked birds, is necessary to develop a full life cycle conservation strategy for this species.