WatchList Species Account for Least Tern (Sterna antillarum)

Qualifies for the list as a Red List Species

Photo: Glen Tepke

The widespread and locally common Least Tern breeds along coastal beaches and on major interior rivers in North America. The Interior and California Least Terns are listed as endangered. It feeds mostly on small fishes and invertebrates. It spends the winter on marine coastlines in Central and South America. For breeding it requires open beaches and islands where tidal or river action keeps the sites free of vegetation. It often breeds in colonies to which the bird returns year after year, but it can respond quickly in response to the emergence of new suitable habitat or the disappearance of old. It sometimes will nest on flat gravel rooftops of buildings primarily near beaches. Its populations and colony sites fluctuate dramatically. Its favored sites on the coast are also favored by human recreationists and developers, but it sometimes uses human-made habitats such as spoilbanks, impoundments, and even bare land associated with airports.

The species is subject to predation by many animals, including Fish Crow, grackles, Ruddy Turnstone, herons, Great Horned Owl, Peregrine Falcon, red fox, coyote, raccoon, ghost crab, rats, and domestic cats and dogs. Predators can take up to 80% of the eggs and chicks at a colony. In the past, the bird was exploited for the millinery trade; populations also suffered from channelization and flooding behind dams, in addition to pesticides. In recent years it has rebounded due to conservation efforts. Both numbers and reproductive success should be monitored. Wherever possible, human interference should be controlled at beaches during the nesting season.