Seasonal Distribution of the Slaty Elaenia, a Little-Known Austral Migrant of South America

Abstract

An analysis of the seasonal and geographic distribution of specimen records of the Slaty Elaenia (Elaenia strepera; Tyrannidae) confirms that the breeding range is restricted to a small area of the Andes Mountains in northwestern Argentina (Jujuy, Tucuman) and southern Bolivia (Tarija, Chuquisaca, probably also Santa Cruz), mainly from 800 to 2500 m elevation. Although the winter range is usually assumed to include much of the western Amazon Basin north to northern Venezuela, the only specimens from the core of the austral winter are from hilly areas in northern Venezuela (Bolivar, Carabobo, and Sucre), approximately 3000 km north of the breeding range; other records from Colombia, Peru, and central Bolivia are from periods when transients would be expected. Therefore, the data so far indicate that the true winter range might be as small as the breeding range and, like the breeding range, is not in the Amazonian lowlands. It is suspected that the true winter distributions of many migratory bird species that winter in the tropics are as imprecisely known as that of the Slaty Elaenia.