The western north Atlantic Ocean constitutes a major route for autumnal migrants moving between eastern North America and the Caribbean or South America. Some shorebirds have long been known to use this route (Lincoln, 1939; Hagar, 1966; Palmer, 1968; McNeil and Burton, 1973), and recently Drury and Nisbet (1964) and Nisbet (1970) have stated that the Blackpoll Warbler (Dendroica striata) proba...