Juvenile Swamp Sparrows are distinguished from juvenile Song Sparrows by examining a combination of features. Head: narrow, dark bill lacking the swollen build of the bill typical of Song Sparrow (1); thin, blackish post (past) ocular (eye) stripe with flared, wedge-shaped posterior (2); creamy sub-moustachial (3) bordered by crisp moustachial (4) and weak malar stripe (5). Overall, an olive cast throughout entire head (as seen on example at right). Underside: light buffy suffusion to chest with fine, crisp brownish streaking and peppering throughout the flanks and belly. Upperparts: dark-centered greater coverts enclosed by reddish border (appears to be a shared characteristic).
Photo: Features guide, Swamp Sparrow.