Analysis of a Sample of Tennessee Warblers Window-killed During Spring Migration in Manitoba

arge numbers of passerine birds killed in collision with lighted structures during night migration flights, particularly in the fall, have yielded important information on the timing of migration of individuals of different ages and gender, route selection and geographic origins of migrants, and molt (e.g., Tordoff and Mengel 1956, Payne 1961, Kemper et al. 1966, Crawford 1978, Raveling and Warner 1978). Large, single samples of birds killed in this manner during the spring migration have been less frequenty reported (but see Hatler and Campbell 1975), although weather-caused mortality in spring occurs frequently (e.g., Green 1962, Whitmore et al. 1977, Zumeta and Holmes 1978).