MIGRATIONS OF THE YELLOW-BELLIED FLYCATCHER IN SOUTHERN ONTARIO

Studies of the migration and molt of the Least Flycatcher (Empidonax minimus) have demonstrated several peculiar features: (1) in the fall adults migrate as much as a month before the young-of-the-year (Hussell et al. 1967, Ely 1970, Hussell 1980, 1981); (2) adults molt the flight feathers in the winter quarters following the fall migration (Dwight 1900, Johnson 1963, Hussell 1980); (3) adults spend an average of no more than about 64 days on the breeding grounds (Hussell 1981). The Yellow-bellied Flycatcher (Empidonax flaviventris) also shows some of these features in'its migration and molt. In adults the postnuptial molt of the flight feathers also occurs in the wintering area (Dwight 1900, Johnson 1963) and adults apparently precede the young in the fall migration (Hussell 1982). In 1966-1968 an intensive study of the spring and fall migrations of Empidonax flycatchers was undertaken at the Long Point Bird Observatory to document the timing of migration and molt in four species (Hussell 1981). Here I report results for the Yellow-bellied Flycatcher from the 1966-1968 study together with a summary of other banding data from Long Point for the years 1966-1980. Museum specimens taken in southern Ontario and Michigan are used to document sexual differences in the timing of spring migration.