PRIMARY SONG BY A JUVENILE WILLOW FLYCATCHER

The timing of song development in suboscines, in which song appears no t to be learned from other adults is poorly known. The Willow Flycatch er (Empidonax traillii) is a suboscine with a primary song typically r eferred to as fitz-bew. I report here an instance of very early singin g by a 6-8-wk-old Willow Flycatcher, which sang in an aggressive conte xt in response to a recording of adult flycatcher song. This is except ionally early development of primary song, even among suboscines. Earl y song development may assist in the defense of winter territories.