Territorial responses to song components in a suboscine, the vermilion flycatcher.

•Vermilion flycatcher songs consist of a first part (variable in number of elements) and a second part (with four elements).•Males respond to the first part alone, to the second part alone, and to complete songs.•Both the first part and second part are important during territorial competition.•Males call more when exposed to the first part than to the second part.•The first part of the song seems to play a special role in territorial competition.