Note types and coding in parid vocalizations.: I:: The chick-a-dee call of the black-capped chickadee (Poecile atricapillus)

The chick-a-dee call of the black-capped chickadee, Poecile atricapillus (L., 1766), consists of four note types and is used in a wide variety of contexts including mild alarm, contact between mates, and for mobilizing members of winter flocks. Because note-type composition varies with context and because birds need to identify flock mates and individuals by their calls, it is important that birds are able to discriminate between note types and birds. Moreover, previous experiments have shown that black-capped chickadees are able to discriminate their four note types, but the acoustical basis of this process is still unknown. Here, we present the results of a bioacoustic analysis that suggests which acoustic features may be controlling the birds' perception of note types and of individual identity. Several acoustic features show high note type and individual specificity, but frequency and frequency modulation cues (in particular, those of the initial part of the note) appear more likely to be used in these processes. However, only future experiments testing the bird's perceptual abilities will determine which acoustic cues in particular are used in the discrimination of note types and in individual recognition.