|
Kentucky warblers (Oporornis formosus) each sing a single song
pattern. To determine whether males could range (estimate the distance
to) conspecific songs, we presented clean and reverberated versions of
strangers' songs to 12 males in a factorial design.
To assess differences between the playbacks and the subjects' own songs or
neighbors' songs, we measured differences in minimal repetition periods
between repeated acoustic elements in songs, features that could
contribute to assessment of reverberation.
Results indicated that Kentucky warblers can range conspecific songs and
that similarity between playback songs and established neighbors' songs or
a subject's own songs did not enhance this ability.
| |
Direct evidence that males misjudged the distance to reverberated
playbacks excluded other interpretations of the results based on
differences in the detectability or habituation of clean and reverberated
songs.
These results suggest further that assessment of reverberation is
sufficient for ranging and that perceptual analysis of song is not
necessarily linked to overt production. As a consequence, repertoires of
songs do not necessarily promote interference between territorial
neighbors.
|
|
Direct indications that subjects misjudged the locations of playbacks
provide the strongest evidence for ranging. Interpretation of different
intensities of response to clean and degraded playbacks must consider the
consequences of degradation for habituation, detection, and recognition of
signals as well as ranging.
These confounding alternatives also arise in interpreting the influence of
familiarity with particular songs on responses to clean and degraded
playbacks. Our results show that territorial Kentucky warblers can range
conspecifics' songs, at least approximately, regardless of familiarity
with the song pattern.
| |
Kentucky warblers differ from species in previous studies of ranging in
having a single song pattern each and from most other birds inhabiting
forests in incorporating rapidly repeated elements in their songs. The
latter attribute might be an evolutionary adaptation to facilitate
ranging.
|
