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Skierczynski, MS & TS Osiejuk (2010) Sharing songs within a local
dialect does not hinder neighbourstranger discrimination in ortolan bunting
(Emberiza hortulana) males. Behaviour 147: 333-351.
Lampe, HM, TJS Balsby, YO Espmark & TD Dabelsteen (2010) Does
twitter song amplitude signal male arousal in redwings (Turdus
iliacus)?
Behaviour 147: 353-365.
Hansen, BT, LE Johannessen & T Slagsvold (2010) Interspecific
cross-fostering of great tits (Parus major) by blue tits (Cyanistes caeruleus)
affects inter- and intraspecific communication. Behaviour 147: 413-424.
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Abstracts
Skierczynski, MS & TS Osiejuk (2010) Sharing songs within a local
dialect does not hinder neighbourstranger discrimination in ortolan bunting
(Emberiza hortulana) males. Behaviour 147: 333-351. Neighbour-stranger
(hereafter N-S) discrimination in birds is common and has most likely evolved to
settle repeated disputes more efficiently and without physical fights. We tested
whether an oscine bird, the ortolan bunting ( Emberiza hortulana), with a
small repertoire size from a population with a local dialect and a high level of
song sharing is able to discriminate between the songs of neighbours and
strangers. We performed playback experiments with eighteen males to measure the
response to a repeated single rendition of a single song type derived randomly
from a repertoire of a neighbour or stranger. Subjects responded more
aggressively to the songs of strangers than neighbours (faster approach, more
calls and songs uttered), suggesting that ortolan buntings can discriminate
between the songs of neighbours and strangers. Our results also suggest that
cues for N-S discrimination may be based on individual within-song type
variation regardless of song-type repertoire composition. We contrast our
results with an earlier study where ortolan buntings from a non-dialect
population were tested. Finally, we predict a positive relationship between the
level of song sharing and within-song type variation, which may be maintained by
selection for N-S discrimination in songbirds with small and moderate repertoire
sizes.
Lampe, HM, TJS Balsby, YO Espmark & TD Dabelsteen (2010) Does
twitter song amplitude signal male arousal in redwings (Turdus
iliacus)?
Behaviour 147: 353-365.
Bird songs may vary in amplitude for several reasons. Variations due to
differences in environmental conditions are well known but whether signal
information varies with song amplitude is less well known. In some species quiet
songs are heard as a soft twitter. These twitter songs are common in
Turdus species and may be used during escalated close range encounters
when a quiet song will attract less attention from others. Male redwings (T.
iliacus) sing a terminating twitter part that is quieter and highly variable
both between and within males compared with the introductory motif part. The
twitter song of redwings, however, is often louder than the twitter in other
Turdus species, especially during escalated song encounters. The seasonal
variation in twitter duration also suggests that the twitter may signal
increased aggression. We tested how male redwings responded to an assumed
escalation in signalling. In an interactive playback experiment we increased the
amplitude of the twitter songs we played back in response to an increase in
twitter duration by the subject. Males gave stronger responses to louder
twitter. This suggests that twitter amplitude may signal arousal in male
redwings.
Hansen, BT, LE Johannessen & T Slagsvold (2010) Interspecific
cross-fostering of great tits (Parus major) by blue tits (Cyanistes caeruleus)
affects inter- and intraspecific communication. Behaviour 147: 413-424.
Bird song is used to attract mates and deter rivals, and also functions as
a species recognition cue. It is a flexible trait affected by learning, hence
the choice of song tutors may affect an individuals' singing. By
interspecifically cross-fostering great tits (Parus major) to blue tits
(Cyanistes caeruleus) in the wild, we have manipulated the species
recognition of great tits, which in turn has influenced their song. In the
present study, we presented breeding great tit and blue tit control males with
playback of the aberrant song of cross-fostered great tit males and playback of
the normal song of control great tit males. Blue tit males responded more to
cross-fostered than control great tit song while great tit males showed the
inverse response pattern. This shows that interspecific cross-fostering may
affect both inter- and intraspecific communication. However, the response of
males of both species towards the song of cross-fostered great tit males was not
of the same magnitude as the response towards ordinary blue tit song; thus, the
real species identity is to some extent maintained in the aberrant song of
cross-fostered males.
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