Behaviour 143, Issue 1
http://www.ingentaconnect.com/content/brill/beh/2006/00000143/00000001
van Dongen, Wouter FD (2006) Variation in singing behaviour reveals possible
functions of song in male golden whistlers. Behaviour 143: 57-82.
Abstract:
Male song has been shown to have two major functions, repelling rivals and
attracting mates. Yet much debate still exists as to what extent male singing
strategies have been influenced by selection pressures imposed by each sex. I
use a combination of song recordings and playbacks to investigate how male
competition and female choice may have shaped song structure and behaviour in
migratory golden whistlers (Pachycephala pectoralis). Song output was low
during territory establishment but increased dramatically when breeding
commenced. Singing during the female fertile period may be an effective
paternity guard against potential cuckolders. During this period, males
decreased their song output when more neighbouring females were fertile,
possibly reflecting an inability to concurrently guard a mate and pursue
extra-pair fertilisations. However, high singing rates were maintained after
the fertile period, suggesting that males may also sing to attract extra-pair
copulations. S
ong repertoire size increased with male age and may signal male quality.
Repertoires included two broad song-types: simple 'whistle' songs and more
complex 'melodic' songs. Whistle songs were often sung by breeding males and
may be more effective at broadcasting information at long-distances. In
contrast, melodic songs were commonly sung in close-range male encounters and
may contain more information about signaller quality. During vocal contests,
males exhibited a range of countersinging behaviours, including song-type
switching, song-type and frequency-matching, and song overlapping, which may
reflect a hierarchical mode of signalling aggression. Each sex may have imposed
different selection pressures on the vocal output of male golden whistlers.
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