Bioacoustic article in Behaviour 146 no. 10
http://www.ingentaconnect.com/content/brill/beh/2009/00000146/00000010
Scarl, JC (2009) Heightened responsiveness to female-initiated displays in
an Australian cockatoo, the Galah (Eolophus roseicapillus). Behaviour 146:
1313-1330.
Many hypotheses have been proposed to explain why in some species, males and
females coordinate their behaviour to defend a territory. The sex of the
individual initiating a joint display may shed light on the function of the
display, but this variable has not been systematically explored. This study
investigates whether male-female pairs in a socially monogamous cockatoo,
the galah, respond differently to male-initiated and female-initiated joint
threat signals, and whether one sex is more likely to initiate a threat
response. Solo male defense calls, solo female calls, male-initiated paired
calls, and female-initiated paired calls were presented to pairs of galahs
at nest cavities during the pre-breeding season. Birds responded most
strongly to female-initiated call bouts, regardless of the number of
stimulus birds giving vocalizations. While paired birds coordinated their
approach responses to the stimuli, males tended to initiate these responses.
These results suggest that the sex of the initiating bird, rather than the
number of calling birds, is most relevant to galahs when assessing threat
near an active cavity. This study indicates that it is critical to consider
the separate roles of the male and female in a joint display in order to
fully understand that display's function.
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