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<tt>Leonard ML, Horn AG, Parks, E 2003. The role of posturing and calling
in the begging display of nestling birds. Behavioral Ecology and
Sociobiology, 54 (2): 188-193</tt><br>
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<tt><br>Abstract<br>
Nestling birds produce a multicomponent begging display that has
visual (e.g. posturing) and vocal (e.g. call rate) elements. Most
work on the function of the display has focused on each component
separately. However, understanding the evolution of complex displays
such as begging requires knowledge of how the components function
collectively. The purpose of our study was to determine how postural
intensity and calling rate together influence parental feeding
decisions in tree swallows, tachycineta bicolor. We compared how
begging components responded to a manipulation in which pairs of
nestlings were either free to approach the parent when it arrived to
feed (unconfined treatment) or confined to the back of their nestbox
by a plexiglass partition (confined treatment). We found no
significant differences in postural intensity between treatments, but
calling rate was significantly higher in the confined treatment. In
both treatments, postural intensity, but not calling rate, correlated
with hunger. Both components positively and independently correlated
with the likelihood of a nestling being fed, although the correlation
with postural intensity was stronger. Previous work suggested that
both posture and call rate advertised hunger in nestling tree
swallows. Here, call rate was not associated with hunger, but rather
was affected by nestling position. These results suggest that calling
may serve an additional role in helping nestlings in disadvantaged
positions attract parental attention. The results also suggest that
calling may have a complex relationship with hunger, position and
nestmates.</tt><br>
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<pre style="margin:
0em;"><br>__________________________________________________________________________
Jérôme SUEUR
Ecole Pratique des Hautes Etudes, Biologie et Evolution des Insectes
Muséum national d'Histoire naturelle, 45 rue Buffon, 75005 Paris - France
Ph. 00 33 1 40 79 31 57 / Fx. 00 33 1 40 79 36 99 / Ml. [EMAIL PROTECTED]
__________________________________________________________________________</pre><br>
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