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Vol. 48 No. 5, 2009
Nestling Begging Call Structure and Bout Variation Honestly Signal Need but Not Condition in Spanish Sparrows
Paulo A. M. Marques1,2,*, Luís Vicente3, and Rafael Márquez2
1Centro de Biologia Ambiental, Museu Nacional de História Natural, Universidade de Lisboa, Portugal
2Fonoteca
Zoológica, Departamento de Biodiversidad y Biología Evolutiva, Museo
Nacional de Ciencias Naturales (CSIC), Madrid, Spain
3Centro de Biologia Ambiental, Universidade de Lisboa, Portugal
Paulo A. M. Marques, Luís Vicente, and Rafael Márquez (2009) Nestling
begging behavior in the context of parent-offspring communication has
long been seen as a signal by which nestlings solicit care. Begging is
a multi-component signal in which both acoustic and visual components
are usually important; however, the present knowledge about the
specific behavioral features that convey the information is still poor.
The aim of this study was to examine how information on nestling’s need
is encoded in the begging calls given by nestling Spanish Sparrows (Passer hispaniolensis).
Nestlings were individually submitted to a food-deprivation period and
stimulated to beg at regular intervals within that period, and their
acoustic reactions were studied. Spanish Sparrow nestlings increased
their response to simulated parental visits in reaction to increasing
food-deprivation periods. Results also confirmed that information on
nestling need might be encoded in variables of calling behavior. The
variables important to convey such information are the initial call
rate (20 s rate), duration of the begging bout, call amplitude, and
call high frequency. As food-deprivation periods increased, nestlings
begged more frequently, extended the calling bout, increased the call
amplitude, and used higher frequencies. During the deprivation period,
nestlings did not change their call latency, call duration, or relative
peak time. The study also found that despite expectations,
lower-condition nestlings did not beg more frequently during the
experiment than their higher-condition siblings. Overall, results
support the view of begging as a reliable signal, namely that begging
should reflect a nestling’s need, and that only some call features
might encode information about need.
Key words: Honest signaling, Vocal begging, Food-deprivation period, Parent-offspring communication, Scramble competition.
*Correspondence: E-mail:pamarques@fc.ul.pt
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