<tt>Osiejuk, T.S. & Olech, B. 2004. Amplitude spectra of Corncrake calls: what
do they signalise? Anim. Biol. 54: 207-220.</tt><br>
<br>
<tt>Abstract. The territorial call of Corncrake (Crex crex) males is a
disyllabic, loud, pulse repetition signal repeated in long series at night.
It seems to be relatively simple as it lacks the repertoire variation
typical for passerines, but still seems to be an equivalent of territorial
and/or advertisement song. In this paper we tested: (1) whether the pattern
of energy distribution within the call (i.e. amplitude spectrum) is
individually invariant; (2) whether it could be a signal used in an
individual recognition system; and (3) whether it is a sexually selected
honest trait related to male body size. We found that amplitude spectra
varied more between than within males, but it is rather unlikely that
energy distribution is a single feature encoding identity of a male. We
found some weak correlations between body size parameters and variables
describing amplitude spectra, either supporting or contradicting the
expected relationship (i.e. larger male ? more energy in lower
frequencies). We also found that the frequency of maximal amplitude, even
within a single call, may rapidly change by a few kHz, which is most
probably an effect of head and body movements, not changes in sound
production itself. The conclusion is that all features of Corncrake calls,
including energy distribution, indicate that this signal has evolved under
a strong pressure towards precise localization of a sender, which is
understandable, as Corncrakes inhabit dense vegetation and call almost
exclusively at night.</tt><br>
<br>
<pre style="margin: 0em;"><br>____________________
Tomasz S. Osiejuk, PhD</pre><br>
<pre style="margin: 0em;">Dept. Animal Morphology
Adam Mickiewicz University
28 Czerwca 1956 / 198
61-485 Poznan, Poland
phone +48 61 8292913
fax +48 61 8292909
e-mail: [EMAIL PROTECTED]
home page: <a href="http://www.staff.amu.edu.pl/~osiejuk";
rel="nofollow">http://www.staff.amu.edu.pl/~osiejuk</a></pre><br>
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