June 14, 2016
The female Chinese Hume Warbler
is attracted to males who sing simple songs, as opposed to the more common
preference among birds of choosing males who sing the most complex songs. This
preference for males with inconspicuous songs may be related to nesting
behavior and driven by the threat of predation, according to research published
in the open access journal Avian Research.
This subspecies of the Hume
Warbler Phylloscopus humei mandellii (P.h.mandellii) is found in central
China, is socially monogamous and both parents feed and raise the offspring
together. As it is a ground-nesting species, it is particularly vulnerable to
predation and the females seem to judge potential male partners based on subtle
characteristics that are advantageous to minimize predation risk such as
nesting behavior.
Researchers analyzed a total of
139 recordings of male bird song. Dr. Yue-Hua Sun from Institute of Zoology,
Chinese Academy of Sciences, Beijing, China said: "Females that chose
large males whose
songs are shorter with a faster increase in volume, tended to lay their eggs
earlier and produce more surviving young. The earlier-hatched nestlings grew up
faster, probably benefitting from higher feeding rates or better food. This suggests
that female preference for larger males, e.g. individuals with the longest wing
and tail lengths, may be driven by greater ability of such males to provide for
their young. Another possibility is that these individuals may occupy better
territories with better food resources and/or better nest sites."
Dr. Yue-Hua Sun adds: "Most
of the Phylloscopus warblers are accomplished singers with complex
songs and large repertoires. However, the Hume warbler sings extremely simple
songs, of which it only has two, a doubled whistle note and a long low
buzz; P.h.mandellii only sings the buzz song type. The males' short
song could also be better for territorial defense, allowing the males to hear
their competitors' responses."
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