Masayo Soma, Mariko Hiraiwa-Hasegawa and Kazuo Okanoya (2009): Early
ontogenetic effects on song quality in the Bengalese finch ( Lonchura
striata var. domestica ): laying order, sibling competition, and song
syntax. Behav. Ecol. Sociobiol. 63(3),363-370.
Abstract: Birdsong differs from other sexual traits in that the acquisition
process involves learning. Especially in close-ended learning species like
the Bengalese finch, conditions experienced during the critical
song-learning period can have a profound influence on song quality.
Therefore, to understand song evolution from a life-history perspective, we
investigated early ontogenetic effects on song quality. In particular, we
focused on maternal effects and sibling competition. In asynchronously
hatching bird species, the age hierarchy among nestlings affects physical
development due to competition for food; mothers may influence this
competition by adjusting their investment in each egg according to its
sequence in the laying order. To independently assess these effects, chicks
of the Bengalese finch were cross-fostered so that the age hierarchies
formed in fostered broods were independent of the laying order. Our results
indicate that song quality partially reflects early ontogenetic conditions,
whereas song duration and note-type repertoire were independent of either
laying order or age hierarchy. The syntactical complexity of note order
declined over the laying sequence. This finding suggests that the song
learning ability is influenced by within-clutch variation in maternal
investment toward eggs. Considering that song syntactical complexity is
subject to female preference in the Bengalese finch, it is likely that
maternal resource allocation strategies play a role in song evolution.
URL: http://www.springerlink.com/content/n1085n85073j6174/
For reprints please contact Masayo Soma (Email:
Oliver Behr, Mirjam Knörnschild and Otto Helversen (2009): Territorial
counter-singing in male sac-winged bats ( Saccopteryx bilineata ):
low-frequency songs trigger a stronger response. Behav. Ecol. Sociobiol.
63(3), 433-442.
Abstract: In many animal species, individuals compete for resources but
avoid escalated conflicts by threat displays, i.e. a mutual signalling
behaviour that enables the opponents to predict the outcome of the conflict
without the necessity of actual fighting. For example, territory holders may
use acoustic signals to communicate not only their own identity and the
borders of their territory but also their competitive quality, fighting
ability and motivation. Here, we show that male sac-winged bats, Saccopteryx
bilineata, adjust their vocal territorial displays according to the
fundamental frequency of territorial songs of their opponents. In playback
experiments with territorial males, low-frequency stimuli elicited a higher
territorial song rate and length than high-frequency stimuli. Male S.
bilineata that sing more often and with lower fundamental frequencies have
been shown to sire more offspring than their competitors. Fundamental
frequency of territorial songs, hence, may reveal male quality and,
consequently, the resulting threat posed to competing males. We argue that
this is reflected in the increased response of competitors to low-frequency
territorial songs shown here. Such competitive signalling behaviour has been
shown in a few mammal species like red deer and baboons but, thus far, not
in bats.
URL: http://www.springerlink.com/content/dj78125156q8up5l/
For reprints please contact Oliver Behr (Email:
Kind regards
Sonja Amoser
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Dr. Sonja Amoser
Steinrieglstraße 286
3400 Weidlingbach
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