Toby J. Hibbitts, Martin J. Whiting and Devi M. Stuart-Fox (2007): Shouting
the odds: vocalization signals status in a lizard. Behav. Ecol. Sociobiol.
61(8), pp 1169-1176.
Abstract: Many species possess multiple sexually dimorphic traits, which
incorporate different sensory modalities (e.g., acoustic, olfactory and
visual), although their relative roles in sexual selection and in
determining reproductive success are still poorly understood for most taxa.
We assessed the role of multiple male traits, including one acoustic
(dominant call frequency) and one visual (yellow throat patch) trait, in
residency advertisement, contest behavior, and breeding success in barking
geckos (Ptenopus garrulus garrulus). We show that male barking geckos
maintain largely exclusive home ranges, with a trend for larger males to
maintain larger home ranges. We also show that larger males have a lower
dominant calling frequency. When aggressive behavior was elicited in the
field using a recorded call of average frequency, resident males with low
frequency calls were more likely to respond aggressively and charge the
speaker compared to males with high frequency calls. However, body size and
small relative throat patch size, rather than call frequency, were the best
predictors of overall aggressiveness. Body size was also the best predictor
of whether males bred. We suggest that call frequency in this crepuscular
species constitutes an effective long-range signal of body size, used by
males for remote rival assessment and to advertise home range boundaries in
low-light environments.
URL: http://www.springerlink.com/content/y425g81325855533/
For reprints please contact: Toby J. Hibbitts
Rindy C. Anderson, Stephen Nowicki and William A. Searcy (2007): Soft song
in song sparrows: response of males and females to an enigmatic signal.
Behav. Ecol. Sociobiol. 61(8), pp 1267-1274.
Abstract: Low-amplitude "soft song" is used by a variety of songbirds; in
some species during aggressive encounters, in others during courtship, and
yet others in both these contexts. In song sparrows (Melospiza melodia),
soft song has thus far been observed only in aggressive encounters, where
its production is a more reliable predictor of attack than any other
signaling behavior. We used song playback to test the response of both male
and female song sparrows to soft song. The design of the playback
experiments took into account the existence of two classes of soft song:
crystallized soft song, which consists of song types also found in the
broadcast repertoire, and warbled soft song, which consists of
less-structured song types not found in the broadcast repertoire. Female
song sparrows responded with significantly less courtship display to the
playback of crystallized soft song than to that of normal broadcast song,
and response to warbled soft song was if anything lower than to that of
crystallized soft song. Male song sparrows responded equally aggressively to
normal broadcast song as to crystallized soft song, and equally aggressively
to warbled soft song as to crystallized soft song. The female results
support the conclusion that neither form of soft song functions in
courtship. The male results suggest that the reliability of soft song as a
signal of aggressive intent is not maintained by a receiver retaliation
rule.
URL: http://www.springerlink.com/content/k3205580332v71vg/
For reprints please contact: Rindy C. Anderson
Sergio Castellano and Alessandra Rosso (2007): Female preferences for
multiple attributes in the acoustic signals of the Italian treefrog, Hyla
intermedia. Behav. Ecol. Sociobiol. 61(8), pp 1293-1302.
Abstract: The advertisement call of frogs and toads is an example of
multiple message signal because different acoustic properties encode
different kinds of biologically significant information. In the Italian
treefrog, Hyla intermedia, pulse rate and frequency have been found to be
under stabilizing female preferences and to encode information important for
mate recognition, whereas the number of calls per call group have been found
to be under directional preferences and, thus, to be important for mate
quality assessment. In this study, we investigate preferences for calls that
differ simultaneously in frequency, pulse rate, and number of calls per call
group, and we ask how these properties interact with each other in
influencing female mating decisions. Results of two-choice phonotaxis
experiments provide no evidence to support the hypothesis that females
process multi-attribute signals in a hierarchical way. In contrast, the
pattern of preferences is consistent with the 'preference function'
hypothesis, that is, with the hypothesis that females rank signals along an
ordinal scale of values and choose accordingly. Pulse rate and frequency
influence mating preferences more than does the number of calls per call
group. The interaction between pulse rate and frequency is not additive but
multiplicative: small differences in either pulse rate or frequency that,
alone, have no effects on female choice, interact synergistically so that
their combination has strong influence on female preferences. A preference
repeatability test shows strong among-female differences in preference for
multi-attribute signals. We suggest that this result reveals not only a
variation in attribute values among females, but also a variation in the way
females weight and combine attribute values into a single preference score.
URL: http://www.springerlink.com/content/e41776815g80738l/
For reprints please contact: Sergio Castellano
Kind regards, Sonja
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University of Vienna, Dept. of Behavioural Biology
Sonja Amoser, PhD
Althanstrasse 14
1090 Vienna
Austria
tel: +43 (1) 4277 54467
fax: +43 (1) 4277 54506
mobile: +43 (664) 500 61 06
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