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Find abstracts below.
M. D. Greenfield and W. A. Snedden. 2003. Selective attention and the
spatio-temporal structure of orthopteran chorouses. Behaviour 140 (1): 1-26.
H. Brumm and D. Todt. 2003. Facing the rival: directional singing behaviour
in nightingales. Behaviour 140 (1): 43-53.
T. J. Hammond and W. J. Bailey. 2003. Eavesdropping and defensive auditory
maskink in an Australian bushcricket, Caedicia (Phaneropterinae:
Tettigoniidae: Orthoptera). Behaviour 140 (1): 79-95.
R. Márquez and J. Bosch. 2003. Temporal encoding of information in the
advertisement call of the Iberian midwife toad (Alytes cisternasii). The
importance of rise time. Behaviour 140 (1): 113-123.
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Abstracts:
M. D. Greenfield and W. A. Snedden. 2003. Selective attention and the
spatio-temporal structure of orthopteran chorouses. Behaviour 140 (1): 1-26.
Abstract: Temporally structured choruses in which neighbouring males
alternate or synchronize their calls are common among rhythmically singing
Orthoptera. In many cases, chorusing appears to be driven ultimately by
psychoacoustic precedence effects that influence females to orient toward
leading male calls and to ignore males whose call onsets follow their
neighbours' onsets by a critical interval, 0-70 msec in some species but as
long as 0.2-2.0 sec in others. When such preferences occur, call timing
mechanisms with which males reduce their production of following calls are
favored by selection. These timing mechanisms are observed among
rhythmically calling species, and they may generate the emergence of group
synchrony or alternation as a byproduct of local pairwise signal
interactions.
Where males are selected to adjust call timing and increase their incidence
of leading calls, they confront a dilemma if density is high: Adjusting call
rhythm in response to all singing neighbours may severely reduce the calling
rate, whereas forgoing rhythm adjustment may lead to a preponderance of
ineffective following calls. Simulations and laboratory experiments
demonstrate that calling males may solve this problem by selectively
attending to only a subset of neighbours.
We studied three orthopteran species, Ligurotettix planum, Ephippiger
ephippiger (both alternating chorusers), and Neoconocephalus spiza
(synchronous choruser), in the field to determine the extent to which
selective attention occurs in natural populations and structures chorusing.
These three species were chosen because previous studies demonstrated
moderate to strong precedence effects in females and timing adjustments in
males with which they reduced production of following calls; moreover,
controlled experiments indicated that selective attention influenced
interactions among calling males in one of the species. As predicted, our
studies of natural choruses showed that males in all three species
maintained high call rates by attending to only some of their neighbours.
Attended neighbours were generally the nearest, and loudest, ones, but other
rules with which attention is applied may also occur. In L. planum and E.
ephippiger, males generally attended to a single calling neighbour, but N.
spiza males often attended to several. We propose that reduced selectivity
in N. spiza reflects the synchronous nature of its chorusing, implying that
a group effect emerging incidentally can influence via feedback the
individual behaviour yielding that collective activity.
H. Brumm and D. Todt. 2003. Facing the rival: directional singing behaviour
in nightingales. Behaviour 140 (1): 43-53.
Abstract: Many animal vocalizations are directional, i.e. the sound energy
is not emitted omnidirectionally but focused in one direction. Such signal
property could be advantageous in order to direct the vocalization towards
the addressee, provided its position is known to the sender. On the other
hand, a directional signal could be disadvantageous when the position of
addressees is not known. Thus, some animals may adjust their behaviour to
either counteract or exploit the directionality of their vocalizations
depending on the context of communication. We tested this hypotheses in
territorial male nightingales (Luscinia megarhynchos) demonstrating the
behavioural significance of vocal directionality for the first time. While
interacting with the playback of a rival, the birds increased the strength
of singing directionality by orientating themselves towards the playback
loudspeaker. At the same time, subjects showed less lateral head movements
per song during the playback procedure suggesting that nightingales mitigate
the directional sound radiation pattern of their songs and emit them in a
more omnidirectional way when the position of potential addressees is
unclear. During interactions, however, when the position of a addressee is
detected, the birds use the directionality of their songs to broadcast them
in the direction of the addressee ensuring the most effective signal
transmission.
T. J. Hammond and W. J. Bailey. 2003. Eavesdropping and defensive auditory
maskink in an Australian bushcricket, Caedicia (Phaneropterinae:
Tettigoniidae: Orthoptera). Behaviour 140 (1): 79-95.
Abstract: We investigated the potential for a novel alternative male tactic
in Caedicia, an Australian genus of duetting phaneropterine bushcrickets
(Orthoptera: Tettigoniidae: Phaneropterinae). Males listen to and track
females as they reply to the calls of other males, using both the male call
and the female reply to initiate their own searching behaviour. We describe
this behaviour as eavesdropping. Calling males produce a high intensity
chirp following their calling song, which has no apparent effect on female
responsiveness. We test the possibility that this loud chirp acts to defend
the temporary pair bond, established between the calling male and the
duetting female, by preventing other males from hearing the female reply. We
suggest means by which the calling male may be able to hear the female reply
whilst producing the masking chirp. This behaviour may be considered a form
of pre-copulatory acoustic mate guarding.
R. Márquez and J. Bosch. 2003. Temporal encoding of information in the
advertisement call of the Iberian midwife toad (Alytes cisternasii). The
importance of rise time. Behaviour 140 (1): 113-123.
Abstract: In order to test the relative importance of the beginning (rise
time) and end of the advertisement call in call localization and call
preference with female Iberian midwife toads we performed two-speaker
playback experiments with synthetic stimuli. In the first set of tests the
alternative stimuli were the initial (rise time) or the final part (fall
time) of a male call (abutting, or antiphonally). In the second set of
tests, two alternative calls were presented differing in the dominant
frequency of the initial part of the call or the final part of the call.
In the first set of tests, the preferred stimulus was always the first one
presented, independently of the shape of the rise time, which seemed to be
unimportant for female choice. The second set of tests did not yield a
conclusive answer about the relative importance of the rise time of the call
but suggest that further studies of this possibility may prove fruitful.
_________________________________
Dr. F R A N K V E I T
Int. Laboratory for Dolphin Behaviour Research
c/o Dolphin Reef Eilat, Southern Beach
P.O.Box 104, Eilat 88100, Israel
e-mail: [EMAIL PROTECTED]
Tel.: +972 - 8 - 6341 868
Fax: +972 - 8 - 6375 921
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