Henrik Brumm (2006): Signalling through acoustic windows: nightingales
avoid interspecific competition by short-term adjustment of song
timing. J. Comp. Physiol. A 192, 1279-1285
Abstract: The function of bird song is closely linked to sexual
selection through female choice and male-male competition, and thus
variation in communication success is likely to have major fitness
consequences for a singing male. A crucial constraint on signal
transmission is imposed by background noise, which may include songs
from other species. I investigated whether singing nightingales
(Luscinia megarhynchos) avoid temporal overlap with the songs of other
bird species in a playback experiment. I analysed the temporal song
patterns of six males, each of which were exposed to songs of other
species. The nightingales significantly avoided overlapping their
songs with the playback songs, and started singing preferentially
during the silent intervals between the heterospecific songs. This
timing of song onset produced a greater variability in pause duration
compared to the nightingales' undisturbed solo singing. These findings
suggest that birds adjust their song timing to avoid acoustic
interference on short temporal scales, and thus are able to improve
the efficiency of acoustic communication in complex sonic
environments. Moreover, the results indicate that temporal song
patterns can be affected by the songs of other species, and thus such
influences should be taken into account when studying bird song in the
field.
doi 10.1007/s00359-006-0158-x
http://www.springerlink.com/content/k8q5460k7543v306/
John J. Rosowski, Michael E. Ravicz, Jocelyn E. Songer (2006):
Structures that contribute to middle-ear admittance in chinchilla,
J. Comp. Physiol. A 192, 1287-1311
Abstract: We describe measurements of middle-ear input admittance in
chinchillas (Chinchilla lanigera) before and after various
manipulations that define the contributions of different middle-ear
components to function. The chinchilla's middle-ear air spaces have a
large effect on the low-frequency compliance of the middle ear, and
removing the influences of these spaces reveals a highly admittant
tympanic membrane and ossicular chain. Measurements of the admittance
of the air spaces reveal that the high-degree of segmentation of these
spaces has only a small effect on the admittance. Draining the cochlea
further increases the middle-ear admittance at low frequencies and
removes a low-frequency (less than 300 Hz) level dependence in the
admittance. Spontaneous or sound-driven contractions of the middle-ear
muscles in deeply anesthetized animals were associated with
significant changes in middle-ear admittance.
doi 10.1007/s00359-006-0159-9
http://www.springerlink.com/content/a650r316414197k2/
Andreas Stumpner, Jorge Molina (2006): Diversity of intersegmental
auditory neurons in a bush cricket. J. Comp. Physiol. A 192,
1359-1376
Abstract: Various auditory interneurons of the duetting bush cricket
Ancistrura nigrovittata with axons ascending to the brain are
presented. In this species, more intersegmental sound-activated
neurons have been identified than in any other bush cricket so far,
among them a new type of ascending neuron with posterior soma in the
prothoracic ganglion (AN4). These interneurons show not only
morphological differences in the prothoracic ganglion and the brain,
but also respond differently to carrier frequencies, intensity and
direction. As a set of neurons, they show graded differences for all
of these parameters. A response type not described among
intersegmental neurons of crickets and other bush crickets so far is
found in the AN3 neuron with a tonic response, broad frequency tuning
and little directional dependence. All neurons, with the exception of
AN3, respond in a relatively similar manner to the temporal patterns
of the male song: phasically to high syllable repetitions and
rhythmically to low syllable repetitions. The strongest coupling to
the temporal pattern is found in TN1. In contrast to behavior the
neuronal responses depend little on syllable duration. AN4, AN5 and
TN1 respond well to the female song. AN4 (at higher intensities) and
TN1 respond well to a complete duet.
doi 10.1007/s00359-006-0164-z
http://www.springerlink.com/content/037770377705555w/
Regards,
Sonja Amoser
=============================================================Sonja Amoser, PhD
Student
University of Vienna, Dept. of Behavior
Althanstrasse 14, 1090 Vienna, Austria
Phone: +43-1-4277-54467 oder +43-664-5006106 (private)
Fax: +43-1-4277-54506
email:
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