Shigeki Mantani, Shizuko Hiryu, Emyo Fujioka, Naohiro Matsuta, Hiroshi
Riquimaroux & Yoshiaki Watanabe (2012): Echolocation behavior of the
Japanese horseshoe bat in pursuit of fluttering prey. J. Comp. Physiol. A
198 (10), 741-751.
Abstract: Echolocation sounds of Rhinolophus ferrumequinum nippon as they
approached a fluttering moth (Goniocraspidum pryeri) were investigated using
an on-board telemetry microphone (Telemike). In 40 % of the successful
moth-capture flights, the moth exhibited distinctive evasive flight
behavior, but the bat pursued the moth by following its flight path. When
the distance to the moth was approximately 3?4 m, the bats increased the
duration of the pulses to 65?95 ms, which is 2?3 times longer than those
during landing flight (30?40 ms). The mean of 5.8 long pulses were emitted
before the final buzz phase of moth capture, without strengthening the sound
pressure level. The mean duration of long pulses (79.9 ± 7.9 ms)
corresponded to three times the fluttering period of G. pryeri (26.5 × 3 =
79.5 ms). These findings indicate that the bats adjust the pulse duration to
increase the number of temporal repetitions of fluttering information rather
than to produce more intense sonar sounds to receive fine insect echoes. The
bats exhibited Doppler-shift compensation for echoes returning from large
static objects ahead, but not for echoes from target moths, even though the
bats were focused on capturing the moths. Furthermore, the echoes of the
Telemike recordings from target moths showed spectral glints of
approximately 1?1.5 kHz caused by the fluttering of the moths but not
amplitude glints because of the highly acoustical attenuation of ultrasound
in the air, suggesting that spectral information may be more robust than
amplitude information in echoes during moth capturing flight.
URL: http://link.springer.com/article/10.1007%2Fs00359-012-0744-z
For reprints please contact Shizuko Hiryu (email:
Nicole Stange & Bernhard Ronacher (2012): Song characteristics and
morphological traits in four populations of the grasshopper Chorthippus
biguttulus L.. J. Comp. Physiol. A 198 (10), 763-775.
Abstract: We investigated four populations of the grasshopper Chorthippus
biguttulus with respect to differences in morphological traits and
characteristics of their communication signals. A special focus was laid on
possible correlations between morphological and song traits of males that
could be used by females to infer quality cues of potential mates. We also
tested whether females exhibit preferences for males of their own
population. Specific song features (onset accentuation, offset, syllable
period) of males?but not of females?differed between populations. We
observed size differences both in males and females from different
populations, but the size ranks of the two sexes were not always correlated.
Environmental factors appear to have a strong influence on different size
traits, compared to genetic origin. In all populations a specific song
feature, the accentuation of syllable onsets, showed a similar correlation
with a morphological trait, hind leg size, but its correlation with other
size indicators sometimes differed in sign. Females did not prefer songs of
males from their own population. The best predictor for song attractiveness
was?unexpectedly?not the onset accentuation but the offset depth.
URL: http://link.springer.com/article/10.1007%2Fs00359-012-0746-x
For reprints please contact Nicole Stange (email:
M. M. Rothbart & R. M. Hennig (2012): Calling song signals and temporal
preference functions in the cricket Teleogryllus leo. J. Comp. Physiol. A
198 (11), 817-825.
Abstract: The acoustic display of many cricket species consists of trains of
pulses (chirps) with intermittent pauses. Here, we investigated the temporal
cues that females of the cricket Teleogryllus leo used to detect a pulse and
a chirp pattern on two different time scales. For both patterns, females
accepted a wide range of combinations that covered the respective pulse and
chirp parameters in the songs of males. In tests with a continuous series of
pulses at different modulation frequencies, the transfer function of pattern
discrimination was also determined. Females exhibited two ranges of high
response scores indicating two temporal filters with an inhibitory
interaction. For the modulation frequency of the pulse pattern, the peak of
the preference function was rather sharply tuned and at a lower pulse rate
than produced by males. These results show that the combined output of both
filters did not increase selectivity, but rather enlarged the accepted range
of signals.
URL: http://link.springer.com/article/10.1007%2Fs00359-012-0751-0
For reprints please contact R. M. Hennig (email:
Alejandro Vélez, Gerlinde Höbel, Noah M. Gordon & Mark A. Bee (2012): Dip
listening or modulation masking? Call recognition by green treefrogs (Hyla
cinerea) in temporally fluctuating noise. J. Comp. Physiol. A 198 (12),
891-904.
Abstract: Despite the importance of perceptually separating signals from
background noise, we still know little about how nonhuman animals solve this
problem. Dip listening, an ability to catch meaningful ?acoustic glimpses?
of a target signal when fluctuating background noise levels momentarily
drop, constitutes one possible solution. Amplitude-modulated noises,
however, can sometimes impair signal recognition through a process known as
modulation masking. We asked whether fluctuating noise simulating a breeding
chorus affects the ability of female green treefrogs (Hyla cinerea) to
recognize male advertisement calls. Our analysis of recordings of the sounds
of green treefrog choruses reveal that their levels fluctuate primarily at
rates below 10 Hz. In laboratory phonotaxis tests, we found no evidence for
dip listening or modulation masking. Mean signal recognition thresholds in
the presence of fluctuating chorus-like noises were never statistically
different from those in the presence of a non-fluctuating control. An
analysis of statistical effects sizes indicates that masker fluctuation
rates, and the presence versus absence of fluctuations, had negligible
effects on subject behavior. Together, our results suggest that females
listening in natural settings should receive no benefits, nor experience any
additional constraints, as a result of level fluctuations in the soundscape
of green treefrog choruses.
URL: http://link.springer.com/article/10.1007/s00359-012-0760-z
For reprints please contact Alejandro Vélez (email:
Kind regards
Sonja
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Dr. Sonja Amoser
Steinrieglstraße 286
3400 Weidlingbach
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