Volume 96:
Veronica L. Bura, Alan J. Fleming, Jayne E. Yack (2009): Whatâs the buzz?
Ultrasonic and sonic warning signals in caterpillars of the great peacock moth
(Saturnia pyri). Naturwissenschaften 96 (6), 713-718.
Abstract: Caterpillars have many natural enemies and, therefore, have evolved a
diversity of antipredator strategies. Most research focuses on those strategies
(crypsis, countershading, and warning coloration) targeting visually guided
predators. In contrast, defensive sounds, although documented for more than a
century, have been poorly studied. We report on a novel form of sound
productionâchirpingâin caterpillars of the common European Great Peacock moth
(Saturnia pyri). Chirps are broadband, with dominant peaks ranging between the
sonic (3.7 kHz) and ultrasonic (55.1 kHz) and are generated by a rapid
succession of mandibular âtooth strikes.â Chirp trains are induced by simulated
predator attacks and precede or accompany the secretion of a defensive chemical
from integumental bristles, supporting our hypothesis that these sounds
function in acoustic aposematism. We propose that these caterpillars generate
multimodal warning signals (visual, chemical, and acoustic) to target the
dominant sensory modalities of different predators, including birds, bats, and
invertebrates.
URL: http://www.springerlink.com/content/1607443p8g713tk4/
For reprints please contact Jayne E. Yack (email:
Mario Penna, Juan Pablo Gormaz, Peter M. Narins (2009): When signal meets
noise: immunity of the frog ear to interference. Naturwissenschaften 96 (7),
835-843.
Abstract: Sound stimulates the tympanic membrane (TM) of anuran amphibians
through multiple, poorly understood pathways. It is conceivable that
interactions between the internal and external inputs to the TM contribute to
the nonlinear effects that noise is known to produce at higher levels of the
auditory pathway. To explore this issue, we conducted measurements of TM
vibration in response to tones in the presence of noise in the frog Eupsophus
calcaratus. Laser vibrometry revealed that the power spectra (nâ=â16) of the TM
velocity in response to pure tones at a constant level of 80 dB sound-pressure
level (SPL) had a maximum centered at an average frequency of 2,344 Hz (range
1,700â2,990 Hz) and a maximum velocity of 61.1 dB re 1 Âm/s (range 42.9â66.6 dB
re 1 Âm/s). These TM-vibration velocity response profiles in the presence of
increasing levels of 4-kHz band-pass noise were unaltered up to noise levels of
90 dB SPL. For the relatively low spectral densities of the noise used, the TM
remains in its linear range. Such vibration patterns facilitate the detection
of tonal signals in noise at the tympanic membrane and may underlie the
remarkable vocal responsiveness maintained by males of E. calcaratus under
noise interference.
URL: http://www.springerlink.com/content/254521747140m040/
For reprints please contact Mario Penna (Email:
Benjamin J. Pitcher, Heidi Ahonen, Robert G. Harcourt, Isabelle Charrier
(2009): Delayed onset of vocal recognition in Australian sea lion pups
(Neophoca cinerea). Naturwissenschaften 96 (8), 901-909.
Abstract: In pinnipeds, maternal care strategies and colony density may
influence a speciesâ individual recognition system. We examined the onset of
vocal recognition of mothers by Australian sea lion pups (Neophoca cinerea). At
2 months of age, pups responded significantly more to the calls of their own
mothers than alien female calls demonstrating a finely tuned recognition
system. However, newborn pups did not respond differentially to the calls of
their mother from alien female calls suggesting that vocal recognition had not
yet developed or is not yet expressed. These findings are in stark contrast to
other otariid species where pups learn their motherâs voice before their first
separation. Variance in colony density, pup movements, and natal site fidelity
may have reduced selective pressures on call recognition in young sea lions, or
alternatively, another sensory system may be used for recognition in the early
stage of life.
URL: http://www.springerlink.com/content/p64r852651367827/
For reprints please contact Benjamin J. Pitcher (Email:
Elodie Briefer, Thierry Aubin, Fanny Rybak (2009): Response to displaced
neighbours in a territorial songbird with a large repertoire.
Naturwissenschaften 96 (9), 1067-1077.
Abstract: Neighbour recognition allows territory owners to modulate their
territorial response according to the threat posed by each neighbour and thus
to reduce the costs associated with territorial defence. Individual acoustic
recognition of neighbours has been shown in numerous bird species, but few of
them had a large repertoire. Here, we tested individual vocal recognition in a
songbird with a large repertoire, the skylark Alauda arvensis. We first
examined the physical basis for recognition in the song, and we then
experimentally tested recognition by playing back songs of adjacent neighbours
and strangers. Males showed a lower territorial response to adjacent neighbours
than to strangers when we broadcast songs from the shared boundary. However,
when we broadcast songs from the opposite boundary, males showed a similar
response to neighbours and strangers, indicating a spatial categorisation of
adjacent neighboursâ songs. Acoustic analyses revealed that males could
potentially use the syntactical arrangement of syllables in sequences to
identify the songs of their neighbours. Neighbour interactions in skylarks are
thus subtle relationships that can be modulated according to the spatial
position of each neighbour.
URL: http://www.springerlink.com/content/1mw8v40946311404/
For reprints please contact Elodie Briefer (Email:
Kind regards
Sonja
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Dr. Sonja Amoser
SteinrieglstraÃe 286
3400 Weidlingbach
Austria
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