Václav Sicha, Petr Procházka, Marcel Honza (2007): Hopeless
solicitation? Host-absent vocalization in the common cuckoo has no
effect on feeding rate of reed warblers. J. Ethol. 25(2), 147-152
Abstract: Begging behavior of nestlings can signal both hunger and
competitive ability. Studies of begging in evicting avian brood
parasites exclude the influence of nestling competition and may
provide new insights into the host-parasite conflict and the
evolution of signaling. Apart from the begging call, common cuckoo
Cuculus canorus nestlings use special vocal displays in the absence of
their hosts, termed here host-absent vocalization (HAV). Since these
conspicuous calls can increase the risk of predation and require
energy, their costs should be balanced by some benefits, such as
increased food provisioning. However, there has been no evidence that
chicks convey information about their hunger by HAV. We therefore
tested experimentally whether cuckoo chicks use HAV as an additional
signal to enhance food-delivery rate by their hosts. We used playback
of HAV recorded from cuckoo nestlings to determine whether their
hosts, reed warblers Acrocephalus scirpaceus, increase their
provisioning in response to an apparent increase in HAV. Older chicks
spent more time in HAV than younger chicks, suggesting that HAV is not
caused by inaccurate discrimination of host arrival stimuli. Negative
correlation of HAV with feeding rate and mass gain between the two
experiments suggested that hunger was the motivation of HAV. The
playback experiment, however, did not prove that HAV affects host
provisioning rate. We discuss possible reasons for this result and
provide alternative explanations for HAV, such as creating a bond
between the hosts and the parasitic young used later in the
postfledging care.
URL: http://www.springerlink.com/content/w13261705p747606/
Tomasz S. Osiejuk, Katarzyna Ratynska, Jakub P. Cyga (2007): Corn
bunting (Miliaria calandra) males respond differently to alternating
and overlapping playback of song. J. Ethol. 25(2), 159-168
Abstract: Interactive playback experiments were used to study the
signal value to the corn bunting, Miliaria calandra, of alternating
and overlapping singing. We subjected 15 males to two stimuli that
differed in the temporal pattern of song playback (alternating or
overlapping). We measured eight characteristics of the males'
response in two categories--song output and movements. Overlapping
and alternating playback elicited a similar song response,
characteristic of highly aroused males. Song response correlated
positively with males' singing activity before playback,
irrespective of stimulus. There were significant differences between
latency of approach to the loudspeaker and number of flights. Birds
approached the loudspeaker more quickly and spent more time close to
it when playback alternated with their songs. The results suggest
overlapping song could be interpreted as a stronger threat but elicits
a more cautious, rather than stronger, response than the alternating
pattern. Males were found to shorten songs during the playback
compared with songs sung before and after stimulation. The only
predictor of degree of song shortening was song activity before the
playback began. It should, therefore, be regarded as a signal which is
related to escalated, close-distance counter-singing.
URL: http://www.springerlink.com/content/r4353h47u8123h65/
Jason P. Edgar, Rob G. Appleby, Darryl N. Jones (2007): Efficacy of an
ultrasonic device as a deterrent to dingoes (Canis lupus dingo): a
preliminary investigation. J. Ethol. 25(2), 209-213
Abstract: In April 2001, a 9-year-old child was attacked and killed by
dingoes on Fraser Island, Australia. The Dingo Management Strategy
formulated in response to this incident proposed ultrasonic deterrents
as one of a number of non-lethal management techniques requiring
further investigation. In this paper, we describe a preliminary
examination of an ultrasonic deterrent to dingoes using four captive
animals as test subjects. Although replication was minimal, the use
of a simple experimental design, in combination with a flexible
analytical technique, sufficiently demonstrated that the unit tested
produced no measurable effect as a deterrent to test subjects.
URL: http://www.springerlink.com/content/7079r455741786jp/
Please contact the authors for PDF requests.
Kind regards
Sonja Amoser
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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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