Communication Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 67

vocalization, frog control, no playback). Ovenbirds and veery were found to reduce
their activity up to 30 m from the playback station and placed their nesting territory
far from the playback station. The reaction to the simulated predator presence was
twofold stronger in the ovenbird than in the veery. Interspecific eavesdropping
represents an important step in the integration of species inside a community and
represents a necessary step for the creation of ecological communities.
The effect of predation risk has been verified in the Siberian jay ( Perisoreus
infaustus ) by Eggers et al. ( 2006 ), simulating by playback the acoustic result of a
corvid presence close to a breeding territory of this species. The reaction of the
Siberian jay was to increase the protective covering of the nests and to reduce the
clutch size.
A further example of eavesdropping was presented by ¨ bernickel et al. ( 2012 )in
three neotropical bats during search phase calls and feeding buzzes using a play-
back methodology. The greater fishing bat ( Noctilio leporinus ) and the lesser
bulldog bat ( Noctilio albiventris ) reacted very well to playback of search phase
calls and feeding buzzes of conspecific and congeneric bats. The greater fishing bat
was attracted by the acoustic cues of Noctilio albiventris , but no reaction was
apparently found in the sac-winged Saccopteryx bilineata . Eavesdropping behavior
has been proved in the two species of Noctilio , and this largely depends on species-
specific traits (e.g., foraging style, social behavior) more than on call design per
se. The advantage to eavesdropping largely depends on the information on abun-
dance of prey that can be shared between species.
Eavesdropping is an important activity in prey-predator and parasitoid
relationships. Eavesdropping has been observed in different species of bats in the
Southern Hemisphere and has also been observed in the Palearctic after the
investigation of Jones et al. ( 2011 ).
In particular the signaling mechanism between tettigoniid bush crickets and bats
is well known where these insects have also an ultrasonic repertoire that can be
tracked by bats in a range of 20-80 kHz. In Europe, the lesser mouse-eared bat
( Myotis blythii oxygnatus ) search their prey in dense grass habitats. This species is
morphologically similar to Myotis myotis but is ecologically distinct. Myotis myotis
forages in forest and requires open space, its preferred prey being carabid beetles,
whereas M. blythii oxygnatus forages on tettigoniids.
The two species can be identified by the analysis of their fecal samples.
There is evidence that the simulated echolocation calls of M. myotis produce in
Tettigonia viridissima an escape response and that repetitive ultrasonic 30-kHz
pulses can cause cessation of song in this insect.
The strategies to localize the two main types of distinct prey were investigated
for these two species:
Tettigonia viridissima for M. blythii oxygnatus and the rustling sound of carabid
beetles for M. myotis .
The two species of bats were utilized in experimental broadcasting of the sounds
of Tettigonia and of the carabids. During the playback experiment using Tettigonia
sounds, both bats were attracted by the call of Tettigonia , which was a real surprise
because M. myotis was also attracted by the sound of Tettigonia . However, spectral
species differences appeared during the experiment: M. blythii oygnathus had a