ecoObs Mini-batcorder 1.0 Kurzanleitung - Seite 6
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locations, since it shields for example echoes from behind the micro-
phone.
•
Many bushcrickets have calls in the ultrasonic spectrum. At a dis-
tance of 2 meters or more to vegetation, the signal strength of these
calls is reduced, hence, generates only few to none trigger events.
Site selection and recording modalities
Even if all tips mentioned before are taken into account, there are some dis-
advantageous locations for bat detection:
•
Hibernaculum or swarming site: A bat detector set up inside or in
front of a hibernaculum will lead to a huge number of recordings in
autumn and spring. This makes data analysis more difficult. Social
calls as well as unspecific echolocation calls near structures may lead
to uninterpretable recordings. The more species and individuals are
recorded at the same time, the less predictions can be made on bat
density or quantification of activity. We recommend avoiding such
sites, if studying general bat activity. Place the batcorder at distances
of at least 50 to 100 meters of such sites to gain a more useful mea-
sure of activity.
•
Bodies of standing water: many bat species are hunting at lakes
and other water bodies. Thus, such sites lead to good results for ac-
cessing the overall species diversity of an area. But comparison of
bat activity to recordings from other sites is difficult for similar reasons
as mentioned before (swarming sites). In addition reflexions from the
the water surface will degrade the quality of the recordings. We rec-
ommend to place the batcorder in a distance of at least 5 to 10 me-
ters to the waterside.
•
Car transects: A method sometimes chosen for monitoring purposes
are car transects. That means, bat activity is measured along a driven
distance. We advise against using this method, since danger of acci-
dents rises, and recording while driving goes along with a lot of noise.
In addition the mechanical strain on the device, echos from the car
surface and the potential displacement of sensitive species have to
be taken into account.
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