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Usage

Detecting bat calls reliably and in a quantitative manner poses high demands

on setup and actual recording location. Automatic triggering, recording and

computerized analyzing on species level highly depends on the proper detec-

tor setup. We therefore recommend to follow the following advice. The user

guidelines were compiled particularly regarding inﬂuences on the triggering

mechanism, automated call analysis (with bcAdmin) and automated discrimi-

nation (batIdent).

Acoustic and electromagnetic inﬂuences

Noise in the audio signal can be induced by either acoustic wor electromag-

netic interferences. Such signals can inﬂuence bat call analysis dramatically.

Even though the batcorder possesses a robust triggering-algorithm in most

environmental setups, known sources of disturbance should be avoided.

While the batcorder will cope with these situations, nevertheless it may

record more parasite recordings or miss some bats. Also, the automated

analysis of calls may suffer. The following list gives sources of perturbation,

based on our knowledge:

•

Strong electromagnetic ﬁelds (for example power lines, big coils,

power switchboards, wind turbines, ...) may lead to additional record-

ings of noise and noise in recordings.

•

AC sources (for example neon lamps, energy saving lamps, ...) may

produce narrow bandwidth ultrasonic noise.

•

Strong wind streaming alongside irregular shaped bodies (for exam-

ple trains, cars, ...) create low frequency noise as well as broadband

noise and can mask bat calls.

•

Reﬂections from nearby objects can interfere with bat calls, since

calls as well as echoes of the calls arrive with very small time differ-

ences at the microphone. This leads to interferences and thus to a

decline of the trigger algorithms performance. Thus, the microphone

should be placed at least at 2m distance (height & range) to any ob-

jects. Recording close to vegetation, walls, underneath bridges, un-

derpasses as well as above sealed roads or water bodies is not rec-

ommended. Often the box extension will improve recordings at such

SAGE