Debusschere, E.

Deneudt, K.

Hernandez, F.

Mortelmans, J.

Reubens, J.

Wydooghe, B.

Open Marine Archive

 43 
Knock knock, who’s there? 
Debusschere Elisabeth, Reubens Jan, Wydooghe Benny, Mortelmans Jonas, Deneudt Klaas and 
Hernandez Francisco 
Flanders Marine Institute (VLIZ), InnovOcean site, Wandelaarkaai 7, 8400 Ostend, Belgium 
E-mail: elisabeth.debusschere@vliz.be 
 
Passive acoustic monitoring is a powerful tool to learn about the relationship of species with their 
environment. Especially species using echolocation for navigation and foraging within their habitat, 
are of interest. The Belgian LifeWatch observatory (as part of the European Strategy Forum on 
Research Infrastructure (ESFRI)) includes a set of hydrophones spatially distributed across the Belgian 
part of the North Sea, using acoustic release bottom mooring frames and a set of microphones along 
the Belgian coast. In that way, echolocation of harbour porpoises (Phocoena phocoena) and bats are 
recorded. Echolocation can be species-specific and used during specific activities, consequently 
species and behaviour could be derived. Harbour porpoises produce echolocation clicks in a certain 
sequence within the small frequency range (120 – 145 kHz), reflecting their behaviour. Their seasonal 
and spatial presence can be derived from these recordings. 
 
Along the Belgian coast, bats are migrating during spring and autumn. Bats can produce sound in the 
frequency range of 5 up to 150 kHz, depending on its morphology, physiology and behaviour (i.e. 
transit calls, foraging calls and social calls). Two abundant species, the common pipistrelle 
(Pipistrellus pipistrellus) and Nathusius' pipistrelle (Pipistrellus pipistrellus) are recorded along the 
Belgian coast. Less frequently recorded are the Nyctaloid and Myotis species groups. 
 
Echolocation calls are mostly produced in the ultrasound frequency range and therefore inaudible for 
the human ear. During the VLIZ Marine Science Day, bat calls can be listened to, using a ten-time 
delayed mode. In addition, the bat calls are visualised to help identifying the behaviour of the animal. 
 
Keywords: acoustic ecology; echolocation; bats; porpoises  


Knock knock, who's there?

http://www.vliz.be/imisdocs/publications/311869.pdf

Knock knock, who's there?

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