Gembloux Agro-Bio Tech (GxABT)
Gembloux Agro-Bio Tech (GxABT)

Assessment of UAV potential for bioacoustic monitoring of birds and bats: Tests under controlled conditions in Belgium

Broset, Stéphane ULiège
Promotor(s) : Lejeune, Philippe ULiège ; Michez, Adrien ULiège
Date of defense : 30-Aug-2018 • Permalink :
Title : Assessment of UAV potential for bioacoustic monitoring of birds and bats: Tests under controlled conditions in Belgium
Translated title : [fr] Evaluation du potentiel des drones pour les inventaires ornithologiques et chiroptérologiques par bioacoustique: test en conditions contrôlées en Belgique
Author : Broset, Stéphane ULiège
Date of defense  : 30-Aug-2018
Advisor(s) : Lejeune, Philippe ULiège
Michez, Adrien ULiège
Committee's member(s) : Hebert, Jacques ULiège
Brostaux, Yves ULiège
Paquet, Jean-Yves 
Language : English
Number of pages : 62
Keywords : [en] UAV
[en] drone
[en] bird
[en] bat
[en] bioacoustics
[en] monitoring
Discipline(s) : Life sciences > Environmental sciences & ecology
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master en bioingénieur : gestion des forêts et des espaces naturels, à finalité spécialisée
Faculty: Master thesis of the Gembloux Agro-Bio Tech (GxABT)


[en] The importance of biodiversity no longer needs to be demonstrated. The conservation of this heritage requires data whose collection methodology may vary according to the taxon studied and the target habitat. The constant evolution of technology allows new approaches to be developed in order to increase the quantity and/or quality of these data, in particular by studying new species and habitats. For several years, UAVs (unmanned aerial vehicles) have contributed to the enhancement of this database through imagery. To date, very few studies provide information on the effectiveness of UAVs for bioacoustic monitoring. Therefore, this master’s thesis aims to evaluate the potential of UAVs for bioacoustic monitoring of birds and bats by means of tests carried out under controlled conditions, i.e. by playing soundtracks of these taxa. The main objective is to compare detection distances and probabilities between UAVs (quadcopter & fixed-wing) and ground recordings. A few tests were also conducted in vivo to get a first insight into the effectiveness of this technique compared to standard methods: point counts (birds) and passive ground recordings (bats). All tests were conducted in Wallonia (Belgium).
The songs of 9 bird species and the calls of 5 bat species, corresponding to a representative sample of the sound variability in terms of frequency and intensity, were played through a loudspeaker placed at different distances from the drone. This experiment was repeated at several altitudes.
The effective detection radius (EDR) is lower for UAV-based recordings than ground-based recordings. Bats detectability is sensitive to altitude making the overall EDR twice smaller for a microphone flying at 5 m than for ground recordings. However, for the majority of bird species (5 out of 9), the EDR remains close for both methods (difference ≤ 20%) regardless of altitude. Under in vivo conditions, the drone has always detected fewer individuals than standard methods for both taxa.
These initial results lead to the conclusion that UAV-based bioacoustic monitoring underestimate reality and cannot therefore substitute standard monitoring methods in the study area. For avian surveys, this method could be complementary to traditional ones in order to obtain data on the diversity or presence of target species in areas difficult to access for human beings. However, the poor performance of chiropterans tests does not justify such use. Obviously these results are only valid for our equipment, hence the use of quieter drones will clearly improve them.
Extensive testing in less accessible areas such like tropical canopies should therefore be considered to reinforce these conclusions.



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  • Broset, Stéphane ULiège Université de Liège > Gembloux Agro-Bio Tech


Committee's member(s)

  • Hebert, Jacques ULiège Université de Liège - ULiège > Ingénierie des biosystèmes (Biose) > Gestion des ressources forestières et des milieux naturels
    ORBi View his publications on ORBi
  • Brostaux, Yves ULiège Université de Liège - ULiège > Agronomie, Bio-ingénierie et Chimie (AgroBioChem) > Modélisation et développement
    ORBi View his publications on ORBi
  • Paquet, Jean-Yves
  • Total number of views 410
  • Total number of downloads 908

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