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Drone images afford more detections of marine wildlife than real-time observers during simultaneous large-scale surveys
Journal article   Open access   Peer reviewed

Drone images afford more detections of marine wildlife than real-time observers during simultaneous large-scale surveys

Amanda J. Hodgson, Nat Kelly and David Peel
PeerJ, Vol.11, e16186
2023
DOI: https://doi.org/10.7717/peerj.16186
PMCID: PMC10629383
PMID: 37941930
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Published32.85 MBDownloadView
Published (Version of Record)CC BY V4.0,  Open Access

Abstract

Conservation Biology Ecology Marine Biology Population Biology
There are many advantages to transitioning from conducting marine wildlife surveys via human observers onboard light-aircraft, to capturing aerial imagery using drones. However, it is important to maintain the validity of long-term data series whilst transitioning from observer to imagery surveys. We need to understand how the detection rates of target species in images compare to those collected from observers in piloted aircraft, and the factors influencing detection rates from each platform. We conducted trial ScanEagle drone surveys of dugongs in Shark Bay, Western Australia, covering the full extent of the drone’s range (∼100 km), concurrently with observer surveys, with the drone flying above or just behind the piloted aircraft. We aimed to test the assumption that drone imagery could provide comparable detection rates of dugongs to human observers when influenced by same environmental conditions. Overall, the dugong sighting rate (i.e., count of individual dugongs) was 1.3 (95% CI [0.98–1.84]) times higher from the drone images than from the observers. The group sighting rate was similar for the two platforms, however the group sizes detected within the drone images were significantly larger than those recorded by the observers, which explained the overall difference in sighting rates. Cloud cover appeared to be the only covariate affecting the two platforms differently; the incidence of cloud cover resulted in smaller group sizes being detected by both platforms, but the observer group sizes dropped much more dramatically (by 71% (95% CI [31–88]) compared to no cloud) than the group sizes detected in the drone images (14% (95% CI [−28–57])). Water visibility and the Beaufort sea state also affected dugong counts and group sizes, but in the same way for both platforms. This is the first direct simultaneous comparison between sightings from observers in piloted aircraft and a drone and demonstrates the potential for drone surveys over a large spatial-scale.

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UN Sustainable Development Goals (SDGs)

This output has contributed to the advancement of the following goals:

#14 Life Below Water

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