Publication Date

2023

Document Type

Dataset

Publisher

Edith Cowan University

School or Research Centre

School of Science

Funders

Australian Marine Mammal Centre

Description

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 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. Data in "All data for analysis - Shark Bay Hodgson et al" include a summary of the sightings from both platforms per transect segment, including associated environmental covariates. Also included are details of each dugong group sighted by each platform. "Comparison between reviewers - Shark Bay Hodgson et al" contains details of the drone image sightings recorded for a subset of drone images that were reviewed by three reviewers. These data were used to compare the reviewers and calculate perception bias for the manual review of the drone images. "Perception bias data - Shark Bay Hodgson et al" contains the data used to calculate the perception bias for the observers onboard the piloted aircraft.

DOI

10.25958/fkdd-qb81

Research Activity Title

Drone images provide superior data over human observers during large-scale aerial surveys of marine wildlife

Research Activity Description

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 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 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.

Methodology

Details of the methods used to collect these data can be found in the forthcoming related publication.

Start of data collection time period

2012

End of data collection time period

2012

Language

English

Codes

See 'Data Description' within each excel file.

File Format(s)

Excel workbooks

File Size

250, 39, 115 KB

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Contact

a.hodgson@ecu.edu.au

Download
Drones for large-scale wildlife surveys_Comparison between reviewers - Shark Bay Hodgson et al.xlsx (38 kB)
Drones for large-scale wildlife surveys_Perception bias data - Shark Bay Hodgson et al.xlsx (114 kB)

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