Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy

Abstract Quantifying the cost‐effectiveness of alternative sampling methods is crucial for efficient biodiversity monitoring and detection of population trends. In this study, we compared the cost‐effectiveness of three novel sampling methods for detecting changes in koala (Phascolarctos cinereus) o...

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Main Authors: Chad T. Beranek, Darren Southwell, Tim S. Jessop, Benjamin Hope, Veronica Fernandes Gama, Nicole Gallahar, Elliot Webb, Brad Law, Allen McIlwee, Jared Wood, Adam Roff, Graeme Gillespie
Format: Article
Language:English
Published: Wiley 2024-07-01
Series:Ecology and Evolution
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Online Access:https://doi.org/10.1002/ece3.11659
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author Chad T. Beranek
Darren Southwell
Tim S. Jessop
Benjamin Hope
Veronica Fernandes Gama
Nicole Gallahar
Elliot Webb
Brad Law
Allen McIlwee
Jared Wood
Adam Roff
Graeme Gillespie
author_facet Chad T. Beranek
Darren Southwell
Tim S. Jessop
Benjamin Hope
Veronica Fernandes Gama
Nicole Gallahar
Elliot Webb
Brad Law
Allen McIlwee
Jared Wood
Adam Roff
Graeme Gillespie
author_sort Chad T. Beranek
collection DOAJ
description Abstract Quantifying the cost‐effectiveness of alternative sampling methods is crucial for efficient biodiversity monitoring and detection of population trends. In this study, we compared the cost‐effectiveness of three novel sampling methods for detecting changes in koala (Phascolarctos cinereus) occupancy: thermal drones, passive acoustic recorders and camera trapping. Specifically, we fitted single‐season occupancy‐detection models to data recorded from 46 sites in eight bioregions of New South Wales, Australia, between 2018 and 2022. We explored the effect of weather variables on daily detection probability for each method and, using these estimates, calculated the statistical power to detect 30%, 50% and 80% declines in koala occupancy. We calculated power for different combinations of sites (1–200) and repeat surveys (2–40) and developed a cost model that found the cheapest survey design that achieved 80% power to detect change. On average, detectability of koalas was highest with one 24‐h period of acoustic surveys (0.32, 95% CI's: 0.26, 0.39) compared to a 25‐ha flight of drone surveys (0.28, 95% 0.15, 0.48) or a 24‐h period of camera trapping consisting of six cameras (0.019, 95% CI's: 0.014, 0.025). We found a negative quadratic relationship between detection probability and air temperature for all three methods. Our power and cost analysis suggested that 148 sites surveyed with acoustic recorders deployed for 14 days would be the cheapest method to sufficiently detect a 30% decline in occupancy with 80% power. We recommend passive acoustic recorders as the most efficient sampling method for monitoring koala occupancy compared to cameras or drones. Further comparative studies are needed to compare the relative effectiveness of these methods and others when the monitoring objective is to detect change in koala abundance over time.
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spelling doaj-art-33348b3c0d45496893cb5e522de657c12025-08-20T02:50:48ZengWileyEcology and Evolution2045-77582024-07-01147n/an/a10.1002/ece3.11659Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancyChad T. Beranek0Darren Southwell1Tim S. Jessop2Benjamin Hope3Veronica Fernandes Gama4Nicole Gallahar5Elliot Webb6Brad Law7Allen McIlwee8Jared Wood9Adam Roff10Graeme Gillespie11Conservation Science Research Group University of Newcastle Callaghan New South Wales AustraliaConservation Science Research Group University of Newcastle Callaghan New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaDepartment of Primary Industries Forest Science Centre Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaNSW Wildlife Drone Hub, Vegetation and Biodiversity Mapping, Science, Economics, and Insights Division New South Wales Department of Climate Change and Energy Parramatta New South Wales AustraliaNSW Wildlife Drone Hub, Vegetation and Biodiversity Mapping, Science, Economics, and Insights Division New South Wales Department of Climate Change and Energy Parramatta New South Wales AustraliaKoala Science Team, Conservation and Restoration Science, Science, Economics and Insights Division New South Wales Department of Planning and Environment Parramatta New South Wales AustraliaAbstract Quantifying the cost‐effectiveness of alternative sampling methods is crucial for efficient biodiversity monitoring and detection of population trends. In this study, we compared the cost‐effectiveness of three novel sampling methods for detecting changes in koala (Phascolarctos cinereus) occupancy: thermal drones, passive acoustic recorders and camera trapping. Specifically, we fitted single‐season occupancy‐detection models to data recorded from 46 sites in eight bioregions of New South Wales, Australia, between 2018 and 2022. We explored the effect of weather variables on daily detection probability for each method and, using these estimates, calculated the statistical power to detect 30%, 50% and 80% declines in koala occupancy. We calculated power for different combinations of sites (1–200) and repeat surveys (2–40) and developed a cost model that found the cheapest survey design that achieved 80% power to detect change. On average, detectability of koalas was highest with one 24‐h period of acoustic surveys (0.32, 95% CI's: 0.26, 0.39) compared to a 25‐ha flight of drone surveys (0.28, 95% 0.15, 0.48) or a 24‐h period of camera trapping consisting of six cameras (0.019, 95% CI's: 0.014, 0.025). We found a negative quadratic relationship between detection probability and air temperature for all three methods. Our power and cost analysis suggested that 148 sites surveyed with acoustic recorders deployed for 14 days would be the cheapest method to sufficiently detect a 30% decline in occupancy with 80% power. We recommend passive acoustic recorders as the most efficient sampling method for monitoring koala occupancy compared to cameras or drones. Further comparative studies are needed to compare the relative effectiveness of these methods and others when the monitoring objective is to detect change in koala abundance over time.https://doi.org/10.1002/ece3.11659camera trapsdetection probabilitydronespassive acoustic recorderspower analysissurvey design
spellingShingle Chad T. Beranek
Darren Southwell
Tim S. Jessop
Benjamin Hope
Veronica Fernandes Gama
Nicole Gallahar
Elliot Webb
Brad Law
Allen McIlwee
Jared Wood
Adam Roff
Graeme Gillespie
Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
Ecology and Evolution
camera traps
detection probability
drones
passive acoustic recorders
power analysis
survey design
title Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
title_full Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
title_fullStr Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
title_full_unstemmed Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
title_short Comparing the cost‐effectiveness of drones, camera trapping and passive acoustic recorders in detecting changes in koala occupancy
title_sort comparing the cost effectiveness of drones camera trapping and passive acoustic recorders in detecting changes in koala occupancy
topic camera traps
detection probability
drones
passive acoustic recorders
power analysis
survey design
url https://doi.org/10.1002/ece3.11659
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