Drones count wildlife more accurately and precisely than humans

Hodgson, Jarrod C.; Mott, Rowan; Baylis, Shane M.; Pham, Trung; Wotherspoon, Simon; Kilpatrick, Adam D.; Segaran, Ramesh Raja; Reid, Ian; Terauds, Aleks; Koh, Lian Pin

doi:10.1101/165019

Cited by 91 publications

(134 citation statements)

References 48 publications

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“…Monitoring wildlife populations is extremely labourintensive and considerable effort is put into identifying efficient automated methods for doing so inexpensively (Borker et al 2014, Perkins et al 2017, Hodgson et al 2018. Passive acoustic monitoring is one of the most promising of such methods (Borker et al 2014, Oppel et al 2014.…”

Section: Discussionmentioning

confidence: 99%

Acoustic activity across a seabird colony reflects patterns of within‐colony flight rather than nest density

Arneill

Critchley

Wischnewski

et al. 2019

Ibis

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Passive acoustic monitoring is increasingly being used as a cost‐effective way to study wildlife populations, especially those that are difficult to census using conventional methods. Burrow‐nesting seabirds are among the most threatened birds globally, but they are also one of the most challenging taxa to census, making them prime candidates for research into such automated monitoring platforms. Passive acoustic monitoring has the potential to determine presence/absence or quantify burrow‐nesting populations, but its effectiveness remains unclear. We compared passive acoustic monitoring, tape‐playbacks and GPS tracking data to investigate the ability of passive acoustic monitoring to capture unbiased estimates of within‐colony variation in nest density for the Manx Shearwater Puffinus puffinus. Variation in acoustic activity across 12 study plots on an island colony was examined in relation to burrow density and environmental factors across 2 years. As predicted fewer calls were recorded when wind speed was high, and on moon‐lit nights, but there was no correlation between acoustic activity and the density of breeding birds within the plots as determined by tape‐playback surveys. Instead, acoustic indices correlated positively with spatial variation in the in‐colony flight activity of breeding individuals detected by GPS. Although passive acoustic monitoring has enormous potential in avian conservation, our results highlight the importance of understanding behaviour when using passive acoustic monitoring to estimate density and distribution.

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Section: Discussionmentioning

confidence: 99%

Acoustic activity across a seabird colony reflects patterns of within‐colony flight rather than nest density

Arneill

Critchley

Wischnewski

et al. 2019

Ibis

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“…While we have demonstrated that RPA technology serves as an effective addition to CMR programs for fur seals, we expect this technique to be applicable to any medium to large animal species that either carries distinctive marks, or to which distinctive marks can be applied, and whose ecology renders these marks detectable in RPA-derived imagery. While the assumption might be that animals must also occur in high-density aggregations for RPA detection to be effective, with ongoing advances in RPA endurance, reduction in labor costs and disturbance, and automated image screening (Hodgson et al 2018), effective monitoring of low-density populations is also on the horizon.…”

Section: Discussionmentioning

confidence: 99%

Remotely piloted aircraft improve precision of capture–mark–resight population estimates of Australian fur seals

et al. 2019

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Remotely piloted aircraft (RPA or drones) have become a powerful tool for use in spatial and temporal ecology. Major benefits for environmental management, including improved accuracy and precision for population monitoring of fauna, are being realized. We used Australian fur seals (Arctocephalus pusillus) as a model system to assess how counts and capture-mark-resight (CMR) estimates derived from RPA surveys compared with both traditionally used ground counts and CMR abundance estimates at two colonies in southeastern Australia. To manage the large volume of data, we implemented a citizen science portal SealSpotter to screen RPA imagery for animals of the target age classes. Capture-mark-resight estimates and direct counts using RPA imagery provided measurable improvement in monitoring precision when compared with traditional techniques. A key methodological assumption of CMR estimates is that there is uniform mixing of marked animals across the focal area. This was also validated using spatial data derived from images and linear models, a novel capability of the RPA technique. Our findings have the potential to improve wildlife monitoring techniques for fur seals and are broadly transferable to a wide range of other animal taxa where CMR techniques are employed. Furthermore, they add to the growing body of evidence that demonstrates the benefits of RPAs for wildlife monitoring exceed those of traditional techniques.

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“…Multispectral sensors may help address this problem. Widely used for landcover classification and vegetation monitoring [68][69][70][71][72][73] this technology uses green, red, red-edge and near infrared wavebands to capture detail not available to standard RGB cameras. Green vegetation materials are characterized by high reflectance in the near infra-red (NIR) domain (outside of the spectral range of human vision); a multispectral camera can provide useful contrast to discriminate between live and dead vegetation.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Chimpanzee Nest Detectability in Drone-Acquired Images

Bonnin

Andel²,

Kerby

et al. 2018

Drones

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Abstract:As with other species of great apes, chimpanzee numbers have declined over the past decades. Proper conservation of the remaining chimpanzees requires accurate and frequent data on their distribution and density. In Tanzania, 75% of the chimpanzees live at low densities on land outside national parks and little is known about their distribution, density, behavior or ecology. Given the sheer scale of chimpanzee distribution across western Tanzania (>20,000 km 2 ), we need new methods that are time and cost efficient while providing precise and accurate data across broad spatial scales. Scientists have recently demonstrated the usefulness of drones for detecting wildlife, including apes. Whilst direct observation of chimpanzees is unlikely given their elusiveness, we investigated the potential of drones to detect chimpanzee nests in the Issa valley, western Tanzania. Between 2015 and 2016, we tested and compared the capabilities of two fixed-wing drones. We surveyed twenty-two plots (50 × 500 m) in gallery forests and miombo woodlands to compare nest observations from the ground with those from the air. We performed mixed-effects logistic regression models to evaluate the impact of image resolution, seasonality, vegetation type, nest height and color on nest detectability. An average of 10% of the nests spotted from the ground were detected from the air. From the factors tested, only image resolution significantly influenced nest detectability in drone-acquired images. We discuss the potential, but also the limitations, of this technology for determining chimpanzee distribution and density and to provide guidance for future investigations on the use of drones for ape population surveys. Combining traditional and novel technological methods of surveying allows more accurate collection of data on animal distribution and habitat connectivity that has important implications for ape conservation in an increasingly anthropogenically-disturbed landscape.

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Drones count wildlife more accurately and precisely than humans

Cited by 91 publications

References 48 publications

Acoustic activity across a seabird colony reflects patterns of within‐colony flight rather than nest density

Acoustic activity across a seabird colony reflects patterns of within‐colony flight rather than nest density

Remotely piloted aircraft improve precision of capture–mark–resight population estimates of Australian fur seals

Assessment of Chimpanzee Nest Detectability in Drone-Acquired Images

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