Successful observation of orangutans in the wild with thermal-equipped drones

Burke, Claire; Rashman, Maisie F.; Longmore, S.; McAree, Owen; Glover‐Kapfer, Paul; Ancrenaz, Marc; Wich, Serge A.

doi:10.1139/juvs-2018-0035

Cited by 35 publications

(24 citation statements)

References 16 publications

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“…Accurate and precise counts of animal populations form the basis of conservation decisions and actions; however, they are lacking for the majority of arboreal species due to difficulties and costs of performing ground surveys. To overcome these difficulties, recent studies have fitted drones with TIR cameras to monitor primate populations (howler monkeys and spider monkeys [23]; orangutans [42]). Here, we demonstrated that a TIR camera fitted to a drone can be successfully employed to determine the presence and count the number of spider monkeys in a closed-canopy forest.…”

Section: Discussionmentioning

confidence: 99%

“…The use of drone technology is rapidly changing the way mammal populations are monitored [17], and the addition of a TIR camera has been successful for monitoring small species in open environments (e.g., rabbits [32]) and ungulates in temperate forests [50], but only a few studies have tested its use for surveying arboreal species living in forested environments (e.g., koalas [21]; howler monkeys, spider monkeys, and kinkajous [23]; orangutans [42]). By comparing a substantial dataset obtained by flying the drone while simultaneously counting monkeys from the ground, we were able to demonstrate that the use of a TIR camera is a feasible and valid method of obtaining data on the presence and number of spider monkeys at their sleeping sites in a closed-canopy forest.…”

Section: Discussionmentioning

confidence: 99%

“…In order to resolve a spider monkey of about 0.5 m in length (from the top of the head to the base of the pelvis, without considering the tail) at 10 pixels when viewed from above, the drone would need to be a maximum of 57.3 m from the animal (see Reference [32] for full details on this calculation; http://www.astro.ljmu.ac.uk/~{}aricburk/uav_calc/). Since monkeys spend almost all of their time in tree canopies [42], we therefore had to fly the drone 57.3 m above the canopy.…”

Section: Calculating Flying Heightmentioning

confidence: 99%

See 2 more Smart Citations

Thermal Infrared Imaging from Drones Offers a Major Advance for Spider Monkey Surveys

Spaan

Burke

McAree

et al. 2019

Drones

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Accurate and precise population estimates form the basis of conservation action but are lacking for many arboreal species due to the high costs and difficulty in surveying these species. Recently, researchers have started to use drones to obtain data on animal distribution and density. In this study, we compared ground and drone counts for spider monkeys (Ateles geoffroyi) at their sleeping sites using a custom-built drone fitted with a thermal infrared (TIR) camera. We demonstrated that a drone with a TIR camera can be successfully employed to determine the presence and count the number of spider monkeys in a forested area. Using a concordance analysis, we found high agreement between ground and drone counts for small monkey subgroups (<10 individuals), indicating that the methods do not differ when surveying small subgroups. However, we found low agreement between methods for larger subgroups (>10 individuals), with drone counts being higher than the corresponding ground counts in 83% of surveys. We could identify additional individuals from TIR drone footage due to a greater area covered compared to ground surveys. We recommend using TIR drones for surveys of spider monkey sleeping sites and discuss current challenges to implementation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Calculating Flying Heightmentioning

confidence: 99%

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Thermal Infrared Imaging from Drones Offers a Major Advance for Spider Monkey Surveys

Spaan

Burke

McAree

et al. 2019

Drones

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“…Additionally, aerial survey is an efficient tool for population assessments, as well as for monitoring encroachment, illegal logging, illegal mining, etc. It is important that these surveys are repeated every 5 to 10 years to monitor population trends, and hopefully less expensive techniques, such as drone technology or remote sensing, will improve and can be used in the future [27].…”

Section: Resultsmentioning

confidence: 99%

Changes to Sabah’s orangutan population in recent times: 2002–2017

Simon¹,

Davies

Ancrenaz

2019

PLoS ONE

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The Bornean orangutan is critically endangered and monitoring its population is needed to inform effective conservation management. In this paper, we present results of 2014–17 aerial nest surveys of the major orangutan populations in Sabah and compare them with baseline data produced during surveys conducted in 2002–03 using similar methods. Our results show three important points: a) by increasing the survey effort (estimated at 15–25% cover), sparsely scattered orangutan sub-populations not recorded in the previous aerial surveys were located and the accuracy of the nest count estimates is expected to improve; b) large populations in the interior forests of Sabah, occupying sustainably managed logged and unlogged forests, have been stable over 15 years and are of vital importance for the species’ conservation; c) fragmented populations located in eastern Sabah, that are surrounded by extensive oil palm plantations, have declined at varying rates.

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“…In primates, infrared thermography has been used to assess the behavior of otherwise unobservable nocturnal species (e.g., Rahlfs & Fichtel, 2009;Tan, Yang, & Niu, 2013;Chen et al, 2015). Coupled with drone technology, infrared thermography has been used to provide population estimates by detecting animal heat-signatures in remote, difficult-tonavigate locations (Kays et al, 2018;Spaan et al, 2019;Burke et al, 2019). Facial infrared thermal imaging has been used to quantify the emotional states of non-human primates (Nakayama, Goto, Kuraoka, & Nakamura, 2005;Kuraoka & Nakamura, 2011;Ioannou, Chotard, & Davila-Ross, 2015;Chotard, Ioannou, & Davila-Ross, 2018) and other animals (McCafferty, 2007).…”

Section: Discussionmentioning

confidence: 99%

Infrared thermography cannot be used to approximate core body temperature in wild primates

McFarland

Barrett

Fuller

et al. 2020

Preprint

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Understanding the physiological processes that underpin primate performance is key if we are to assess how a primate might respond when navigating new and changing environments. Given the connection between an animal’s ability to thermoregulate and the changing demands of its thermal environment, increasing attention is being devoted to the study of thermoregulatory processes as a means to assess primate performance. Infrared thermography can be used to record the body surface temperatures of free-ranging animals. However, some uncertainty remains as to how these measurements can be used to approximate core body temperature. Here, we use data collected from wild vervet monkeys (Chlorocebus pygerythrus) to examine the relationship between infrared body surface, core body, and local climate, to determine to what extent surface temperatures reflect core body temperature. While we report a positive association between surface and core body temperature – a finding that has previously been used to justify the use of surface temperature measurements as a proxy for core temperature regulation – when we controlled for the effect of the local climate in our analyses, this relationship was no longer observed. That is, body surface temperatures were solely predicted by local climate, and not core body temperatures, suggesting that surface temperatures tell us more about the environment a primate is in, and less about the thermal status of its body core in that environment. Despite the advantages of a non-invasive means to detect and record animal temperatures, infrared thermography alone cannot be used to approximate core body temperature in wild primates.

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Successful observation of orangutans in the wild with thermal-equipped drones

Cited by 35 publications

References 16 publications

Thermal Infrared Imaging from Drones Offers a Major Advance for Spider Monkey Surveys

Thermal Infrared Imaging from Drones Offers a Major Advance for Spider Monkey Surveys

Changes to Sabah’s orangutan population in recent times: 2002–2017

Infrared thermography cannot be used to approximate core body temperature in wild primates

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