Detection of two Arctic birds in Greenland and an endangered bird in Korea using RGB and thermal cameras with an unmanned aerial vehicle (UAV)

Abstract

Unmanned aerial vehicles (UAVs), so-called ‘drones’, have been widely used to monitor wild animals. Here, we tested a UAV with red, green, and blue (RGB) and thermal cameras to detect free-living birds in a high Arctic region in North Greenland and in a restricted area in the Republic of Korea. Small flocks of molting pink-footed geese ( Anser brachyrhynchus ) near sea ice and incubating common ringed plovers ( Charadrius hiaticula ) in the Arctic environment were chosen for the RGB and thermal image studies. From the acquired images, we built mosaicked RGB images and coregistered thermal images, and estimated the animal shapes. Our results showed that geese were discriminated in both RGB and thermal images with water and sea ice backgrounds. Incubating plover bodies were not distinguished in RGB images due to their cryptic coloration, but they were detected in thermal images with cold background areas in the Arctic environment. We further conducted a blind survey in a restricted area under military control in Korea near the breeding sites of black-faced spoonbill ( Platalea minor ), which is an endangered species. From UAV flights with RGB and thermal cameras operated out of the restricted area, we acquired images of white objects in the mudflats and verified that the objects were resting spoonbills by watching the birds. We suggest that thermal cameras and UAVs can be applied to monitor animals in extreme environments and in restricted areas and help researchers find cryptic wader nests.

Remotely Piloted Aircraft System (RPAS)-Based Wildlife Detection: A Review and Case Studies in Maritime Antarctica

“…RPAS-based individual detection and population surveys extended include identifying and counting birds or mammals in cryptic habitats. When the RPAS is equipped with a thermal camera, the results can be used to easily discriminate homeothermic animal body temperatures from the surrounding backgrounds, such as rainforests with a partially exposed body through openings between leaves and clouds, preventing thermal radiation from passing through (e.g., detecting orangutans [ 61 ]) and sea ice revealing a high thermal contrast between bodies and snow/ice surface (e.g., identifying pink-footed geese ( Anser brachyrhynchus ) [ 44 ]). To improve detection quality, thermal cameras were used with RGB cameras [ 28 , 49 , 62 , 63 ], and white-spotted shapes were discovered in grayscale thermal images that could even detect small cryptic nests [ 44 , 51 , 64 ].…”

“…Cautiously operated RPAS reduces unexpected damage to human life by not piloting a manned aircraft or not exploring an unfamiliar area firsthand. This advantage produces fruitful results in extreme environments such as the polar regions [ 26 , 44 ] and deserts [ 93 ] or topographically inaccessible zones that researchers cannot easily approach, such as seaside cliffs [ 94 ].…”

Possibility of applying unmanned aerial vehicle and thermal imaging in several canopy cover class for wildlife monitoring – preliminary results

“…drones) are capable of moving fast, scanning forests from top to bottom and are very promising for expanding the scale of canopy surveys that are very useful in studying wildlife ecology. Drone imagery has proven useful for wildlife surveys in open areas, for example, guanaco [1], Artic birds [2], kangaroo [3], caribou [4], waterfowl [5], hippos [6], and crocodile [7]. Meanwhile, for animals living in tree canopies, UAVs are not widely used because of the difficulty of visually detecting these animals with standard aerial imagery.…”

An experimental approach to exploring the feasibility of unmanned aerial vehicle and thermal imaging in terrestrial and arboreal mammals research

“…In the past decade, unmanned aerial vehicle technology has entered a new era in wildlife research and monitoring [3][4][5]. Imagery from aerial surveys has been useful for surveys of animals in open areas; for example, counting elephant [6], Arctic birds [7], and hippos [8]. Aerial surveys to monitor wildlife in tropical areas are still rare because species live in rainforest habitat, where a thick canopy shades them from visual detection.…”