A recent study conducted in the dense rainforests of Cape Tribulation, Australia, has demonstrated the remarkable effectiveness of thermal drones in detecting elusive tree kangaroos. These arboreal marsupials, notoriously difficult to spot from the ground, are now more easily identifiable thanks to this innovative technology. The research, led by Emmeline Norris, a Ph.D. candidate at James Cook University, marks a significant advancement in wildlife monitoring and conservation efforts.
Norris’s initial research focus was on spectacled flying foxes. However, during a routine drone flight from a 47-meter crane at the Daintree Rainforest Observatory in November 2024, she made an unexpected discovery. Within the first 20 minutes of her flight, the thermal drone picked up the heat signatures of two Bennett’s tree kangaroos (Dendrolagus bennettianus), one perched high in the canopy and the other foraging below. The following morning, further drone flights revealed four more individuals, a discovery that Norris described as “mind-blowing.”
The study, which successfully located six Bennett’s tree kangaroos across a 17-hectare area, highlights the potential of thermal drones to revolutionize the study of these elusive creatures. The animals appeared undisturbed by the drone’s presence, suggesting that this method is not only effective but also minimally invasive. John Kanowski, chief science officer at the Australian Wildlife Conservancy, who was not involved in the study, praised the research, noting the impressive results and the clear value of the methodology. He also pointed out that the observed density of tree kangaroos at the study site was comparable to that reported for Lumholtz’s tree-kangaroo, another species found in Australia.
Of the 14 known tree kangaroo species, 12 inhabit New Guinea, while the remaining two, the Lumholtz’s (D. lumholtzi) and Bennett’s tree kangaroos, are endemic to Australia. Traditional methods for surveying these animals, such as spotlighting and handheld thermal cameras, have limitations. Spotlighting, which relies on detecting the reflection of light from a kangaroo’s eyes, is only effective when the animal is looking directly at the light source. Handheld thermal cameras, while useful, are restricted by the height of the trees and are most effective when the animals are relatively low in the canopy.
The challenges associated with traditional surveying methods are particularly pronounced when studying Bennett’s tree kangaroos. While Lumholtz’s tree kangaroos inhabit areas with more accessible terrain due to logging and agricultural activities, Bennett’s tree kangaroos primarily reside in intact, dense rainforests. This makes ground-based surveys considerably more difficult. The ability of thermal drones to fly above the dense canopy, reaching heights of 40 meters or more, offers a significant advantage in these challenging environments. This capability opens up the possibility of conducting comprehensive surveys of Bennett’s tree kangaroo populations, providing crucial data on their distribution and abundance, which are currently poorly understood.
Kanowski suggested that thermal drones could also be employed to survey Lumholtz’s tree kangaroos. He noted that previous population estimates for this species, based primarily on spotlighting, may have underestimated their true numbers. The use of thermal drones could provide a more accurate assessment of their populations and densities.
Despite the promising results, the study also highlighted a practical challenge. The research relied on a tall crane to launch the drones at the required altitude. However, this type of infrastructure is not readily available in most rainforest areas. Norris acknowledged this limitation and indicated that future research would explore alternative launch points, such as nearby mountaintops or existing buildings, to make the technology more accessible for broader application in conservation and research. The development of more accessible deployment strategies will be crucial for realizing the full potential of thermal drones in the ongoing study and protection of these unique and vulnerable marsupials.