Researchers in southwestern China tracked a herd of 17 wild Asian elephants for 20 days using small drones fitted with infrared cameras, after the animals settled at the Xishuangbanna Tropical Botanical Garden in Yunnan in May and June 2021. Hourly flights located the herd 62.7% of the time, with detection peaking near 95% around midnight. The work offers a tested method for finding large mammals in dense, warm terrain where ground searches fail.
Detection dropped as temperature, rainfall and solar radiation rose, and climbed with humidity and visibility. The findings arrive as Yunnan’s recovering elephant population pushes closer to farms and villages.
China counted about 360 wild Asian elephants in Yunnan in 2021. In the 1980s the figure was around 170. The recovery is real, and it is the source of a problem that drone cameras are now being asked to help solve.
More elephants need more land. The land they once used has been cut back. Between 2011 and 2019, forestry authorities logged 361 conflict incidents across three Yunnan prefectures, with direct losses recorded in the tens of millions of yuan. Crops trampled, stores raided, people hurt. The animals and the people now share narrowing ground.
The question is not whether the herds will keep moving toward farmland. They will. The question is whether managers can see them coming. A study at the Xishuangbanna Tropical Botanical Garden tested one answer: send up a small drone with a thermal camera, every hour, and find out where the elephants are before anyone else does.
A thermal camera finds what the eye cannot
When the herd of 17 elephants entered the botanical garden in May 2021, researchers ran drone flights every hour for 20 days. Across that campaign, the drones located the elephants 62.7% of the time. That is the headline figure, and it hides a sharper one.
Detection was not steady through the day. It peaked at night. Around midnight, under good conditions, the thermal sensor found the herd roughly 95% of the time. The reason is physical: a warm elephant body stands out clearly against cool ground, and that contrast collapses under the midday sun.
The drones also captured what the elephants were doing. The herd spent 45.9% of its time feeding, the largest share, followed by resting, moving and a small slice drinking. The animals favoured ground near water and gentle slopes. Forest canopy structure barely affected where they chose to be.
Weather set the limits. Detection fell as temperature, rainfall and solar radiation climbed, and improved with higher humidity and better visibility. A government overview of conflict patterns, published by the National Forestry and Grassland Administration, shows why such precision matters: most damage clusters near forest edges and rivers, the same gentle, watered ground the elephants prefer. The study’s recommendation follows from its own numbers. Fly at night, use short clear-weather windows, and search the riparian corridors first.
What the footage shows is location and behaviour. What it cannot show is the cost of the watching itself.
The land that pushed the herds out
The conflict the drones are meant to manage has a traceable cause. In parts of Xishuangbanna, more than 60% of the original lowland rainforest has been converted to rubber and other plantations since the 1970s, a 2023 study in Scientific Reports found. Habitat shrank. Elephant movement funnelled into the remaining river valleys and forest patches.
Pan Wenshi, a retired elephant ecologist at Peking University, has argued that the rapid spread of rubber and tea has fragmented elephant range and pushed herds toward villages and cropland. That market pressure is not local. Western demand for natural rubber, tropical timber and tea helps drive land-use change in Yunnan, where plantations supplying global tyre and beverage firms replaced low-elevation forest the elephants once used. The herd at the botanical garden was, in part, walking through the gaps that demand left behind.
China has responded with structure. The National Park for Asian Elephants, approved in 2021, covers about 2,530 square kilometres across Pu’er and Xishuangbanna, and forestry officials have said technology such as satellite and drone monitoring is meant to give early warning of elephant movements.
So the recovery and the conflict are the same story told twice. More elephants survived. Their forest did not. The drone, flown at midnight along a river, is a tool built to manage a frontier that consumption helped create.
Beyond the headline
The bigger picture
Thermal drone tracking is not just a neat trick; it signals a wider move toward continuous, data-rich watching of the human-wildlife frontier. As warming, plantations and roads compress elephant range, managers lean on sensor networks — satellites, drones, camera traps — to anticipate conflict rather than count the damage after it happens.
The science gap
Drone footage can show where elephants are and what they seem to be doing. It says little about stress, long-term behaviour change, or how repeated overflights affect calves and breeding. Without pairing thermal data with hormone tests, GPS collars and field work, managers risk over-reading short-term movement and under-counting the quieter harm of noise and light on pressured herds.
The reach
The same tools refined over a Yunnan garden could reshape how Western zoos, safari lodges and utilities manage large animals in their care. If insurers or regulators start treating high-resolution movement data as a welfare and liability standard, demand could spread well beyond reserves — touching power-line planning in elephant range states and enclosure design in European parks.
What a tested method changes for the people watching
The study turns an ad-hoc tactic into a protocol others can copy. That matters for distinct groups now weighing how to use it.
- Conservation funders and policy watchers
Track whether drone monitoring is written into the management plan for China’s Asian Elephant National Park over the next one to three years. Formal integration means funding lines, training and standard protocols; its absence means drones stay tied to individual projects. The National Forestry and Grassland Administration’s press briefing on the park and Yunnan’s elephant population sets the baseline.
- Ethical consumers and investors
If you buy or hold companies using natural rubber or tea from Yunnan, check their zero-deforestation commitments against independent data before you act. Cross-reference plantation expansion claims with platforms such as Global Forest Watch, which maps the forest loss that drives elephants toward farms in the first place.
- Wildlife technologists and rangers
The operational lesson is concrete: fly at night, use short clear-weather windows, and search rivers and gentle slopes first. Detection collapses in heat, rain and strong sun, so daytime flights waste battery and time. Replication elsewhere should start by mapping local riparian corridors before the first launch.
Explainer
- Asian elephant
- Elephas maximus, the smaller of the two living elephant species, found across South and Southeast Asia. China’s wild population, almost all in Yunnan, numbered about 360 in 2021. The 2022 revision of China’s Wildlife Protection Law classes the species as first-class nationally protected, banning hunting and trade outright.
- National Park for Asian Elephants
- A Chinese protected area approved in 2021 covering about 2,530 square kilometres in Pu’er and Xishuangbanna. It aims to merge fragmented reserves and surrounding collective forests into one managed system. Officials have said it is designed to secure migration corridors that decades of plantation growth had severed.
- Xishuangbanna
- A prefecture in southern Yunnan bordering Laos and Myanmar, holding much of China’s remaining tropical rainforest and elephant range. It is also where rubber expansion has been most intense. Its tropical botanical garden, run by the Chinese Academy of Sciences, became an accidental field site when a wild herd moved in.
- Wildlife Protection Law
- China’s national statute governing the protection of wild animals, revised in 2022. It requires local governments to compensate farmers for verified crop and property losses caused by protected wildlife. That compensation clause is what turns each trampled field near Xishuangbanna into a line item for the state.
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