BEIJING－Chinese researchers have used drones to monitor the health and living conditions of 60,000 Tibetan antelopes roaming Nagqu prefecture in the Tibet autonomous region.

The researchers, from the Shaanxi Institute of Zoology, studied the birth, migration and habitat of antelopes in the Changtang National Nature Reserve using drones and ground observation methods.

The drones conducted 12 observation flights in the reserve that covered more than 100 square kilometers. The intricate images processed by the drones were able to recognize newborn antelopes.

The 60,000 antelopes were observed forming a large migratory group almost 6-kilometers long, China Science Daily reported on Monday.

The antelope population was calculated using the drones' data-processing software, said Wu Xiaomin, a researcher with the institute. The software divided the ground into grids and counted the antelopes with the help of infrared camera recognition.

The researchers believe the antelope population has increased significantly this year, based on ground observations and data analysis. Disturbances during the migration of the antelopes are also gradually decreasing, while the quality of their habitat has improved as the environment has been further restored.

In previous years, the survival rate of newborn antelopes was about 80 percent after a long-distance migration. This year, the researchers found the survival rate was more than 90 percent.

Since 2013, the researchers have studied the migration of Tibetan antelopes by using China's domestically developed Beidou Navigation Satellite System.

They have recorded basic data, including the migration routes and times, and the spread of the species around the Changtang National Nature Reserve where many endangered wild animals live.

Tibetan antelopes are mostly found in Tibet and the Xinjiang Uygur autonomous region. The species is under first-class State protection in China.

In the 1980s, the Tibetan antelope population declined from 200,000 to 20,000, due to illegal hunting. It has recovered thanks to the country's efforts to improve its habitat and crack down on poaching.

Xinhua