CHENGDU, Dec. 17 (Xinhua) -- Footage and images of a pair of sub-adult giant panda twins in the wild have been released by the Wolong National Nature Reserve in southwest China's Sichuan Province.

The images and video clips, captured by an infrared camera in July for the first time, show two wild pandas, about 2 years old and the same size, playing under a tree at an altitude of 3,100 meters near a bamboo forest on Niutou Mountain.

Sub-adult pandas refer to giant pandas aged between 2 and 5 years old. "From the size of their skulls and bodies and the luster of their fur, we preliminarily determined that they are a pair of sub-adult giant pandas," said Shi Xiaogang, head of the reserve's Mujiangping protection station.

"The way they interact showed they are more likely twin sub-adults," said Wang Pengyan, senior engineer at the reserve. "Both of them have long snouts, a typical appearance of young pandas. The pair is believed to have been born in the summer of 2017."

It is not a common phenomenon because most panda mothers in the wild would abandon one cub because they lack the energy to raise two cubs together.

"Wolong is rich in resources and has enough food for the mother to raise two cubs. Additionally, the mother was lucky to find a suitable nest for her family," said Wang.

In Wolong, pandas usually use tree holes to breed their cubs. A large hole is necessary for the mother to raise twins at the same time, said Wang.

The new footage shows that the protection of natural resources in Wolong is effective. It also provides valuable information for giant panda experts to further study the natural breeding habits of wild giant pandas in the Qionglai Mountains.

Duan Zhaogang, Party secretary of Wolong National Nature Reserve Administration, said Wolong will speed up the field investigation of wild giant pandas and further improve the protection of giant pandas and their habitats.

Fewer than 2,000 pandas live in the wild, mostly in the provinces of Sichuan and Shaanxi.