Experts said the team's work marked a significant breakthrough in efforts to guide the animals back to their habitats, adding that it was a decisive moment when the herd crossed the bridge, as it meant the elephants were about to end their journey north and head for home.

Chen Mingyong, a professor at Yunnan University's School of Ecology and Environmental Science, said: "Habitats for Asian elephants can be divided into 'most suitable', 'suitable', 'general' and 'not suitable'. The tropical rainforest and evergreen broad-leaf forest in Xishuangbanna are the most suitable habitats for the species. The further north the elephants go, the lower the temperature. There is also less food and a less suitable environment for them."

The Yuanjiang River, one of the oldest in Yunnan, separates "suitable habitat" and "general habitat", with clear differences in vegetation on its southern and northern banks. Crossing the river meant the herd was heading for more suitable habitat, which also helped increase stability and security for the animals, Chen said.

Although climate and a willingness among the elephants were key factors in the herd moving toward home, the efforts of scientists and workers also played a major role.

The Yuanjiang River was a natural barrier. Yang Yingyong, executive deputy commander of the Yuxi safety precautions and emergency response headquarters in charge of the roaming elephants, said the water flow in the river rose from 73 cubic meters per second on average in mid-May when the herd waded across it, to 120 cubic meters per second in August, so it was impossible for it to wade through the river again.