Along with the birds flying over the Ailao Mountains in Yunnan province, a forest police team has likewise been "migrating" since September and will stay in the mountains until March to prevent poaching and other wildlife crimes.

Nicknamed the "migratory police station", the seven officers with the forest police station of Hongtupo, Nanhua county, in the Chuxiong Yi autonomous prefecture, carry extra clothing, quilts and daily necessities while "migrating" in the forests on an annual mission to safeguard the avian travelers.

Zhang Yueping, who has worked at the station for 17 years and now heads it, said the Ailao Mountains, which are rich in biodiversity, are located along an important route for 430 kinds of migratory birds.

Established in 1984, the station, which is at the foot of a mountain, initially had neither running water nor phone service, but it evolved into a small apartment in 2010, he said. "We now have bunk beds instead of living in tents."

According to Zhang, some local villagers who used to live in extreme poverty hunted birds for food or as a source of income, which resulted in a "silent mountain" where no birds were twittering.

Inspections usually occur at night, when "we brave the darkness and bumpy mountain road with no torchlight to catch poachers," according to Officer Yang Zhengqiang.

Sometimes, when the officers have to go far, they carry a tent in case they can't return to the apartment in time.

Officer Liu Yan, who once worked at the station, said winter was the toughest time, because her quilt was never dry due to the high humidity in the mountains. "Once I strayed away from my companions, and I can't describe the feeling of loneliness."

Despite the hardships, officers said their work is worthwhile, with the number of birds as well as the number of species in the forests increasing over the years.

To facilitate the effort, the local public security bureau has worked with the Ailao Mountains National Nature Reserve to set up bird and plant monitoring stations. Infrared monitoring devices are also used to help prevent poaching.

Due to the combination of officers and technology, all kinds of animals and plants have returned to the reserve.

The police station has gradually become a stopover for wild animals, officers said. Each year, they release more than 1,000 rehabilitated birds and other animals, such as black gibbons, bears and pythons — enough to open a minizoo.

In 2019, the mountain reserve had zero report of illegal poaching, according to Zhang, the head of the police station. With birds returning, the transformation has also led to an increase in local people's income, because many villagers have opened homestays to host visitors who come to the mountains to watch the birds each year, he added.

"The environment is improving year by year, and people's lives get better and they have stronger awareness of protection, making our jobs very fulfilling," Zhang said.