A farmer in northwest China still shakes when he remembers his encounter with wolves.

"I was terrified by three wolves, two yellow and one black just 10 meters away, as I was irrigating my field early one morning," said 50-year-old Han Bin from Liangzigou village in Yumen city, Gansu.

Before he could figure out what to do, the wolves ran away along a ditch.

Han once had more than 20 sheep, but three of them have been killed by wolves.

Although there have been no reports of wolf attacks on people, villagers now walk in groups in the evening and parents collect their children from school.

Predators return

Yumen was the first Chinese oil base located in the Hexi Corridor, the main path of the ancient Silk Road, west of the Yellow River.

"Yumen is not the only place plagued by wolves," said Zhang Guodong, vice director of the wildlife preservation management bureau of Gansu Province.

He said wolves loomed large in most counties and cities along the 1,000-kilometer corridor and the number of cattle killed by them had risen in recent years.

The official couldn't give an exact annual figure for cattle deaths but Zhao Jianjia, who tends a section of the Shandan Horse Ranch, said wolves had taken 400 of the ranch's 25,000 yaks since last autumn.

The famous ranch, now being run by the China Animal Husbandry Group, has been the training ground for Chinese cavalry's finest horses for 2,000 years.

The largest wolf pack seen by ranch workers consisted of seven animals. Wolves normally attack at night but have also been known to carry out forays during daylight hours.

"We had never seen so many before," Zhao said. "We were all frightened and some colleagues found it difficult to sleep at night."

The Hexi Corridor is one of the main wolf habitats in China. In the 1950s, government officials called on villages to exterminate wild animals such as wolves to increase livestock production.

Wolves became endangered in the 1970s because of their being hunted, said Zhang. Now the animal is protected and hunting has been banned since the 1990s.

Zhang does not know the wolves' current population, only that their number is growing as a result of their protected status.