On a verdant green prairie in west China's Xinjiang, a silver fox launches itself through the air at a rat like a cruise missile, pinning its prey with uncanny accuracy.

Local authorities in Xinjiang Uygur Autonomous Region have mobilized an army of specially-bred and trained silver foxes to combat a destructive plague of rats.

This year, about 5.5 million hectares of grasslands, or more than 10 percent of the total coverage in Xinjiang, have been overrun by disease-infested rats. The rats have ravaged the grasslands, eating grassroots and damaging the prairies with underground digging, according to the regional locust and rat control headquarters.

"Foxes are excellent natural predators of the rodent. One fox can catch about 20 rats per day. There has been a decline in the rat population in several counties where the measure has been adopted," said Ni Yifei, deputy head of the headquarters.

The headquarters' fox training base was set up in Altai Prefecture in 2004. It has already trained an army of 284 foxes that have been released into the wild.

With dozens of foxes released since 2004, the biological-control-of-rats experiment in Fuhai County, Altai, has reduced the number of rats in the area by 70 percent and the number of burrows per hectare of land has dropped from 50 to 15, the autonomous region's department of animal husbandry said.

Silver foxes have been domesticated and raised in Xinjiang for their rich fur used in garments.

The fox breeding and training base was established with 800,000 yuan (US$118,000) of government funding. The base bought 20 silver foxes from a local fur farm in 2004, after which the breeding program for the rat-killing army started.

Ni said the silver fox was chosen to be the rat fighter for its distinctive ability to run, hunt and live under the harsh living conditions on the prairie.

The fox army is not alone in the fight though. It has allies - eagles, birds, chickens, ducks and wolves - which have also been trained and deployed by the autonomous region's government to keep the rat numbers down.

"It is a green way to tackle the rat problem," said Lin Jun, head of the headquarters.

However, the biological control of the rat plague is being tried in only a few areas.

"China mainly relies on poisons to kill rats," Lin added.

In addition to Xinjiang, rat plagues are threatening more than 9 million hectares of grassland in north China's Inner Mongolia Autonomous Region.

This year's persistent drought and grassland degradation have been held to blame for the rat plague, as rats are more adaptable to dry weather, according to experts.

Inner Mongolian authorities have mobilized more than 70,000 workers and sprayed over 670 tonnes of poison over 9 million hectares of grassland.

(Xinhua News Agency July 29, 2010)