Gerbils' burrowing is damaging the roots of plants
Chinese authorities are using contraceptive pills to cut down the number of gerbils in a north-western province plagued by the rodents.
Forestry officials are leaving pills by the gerbils' burrows to try to cut back the rodents' exploding numbers.
The gerbils, officials say, are threatening the fragile desert ecosystem in the vast Xinjiang region.
Their burrowing in the Gurbantunggut Desert damages roots of the few plants that thrive there, officials say.
Authorities are using the pellets - which prevent females getting pregnant and cause abortion in those already pregnant - disguised as bran feed, the state news agency Xinhua said.
Use of the contraceptive pills is deemed to be more humane than killing the rodents and, according to officials, have little effect on other animals.
"It's a good way to tackle the desert rat plague," local forestry official Du Yuefei said.
More than 180kg (400 lb) of the tainted feed has so far been spread across an area of about 49,000 hectares in the arid region.
Officials had previously installed hundreds of perches for the gerbils' natural predators - eagles and owls - but the move failed to halt the rodents' rising numbers.
The scheme has already caused a slight drop in gerbil numbers, Mr Du said, with 11 gerbils caught in every 100 traps laid out for them. Previously an average of 12 were caught in the traps, the AP news agency reports.
If it continues to be successful, other regions in an increasingly arid China may adopt the scheme.