Environmental groups are suing to force the Obama administration to impose more restrictions on oil and gas drilling, grazing and other activities blamed for the decline of greater sage grouse across the American West.
The lawsuit filed Thursday says a sweeping conservation effort the government announced last September is riddled with loopholes and won't be enough to protect the bird from extinction.
The suit follows several legal challenges against the same rules from the opposite end of the political spectrum. Mining companies, ranchers and officials in Utah, Idaho and Nevada say the administration's actions will impede economic development.
Sage grouse range across habitat spanning 11 states. Their numbers dropped sharply in recent decades.
The new rules are part of a costly effort to keep them off the endangered species list.