The Trump administration on Thursday moved to roll back an Obama-era conservation plan to protect the threatened chicken-sized sage-grouse, a change that would allow for oil drilling on previously off-limit lands in the West.

The Interior Department made the decision in releasing the environmental impact statement of its plan to modify the 2015 sage-grouse protection agreement, which it said takes into account state concerns in factoring in changes that still seek to protect the bird, but allow for exceptions to drill for oil and natural gas.

“With today’s action, we have leaned forward to address the various states’ issues, while appropriately ensuring that we will continue to be focused on meaningfully addressing the threats to the Greater Sage-Grouse and making efforts to improve its habitat,” said Deputy Secretary of the Interior David Bernhardt.

Environmental groups immediately criticized the decision, saying the previous administration took painstaking steps to implement a plan that all states and affected groups could abide by. The plan had massive support when it was approved.

The Obama administration plan took steps to protect the bird's habitat without taking the stricter action of listing it as endangered species, which would have required stiffer protections for the animal.

"This rolls back a conservation plan that was carefully crafted by states, ranchers, conservationists, and public officials to protect this iconic western bird and the unique sagebrush landscape it inhabits," said Bobby McEnaney, senior director for the Western Renewable Energy Project at the Natural Resources Defense Council.

Interior Secretary Ryan Zinke’s "move to unravel" the grouse protection plan "is his single largest land use decision to date," McEnaney added. "It has no basis in science — it’s a bald-faced giveaway to the oil and gas industry.”

The documents released by Interior on Thursday provide the foundation for opening up more oil and natural gas drilling on the previously protected lands. The agency outlines procedures for granting waivers to oil and mining companies under the new sage-grouse plan's environmental review.

“If you allow exception after exception, that might make sense for a particular project in a particular spot, but you add them all together and you have death by a thousand cuts,” said Tracy Stone-Manning, vice president of the National Wildlife Association.

The range of the grouse extends across 270,000 square miles in parts of 11 states in the western United States. The bird's population once numbered in the millions but fell to a few hundred thousand in recent decades.