The U.S. Fish and Wildlife Service has ruled the Sacramento Mountains checkerspot butterfly does not warrant listing as an endangered species and protection of its habitat.
Agency officials, in a decision published Wednesday, said they found no current significant threats to the 2-inch butterfly and that none of the factors which could threaten it were likely to increase in the foreseeable future.
"The finding was the worst possible outcome for the butterfly, and we're very surprised," said Nicole Rosmarino, wildlife program director for WildEarth Guardians.
She said the agency is "shirking its duty to protect the butterfly that's on the knife-edge of extinction."
"The finding really puts the burden on the butterfly to change its behavior rather than requiring humans to change theirs," she said.
Noah Greenwald of the Center for Biological Diversity said the threats to the butterfly are likely to get worse. He pointed to rural sprawl, off-highway vehicle use, chemical spraying, grazing and climate change.
"The agency is playing Russian Roulette with the survival of this unique New Mexico butterfly and blindly hoping that none of the many known threats result in the fatal shot," he said.
Fish and Wildlife agreed late last year to study the rare butterfly, found only in the mountains of southern New Mexico, to see whether the subspecies deserved protection under the Endangered Species Act.
The 12-month review determined the listing was not warranted at this time, said Fish and Wildlife spokeswoman Charna Lefton.
"We did the research. We did the homework," she said.
A conservation plan for the butterfly was finalized in 2005 by the agency, Otero County, the village of Cloudcroft and the U.S. Forest Service and remains in place, Lefton said.
It calls for actions designed to protect the species, Lefton said.
A court settlement with WildEarth Guardians and the Center for Biological Diversity resulted in the decision to consider a possible listing. The groups had sued in January 2008 to force the agency to make a decision.
The petitioners contended the butterfly faced threats to its habitat from climate change.
Fish and Wildlife officials said there is "substantial uncertainty" over how climate change will affect the butterfly or its habitat.
"The uncertainty associated with the information we reviewed does not permit us to make an accurate prediction whether climate change will affect the future viability of the subspecies," the decision said.
The agency, in deciding not to list the butterfly, said it would ask the public to submit any new information that becomes available. It said such information would help the agency monitor and encourage the conservation of the subspecies.
Calling the agency's decision "reckless and illegal," WildEarth Guardians on Wednesday filed a notice of its intent to sue over the butterfly. The group claims Fish and Wildlife violated the Endangered Species Act.
The U.S. Forest Service has estimated about 2,700 acres of suitable butterfly habitat exists but said the number of butterflies isn't known because of the difficulty of doing surveys.
The Center for Biological Diversity asked the government for an emergency listing of the butterfly as endangered in January 1999. In December 1999, the agency said a listing may be warranted but an emergency listing was not.
The agency proposed listing the butterfly as endangered in September 2001 and published a draft conservation plan, economic analysis and environmental assessment in 2004.
It withdrew the decision in December 2004, saying threats were diminishing and the butterfly didn't need protection.
The Center for Biological Diversity and WildEarth Guardians again requested an emergency listing in 2007. The government concluded a few months later it wasn't warranted.