A coalition of conservation organizations notified the U.S. Fish and Wildlife Service (USFWS) Friday that they intend to sue over last month's withdrawal of Endangered Species Act protection for the mountain plover.

The 60-day notice of intent to sue is required under the act and gives the Interior Department that much time to respond or settle out of court.

Conservationists said the decision by the USFWS not to list the plover as threatened was unexpected, given dramatic declines of the grassland bird.

"The denial of protection for the mountain plover is yet another unfortunate example of the Bush Administration's attack on America's bedrock conservation and wildlife protection laws," added Jeff Kessler, conservation director for Biodiversity Conservation Alliance in Laramie.

Sharon Rose, spokeswoman for the Mountain-Prairie Region of USFWS, said officials haven't had time to review the notice and therefore could not comment on the impending lawsuit.

"The data did not indicate that threats were likely to endanger the species throughout its range," Rose said.

Threats to the plover include oil and gas development in plover breeding habitat in Wyoming and Montana, the loss of key habitat such as prairie-dog towns throughout the Great Plains, and the conversion of plover winter range in California to cropland and urban sprawl.

The groups argue that the decision not to list the plover was politically motivated. They also state that the Service refused to consider the best available data in making its decision, which is contrary to the ESA.

In its listing withdrawal notice, the USFWS dismissed two long-term data sets - the Breeding Bird Survey, which shows declining trends of plovers in their breeding range in the Great Plains from 1966-1996, and the Christmas Bird Count, indicating declines of plovers on their wintering range in California from 1955-1999, Kessler explained. These are the only long-term data sets available to assess the population trends for this species.

"There's a double standard here," said Erin Robertson, staff biologist for Center for Native Ecosystems. "On the one hand the Service is dismissing all the long-term data; on the other hand they'92re relying heavily on one small, preliminary study. They seem to be grasping at straws to avoid a listing."

The conservation groups provided a 36-page report to the Service in March 2003 documenting recent scientific research showing the loss of key breeding strongholds. The report is available at: ( http://www.fguardians.org/mplover.html ).

The alliance of conservation groups advocating prompt plover protection includes the Biodiversity Conservation Alliance, the Center for Biological Diversity in Denver, Center for Native Ecosystems in Boulder, Colo., and Forest Guardians in Santa Fe, N.M.