Since the delisting went into effect March 28, at least 35 wolves have been killed in Idaho, Montana and Wyoming.
"That's more than one a day under the state plans," said Louisa Willcox, a senior wildlife advocate for the Natural Resources Defense Council in Livingston, Mont.
"We believe that is excessive and we'll wind up right back on the brink of extinction if this continues."
The suit was expected, and wolf management program representatives for the three states immediately said they would intervene on behalf of the federal government.
Environmental groups also requested a preliminary injunction to stop wolf kills until the lawsuit was resolved.
The suit says federal officials ignored scientists who said a connected population of 2,000 to 5,000 wolves was necessary to ensure long-term genetic viability of the wolf in the northern Rockies.
Gray wolves once were plentiful from central Mexico to the Arctic, but virtually disappeared from the American West by the 1930s. In 1974, they were listed as endangered, and since then about $27 million has been spent by the federal government to conserve the wolves.
In 1995 and 1996, officials reintroduced 66 wolves to central Idaho and the Yellowstone National Park area. The population has soared beyond the program's goal of 300, to 1,500 wolves throughout the northern Rockies region. The growth rate of the population is estimated at 24% annually.
Since delisting, wolves are managed by each state under plans approved by the U.S. Fish and Wildlife Service. They are required to maintain about 300 wolves throughout the tri-state area, but the current state plans call for a total of at least 1,050 wolves.
Wyoming's wolf management plans have received the most criticism. In certain areas, wolves are deemed predatory and can be baited or shot by hunters using aircraft. Officials are working out details, including possible permits, for the fall wolf-hunting season in areas where wolves are categorized as trophy game animals.
In Idaho, state law was amended the day the delisting went into effect. There, people are allowed to kill wolves that are "molesting or attacking" pets and livestock.
Montana has not determined how many wolves may be killed during the fall hunting season.
The lawsuit challenging wolf delisting is expected to drag on for years. A 2007 decision to delist gray wolves in Wisconsin, Michigan and Minnesota is still in court. The ruling on the injunction request, however, should occur within the next few weeks.
A separate suit has challenged a revision to the Endangered Species Act that would allow wolves listed as endangered to be killed if they threatened dogs or seriously decreased deer, elk or moose populations.
© 2008 The Los Angeles Times