A coalition of environmental groups filed a lawsuit on Thursday against US wildlife officials arguing that the government's management plan for the endangered Mexican gray wolf, one of the most imperiled mammals in North America, does not go far enough.
The Western Environmental Law Center filed the suit on behalf of several organisations in a federal Arizona court, alleging the US Fish and Wildlife Service's plans for the wolves violate the Endangered Species Act and other laws.
At issue is a final rule published in January that, while allowing more territory for the wolves to roam, also capped their population and provided more leeway to state wildlife agencies and others to kill the wolves to protect livestock as well as deer and elk herds prized by hunters.
"Unfortunately, politics supplants wildlife biology in key parts of the USFWS Mexican gray wolf plan," attorney John Mellgren of the Western Environmental Law Center said in a statement. "Our goal in this case is to put the science back into the management of Mexican wolves in the US"
The Fish and Wildlife Service declined to comment on the litigation.
The agency ruled that 300 to 325 Mexican wolves would be needed in the US Southwest for the animals to be considered recovered and stripped of protections under the federal Endangered Species Act.
Conservationists counter that the revisions were still insufficient to guarantee a strong comeback and said a minimum of 750 were needed for the animal's long-term survival.
The number of imperiled wolves found only in the American Southwest climbed to 109 in 2014, marking the fourth consecutive year that the population of Mexican gray wolves has risen by at least 10 per cent.
But Bethany Cotton, the wildlife programme director for WildEarth Guardians who is among the plaintiffs in the case, said the increase was "not nearly fast enough."
Wild Mexican wolves were believed to be all but extinct in the United States in 1998 when the US Fish and Wildlife Service began reintroducing the animal to its native range.
In Mexico, the animals are believed to have been extinct in the wild since the 1980s. In 2014, wildlife managers there announced the first litter of wolf pups to be born in the wild since then, local media said, following reintroduction programs.