HELENA, Mont.  The federal agency that removed the gray wolf from the endangered species list in March has changed its mind and is asking a federal judge to vacate the decision.

The request, by the United States Fish and Wildlife Service, follows a temporary order by Judge Donald Molloy of Federal District Court in Missoula, Mont., against the service’s decision in March to remove the wolf from the list. The agency said then that the wolf population in the Northern Rockies had fully recovered.

The order stopped a plan to allow hunting of the wolves in Montana, Idaho and Wyoming until a lawsuit by environmentalists challenging the wolves’ removal from the endangered species list could be heard.

On Monday the Fish and Wildlife Service asked Judge Molloy to vacate the delisting and allow officials to reconsider their finding and further study the issue.