A female gray wolf was reported dead in northwest Colorado this week, becoming at least the seventh of the state’s reintroduced wolves to die.

Colorado Parks and Wildlife did not indicate in its news release what may have caused the animal’s death but said a final determination will be made after a necropsy.

The agency said it was alerted to the death by the wolf’s collar on Thursday. The U.S. Fish and Wildlife Service is also investigating the incident because gray wolves are protected under the federal Endangered Species Act.

The wolf, numbered 2512-BC, was one of 15 relocated from Canada to Colorado in January, marking the second wave of reintroductions by the state after voters approved the effort in 2020. Another group of 10 wolves captured in Oregon was loosed in December 2023.

The latest death is at least the fourth among the Canadian wolves after federal agents shot one animal suspected of preying on Wyoming livestock in March, followed by a second mortality in Wyoming and another in Rocky Mountain National Park last month. CPW officials have said the agency plans to release 10 to 15 wolves annually for three to five years, until Colorado’s gray wolf population is stable and self-sustaining.

Colorado ranchers continue to oppose the reintroduction over concerns of wolves killing livestock, and CPW commissioners earlier this year denied a petition brought by ranchers that sought to delay the program.

Some of the animals introduced in 2023 were later shot, prompting an investigation by federal officials.