A gray wolf that was found dead in Larimer County, Colorado, last month was most likely killed by a mountain lion, federal wildlife officials announced this week. They based their conclusion on necropsy results, which showed puncture wounds in the wolf’s skull that were consistent with a lion’s bite, according to U.S. Fish and Wildlife spokesperson Joe Szuszwalak.
“The cause of death is trauma, consistent with predation,” Szuszwalak tells Outdoor Life in an email. “Although not definitive, the puncture wounds in the skull are consistent with those typically inflicted by a mountain lion.”
Szuszwalak says the agency is unable to provide any other details about the wolf or the necropsy results, as a final report has not been released. (USFWS was also unable to provide photos of the wolf upon request.)
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The dead wolf was first discovered on April 18, according to CPW. One of 10 gray wolves that were released in Colorado in December as part of a voter-approved reintroduction effort, it is the first (and so far, the only) reported death among the reintroduced wolves. USFWS has led the investigation, as the reintroduced population is federally protected under the Endangered Species Act.
Like every other gray wolf that was released in western Colorado between December 18 and 23, the wolf had been fitted with a GPS collar. These collars emit mortality signals when the animal is stationary for a significant period of time, which is likely how wildlife officials were able to find it.
The GPS collars have also allowed the state agency to keep close tabs on the wolves’ whereabouts and share that information with the public through “activity maps” that are updated monthly. While it’s unclear exactly where in Larimer County the wolf was found, the location is significant because the county lies on the northern edge of Colorado’s heavily populated Front Range.
The 10 wolves were initially released in Summit and Grand Counties, which lie west of the continental divide. By late April, roughly four months after the initial release, CPW’s activity map showed that at least one of the wolves had entered Larimer County. This marked the first time that any of the wolves had crossed east of the continental divide.
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There is a growing body of evidence from other states showing that cougars regularly prey on gray wolves. Wildlife officials with the Washington Department of Wildlife have confirmed at least four separate instances of GPS-collared wolves being killed by mountain lions since 2013. In most cases, the necropsy results revealed distinct holes in the wolves’ skulls that were consistent with cougar bites. The agency says it’s likely that other, similar deaths have gone unreported in Washington and elsewhere.
“Because we generally don’t find or recover carcasses from wolves that aren’t collared, we can’t be sure how many other wolves have died in a similar manner,” WDFW biologist Trent Roussin explained in a 2022 article.
