It’s been a week of bad news for supporters of Colorado’s voter-mandated efforts to reintroduce gray wolves.
Colorado Parks and Wildlife officials announced May 30 that agents had shot and killed wolf 2405, a yearling male belonging to the first litter of wolf pups born in the state since reintroduction, after a series of livestock attacks in Pitkin County. That news was followed Monday by CPW’s announcement of the death of a recently reintroduced wolf, 2507-BC, in northwest Colorado on May 31.
The latest confirmed death means at least five of the 15 wolves relocated from Canada in January have now died. Two of the animals traveled north into Wyoming, where wolves are largely unprotected under federal and state laws; one was killed by federal officials after livestock attacks, and the other is widely assumed to have been legally hunted – Wyoming wildlife officials have invoked a hunter confidentiality law when asked for details. The causes of death for three wolves found dead in Colorado are all under investigation by CPW and the U.S. Fish and Wildlife Service.
Roughly 20 other adult or yearling gray wolves remain alive and in the wild across the state, and advocates and CPW officials hope that an unknown number of pups born this spring can soon be confirmed and added to the total.
But for now, with a small population working to establish itself in the early stages of the program, the deaths of one-third of the individuals reintroduced this year have pushed Colorado wolves’ survival rate below a critical threshold outlined in CPW’s formal reintroduction plan.
Citing research derived from other states’ wolf management plans and the federally-led effort to restore wolves to Yellowstone National Park in the 1990s, that plan, adopted by the Colorado Parks and Wildlife Commission in 2023, anticipated that survival rates for reintroduced wolves would range between 70% and 85% in the early years of the program. Early survival rates were listed among the benchmarks CPW said it would use to measure “short-term success.”
“A survival rate of less than 70%” for reintroduced wolves within six months of release, the plan says, “would initiate protocol review.”
“An unusually large number of losses during the first year of releases or following any modification to established protocols will prompt a full review of management procedures,” the document continues. “To assure high initial post-release survival, the project may be suspended at any time until likely cause(s) of problems are identified, and acceptable solutions can be implemented to resolve the problem(s).”
CPW spokesperson Travis Duncan confirmed to Newsline that the agency would review its procedures, but not until causes of death for the animals are established.
“Out of an abundance of caution, CPW will assess the mortalities of wolves translocated in 2025 to determine if any translocation protocols should be modified,” Duncan said. “This cannot occur until final determinations from the USFWS necropsies have been made on the cause of the mortalities.”
The 70% target in CPW’s plan comes from a 2015 technical report by the Oregon Department of Fish and Wildlife assessing that state’s wolf population. The Oregon report, in turn, cited three previous studies from wildlife biologists who found that wolf populations can be sustained with mortality rates as high as 25% to 30%. Crossing that threshold, the report’s authors wrote, results in an “increased risk of conservation failure and biological extinction.”
The target also roughly aligns with benchmarks set by planners of the first-ever managed wolf reintroduction program, undertaken by the USFWS in and around Yellowstone National Park beginning in 1995. Federal officials projected that the restoration effort would be successful if overall mortality could be limited to 20% – 10% from authorized killings of wolves due to livestock conflicts and another 10% from “natural causes, accidents, or illegal killing.”
The 1990s efforts near Yellowstone met or exceeded those expectations, successfully reestablishing sustainable wolf population in two different areas ahead of the predicted schedule of three to five years. In the Yellowstone area, 24 of 31 relocated wolves survived the program’s first two calendar years, along with 19 of 23 of their pups, for a total mortality rate of 20%. In a parallel effort in central Idaho, wolves fared even better. Although no pups were born within the first year of reintroduction, 30 of 35 relocated individuals survived the program’s first 20 months, a 14% mortality rate.
CPW biologists will have a better understanding of the state of reintroduction once the number of pups born in Colorado in 2025 is confirmed. The agency says it’s monitoring four “potential dens” of breeding pairs.
But it’s clear now that Colorado’s restoration effort is falling short of the successes experienced in the northern Rockies in the 1990s: Including three deaths confirmed in 2024, eight of the state’s first 25 relocated wolves have died, a mortality rate of 32% – with more than half of calendar year 2025 left to go.
The state’s plan calls for winter releases of 10 to 15 wolves annually in the program’s first three to five years, with an initial target of a stable population of at least 50 animals within the state. Without a turnaround in survival rates and pup production, however, that timeline could be in jeopardy.
“CPW is developing plans for the coming year’s translocation efforts, so Colorado’s wolf population will continue to grow, leading toward a self-sustaining population,” the agency promised in a press release this week.
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