Wolves of Greater Yellowstone

Predator control, practiced in Yellowstone in the late 1800s and early 1900s, removed its wolves.² Between 1995 and 1997, 41 wild wolves from Canada and northwest Montana were released in the park, and wolves from the growing population dispersed to set up territories outside the park.² At the end of 2025 the park had 84 wolves in seven packs and one new group.¹ Only 17 pups survived the year, the fewest since 1996, which the park puts down to a mix of causes that may include disease.¹ Inside the park wolves are not hunted. Outside it, Montana, Wyoming and Idaho each run hunting and trapping seasons with their own rules, and park wolves that cross the line can be legally killed.¹ Most of those deaths happen in the Gardiner Basin on Montana's side of the northern boundary, the winter range of northern Yellowstone's elk and other hoofed animals.¹ In 2025 hunters in Montana killed three wolves from park packs.¹

Federal protection has changed more than once. Wolves in the Northern Rockies were delisted in 2011 in Montana and Idaho, by an act of Congress, and in 2017 in Wyoming.^3,9 In February 2024 the U.S. Fish and Wildlife Service found that listing wolves in the western states was not warranted; in August 2025 a federal judge in Missoula vacated most of that finding and sent it back to the agency, and Montana's wolf season went ahead.^9,1

Montana changed its own count in 2026. Its 2025 report gave two estimates for the state: 1,094 wolves under its original model and 725 under a preliminary updated one, still to go through peer review.⁴ The state's wildlife commission then cut the statewide quota for the 2026-27 season to 300, from 452 the season before; FWP had recommended 250.^8,7 Units 313 and 316, which the park's report names in its account of hunting along the northern boundary, had a separate quota of three wolves each in 2025-26;^1,4 a local news report gives a limit of one wolf per unit for 2026-27.⁷

Wolves also kill livestock. In 2025, USDA Wildlife Services confirmed 68 livestock killed by wolves in Montana (44 cattle, 18 sheep and six dogs), and the state's Livestock Loss Board paid $92,917; 43 wolves were killed in response.⁴ In Wyoming, wolves were confirmed to have killed or injured 59 head of livestock, and 49 wolves were removed.⁶ Wyoming's report records no livestock conflicts inside the park.⁶

The question that made Yellowstone's wolves famous is still argued. A 2025 paper by Ripple and colleagues reported a roughly 1,500% increase in willow crown volume on the northern range between 2001 and 2020 and called it a relatively strong trophic cascade from fewer elk browsing.¹⁰ A comment by MacNulty and colleagues called that analysis invalid: crown volume was modelled from the same height measurements, plots were not matched across years, and hunting of elk outside the park was left out.¹¹ A 20-year experiment by Hobbs and colleagues, published in 2024, found that willows grew to the heights expected for restored communities only where browsing was kept out and simulated beaver dams were in place.¹² It concluded that the return of large carnivores had not restored the streamside plant communities.¹² Meanwhile Montana counted at least 7,226 elk in the northern Yellowstone herd in April 2025, 6,124 of them outside the park in Montana, above the objective of 3,000 to 5,000 elk for the Montana part of the winter range.¹

Who needs an answer

• Montana's Fish and Wildlife Commission and the wildlife agencies of Wyoming and Idaho, setting each year's quotas and seasons right up to the park line.
• Park managers, who track which park wolves die outside the boundary and why.
• The U.S. Fish and Wildlife Service, which has to make a new decision on whether western wolves warrant federal protection.
• Ranchers and the boards that pay for confirmed losses, deciding where to spend on prevention and when to remove wolves.
• Elk hunters and the towns at the park's edge.

The domains it chains

Predators hunting elk and bison. Elk moving between summer range in the park and winter range in Montana. People hunting both elk and wolves. Willows, beavers and the water table along streams. Cattle and sheep on private land. Laws that change at the park line and at each state line.

What a twin should let people try

• Quotas near the boundary: how many park wolves would die under one wolf per unit, three, or none, given where packs travel in winter?
• Counting: how would harvest limits change if the state's lower population estimate is right, or if the older one is?
• The cascade: with elk numbers, bison, hunting and beaver dams as separate dials, how much of the change in willows does each explain?
• Livestock: where on the landscape would prevention cut losses most, and how many wolf removals would it avoid?

Where to start

The park's annual wolf reports give pack counts, territories, kills and deaths, with population counts back to 1995, and Montana's annual reports give statewide estimates, harvest and livestock losses, with current and past harvest reports linked from the state's wolf page.^1,4,5 Wyoming publishes the same kind of annual report.⁶ The willow height data behind both sides of the cascade argument come from the long-term plots of Hobbs and Cooper.¹¹ An agent-based tool such as NetLogo can hold packs and hunters on either side of the boundary. Circuitscape can map the routes dispersing wolves take out of the park. The use case on ecosystems and land management lists other tools.