Dan MacNulty

Grey wolf standing in Yellowstone’s Lamar Valley beside a coyote, with sagebrush grassland and large boulders in the foreground; image from BBC Wildlife Magazine March 2026 feature on wolf reintroduction.

Thirty years after wolf reintroduction, has Yellowstone’s celebrated “trophic cascade” — popularized by How Wolves Change Rivers — delivered what many claim?

BBC Wildlife Magazine (March 2026) revisits the debate.

Access here (free sign-in required): 🧪 www.ziniounlimited.com/article/bbc-...

A new exchange in @esajournals.bsky.social highlights a common omission in the Yellowstone trophic cascade story: >100 beavers were reintroduced, spanning years before and after wolf reintroduction. 🧪
Beschta et al (comment): doi.org/10.1002/ecm....
Hobbs et al (reply): doi.org/10.1002/ecm....

Yes, wolf densities in northern Yellowstone are among the highest documented for any wild wolf population. No new aspen clones have been documented. Many clones have died out since wolf reintroduction, including the ones documented in the map and photo I included in my original post.

Climate warming is indeed a factor, as is continued browsing by elk, moose, mule deer, and bison. Wolf density in the area has been exceptionally high for decades.

New critique prompts correction of high-profile Yellowstone aspen study. Correction fixes a math error, but lack of young aspen across >50% of sampled sites complicates story of “widespread” aspen recovery after wolf reintroduction. 🧪 www.eurekalert.org/news-release...

No. They're mostly even-aged.

Data from Kauffman et al. suggests many mature aspen trees in northern Yellowstone are at or near their maximum lifespan.

There is a reasonably large body of evidence that implicates elk browsing as the principle reasons for the gap. Much of this evidence comes from exclosure studies. For example: Fig 2B in Kauffman et al. 2010; doi.org/10.1890/09-1...

In LiveScience, Ripple defends his willow paper by saying “the basic scientific logic of the paper is solid.” Yet the analysis relies on a tautology: re-expressing height as “volume” and treating it as new evidence. That is circular reasoning, not solid logic. 🧪 www.livescience.com/animals/land...

Painter et al.’s reply fixes the math but sidesteps the bigger problem: mean-based effect sizes from zero-inflated, non-equilibrium data are misleading indicators of trophic cascade strength. The claim of a strong & ecologically significant aspen cascade remains overstated. 🧪 doi.org/10.1016/j.fo...

Please elaborate if u wish

They did not.

Our critique is now published in Forest Ecology & Management. We show why the corrected 17.5× increase in average sapling density still overstates aspen recovery: mean-based metrics are driven by a small minority of plots, while most showed little or no change.
🧪 authors.elsevier.com/a/1mMLU1L%7E...

Painter et al. have issued a corrigendum conceding that the headline 152× increase in aspen sapling density was an error (now 17.5×), consistent with our critique. But the revised result still relies on averages that mask how most aspen stands showed little or no change. 🧪 doi.org/10.1016/j.fo...

Have Wolves Saved Yellowstone’s Aspens? - Mountain Journal Claims that wolves have rescued Yellowstone National Park aspen trees through a ‘trophic cascade’ oversimplify a complex story

“The narrative that wolves are a kind of silver bullet that saved the aspen in Northern Yellowstone is oversimplified” - Nick Bergeron, USU researcher🧪 mountainjournal.org/have-wolves-...

IFLScience reports that Ripple et al. “stand by their original assessment” and “have prepared a detailed reply explaining why [MacNulty et al.’s] criticisms are inaccurate.” Their reply “is set to be published as soon as possible.”🧪
www.iflscience.com/yellowstones...

"For readers, the lesson is plain. Big claims deserve clear tests that do not stack the deck or skip steps."🧪

The story of Wolf 1329M provides a textbook example of the source-sink dynamic that limits the spread of Yellowstone wolves beyond the Greater Yellowstone Ecosystem. 🧪
wyofile.com/what-happens...

Drilling lease slated 2 miles from world’s largest sage grouse lek, center punching planet’s longest mule deer migration - WyoFile Parcel 0712 is part of a complex of oil and gas leases in ecologically valuable sagebrush-steppe that the Bureau of Land Management has proposed for auction in June.

World’s largest sage grouse lek and longest mule deer migration threatened by oil & gas lease sale in western Wyoming. wyofile.com/drilling-lea...
Public comments due Monday, 17Nov.
eplanning.blm.gov/eplanning-ui...

🧪Now that the flaws in Ripple et al. (2025) are on record, it’ll be an interesting test of scientific integrity to see if and how that paper is used. This Science letter, for instance, cites Ripple et al. (2025) in calling for strict wolf protection across Europe. www.science.org/doi/10.1126/...

Line chart showing Yellowstone aspen sapling density from 2007–2021. Median and 75th-percentile lines stay near zero, while only the upper percentiles (90th and 95th) rise sharply—indicating gains in just a few plots.

Even 17.5× is inflated—it reflects average sapling density driven by a minority of plots. Most aspen plots (green = median) stayed flat—half had no saplings, and only a small fraction (purple, pink) increased.
doi.org/10.32942/X2W...

🧪About that “152×” Yellowstone aspen claim (see WaPo headline). In a new preprint we show it’s a math error that inflated the effect by 768%. Corrected: 17.5×. Preprint: doi.org/10.32942/X2W...

Could Colorado see widespread ecosystem changes from wolf restoration? In Yellowstone National Park — where gray wolves were reintroduced starting in 1995 — researchers have gone back and forth on whether the restoration of wolves has impacted the ecosystem.

Claims about “wolves reshaping ecosystems” are powerful—but only if they’re accurate. This Aspen Times article on Colorado’s wolf reintroduction shows why getting the Yellowstone trophic cascade story right matters for public understanding and policy:
www.aspentimes.com/news/colorad...

🧪 phys.org/news/2025-10...

🧪You may have heard that large-carnivore recovery in Yellowstone National Park triggered one of the world’s strongest trophic cascades. Our new open-access article explains why that story doesn’t hold up: www.sciencedirect.com/science/arti...

Feedgrounds grow elk herds? Wolves, grizzlies might mop up benefits, study finds. - WyoFile U.S. Geological Survey analysis using demographic data from 13 Greater Yellowstone Ecosystem elk herds suggests few overall benefits from feeding, including for hunting.

wyofile.com/feedgrounds-...

🧪 New preprint

We critically evaluate claims of a strong trophic cascade in Yellowstone following wolf recovery, identifying major methodological flaws that undermine this conclusion.

Read the full analysis here (open access): doi.org/10.32942/X2Q...

#Ecology #Yellowstone #TrophicCascades

Mountain lion ‘eradication bill’ backed up a tree by overwhelming opposition - WyoFile Environmental groups, outfitters, hunters, houndsmen testified by the dozen against a measure that would have stripped cougars of any protections, and wildlife professionals of management authority.

A bill that threatened to decimate Wyoming's mountain lion populations fell spectacularly flat on Tuesday.

Environmental groups, hunting orgs, houndsmen and citizens testified by the dozen encouraging lawmakers to kill a La Barge representative’s proposal to do away with science-based management.

Overlooked No More: Annie Easley, Who Helped Take Spaceflight to New Heights She broke barriers at NASA and contributed to its earliest space missions as a rocket scientist, mathematician and computer programmer.

www.nytimes.com/2025/02/01/o...

Two bills seeking to roughly halve Montana’s wolf population pass out of committee HB 176 and 222, which seek to reduce wolf numbers, will advance to the Montana House for a floor vote.

Two bills seeking to roughly halve Montana’s wolf population pass out of committee. HB 222 and HB 176 seek to reduce Montana’s wolf population by expanding the hunting season and lifting hunting and trapping limits. montanafreepress.org/2025/01/24/t...