Second-Order Wins✓✓ 3 independent sources
Wolves Came Back to Yellowstone. So Did the Willows.
31 wolves reintroduced in 1995; willow and aspen recovery documented across northern Yellowstone
National Park Service monitoring documents elk behavior shifts and vegetation rebounding along Yellowstone's rivers, and Beschta & Ripple's peer-reviewed work recorded riparian vegetation recovering across the two decades after reintroduction. Scientists still debate how strong each link in the famous 'wolves changed rivers' chain is — but the core cascade, predators back → browsing pressure redistributed → trees returning, is measured fact.
In 1995, 31 wolves returned to Yellowstone after a 70-year absence. Elk changed their habits, young willows and aspen stopped being mowed down — and the recovery is measured, not mythical.
The receipts
- National Park Service: Yellowstone Wolf Reports (annual project reports)
- Biological Conservation: Riparian vegetation recovery in Yellowstone: The first two decades after wolf reintroduction (Beschta & Ripple)
- Ecology Letters (comment): Non-random sampling measures the occurrence but not the strength of a textbook trophic cascade (the honest caveat)