A four-minute video called “How Wolves Change Rivers” has been watched more than 46 million times. It tells a tidy story: bring back the wolves, and the rivers themselves move. That is a lot of people absorbing a claim that the scientists who study Yellowstone still cannot agree on.
A quick note before going further. I am not an ecologist, wildlife biologist, or hydrologist, and nothing here is a verdict on the science. This is a piece of reading and reflection on a live scientific disagreement. The studies at its center are observational, drawn from field sites in one specific park, and even the researchers involved describe their findings in careful, hedged terms.
The viral story, told cleanly
Gray wolves had been largely absent from Yellowstone, mostly wiped out by a predator-control program, between 1914 and 1926. Then, in early 1995, they came back.
The first wolves arrived by truck through the Roosevelt Arch on January 12, 1995. In total, fourteen wolves went into three Lamar Valley acclimation pens that first year and were released by late March. A second group followed, bringing the total to 31 wolves by the end of 1996…