Grizzly bear north of Obsidian Cliff; Jim Peaco; May 2014. Park Service.

The August 2023 issue of Global Change Biology published a study on the state of the GYE grizzly population from 2000 to 2020. Among other things, the authors found that, at least until 2020, the bear’s foods were sufficient across the landscape, but also found that the bears’ population growth nevertheless slowed — did not stop, but slowed down — from 2010 to 2020.

What’s happened in the five years since 2020 was beyond the scope of the study. But we’re left with the fact of a slowing from 2010 to the study’s end in 2020.

So what? What, if anything, might this decade of slowing mean for recovery of the bear?

First, it’s been standard practice to point to the population’s increasing numbers as bedrock evidence that the grizzly has recovered and can be delisted. By this analysis, the state of the bear population is reduced to a numbers game.

But there were already other lines of evidence available for assessing recovery, whether recovery of an ecosystem or a single species within it. In 2007, for example, American Naturalist published “Slow Recovery from Perturbations as a Generic Indicator of a Nearby Catastrophic Shift.”

These authors wrote, “Such recovery rates decrease as a catastrophic regime shift is approached, a phenomenon known in physics as “critical slowing down.” They add, “In all the models we analyzed, critical slowing down becomes apparent quite far from a threshold point, suggesting that it may indeed be of practical use as an early warning signal.”

A record of evidence

The concept of critical slowing down as a predictive early warning has repeatedly been tested within the context of ecological systems. For example, authors of a 2014 PNAS analysis concluded that “critical slowing-down indicators may be used as early warnings for the collapse of ecological networks.”

For just one more example, a July 13 2022 article in Nature applied the concept to “signals of declining forest resilience under climate change.” The authors explain that they “integrate satellite-based vegetation indices with........

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