Of Bears And Biases: Scientific Judgment And The Fate Of Yellowstone’s Grizzlies

The grizzly, or brown, bear in the Greater Yellowstone Ecosystem is posed to lose protections under the Endangered Species Act. Georgia Evans / Shutterstock

In March, the U.S. Fish and Wildlife Service (USFWS) announced its intent to remove protections afforded by the U.S. Endangered Species Act (ESA) to grizzly bears in the Greater Yellowstone Ecosystem (GYE).

Citing four decades of growth in the bear population, the USFWS Director Dan Ashe heralded the decision as “a historic success for partnership-driven wildlife conservation.”

However, conservation organizations oppose “delisting” GYE grizzlies. They cite persistent threats to grizzlies, public opposition to delisting and ongoing scientific uncertainty regarding the population’s viability. Indeed, scientific uncertainty, especially threats posed by a changing climate, is one reason a federal court reversed a similar decision back in 2009, returning federal protections to GYE grizzlies.

According to the ESA, decisions about the listing of species are to be made “solely on the basis of the best scientific and commercial data available.” The ESA also mandates that decisions about whether to list a species be guided by a scientific assessment of potential threats to a species.

The ESA is hardly unique in this regard. Numerous environmental statutes mandate that government agencies consider “the best available science” when making decisions. And agencies routinely consult with scientific experts to fullfill such mandates.

These requirements ostensibly insulate decisions from undue political influence. Such provisions work reasonably well when science offers clear and simple, black-and-white answers. But when there is uncertainty, is the expectation of scientific objectivity realistic?

To gain insight into what role bias may play in listing decisions, we surveyed a group of grizzly bear researchers. We found that experts' judgments were associated with a number of factors outside the “best commercial and scientific data,” including their professional affiliations and social norms. Furthermore, we found that while there is no consensus in the scientific community regarding the threats to grizzly bears, the majority of scientists support continued listing.

The Conversation

The Yellowstone grizzly: a case study in scientific uncertainty

In December of 2014, we (along with graduate student Harmony Szarek and Dr. Eric Toman) contacted 593 individuals who published research related to grizzly or brown bears during the prior decade. We asked them to judge the risk (likelihood and severity) of seven threats identified by the USFWS and to recommend the appropriate conservation status – delisted, threatened or endangered – for GYE grizzlies.

In total, 60 percent of 211 respondents recommended continued protection under the ESA, about one-fifth indicated the population should be delisted and a similar proportion were unsure. When unsure respondents were removed, 74 percent of 172 experts recommended continuing ESA protections (see project report).

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