Biologist: Yellowstone Grizzlies Can't Afford Any Increase In Mortality
On Monday we aired an interview with Dan Ashe, the director of the U.S. Fish and Wildlife Service. That agency has proposed removing Yellowstone area grizzly bears from the endangered species list. Today we’ll hear from David Mattson, a retired bear biologist and prominent critic who thinks that’s a bad idea.
David Mattson is an ecologist who spent more than 20 years studying grizzly bears in and around Yellowstone. Now retired, Mattson helps run a bear advocacy website called Grizzly Times. I interviewed him at his home outside Livingston.
Eric Whitney: How many [grizzly] bears are there in the Greater Yellowstone Ecosystem? Is there even consensus on that?
David Mattson: No, there is absolutely no consensus on the size of the grizzly bear population in Yellowstone. There are some estimates, and all of those estimates are beset by bias of one sort or another. On the one hand you'll hear them claiming there's a thousand bears, based on use of one method. On the other hand they'll say there's 700 bears, based on the use of a different estimator altogether.
EW: What's your estimate of the number of [grizzly] bears in the ecosystem?
DM: I would be loathe to offer any kind of estimate of the total number of bears in the ecosystem right now. Perhaps what's germane is how many more we have now compared to what we had in the early 1970s, when the population was listed. All of the evidence I've seen that is of any credible nature would suggest we've got twice as many bears now as when we had the population listed. But what you'll hear from the [U.S.] Fish and Wildlife Service is that the population has tripled and even quadrupled in size, and I think that's a gross exaggeration.
EW: Another thing that the Fish and Wildlife Service is saying is that the number of bears has reached the [Greater Yellowstone Ecosystem’s] carrying capacity.
DW: Your interviewee is laughing.
Fish and Wildlife Service's representation of carrying capacity, it's designed more to obfuscate and to otherwise obscure something that's fairly obvious, rather than clarify.
I would argue that carrying capacity has in fact declined.
Carrying capacity is not static, it's not a constant. It varies hugely, and I would argue that because we've lost whitebark pine, we've lost cutthroat trout, we've lost most of the elk in the ecosystem, we've experienced a millenial drought which is promising more of the same to come, that we've seen a decline in carrying capacity. And so it's probably no surprise that the bear population is bumping its head up against carrying capacity.
EW: One of the reasons they argue that the population is recovered is because bears are beginning to, they're starting to go to new places, and I think they argue that's evidence they've reached their carrying capacity here, and they have to move out to find - that’s why we’re seeing bears farther afield in the Greater Yellowstone than we have previously.
DM: I think it's a pretty straightforward notion, that if the carrying capacity of an ecosystem drops in the core, then the bears will have to do something. They'll have to go somewhere to find food. Yes, we have seen an increase in the distribution of the bear population, probably by 30 to 40% since the early 2000s. But at the same time, we haven't seen any increase in the population. So we've got the same number of bears now as we did 15 years ago, spread out over a 30 to 40% larger area. That is not equivalent to a population spreading out because of a static situation in the ecosystem related to foods.
In fact, what we've had is a decline in carrying capacity, which has forced the same number of bears to redistribute themselves in search of foods.
EW: Do you want to keep Yellowstone grizzlies on the endangered species list forever?
DM: I think it is important to keep them listed up until we have had a chance to reform state wildlife management, because state management is such a poor alternative. It's a really poor alternative at a time when the population is becoming increasingly vulnerable.
So the longer term prospects for grizzly bears are going to be in a couple of places. One is, changing state management of wildlife so that it is more representative of the broader public interest, so that it better serves the public trust, to where we do a better job at fostering coexistence between humans and grizzly bears, which means a change in attitude, probably a change in culture, improvements in how we manage foods, how we manage livestock.
All of that's possible, but I would argue we're not going to make any advances on that front unless we have the incentives to do so, and if we delist the Yellowstone grizzly bear population, a lot of those incentives will go away.
EW: Director Ashe said the feds will never walk away from management, because the vast majority of land in the Greater Yellowstone is owned by the federal government. He says the idea that the feds are going to walk away from bear management is a misconception.
DM: Claiming that the feds will never walk away from grizzly bear management simply because the feds own a lot of land is yet another disingenuous statement. Whether you own the land or not doesn't mean you will take meaningful action. And in the past, the Forest Service has been remarkably reluctant to take the measures needed to conserve grizzly bears. It was only by dint of litigation. Ownership does not translate into constructive action in terms of grizzly bear conservation.
EW: Dan Ashe says that many other species have been successfully recovered by the U.S. Fish and Wildlife Service and the states under the Endangered Species Act. So isn't that evidence that we should trust them to do likewise with Greater Yellowstone grizzly bears.
DM: (laughs) Successful recovery is in the eye of the beholder, and it's clear that the recent Fish and Wildlife Service agenda has been to "delist," and you can put that in quotes, species, as a way of presumably, then, saving the Endangered Species Act from attacks by conservative politicians. So, it's a kind of twisted logic to say, the fact we've recovered and delisted so many species is proof of the ability of states to manage these populations, the Fish and Wildlife Service to manage these populations, at the same time you're saying we need accelerate delisting so that we can prove a political point.
So I would argue the whole process is basically political. I would argue that that very statement by Dan Ashe is political, more than it is empirical.
EW: Do you believe that the population is big enough that it could sustain any mortality from sport hunting? Do you think that mortality is already so high that any hunting at all would be detrimental?
DM: What I would be willing to predict is that if we waited two years, if we looked two years out into the future using the exact same methods we're using now, that we will be down at a population estimate of 600, at which point, even by their reckoning there will be no prospect of any sport hunting at all, and that not too long after that we will be below 600, headed to 500, using their methods. Under a scenario like that, with the drivers afoot leading to elevated grizzly bear mortality as-is, I don't think we can afford to have any increase in mortality for any reason at all.
EW: On YouTube I watched a video of you in Jackson, WY last year, giving a talk, and I think you used the word kinship, you said that you personally have a kinship with grizzly bears. And I think as long as we're questioning the motives at the Fish and Wildlife Service, is that biasing your scientific view of this population?
DM: I didn't say I felt a kinship. I'm unendingly fascinated by Yellowstone grizzly bears. I don't know that that would overtly bias my view of the politics, just by virtue of being fascinated by them and how they connect with the world around them.
What I will say is, is that I have no tolerance, and no patience for any government official, or any government bureau that, for whatever reasons, contributes to betraying the trust placed in them by the public. My concern is governance, and the quality of governance, and the use of science in making decisions in service of the public trust. I find it incredibly disturbing that there are so many signs and signals of the public trust being betrayed in this decision making process.
So if I'm biased, that's my bias.