Yellowstone National Park Superintendent Dan Wenk, seen in front of park headquarters in Mammoth, will retire from the Park Service at the end of September. (National Park Service)

Yellowstone National Park Superintendent Dan Wenk on Thursday discounted speculation that a disagreement with Secretary of the Interior Ryan Zinke over bison led to his removal from the Park Service’s flagship post.

In a telephone press conference Wenk said bison numbers and habitat in Yellowstone were the only subject of disagreement between him and Zinke, but that he and Zinke were discussing the topic professionally. “I believe we were working through that issue,” Wenk said.

Montana agricultural interests — a key constituency for Zinke, once a Montana congressman — see bison as a threat, despite a lack of scientific evidence that they can spread the bovine disease brucellosis to cattle in the wild. Montana resistance to a larger population led to an agreement in 2000 to limit the number of bison in the world’s first national park to between 3,000 and 3,500.

But the number had climbed to 5,500 when Zinke toured Yellowstone as a congressman in the fall of 2016, Wenk said. Secretary of the Interior Bruce Babbitt signed the bison plan when it was adopted 18 years ago, Wenk said.

“I’m sure he [Zinke, as the current secretary] feels fidelity to the numbers in that document,” Wenk said.

To meet the population goals some bison are trapped inside Yellowstone and shipped to slaughter. But bison generally don’t leave the park  — and cause worry among stock growers — unless there are more than 4,200, Wenk said. Seasonal environmental factors weigh on that annually, but, Wenk said, he believes the park can generally host more than 3,500 without issue.

“I think we’re dealing more with a social carrying capacity outside of the park,” rather than habitat limitation inside Yellowstone, he said.

“I’ve been told by the Washington office that [bison numbers] is not the reason for my removal,” he said.

That’s at odds with some media reports that held up bison as the linchpin in Wenk’s forced transfer. “Yellowstone chief says Zinke is pushing him out over bison spat,” read one headline. “Zinke Forced Me Out As ‘Punitive Action’ Over Bison Dispute,” read another. A third story said Zinke was “ousting Dan Wenk over bison.”

Bison numbers had climbed to 5,500

There were still some 5,500 bison in Yellowstone at the end of 2016, 2,000 more than the Interagency Bison Management Plan calls for.

Yellowstone is “‘managing for a decrease,” Wenk said. By 2017, the population was down 600 animals from 2016 and by the end of the summer it is expected to be 1,000 fewer than the 2016 count, he said. He expects the park will continue to manage for a stable to decreasing population after he is replaced, Wenk said.

But there’s only so much the park can do in terms of rounding bison up. Park border hunting also can only have so much effect on population size.

“I think there’s limits to how aggressive we can be,” he said.

Wenk walks on boardwalk at Yellowstone’s Mammoth Hot Springs. (National Park Service)

As a conservation advocate supervising a preserve surrounded by three red states, however, Wenk has had his share of friction with neighbors and said some people are glad to see him go.

Friction included worries regarding the effect of hunting on grizzly bears, and whether a trophy grizzly season outside Yellowstone would diminish park visitors’ opportunities to see bears.

He pointed to a letter from the board that oversees the senior executive service — a high tier of federal employees — that states his talents could be better used as director of the National Capital Region in Washington, D.C.

Read: Memos chart Yellowstone super’s fight to keep job

“I have no other reason,” for the transfer order other than the board’s letter, he said. “I have no other information.”

As a member of the Senior Executive Service, Wenk received an executive salary but agreed to reassignment for whatever reason and on an expedited schedule.

“I knew I could be moved,” Wenk said. He is currently the member of the service with the longest tenure in a position he said.

Wenk would not agree with a reporter’s proposition that his reassignment was part of a Trump administration “purge” of other National Park Service senior executives, some of whom have resigned rather than move.

“They made it very clear to me they wanted me to come back as director of the National Capital Region,” he said of administration officials. “I was certainly not being forced out of the National Park Service.”

Wenk made it known in 2016 that he would retire from his position as Yellowstone superintendent, he said. In other words, he would not be transferred. He eventually set that retirement date as early 2019.

So the transfer order caught him off-guard, he said. The prospect of moving to Washington was not in his cards.

“I was surprised,” he said of his reassignment, “and the decision [to resign] was relatively easy.”

He told reporters he regrets using the word “abused” to describe his transfer when news of it became public. But the transfer order still feels “a little punitive,” he said.

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“I didn’t think it was fair for me to go back,” to Washington, he said. Having it feel punitive and the action actually being punitive are two different things, he said.

Wenk will leave his post Sept. 29 after 43 years in the service. He is 66 years old.

Angus M. Thuermer Jr. is the natural resources reporter for WyoFile. He is a veteran Wyoming reporter and editor with more than 35 years experience in Wyoming. Contact him at or (307)...

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