In May 2018, Yellowstone National Park’s superintendent was ordered by then-Secretary of the Interior Ryan Zinke to manage the park’s bison “more actively like cattle on a ranch,” according to a park briefing statement.
About a month later, Yellowstone Superintendent Dan Wenk was removed from his post. Wenk was replaced by current Superintendent Cam Sholly who took over in October 2018.
https://billingsgazette.com/lifestyles/recreation/foia-documents-reveal-interiors-2018-push-to-manage-yellowstone-bison-like-cattle/article_fcb7d2c8-5105-5bdc-95de-872ab65bb1d7.html