Fear of Wolf Predation Is Not Slowing Over-Browsing by Elk

A new study contradicts the widely held hypothesis that fear of recently reintroduced wolves in Yellowstone National Park would force elk to browse more selectively and therefore lead to a resurgence of growth of aspen trees. In fact, a study conducted by Matthew Kauffman, a scientist with the U.S. Geological Survey, found that since wolves were reintroduced in the park in 1995, elk have continued to browse young aspen at a rapid rate, preventing the trees from re-growing in many sections of Yellowstone. Relying on a map showing areas where elk have been killed by wolves in the park, Kauffman discovered that even in those areas — where grazing should theoretically have been reduced in a so-called “landscape of fear” — elk consumed young aspen at a rate similar to regions where wolf packs were not as active. Writing in the journal Ecology, Kauffman said that while elk have changed their foraging behavior somewhat in response to the wolf reintroduction, the changes do not appear to be sufficient to cause a revival of aspen stands. Since the reintroduction of wolves, elk populations have declined by roughly 60 percent in Yellowstone, but Kauffman concluded that they would have to decline even further to bring about a regeneration of aspen.