Fauna versus flora

Botanist says deer threaten wildlife

Like Aldo Leopold before him, UW–Madison botanist Don Waller is about to take an unpopular stand on Wisconsin’s booming deer herd.

Next week, when Wisconsin’s Conservation Congress holds a public hearing here to gather public input on how best to manage the estimated 1.4 million deer in the state, Waller is likely to find himself in the cross hairs of both hunters and animal rights activists. He plans to paint a vivid picture of the damage the large deer herd is doing to Wisconsin’s biodiversity.

The list of casualties, says Waller, includes trees like eastern hemlock and white cedar, wildflowers such as orchids and lilies, and shrubs like Canada yew. Moreover, the combined effect of over-browsing by a deer herd with population densities now in the range of 20 to 30 animals per square mile has, in some areas, significantly reduced vegetation needed by many songbirds and butterflies.

“We’ve created a landscape that fosters high deer density,” said Waller noting that much of northern Wisconsin is now a blend of openings, conifer stands and young aspen stands, ideal deer habitat. “But there’s a downside to this kind of landscape and wildlife management.”

Fifty years ago, another UW–Madison professor, wildlife ecologist Aldo Leopold, faced a similar situation, and successfully persuaded the state to alter the way deer were harvested, specifically by opening the hunt to include young bucks and does. He was criticized for it until his death in 1949 (see sidebar).

In Waller’s view, the issue remains essentially the same: The deer herd, he argues, is managed in one dimension, with little thought or policy directed to the idea that deer are one component of an interconnected system of plants and animals.

The problem, says Waller, is of such proportion that “catastrophic disintegration” looms for some of Wisconsin’s distinct biotic communities.

“There is good evidence that native species, particularly orchids and lilies, are getting hammered by deer. They are high on the list of preferred deer foods.”

Waller and his students, in fact, have collected much of the hard data to support such a conclusion. Under grants from the National Science Foundation and the U.S. Department of Agriculture, Waller has conducted studies over six years of the influence of deer on plant communities, principally in northern Wisconsin. The results portray a dire future for plants and trees that were once common elements of the Wisconsin landscape.

Eastern hemlock, for example, was at the time of European settlement a dominant or important component in roughly two-thirds of Wisconsin’s northern forest area. It is now confined to a few remnant stands and, in those stands, is experiencing a widespread failure to regenerate. Seeds sprout, says Waller, but trees rarely survive beyond the seedling stage because they are a preferred menu item for deer, which today roam in densities two to four times as great as when Europeans first settled the area.

Thomas P. Rooney, a UW–Madison graduate student in botany, working in Pennsylvania’s Heart’s Content, one the last virgin forests in the eastern United States, has documented the devastation inflicted by deer that exist in densities even higher than those in Wisconsin. Cataloging plants in the two virgin stands browsed by deer, he found that in one stand nearly 60 percent of native species had disappeared. In the other, he could not find nearly 80 percent of the plant species found in a 1929 survey of the same tract.

The heart of the problem is single-minded management, Waller says. When it comes to deer, which have a powerful political constituency in the hunting public, management historically has been focused on keeping deer populations as high as possible without degrading the herd.

What’s needed to ensure the overarching health and diversity of Wisconsin’s biotic communities, argues Waller, is a more encompassing approach to management: “It is important to have a broader, ongoing monitoring of biotic impacts. That, heretofore, has not been an element of deer management.”

Waller plans to suggest as much at the Madison hearing, one of a series of 29 being held throughout Wisconsin. That proposal, he says, will be controversial because it involves reducing deer population density in some deer management units through expanded hunting opportunities.

Reducing densities will be unpopular with some members of the hunting public and the method for achieving those densities, hunting, which Waller says is far and away the best management technique at the DNR’s disposal, will not be favored by other groups such as animal rights activists.

“This is a radical notion to some people. But some managers, particularly foresters and wildlife biologists, are starting to listen to the message,” Waller says.