Many people may consider deer a welcome member of the Apostle Islands’ ecosystem. But according to a recent study conducted by a Northland College professor, deer are having an adverse effect on some of the islands’ important vegetation.

“Deer very recently colonized Sand Island and very quickly began denuding the vegetation,” said Gus Smith, Associate Professor of Natural Resources and Biology at Northland College. “They’re now mowing down on the last remnant vestiges of old Wisconsin forest.”

According to Smith, the Apostle Islands contain “museum quality conifer forest,” an ecosystem rich in Canada yew, northern white cedar, eastern hemlock, and various maple trees—all of which deer feed on.

Smith has been sampling Sand Island as part of the curriculum for his Field Ecology class since 2003. The results of that work suggested deer were making an undesirable imprint on the island’s rich flora.

Smith received a grant through the National Park Service and began the two-year study, which, aside from Sand Island, focused on the effects of deer browse on, York, Oak, Basswood and Raspberry Islands. Northland College alumni Emily Fawver and Frank Maragi joined him in the research.

The team began the study on Sand Island by counting deer pellets, which, when put into a complicated equation, gave them an estimate of the deer population on the island. They then marked a series of two-by-five meter plots within a larger plot, roughly 17 feet in diameter, and counted the number of stems that deer had browsed in each plot.

His team estimates that deer have removed 38 percent of Canada yew— a native coniferous shrub that deer prefer feeding on—from Sand Island and nearly the same amount from York Island.

“Preliminary estimates suggest that only 24 percent of the stems of Canada yew are new growth, so deer are removing more than the plant can replace,” Smith said. “Yew is not keeping up with the deer browse, so it is going into decline.”

Smith believes that because the shrub has been virtually eliminated from the state’s mainland through deer browsing and human activity, deer have migrated to islands like Sand and York.

“It’s great habitat there for deer,” Smith said of the islands and their quantity of vegetation.

Because of the team’s findings, a deer hunt was implemented two years ago on Sand Island and one year ago on York Island. The other islands (Oak and Basswood), which do not have the same type of coniferous forest and, thus, are not as at risk to deer browse, have had hunting for years, Smith said.

This October, the Wisconsin Department of Natural Resources granted a “nuisance” hunt to the National Park Service in order to kill animals that are doing damage to the landscape. This is typically a management tool granted to farmers in order to kill animals that do agricultural damage in greater numbers, Smith noted.

Smith is currently at work on a report of his team’s findings. He hopes to finish it this winter and submit it to the National Park Service, which will use it to guide its management of the islands.

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