Isle Royale - Ecology

Ecology

A number of habitats exist on the island, the primary being boreal forest, similar to neighboring Ontario and Minnesota. Upland areas along some of the ridges are effectively "balds" with exposed bedrock and a few scrubby trees, blueberry bushes, and hardy grasses. Occasional marshes exist, which are typically the by-product of beaver activities. There are also several lakes, often with wooded or marshy shores. The climate, especially in lowland areas, is heavily influenced by the cold waters of Lake Superior.

The island is well known among ecologists as the site of a long-term study of a predator-prey system, between moose and eastern timber wolves. There is a cyclical relationship between the two animals: as the moose increase in population, the wolves do also. Eventually, the wolves kill too many moose and begin to starve/lower reproductive rates. However, the introduction of canine parvovirus by a guest's (illegal) dog to the wolf population led to steep declines in the early 1980s.

Before the self-introduction of wolves to the island (crossing winter ice from Ontario), coyotes were the primary predators for a time. Prior to that, the lynx dominated, preying on caribou and snowshoe hares. Human activities wiped out both the lynx and caribou, but some hares remain. Other common mammals are red foxes, beavers, and red squirrels. Some foxes are quite used to human contact, and can be seen prowling the campgrounds at dawn, looking for stray scraps left by unwary campers. For its part, the wolf is an elusive species which avoids human interaction. Few documented cases of direct wolf/human contact exist. Ermine have been periodically sighted around docks. Other mammals that can be seen include mink (along the various lake shores) and muskrats (occasionally at beaver ponds). Several species of bat also exist on the island. Reptiles include the eastern garter snake, painted turtle, and northern redbelly snake. Six species of frogs and three species of salamander also live on the island.