The park’s 21 islands and coastal strip along the mainland provide habitat for a wide variety of wildlife. Islands of different sizes and shapes, distances from the mainland and each other, and diverse disturbance histories provide a great opportunity to study island biogeography. Size and distance of the islands from the mainland are important factors in explaining the distribution and abundance of mammal species.
Wildlife find their way to the islands in a variety of ways. Some swim, others cross the ice, and some manage to “hitch-hike” to the islands on boats. Those that hibernate, like zhigaag (skunks) and chipmunks, don’t tend to occur on the islands. With warming conditions, the thickness and duration of ice within the islands is declining. Research is underway to study the potential effects of changing ice conditions on wildlife.
Waawaashkeshi (white-tailed deer) populations ebb and flow in the islands over time, depending on habitat conditions – peak populations in the 1940’s and 1950’s following extensive logging, to large declines in the 1960’s following severe winters, liberal hunting, and habitat changes. Currently, deer populations occur on Oak, Stockton, Basswood and Hermit at low densities. Deer can swim however and are occasionally seen on other islands.
Similarly, amik (beaver) respond to habitat changes. Following logging and associated habitat changes, they established and colonized all the available watersheds on Stockton and Outer Islands. With time, forests matured, favorable beaver habitat has been reduced, and numbers declined. Active beaver lodges occur on Sand, Michigan and Outer Islands. However, like deer, beaver can swim between islands and are occasionally found on other islands.
Carnivores are important part of the park’s ecological communities. The diversity of carnivores on the islands is surprising. Ten of the twelve carnivore species that occur in Wisconsin have been documented in the park, including State endangered waabizheshi (American marten). Some species, such as makwa (black bears - makwa), have been found on most of the islands. Others, like ma'iingan (wolves), occur on the Mainland, but are very rare on the islands. Other species include coyote, red and gray waagosh (fox), gidagaa-bizhiw (bobcat), ojiig (fisher), nigig (otter), zhingos (weasel), and esiban (raccoon).
Small mammals contribute to the health and biodiversity of ecosystems. There are ten species in the park; four of which only occur on the mainland. Red backed voles, the favorite food of American marten, are the most abundant small mammal species on the islands. Other island small mammal species include ajidamoo (red squirrel), deer and white-footed waawaabiganoojiinh (mouse), and common and short-tailed shrew. Species only found on the mainland include eastern chipmunk, meadow jumping mouse, eastern meadow vole, and zhagashkaandawe (flying squirrel).