Wisconsin lies within three well-defined “life zones” conducive to species diversity: the Canadian, the transition, and the upper austral (or Carolinian). The Canadian, not surprisingly the coldest, features small mammals such as the snowshoe hare but also the state’s primary large mammals, the deer and the black bear. The warmest zone, the Carolinian, falls in the southern tier of the state and lacks big game mammals. In total, Wisconsin has 73 species of mammals, 339 native bird species, and more than 200 species of amphibians, reptiles, frogs, bats, butterflies, and insects.

Of Wisconsin’s two large mammals, the ubiquitous white-tailed deer is a traffic (and garden) nightmare. The other resident big mammal, the black bear, is still relatively common in the North Woods and has also been seen in central and—gasp—southern counties.

Wisconsin lies smack in the middle of several migratory waterfowl flyways, so birding is a big activity in the state. Tundra swans, sandhill cranes, and Canada geese are three of the most conspicuous species. The latter are so predominant at the Horicon Marsh National Wildlife Refuge that ornithologists make pilgrimages there each spring and especially fall.