Twenty-five percent of Wind Cave National Park is tree covered. The forested area includes ponderosa pine forests and scattered groves of aspen, elm, bur oak, boxelder and birch. These scattered groves are generally found along drainage areas. The ponderosa pine forest occupies the higher elevations in the park.
Maine ocean islands provide the only nesting sites for Atlantic puffins in the United States. Eastern Egg Rock in the midcoast region, Seal Island and Matinicus Rock at the mouth of Penobscot Bay, and Machias Seal Island and Petit Manan Island off the downeast coast provide habitat for more than 4,000 puffins each summer.