Most ecosystems in this country cannot be studied in their entirety because of missing members of the animal communities. Ever since wolves were restored to the Greater Yellowstone Ecosystem all of the major players in the ecosystem's intricate web of interactions are back in place, making Yellowstone one of the best locations for ecosystem study on Earth.
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.