This is a Common Loon nesting on a floating raft made by local Loon Rangers in Gaylord, Michigan. This raft keeps the babies safe from predators which is especially important as Michigan's Loon population is declining.
It is important to note that you should never get too close to a nesting Loon. They are very sensitive and will abandon the nest if disturbed. Best to use your zoom lens from a far distance. They typically have two loon chicks which learn to swim within a day. I hope to get photos of the babies soon!