The only “charismatic mega-fauna” (lions, tigers and bears...) found at Sagamore Hill are the hunting trophies hanging in the hallway of Theodore Roosevelt's home. The park’s animals generally consist of a range of urban-tolerant species, but some - including spotted salamanders and box turtles - are locally uncommon and generally are not known to persist well in developed landscapes. Sagamore Hill also hosts at least twenty-one species of dragonflies and damselflies, including the rare Comet Darner.

Birds were a particular interest of Roosevelt and were a common subject of his writings. A recent survey found more than a hundred species of birds utilizing the fields, forests, beaches, and marshes at Sagamore Hill, including 26 confirmed breeding species and an additional 24 probable breeding species.