Island biogeography explains why there are fewer species of animals on San Juan Island than on the neighboring mainland: they must find a way to cross seven to 20-miles stretches of open water or vast expanses of open sky. Not all animal species are native. Some, such as the red fox, European rabbit, and Norway rat, were introduced to the island by humans, which changed the island’s natural balance. The future of all these species is intricately tied to the environmental health of the land, water, and air of San Juan Island National Historical Park, the Straits of Juan de Fuca, Georgia, Haro, and beyond.