A study commissioned by the U.S. Geological Survey and U.S. Fish & Wildlife found San Francisco International airport has the largest most stable population of the San Francisco garter snake which is an endangered species. The snakes are not IN the airport so you can breathe a sigh of relief. The snakes live on the airports property located across the highway from the airport. The area is also off limits to the public. The airport is also a home to grazing goats during the Summer fire season.