Sea of Cortez Desert Islands - The desert islands in the Sea of Cortez are little known except to a few intrepid tourists, sailors, and fishermen. Though at first glance these stark islands may appear barren, they are a refuge for an astounding variety of plants and animals. While many of the species are typical of the greater Sonoran Desert region, some are endemic or unique to one or two islands. For example, Isla Santa Catalina is home to the world's only rattlesnake that has lost its ability to grow a rattle. Other islands host nesting birds, such as Isla Rasa, a tiny, flat flow of basalt lava that attracts nearly half a million elegant and royal terns and Heermann's gulls each spring.