The Desert Islands of Mexico's Sea of Cortez

Book excerpt: 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 worldÕs 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 HeermannÕs gulls each spring. The Desert Islands of MexicoÕs Sea of Cortez is one of the few books devoted to the biogeography of this remarkable part of the world. The book explores the geologic origin of the gulf and its islands, presents some of the basics of island biogeography, details insular lifeÑincluding residents of the intertidal zone Ñand provides a brief outlook for preserving this area. More than a simple guidebook, AitchisonÕs writing will take both actual and armchair travelers through a gripping tale of natural history. Like the rest of our fragile planet, the Sea of Cortez and its islands are threatened by humans. Overfishing has eliminated or greatly diminished many fish stocks, and dams on rivers that once flowed into the gulf prevent certain nutrients from reaching the sea. The tenuousness of this area makes the bookÕs extraordinary photographs and the firsthand descriptions by a well-known teacher, writer, and photographer all the more compelling.