The Colorado River, running from its sources in the Rocky Mountain areas of Wyoming and Colorado to its mouth at the head of the Gulf of California, is the only large body of water passing through the arid areas of southern Nevada, western Arizona, and southeastern California. The flow of this once mighty river is now controlled and managed for human benefit. There is a series of dams, and most if not all of the water is diverted before it reaches the delta. This river has always supported a rich variety of life, but the major changes recently imposed by man have affected, and still are affecting, that life. Birds of the Lower Colorado River Valley covers the birdlife along that portion of the river running from Davis Dam in southern Nevada to the Mexican boundary, summarizing the past and present status of the more than 400 species reported from this stretch of the river.