Russell Greenberg is head of the Smithsonian Migratory Bird Center at the National Zoological Park in Washington, D.C. He is the author of more than 110 papers and chapters on migratory birds. In addition, he is coauthor or coeditor of several books, including Birds of Two Worlds: The Ecology and Evolution of Migration (Johns Hopkins University Press, 2005) and Terrestrial Vertebrates of Tidal Marshes: Ecology, Evolution, and Conservation (Cooper Ornithological Society, 2006).