Walter D. Koenig is Senior Scientist at the Lab of Ornithology and the Department of Neurobiology and Behavior at Cornell University. He has studied cooperative breeding in acorn woodpeckers for over forty years. He is co-editor of Cooperative Breeding in Birds: Long-Term Studies of Ecology and Behavior (Cambridge, 1990) and Ecology and Evolution of Cooperative Breeding in Birds (Cambridge, 2004), and has published widely, primarily in the fields of population and behavioral ecology.