Acorn Woodpecker

Melanerpes formicivorus


About the Author(s)

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Walter D. Koenig graduated from Stanford University in 1972 and received his Ph.D. from the University of California, Berkeley in 1978 working under the direction of Frank A. Pitelka. Koenig began studying Acorn Woodpeckers at Hastings Reservation in 1974, continuing work begun there by Michael and Barbara MacRoberts. After postdoctoral work and a brief stint at Occidental College, he returned to Hastings Reservation where he was a research zoologist with the Museum of Vertebrate Zoology and an adjunct professor in the Department of Integrative Biology, UC Berkeley until 2008. At that point he moved to the Cornell Lab of Ornithology and the Department of Neurobiology and Behavior, Cornell University, where he was a senior scientist until his retirement (and return to Hastings Reservation in California) in 2016. Besides continuing work on Acorn Woodpeckers, Koenig is currently interested in acorn production patterns in California oaks. He is coauthor (with Ron Mumme) of Population Ecology of the Cooperatively Breeding Acorn Woodpecker (1987), coeditor (with Pete Stacey) of Cooperative Breeding in Birds (1990), and coeditor (with Janis Dickinson) of Ecology and Evolution of Cooperative Breeding in Birds (2004) and Cooperative Breeding in Vertebrates: Studies of Ecology, Evolution, and Behavior (2016). E-mail:

Eric L. Walters graduated from the University of Victoria (Victoria, British Columbia) in 1990. He began studying woodpeckers in 1992 as a volunteer for Edward Miller and eventually completed his M.Sc. on habitat and space use by Red-naped Sapsuckers with Miller at the University of Victoria in 1996. He received his Ph.D. from Florida State University in 2004, where he worked with Frances James and studied species interactions associated with Red-cockaded Woodpecker cavities. He began studying Acorn Woodpeckers as a postdoctoral fellow (University of California, Berkeley, 2006–2008) and then as a postdoctoral associate (Cornell University, 2008–2011) with Walt Koenig at the Hastings Reservation (Carmel Valley, California). In 2011, he moved to Norfolk, Virginia to join the faculty at Old Dominion University, where he is currently an Associate Professor in the Department of Biological Sciences, but returns annually (March-July) to conduct research at Hastings. Since 2012, he has been an Affiliated Researcher at the Museum of Vertebrate Zoology (UC Berkeley). Following Koenig’s retirement in 2016, Walters assumed the lead of the Hastings woodpecker study and he and his research group continue to study the evolution of cooperative breeding in acorn woodpeckers. Walters’ other interests include the ecology and evolution of seed dispersal and the role that birds play in tick-mediated pathogen transfer. E-mail:

Peter B. Stacey graduated from Middlebury College in 1970 and received his Ph.D. from the University of Colorado, Boulder in 1978. After completing a study of the behavior of pumpkinseed sunfish for his master's thesis, he began his dissertation work on the Acorn Woodpecker in the Southwest in 1974 with Carl Bock. He then took a postdoctoral fellowship at the University of Chicago, splitting his time between the Acorn Woodpeckers and a study of foraging behavior of yellow baboons in East Africa. After appointments at Indiana State University, as curator of birds with the Denver Museum of Natural History, and at the University of Nevada, Reno, he recently retired as Research Professor of Biology at the University of New Mexico. During this time he developed an interest in Conservation Biology and Restoration Ecology, and conducted field studies of the federally threatened Mexican Spotted Owl and the endangered Southwestern Willow Flycatcher. He also used theoretical models and computer simulations to explore the importance of dispersal for the conservation of species that occur in connected series of populations, or metapopulations. His most recent work has focused upon the ecological assessment and restoration of riparian habitats in the American Southwest, which are key centers of avian biodiversity, and which are critically important to both Acorn Woodpeckers and Mexican Spotted Owls. E-mail:

Ronald L. Mumme became interested in ornithology as an undergraduate at the University of South Florida, where he received his B.A. in 1975. He spent the next 3 years working as a laboratory technician and as a biologist with the Southwest Florida Water Management District. In 1978 he began graduate work in the Department of Zoology, University of California, Berkeley, where he studied the social behavior of the Acorn Woodpecker at Hastings Reservation in collaboration with Walt Koenig and Frank A. Pitelka. After obtaining his Ph.D. in 1984, Mumme became a postdoctoral fellow at Cornell University and an assistant professor at Memphis State University (now the University of Memphis). In 1990 he moved to northwestern Pennsylvania and joined the faculty of Allegheny College, where he is now professor of biology. His current research focuses on the behavioral ecology of the Hooded Warbler. E-mail:

Mark T. Stanback obtained his B.S. from Davidson College in North Carolina in 1984. He conducted postgraduate work at Hastings Reservation on brood reduction and nestling size variation in Acorn Woodpeckers, obtaining his Ph.D. from the University of California, Berkeley in 1991. After a postdoc studying the endocrinology of cooperative breeding in the Acorn Woodpecker at the University of Washington, Stanback returned to his roots as assistant professor of biology at Davidson College, where he teaches Animal Behavior, Vertebrate Zoology, and Evolutionary Biology. In addition to working with Eastern Bluebirds, Tree Swallows, and Brown-headed Nuthatches at Davidson, Stanback has recently reactivated a study of hornbills in Namibia that he began in the 1990’s. His work with these birds focuses on reproductive allocation, sperm storage, and brood reduction. E-mail:

Recommended Citation

Koenig, W. D., E. L. Walters, P. B. Stacey, M. T. Stanback, and R. L. Mumme (2019). Acorn Woodpecker (Melanerpes formicivorus), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.