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Caldwell Hahn

Research Wildlife Biologist

Contact Info

Short Biography

US Geological Survey, Patuxent Wildlife Research Center, Research Biologist, 1996-present

Rutgers University, Adjunct Faculty, 2007-present



Harvard University, Museum of Comparative Zoology, Post-doctoral Fellow in Sociobiology,

            advisor Bert Holldober, 1978-79

Smithsonian Tropical Research Center, Post-doctoral Fellow in Sociobiology,  advisor

Mary Jane West Eberhard, 1977-78

Rutgers University, Ph.D., Institute of Animal Behavior, advisor, Colin Beer, 1977

Tufts University, M.S., advisor, Benjamin Dane, 1973

Wellesley College, B.A., 1970

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SELECTED PUBLICATIONS: Hahn, D.C., S.G. Summers, K. Genovese, H. He, M.H. Kogut, 2013. Enhanced innate immune responses in a brood parasitic species: oxidative burst and degranulation. Avian Diseases 57: 285-289. Hahn, D.C. 2011. Patterns of maternal yolk hormones in Eastern screech owl eggs (Megascops asio). General and Comparative Endocrinology 172 (3):423-429. Reisen, W. K. and D. C. Hahn. 2007. Comparison of immune responses of brown-headed cowbird and related blackbirds to West Nile and other mosquito-borne encephalitis viruses. Journal of Wildlife Diseases 43(3):439-449. . Hahn, D.C, N.M. Nemeth, E. Edwards, P.R. Bright, and N. Komar. 2006. Passive West Nile virus antibody transfer from maternal Eastern Screech-Owls (Megascops asio) to progeny. Avian Diseases 50(3): 454-455. Hahn, D. C. and R.J.C. O'Connor. 2002. Contrasting determinants of abundance in ancestral and colonized ranges of an invasive brood parasite, pp. 219-228 in J. Michael Scott, Patricia J. Heglund, Michael L. Morrison, Jonathan B. Haufler, and William A. Wall, editors. Predicting species occurrences : issues of accuracy and scale. Island Press, Washington, DC. xvii, 868 pp. [pdf] Hahn, D. C., R. D. Price, and P. C. Osenton. 2000. Use of lice to identify cowbird hosts. Auk 117(4):943-951. Hahn, D. C., J. A. Sedgwick, I. Painter, and N. Casna. 1999. A spatial and genetic analysis of Cowbird host selection. Pages 204-217 in M. L. Morrison, L. S. Hall, S. K. Robinson, S. I. Rothstein, D. C. Hahn, and T. D. Rich, editors. Research and management of the Brown-headed Cowbird in western landscapes. Studies in Avian Biology 18. 312pp. Hahn, D. C. and J. S. Hatfield. 1995. Parasitism at the landscape scale: Cowbirds prefer forests. Conservation Biology 9(6):1415-1424 . Hahn, D. C. and R. C. Fleischer. 1995. DNA fingerprint similarity between female and juvenile brown-headed cowbirds trapped together. Animal Behaviour 49(6):1577-1580. Hahn, D. C. 1981. Asynchronous hatching in the Laughing Gull: Cutting losses and reducing rivalry. Animal Behavior 29(2):421-427. Burger, J., D. C. Hahn, and J. Chase. 1979. Aggressive interactions in mixed-species flocks of migrating shorebirds. Animal Behaviour 27(2):459-470. [Download File]


My Science Topics

Science Topic
Ecology and Environmentbiodiversity
Ecology and Environmentbiogeography
Ecology and Environmentecological processes
Plants and Animalsanimals
Plants and Animalsendangered species
Plants and Animalsgenetic diversity
Plants and Animalsinvasive species
Plants and Animalsmigratory species
Plants and Animalswildlife

My USGS Science Strategy Areas

The Role of Environment and Wildlife in Human Health

Climate Variability & Change

I work on the associations between climate change, wildlife disease, and invasive species.  My work is primarily with birds, using species suited to particular problems.   West Nile virus studies used Eastern Screech Owl and the New World cowbirds, a genus of parasitic birds.  Evolution of immune defenses studies use several cowbird species, tree swallow, and owls.

Honors and Invited Presentations


Invited speaker, Huck Institute of Life Sciences, Penn State University, spring, 2012. "Invasive Species & Climate Change:  the role of immunity"

Invited speaker, Ethological Society Meeting on Cooperation and Conflict, Zurich, 2011

Organizer,  Symposium on Immunity & Climate Change, American Ornithological Union, San Diego, 2010

USGS Climate Change Center Grant, 2009-2010

Invited speaker, European Society Evolutionary Biology, Turino, 2009.  "Enhanced Innate Immunity Favored in a Parasite-rich environment"

Invited seminar, Institute for Ecology, University of Bern, Switzerland, 2009

Invited seminar, Children’s Hospital, Ludwig-Maximilians University, Munich, 2009.  "The Hygiene Hypothsis Examined in a Model Wildlife Species"

USGS Climate Change Center Grant, 2009

Elected Fellow, American Ornithological Union (2008), "for exceptional and sustained contributions to ornithology"

Invited speaker, Jacques Monod Conference “Genetics of Host-Parasite Coevolution”, French National Science Foundation, Roscoff, France, September 2007.

Invited speaker, Dept. Ecology & Evolution, University of Lausanne, Switzerland, 2007

Invited presentation, Symposium on Evolutionary Biology & Human Health, American Institute of Biological Sciences (AIBS), Washington, DC, 2007

 Invited speaker, University of Fribourg, Workshop on Evolution, Switzerland, February, 2002.

Society for Conservation Biology, Founding Member, Policy Committee, 2002

USGS- Patuxent Scientific Achievement Award, 2001

Invited Speaker, Conference on Innovation in the Biosciences, Marie Curie Fellowship Association, Bedford, England, 2000.

Invited Speaker, European Science Foundation, Workshop on Host-Parasite Coevolution, Perpignan, France, 1999

National Science Foundation Panel Member (Ad Hoc), Physiology and Ethology, 1998 - 2001

 National Geographic Society Grant, 1999-2001

National Science Foundation Panel Member (Ad Hoc), Division Environmental Biology,

1997 Invited speaker, Partners in Flight Symposium on Cowbird Management, Sacramento,

 Elected Member, American Ornithological Union, 1996

 Federal Executive Leadership Program, 1995-6

 Visiting Fellow, BBC Science Units, London, 1987

National Press Foundation Grant, 1986

Columbia University, School of Journalism, Science Writers' Seminar, 1986

Society of Technical Writers, Merit Award, 1985 Agency for International Development, Merit Award, 1984

American Philosophical Society, Research Award, 1980

Harvard University, Post-doctoral Fellow, Museum Comparative Zoology, 1978-79

National Institute of Mental Health, Research Grant, 1978

Smithsonian Tropical Research Institute Post-doctoral Fellow, 1977-78

Organization of American States, Research Fellow, 1977 lst Prize,

Outstanding Graduate Student Research Presentation, American Ornithologists' Union, l976

Chapman Research Awards, American Museum of Natural History, 1976; 1975

Sigma Xi Research Awards, 1975; 1974

National Institutes of Health pre-doctoral awards: 1974; 1973; 1972

Wellesley College Scholar, 1970

Wellesley College Pendleton Scholar, 1966

Contact Information

Caldwell Hahn
12100 Beech Forest Road
Laurel, MD 20708
703-532-8465 - Mobile
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