Skip to main content
U.S. flag

An official website of the United States government

Caldwell Hahn, Ph.D.

Dr. Caldwell Hahn is an Emeritus at the Eastern Ecological Science Center

Dr. Caldwell Hahn works on wildlife disease and ecological immunology.   She is currently collaborating to use peptide arrays to characterize the immune and metabolic responses of black and mallard ducks (Anas spp). to avian influenza.  She is also characterizing the innate immune responses (degranulation & oxidative burst) of several duck species at the PWRC waterfowl complex, including black duck and lesser scaup, a diving duck.  Previously Dr. Hahn characterized the immune responses of both raptors and songbirds utilizing experimental infection with the invasive West Nile virus (WNV) and endemic encephalitis viruses (SLEV, WEEV).    She has also worked with CDC, Dr. Nicholas Komar, and University of Colorado Vet School, Drs Richard Bowen and Nicole Nemeth, passive immunity of screech owls to WNV via maternal antibodies.  Dr. Hahn began to work on how immune adaptations are shaped by species’ niche and life history while working with the New World cowbirds, a genus of avian brood parasites (Molothrus, Icteridae).  Her initial discovery that the principal North American brood parasite, the brown-headed cowbird, inhabits a niche with heightened exposure to ectoparasites (avian lice ; Phthiraptera) led to her examining and characterizing several of the  cowbird’s immune adaptations to its parasitic life history strategy,  including: (1) greater resistance to infection with WNV and other virulent encephalitis viruses when compared with related, non-parasitic species;  (2) more effective innate immune responses (degranulation and oxidative burst);  and (3) higher levels of particular immune components in their eggs.  She is also investigating relationships between immune and endocrine adaptations.

Recent Accomplishments


  • Harvard University, Museum of Comparative Zoology, Post-doctoral Fellow in Sociobiology, advisor Bert Holldober
  • Smithsonian Tropical Research Center, Post-doctoral Fellow in Sociobiology,  advisor Mary Jane West Eberhard
  • Rutgers University, Ph.D., Institute of Animal Behavior, behavioral ecology, advisor Colin Beer,  Richard D. Alexander
  • Tufts University, M.S.,  animal behavior, advisor, Benjamin Dane
  • Wellesley College, B.A.

Professional Studies/Experience

  • Geological Survey, Patuxent Wildlife Research Center, Research Biologist, 1990-present
  • Rutgers University, Adjunct Faculty, 2007-present
  • Smithsonian Institution, Research Associate 1995-1998
  • US Fish & Wildlife Service –Fort Collins Science Center, 1988-1990
  • National Academy Sciences, IOM, 1986-1988
  • Agency for International Development, 1982-1985
  • World Wildlife Fund, 1980-1982


  • Rutgers University, Adjunct Faculty, 2007-present