Thomas P. Hahn

Thomas Hahn

Position Title

Department of Neurobiology, Physiology and Behavior

102 Animal Communication Lab

Profile Introduction

Environmental regulation of avian annual cycles of behavior, physiology and morphology; behavioral and physiological responses of birds to unpredictable environmental events.

Research Interests

Interfaces of behavior, endocrine and neuroendocrine physiology, ecology, and evolution. Specifically environmental regulation of avian annual schedules of reproduction, plumage molt and migration; scheduling tradeoffs between current reproduction and survival (future reproduction); evolution of mechanisms of responses to environmental cues such as day length, food, social factors; effects of unpredictable environmental events on behavior and physiology of free-living birds.

Avian communication, especially use of heterospecific mimicry in song, and learned non-song vocalizations.

Grad Group Affiliations

  • Animal Behavior
  • Avian Sciences
  • Ecology Graduate Group

Specialties / Focus

  • Behavior and Conservation
  • Behavior Ecology and Sociobiology
  • Communication
  • Physiology and Behavior


  • NPB 102 Animal Behavior, Winter
  • NPB 152 Hormones and Behavior, Spring
  • PSC 123 Hormones and Behavior, Spring
  • NPB 117 Avian Physiology, Usually spring
  • ANB 201 Animal Behavior Methods and grant writing, Spring


  • Hahn Lab, Animal Communication Lab
    • Current students and postdocs: Aaron Haiman, (PhD student, Animal Behavior); Beth Schultz (PhD student, Animal Behavior); Helen Chmura (PhD student, Animal Behavior); Brandi Gartland (PhD student, Animal Behavior); William Rockey (PhD student, Ecology); Rachael Smith (Masters student, Avian Sciences); Naomi Ondrasek (postdoc). Former students and postdocs: Kati Brazeal (PhD 2014, Animal Behavior, currently postdoc, University of Nebraska); Maxine Zylberberg (PhD 2011, Animal Behavior, currently postdoc, UCSF); Danielle Brown (PhD 2011, Animal Behavior, currently lecturer, Middle Tennessee State University); Heather Watts (former postdoc, currently Assistant Professor, Loyola Marymount University); Jamie Cornelius (PhD 2009, Animal Behavior, currently Assistant Professor, Eastern Michigan University); Rodd Kelsey (PhD 2009, Animal Behavior, currently Biologist, Nature Conservancy); Shelley Parker (masters 2009, Avian Sciences); Kendra Sewall (PhD 2008, Animal Behavior, currently Assistant Professor, Virginia Tech);Kirsten Sanford (PhD 2006, MCIP, currently free-lance science educator, Bay Area);Marcel Losekoot (MS 2006, Avian Sciences, currently technician, Bodega Marine Lab);Elizabeth MacDougall-Shackleton (PhD 2000, Princeton University, currently associate professor, University of Western Ontario); Scott MacDougall-Shackleton (postdoc, Princeton University, currently associate professor, University of Western Ontario);Maria Pereyra (postdoc, UCD, currently assistant professor, University of Tulsa).

Field Sites

  • Numerous, in Wyoming, Washington, Oregon and California.

Professional Societies

  • Society for Integrative and Comparative Biology
  • Society for Behavioral Neuroendocrinology


  • 1984 BS (Biological Sciences) Stanford University
  • 1985 MS (Biological Sciences) Stanford University
  • 1993 PhD (Zoology) University of Washington


Hahn, T., and M. Denny.  1989.  Tenacity-mediated selective predation by oystercatchers on intertidal limpets and its role in maintaining habitat partitioning by "Collisella" scabra and Lottia digitalis.  Marine Ecology Progress Series 53: 1-10.

Wingfield, J. C., T. P. Hahn, R. N. Levin, and P. Honey.  1992.  Environmental predictability and control of gonadal cycles in birds.  Journal of Experimental Zoology 261: 214-231.

Hahn, T. P., J. Swingle, J. C. Wingfield, and M. Ramenofsky.  1992.  Adjustments of the prebasic molt schedule in birds.  Ornis Scandinavica 23: 314-321.

Wingfield, J. C., T. P. Hahn, and D. Doak.  1993. Integration of environmental factors regulating transitions of physiological state, morphology and behaviour.  pp. 111-122 In: Avian Endocrinology (P. Sharp, ed.).  Journal of Endocrinology Ltd, Bristol.

Wingfield, J. C., and T. P. Hahn. 1994. Testosterone and territorial behavior in sedentary and migratory sparrows. Animal Behavior 47: 77-89.

Hahn, T. P. 1995. Integration of photoperiodic and food cues to time changes in reproductive physiology by an opportunistic breeder, the red crossbill, Loxia curvirostra (Aves: Carduelinae). Journal of Experimental Zoology 272: 213-226.

Hahn, T. P., J. C. Wingfield, R. Mullen, and P. J. Deviche. 1995. Endocrine bases of spatial and temporal opportunism in arctic-breeding birds. American Zoologist 35: 259-273.

Hahn, T. P. 1996. Cassin's Finch. (Carpodacus cassinii). In The Birds of North America, No. 240 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia; The American Ornithologists' Union, Washington, D. C.

Hahn, T. P., T. Boswell, J. C. Wingfield, and G. F. Ball. 1997. Temporal flexibility in avian reproduction: Patterns and mechanisms. Current Ornithology 14: 39-80. V. Nolan, Jr., E. D. Ketterson, and C. F. Thompson (eds.), Plenum, New York and London.

Hahn,T.P. 1998. Reproductive seasonality in an opportunistic breeder, the Red Crossbill, Loxia curvirostra. Ecology 79: 2365-2375.

Harbison HE, Nelson DA and TP Hahn. 1999. Long-term persistence of song dialects in the mountain white-crowned sparrow. Condor. 101:133-148.

MacDougall-Shackleton, S. A., E. A. MacDougall-Shackleton, and T. P. Hahn. 2001. Physiological and behavioural responses of female mountain white-crowned sparrows to natal- and foreign-dialect songs. Canadian Journal of Zoology 79: 325-333.

MacDougall-Shackleton, S. A, P. J. Deviche, R. D. Crain, G. F. Ball, and T. P. Hahn. 2001. Seasonal changes in brain GnRH immunoreactivity and song-control nuclei volumes in an opportunistically breeding songbird. Brain, Behavior and Evolution 58: 38-48.

MacDougall-Shackleton, E. A., E. P. Derryberry, and T. P. Hahn. 2002. Non-local male mountain white-crowned sparrows have lower paternity and higher parasite loads than males singing local dialect. Behavioral Ecology 13: 682-689.

Breuner, C. W. and T. P. Hahn. 2003. Integrating stress physiology, environmental change, and behavior in free-living sparrows. Hormones and Behavior 43: 115-123.

Sewall, K. B, T. R. Kelsey, and T. P. Hahn. 2004. Discrete variants of evening grosbeak flight calls. Condor 106: 161-165.

Hahn, T. P., M. E. Pereyra, S. M. Sharbaugh and G. E. Bentley. 2004. Physiological responses to photoperiod in three cardueline finch species. General and Comparative Endocrinology 137: 99-108.

Hahn, T. P., K. W. Sockman, C. W. Breuner and M. L. Morton. 2004. Facultative altitudinal movements by mountain white-crowned sparrows, Zonotrichia leucophrys oriantha, in the Sierra Nevada. Auk 121: 1269-1281.

MacDougall-Shackleton, S. A., G. F. Ball, E. Edmonds, R. Sul, and T. P. Hahn. 2005. Age and sex related variation in song-control regions in Cassins finches, Carpodacus cassinii. Brain, Behavior and Evolution 65: 262-267.

Sockman, K. W., K. B. Sewall, G. F. Ball, and T. P. Hahn. 2005. Modulation of male song effort in response to female reproductive competence: The economy of a courtship decision in the Cassin's finch. Biology Letters 1: 34-37.

MacDougall-Shackleton, E. A., E. P. Derryberry, J. Foufopoulos, A. P. Dobson, and T. P. Hahn. 2005. Parasite-mediated heterozygote advantage in an outbred songbird population. Biology Letters 1: 105-107.

Pereyra, M. E., S. M. Sharbaugh, and T. P. Hahn. 2005. Interspecific variation in photo-induced GnRH plasticity among nomadic cardueline finches. Brain Behavior and Evolution 66: 35-49.

MacDougall-Shackleton, S. A., M. E. Pereyra, and T. P. Hahn. 2005. GnRH, photorefractoriness, and breeding schedules of cardueline finches. Pp. 97-110 in Functional Avian Endocrinology, A. Dawson and P. J. Sharp, eds. Narosa Publishing House, New Delhi, India.

Hahn, T. P., M. E. Pereyra, M. Katti, G. M. Ward, and S. A. MacDougall-Shackleton. 2005. Effects of food availability on the reproductive system. Pp. 167-180 in Functional Avian Endocrinology, A. Dawson and P. J. Sharp, eds. Narosa Publishing House, New Delhi, India.

Goodson, J. L., C. J. Saldanha, T. P. Hahn, and K. K. Soma. 2005. Recent advances in behavioral neuroendocrinology: Insights from studies on birds. Hormones and Behavior 48: 461-473.

MacDougall-Shackleton, S. A., M. Katti, and T. P. Hahn. 2006. Tests of absolute refractoriness in four species of cardueline finch that differ in reproductive schedule. Journal of Experimental Biology 209: 3786-3794.

Lynn, S. E., T. P. Hahn and C. W. Breuner. 2007. Free-living male mountain White-crowned Sparrows exhibit territorial aggression without modulating total or free plasma testosterone. Condor 109: 173-180.

Hahn, T. P. and S. A. MacDougall-Shackleton. 2008. Adaptive specialization, conditional plasticity, and phylogenetic history in the reproductive cue response systems of birds. Philosophical Transactions of the Royal Society B 363: 267-286.

Hahn, T. P., J. M. Cornelius, K. B. Sewall, T. R. Kelsey, M. Hau, and N. Perfito. 2008. Environmental regulation of annual schedules in opportunistically-breeding songbirds: Adaptive specializations, or variations on a theme of white-crowned sparrow? General and Comparative Endocrinology 157: 217-226.

Breuner, C. W., S. H. Patterson, and T. P. Hahn. 2008. In search of relationships between the acute adrenocortical stress response and fitness. General and Comparative Endocrinology 157: 288-295.

Sewall, K. B. and T. P. Hahn. 2009. Social experience modifies behavioural responsiveness to a preferred vocal signal in red crossbills, Loxia curvirostra. Animal Behaviour 77: 123-128.

Hahn, T. P., H. E. Watts, J. M. Cornelius, K. R. Brazeal, and S. A. MacDougall-Shackleton. 2009. Evolution of environmental cue response systems: Adaptive variation in photorefractoriness. General and Comparative Endocrinology 163: 193-200.

MacDougall-Shackleton, S. A., T. J. Stevenson, H. E. Watts, M. E. Pereyra and T. P. Hahn. 2009. The evolution of photoperiod response systems and seasonal GnRH plasticity in birds. Integrative and Comparative Biology 49: 580-589.

Cornelius, J. M., C. W. Breuner and T. P. Hahn. 2010. Under a neighbour's influence: public information affects stress hormones and behaviour of a songbird. Proceedings of the Royal Society B 277: 2399-2404.

Cornelius, J. M., N. Perfito, R. Zann, C. W. Breuner, and T. P. Hahn. 2011. Physiological trade-offs in self-maintenance: Plumage molt and stress physiology in birds. Journal of Experimental Biology 214: 2768-2777.

Stevenson, T. J., T. P. Hahn and G. F. Ball. 2012. Variation in Gonadotropin Releasing-Hormone-1 Gene Expression in the Preoptic Area Predicts Transitions in Seasonal Reproductive State. Journal of Neuroendocrinology 24: 267-274.

Cornelius, J. M., C. W. Breuner and T. P. Hahn. 2012. Coping with the extremes: Stress physiology varies between winter and summer in breeding opportunists. Biology Letters 8: 312-315.

Watts, H. E. and T. P. Hahn. 2012. Non-photoperiodic regulation of reproductive physiology in the flexibly-breeding pine siskin (Spinus pinus). General and Comparative Endocrinology 178: 259-264.

Cornelius, J. M. and T. P. Hahn. 2012.  Seasonal pre-migratory fattening and increased activity in a nomadic and irruptive migrant, the Red Crossbill Loxia curvirostra.  Ibis 154: 693-702.

Drnevich, J., K. Replogle, P. Lovell, T. Hahn, F. Johnson, T. G. Mast, C. Strand, S. London, M. Mukai, J. C. Wingfield, A. P. Arnold, G. F. Ball, E. Brenowitz, J. Wade, C. V. Mello, and D. Clayton. 2012. Impact of experience-dependent and -independent factors on gene expression in songbird brain.  Proceedings of the National Academy of Sciences USA 109: 17245-17252.

Stevenson, T. J., T. P. Hahn, S. A. MacDougall-Shackleton, and G. F. Ball. 2012. Gonadotropin releasing hormone plasticity: A comparative perspective.  Frontiers in Neuroendocrinology 33: 287-300.

 Zylberberg, M., K. C. Klasing and T. P. Hahn. 2013. House finches (Carpodacus mexicanus) balance investment in behavioural and immunological defenses against pathogens. Biology Letters 9: 20120856.

Kremen, N. A, C. C. Calvert, A. Larsen, R. A. Baldwin, T. P Hahn and A. J. Fascetti. 2013. Body composition and amino acid concentrations of select birds and mammals consumed by cats in northern and central California. Journal of Animal Science 91: 1270-1276.

Cornelius, J. M., H. E. Watts, H. Dingle and T. P. Hahn.  2013.  Obligate versus rich patch opportunism:  Evolution and endocrine mechanisms.  General and Comparative Endocrinology 190: 76-80.

Schoech, S. J., R. Bowman, T. P. Hahn, W. Goymann, I. Schwabl, and E. S. Bridge. 2013. The effects of low levels of light upon the endocrine physiology of western scrub jays (Aphelocoma californica).  Journal of Experimental Zoology A: Ecological Genetics and Physiology 319 (9): 527-538.

Wilcoxen, T. E., E. S. Bridge, R. K. Boughton, T. P. Hahn, and S. J. Schoech. 2013. Physiology of reproductive senescence in Florida scrub jays: Results from a long-term study and GnRH challenge.  General and Comparative Endocrinology 194: 168-174.

Rosvall, K. A., C. Bergeon Burns, T. P. Hahn and E. D. Ketterson. 2013.  Sources of variation in HPG axis reactivity and individually consistent elevation of sex steroids in a female songbird.  General and Comparative Endocrinology 194: 230-239.

Bergeon Burns, C., K. A. Rosvall, T. P. Hahn, G. E. Demas, E. D. Ketterson. 2014.  Examining sources of variation in HPG axis function among individuals and populations of the dark-eyed junco. Hormones and Behavior 65: 179-187.

Patterson, S. H., T. P. Hahn, J. M. Cornelius and C. W. Breuner.  2014.  Natural selection and glucocorticoid physiology.  Journal of Evolutionary Biology 27: 259-274.

Cornelius, J. M., M. Zylberberg, C. W. Breuner, and T. P. Hahn.  2014. Assessing the role of reproduction and stress in the spring emergence of hematozoan parasites in birds. Journal of Experiental Biology 217: 841-849.

Zylberberg, M., K. C. Klasing and T. P. Hahn. 2014. In house finches (Haemorhous mexicanus), risk takers invest more in innate immune function.  Animal Behaviour 89: 115-122.

Ho, W. W., S. G. Connolly, P. J. Reynolds, J. M. Cornelius, E. A. MacDougall-Shackleton, M. L. Morton, M. E. Pereyra, and T. P. Hahn.  2014.  Limited exposure to non-natal dialect during juvenile dispersal in mountain white-crowned sparrows. Auk 131: 208-214.

Hahn, T. P., K. R. Brazeal, E. M. Schultz, H. E. Chmura, J. M. Cornelius, H. E. Watts, S. A. MacDougall-Shackleton. 2015. Chapter 36: Annual Schedules, pp 847-867 in C. Scanes (ed), Sturkie’s Avian Physiology, Elsevier.