Hahn Lab


Research Interests

The research interests of the Hahn lab focus on the interface of behavior, endocrine and neuroendocrine physiology, ecology, and evolution. Specifically research focuses on 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. The Hahn lab also has expertise in avian communication, especially use of heterospecific mimicry in song, and learned non-song vocalizations.

Study System


Research in the Hahn lab is primarily conducted in avian systems, particularly the cardueline finches. Current projects include work on red-headed crossbills, evening grosbeaks, pine siskins, house finches, and the lesser goldfinch. Work in a variety of finch species has allowed the lab to evaluate findings in light of phylogeny. The lab has special expertise in the red-headed crossbill, which are a particularly interesting study system for studies of seasonal behaviors as they are flexible breeders and facultative migrants. Key food resources, cone crops, influence the behavior of the crossbill: the migrate in search of food resources and can extend the breeding season when resources are high. Currently, work in the crossbill is conducted outside of Grand Teton National Park in Wyoming.

Previous work has included studies of the mountain white crowned sparrow at Tioga Pass, a long term field site outside of Yosemite.

Lab and Field Techniques

The Hahn Lab often collaborates with the Ramenofsky- Wingfield Lab and employs similar molecular techniques. The Hahn Lab also has expertise in immune assays and analysis of bird song. The lab emphasizes the importance of natural history in understanding the physiology and behavior of study species and members of the lab can be good resources for those looking to better incorporate natural history in their research.

Select Publications

  • 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., 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.
  • 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.
  • 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.

Current Grad Students and Post Docs

Naomi Ondrase
Kati Brazeal
Beth Schultz
Aaron Haiman
Kai-Yin Lin
Helen Chmura (co-advised by Marilyn Ramenofsky and John Wingfield)
William Rockey
Brandi Gartland
Rachael Smith