Associate Professor - Retired Profile Image
Associate Professor - Retired Biological Sciences 402-472-5018

Research Interests

Research in our lab examines various dimensions of animal energetics with an emphasis on the influence of energetics on reproductive trade-offs.  Energy flow through organisms has long been recognized as a central process underlying ecological interactions and evolutionary adaptation.  The rate and amount of net energy acquisition and storage are clearly linked to production, therefore it is reasonable to propose energetic 'costs' and physiological limits as selective forces affecting the expression of reproductive strategies. Currently, my students and I are focusing on questions in the following general areas: stress physiology and endocrinology, eco-immunology, metabolic physiology, microhabitat choice, and reproductive success in birds (sharp-tail grouse and passerines), and reptiles (box turtle).  We are completing a project which examines corticosterone and stress responses in grouse during the lekking period. Ongoing work uses a marked population of ornate box turtle,  Terrapene ornata,  at UNL’s Cedar Point Biological Station. Our interest in the turtles is based on their ability to survive extended periods of low resource availability, and an ability to delay reproduction until conditions improve. Species with these life history characteristics may be particularly challenged by climate change, or, through behavioral or physiological compensation, they may be able to adapt within their lifetime. To better understand the impact of long-term climate change on box turtle populations, we are collecting data to describe relationships between temperature, behavior, physiology, and reproductive output. Key physiological variables that are currently being examined are: metabolic rates associated with resting and activity at different temperatures, body condition,  indicators of stress (testosterone, corticosterone), blood chemistry, and immune function. We are fundamentally field biologists, so the physiology is always framed by behavioral observations and ranging behavior through radio-telemetry. These data together with habitat variables will become part of a model that predicts the impact of warming on energy requirements, survival and reproduction in this species.  

Recent Publications

  • Cheviron, Z.A., G.C. Bachman, J.F. Storz. 2013   Contributions of phenotypic plasticity to differences in themogenic performance between highland and lowland deer mice.  The Journal of Experimental Biology
  • Cheviron, Z.A., G.C. Bachman, A.D. Connaty, G.B. McClelland, J.F. Storz. 2012 (In press). Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice. Proc. Nat. Acad. Sci  
  • Bachman, G.C. 2003. Food supplements modulate changes in leucocyte numbers in breeding male ground squirrels. The Journal of Experimental Biology: 206:2373-2380.
  • Chappell, MA,   G. C. Bachman  2002  Energetic costs of begging behaviour. In. The Evolution of Begging: Competition, Cooperation and Communication. ed. J. Wright and M.L Leonard.
  • Bachman, G., F. Widemo. 1999. Relationships between body composition, body size, and alternative reproductive tactics in a lekking sandpiper, the Ruff (Philomachus pugnax).  Functional Ecology: 13:411-416.
  • Chappell, M.A. and G.C. Bachman. 1998 The exercise capacity of house wren nestlings: begging chicks are not working as hard as they can. Auk 115(4):863-870.
  • Bachman, G.C., Chappell, M.A. 1998. Energetic cost of begging in house wrens (Troglodytes aedon). Animal Behaviour 55:1607-1618.
  • Chappell, M A; Bachman, G C; Hammond, K A.1997. The heat increment of feeding in house wren chicks: Magnitude, duration, and substitution for thermostatic costs. Journal of Comparative Physiology B Biochemical Systemic and Environmental Physiology, v.167, n.4, (1997): 313-318.
  • Bachman, G.C. and S.L. Vehrencamp. 1995. "Ecological Energetics of Terrestrial Vertebrates" , p. 549-565 in "Encyclopedia of Environmental Biology", Academic Press.
  • Chappell, M.A., G.C. Bachman , J. Odell. 1995.   Repeatability of maximal aerobic performance in Belding's ground squirrels, Spermophilus beldingi. Functional Ecology 9(3):498-504.
  • Chappell, M.A. and G.C. Bachman. 1995. Aerobic performance in Belding's ground squirrels (Spermophilus beldingi): Variance, ontogeny, and the aerobic capacity model of endothermy.  Physiological Zoology 68(3):421-442
  • Bachman, G.C. 1994. Food restriction effects on the body composition of free-living ground squirrels. Physiological Zoology 67(3):756-770.
  • Bachman, G.C. 1993. The effect of body condition on the trade-off between vigilance and foraging in Belding's ground squirrels. Animal Behaviour 46:233-244.
  • Gibson, R.M., and G.C. Bachman.  1992. The costs of female choice in a lekking bird. Behavioral Ecology 3:300-309.

Interim Director, Honors Program

  • Influence of energy supply and demand on animal behavior
  • Ph.D. University of California-Los Angeles
  • B.A. University of California-San Diego