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Gregory W Thiemann

Gregory W Thiemann

Associate Professor

Undergraduate Program Director


PhD, Dalhousie University
MSc, Dalhousie University
BSc (Honours), McMaster University

Research Keywords

Arctic Ecosystems; Food Web Ecology; Wildlife Conservation; Resource Management; Animal Physiology.

Gregory W Thiemann

Contact Information

4700 Keele Street
Toronto, ON M3J1P3

416 736 2100

Research Interests

My research focuses on the foraging ecology and conservation of Arctic carnivores. By examining the trophic relationships between top predators and their prey, we can define the structure of food webs and monitor changes in ecosystems over time. By understanding where, when, and how predators hunt for food, we can better act to protect wildlife populations and entire ecosystems.

Much of my research has involved the use of fatty acid signature analysis to examine the diets of marine and terrestrial carnivores. This technique is based on the knowledge that ingested dietary fatty acids (such as “omega-3’s”) are predictably incorporated into a predator’s fat stores. Therefore, the fatty acid profile of an animal can be used to make inferences about its foraging habits.

Long-term climate warming is having rapid and widespread effects on northern ecosystems. This in turn is altering the relationships between northern aboriginal communities and the wildlife populations they utilize. Accurate information on the current structure and functioning of food webs will help us predict how wildlife populations will change in the future and how these changes will impact the lives of people in the North. FES is uniquely positioned to examine the complex ecological, social, and economic changes that will result from a warming Arctic environment.

Research Projects

  • Characterizing the Denning Habitat and Movements of Polar Bears in Southern Hudson Bay
  • Community-Based Monitoring of Polar Bear Foraging in Nunavut
  • Foraging Habits and Contaminant Burdens of High Arctic Ringed Seals
  • Nutritional Physiology of Bears Under Human Care

Research Output

Galicia, M.P., G.W. Thiemann, and M.G. Dyck. 2020. Correlates of seasonal change in the body condition of an Arctic top predator. Global Change Biology 26: 840–850.

Shave, J.R., A.E. Derocher, S.G. Cherry, and G.W. Thiemann. 2019. Chronic stress and body condition of wolf-killed prey in Prince Albert National Park, Saskatchewan. Conservation Physiology 7(1): coz037.

Brown, T.A., M.P. Galicia, G.W. Thiemann, S.T. Belt, D.J. Yurkowski, M.G. Dyck. 2018. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue. PLoS ONE 13(1): e0191631.

Laforest, B.J., J. Hebert, M.E. Obbard, G.W. Thiemann. 2018. Traditional Ecological Knowledge of polar bears in the northern Eeyou Marine Region, Québec, Canada. Arctic 71: 40-58.

Sciullo, L., G.W. Thiemann, N.J. Lunn, S.H. Ferguson. 2017. Intraspecific and temporal variability in the diet composition of female polar bears in a seasonal sea ice regime. Arctic Science 3: 672–688.

Bromaghin, J.F., S.M. Budge, G.W. Thiemann and K.D. Rode. 2017. Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data. Ecology and Evolution 7: 6103-6113.

Regehr, E.V., K.L. Laidre, H. Resit Akçakaya, S.C. Amstrup, T.C. Atwood, N.J. Lunn, M. Obbard, H. Stern, G.W. Thiemann, and Ø. Wiig. 2016. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters 12: 20160556.

Sciullo, L., G.W. Thiemann and N.J. Lunn. 2016. Comparative assessment of metrics for monitoring the body condition of polar bears in Western Hudson Bay. Journal of Zoology, London 300: 45-58.

Galicia, M.P., G.W. Thiemann, M.G. Dyck, S.H. Ferguson and J.W. Higdon. 2016. Dietary habits of polar bears in Foxe Basin, Canada: possible evidence of a trophic regime shift mediated by a new top predator. Ecology and Evolution 16: 6005-6018.

Galicia, M.P., G.W. Thiemann, M.G. Dyck, and S.H. Ferguson. 2015. Characterization of polar bear (Ursus maritimus) diets in the Canadian High Arctic. Polar Biology 38: 1983-1992.