Gregory W Thiemann | EUC | York University

Associate Professor

Sustainable Environmental Management Program Coordinator

Credentials

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

Research Keywords

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

Research Keywords

I supervise students in the graduate programs in MES (Environmental Studies), PhD (Environmental Studies), MSc (Biology), PhD (Biology).

Contact Information

4700 Keele Street
Toronto, ON M3J 1P3

416 736 2100

thiemann@yorku.ca

Google Scholar Profile

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 involves the use of biochemical tracers to examine the diets of carnivores. Naturally occurring tracers, such as fatty acids and stable isotopes, can reveal individual dietary habits that influence population-level processes. We also use satellite tracking technology to study animal movements and space-use strategies. Our work involves collaboration with federal, provincial, and territorial government agencies and partnership with northern Indigenous communities.

Long-term climate warming is having rapid and widespread effects on northern ecosystems. This in turn is altering the relationships between northern Indigenous communities and the wildlife populations they utilize. Our research aims to help predict how wildlife populations will change in the future and how these changes will impact the lives of people in the North. EUC is uniquely positioned to examine the complex ecological, social, and economic changes that will result from a warming Arctic environment.

Research Projects

Drivers and consequences of individual specialization in an Arctic marine top predator (2021-ongoing; NSERC)
Climate, conflict, and coexistence: identifying the drivers of human-polar bear interaction in Southern Hudson Bay (2021-ongoing; WWF-Canada)
Characterizing the Denning Habitat and Movements of Polar Bears in Southern Hudson Bay (2018-ongoing; Ontario MNDMNRF, Earth Rangers)
Community-Based Monitoring of Polar Bear Foraging in Nunavut (2010-ongoing; Government of Nunavut, in-kind)
Nutritional Physiology of Bears Under Human Care (2018-ongoing; Toronto Zoo, in-kind)
Community-based monitoring of ice-breeding seals and predator-prey dynamics in the Gulf of Boothia (2012-2019; Aboriginal Affairs and Northern Development Canada, Nunavut General Monitoring Plan)

Research Output

Ross T.R., G.W. Thiemann, B.J. Kirschhoffer, J. Kirschhoffer, G. York, A.E. Derocher, A.C. Johnson, N.J. Lunn, D. McGeachy, V. Trim, J. M. Northrup. 2024. Telemetry without collars: performance of fur- and ear-mounted satellite tags for evaluating the movement and behaviour of polar bears. Animal Biotelemetry 12:18. https://doi.org/10.1186/s40317-024-00373-2

Penk, S.R., P. Sadana, L.C. Archer, A.M. Pagano, M.R.L. Cattet, N.J. Lunn, G.W. Thiemann, P.K. Molnár. 2023. A body composition model with multiple storage compartments for polar bears (Ursus maritimus). Conservation Physiology 11, coad043. https://doi.org/10.1093/conphys/coad043

Ross, T.R., G.W. Thiemann, B.G. Young, S.H. Ferguson. 2022. Complementary diet analyses reveal intraspecific and temporal variation in ringed seal (Pusa hispida) foraging in the Canadian High Arctic. Polar Biology 45: 465–480. https://doi.org/10.1007/s00300-021-02999-x

Thiemann, G.W., K.D. Rode, J.A. Erlenbach, S.M. Budge, C.T. Robbins. 2022. Fatty acid profiles of feeding and fasting bears: Estimating calibration coefficients, timeframe of diet estimates, and selective mobilization during hibernation. Journal of Comparative Physiology B 192: 379-395. https://doi.org/10.1007/s00360-021-01414-5

Galicia, M.P., G.W. Thiemann, M.G. Dyck, and S.H. Ferguson. 2021. Polar bear diet composition reveals spatiotemporal distribution of Arctic marine mammals across Nunavut, Canada. Ecological Indicators 132: 108245. https://doi.org/10.1016/j.ecolind.2021.108245

Galicia, M.P., G.W. Thiemann, M.G. Dyck and S.H. Ferguson. 2021. Are tissue samples obtained via remote biopsy useful for fatty acid-based diet analyses in a free-ranging carnivore? Journal of Mammalogy 102: 1067-1078. https://doi.org/10.1093/jmammal/gyab041

Florko, K., G.W. Thiemann, J.F. Bromaghin, and E S. Richardson. 2021. Polar bear (Ursus maritimus) diet composition and body condition in relation to sea ice habitat in the Canadian High Arctic. Polar Biology 44: 1445–1456. https://doi.org/10.1007/s00300-021-02891-8.

Galicia, M.P., G.W. Thiemann, M.G. Dyck, S.H. Ferguson, and I. Stirling. 2021. Prey selection of polar bears in Foxe Basin, Nunavut, Canada: evidence of dietary flexibility in a specialized predator. Oxford Open Climate Change 1(1): kgab002. https://doi.org/10.1093/oxfclm/kgab002

Florko, K., G.W. Thiemann and J.F. Bromaghin. 2020. Drivers and consequences of apex predator diet composition in the Canadian Beaufort Sea. Oecologia 194: 51-63. https://doi.org/10.1007/s00442-020-04747-0.

Rode, K, T. Atwood, G.W. Thiemann, M. St. Martin, R. Wilson, G. Durner, E. Regehr, S. Talbot, K. Sage, A. Pagano and K. Simac. 2020. Identifying reliable indicators of fitness in a large mammal. PLoS ONE 15(8): e0237444.

Ferguson, S. D., Yurkowski, B. Young, A. Fisk, D. Muir, X. Zhu, and G.W. Thiemann. 2020. Comparing temporal patterns in body condition of ringed seals living within their core geographic range with those living at the edge. Ecography 43:1521-1535. https://doi.org/10.1111/ecog.04988.

Yurkowski, D., E. Richardson, N. Lunn, D.C.G. Muir, A. Johnson, A.E. Derocher, A. Ehrman, M. Houde, B. Young, C. Debets, L. Sciullo, G.W. Thiemann and S.H. Ferguson. 2020. Contrasting temporal patterns of mercury, niche dynamics, and body condition of polar bears and ringed seals in a melting icescape. Environmental Science & Technology 54: 2780-2789.

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. https://doi.org/10.1111/gcb.14817

Courses

Course Code	Title
ENVS 2420	Ecology and Conservation Science
ENVS 4447	Northern Ecosystems: A Natural History of Arctic Regions
ENVS 5112	Ecology in Environmental Studies