Greg is currently an Associate Professor at York University, Faculty of Environmental Studies, in Toronto, ON.
Current Research Interests
My research focuses primarily on the foraging ecology and conservation of large predators. 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 forage, we can better act to protect not only the predators themselves, but the entire ecosystems of which they are a part.
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 a valuable ecological tool because mammalian predators have distinct limitations on which fatty acids they can synthesize. Other fatty acids are incorporated into predator fat stores directly, or at least predictably, from the diet. As a result, the fatty acid profile of the predator will reflect the fatty acid composition of its prey. This technique, especially when combined with other diagnostic tools such as stomach content measurements or stable isotope analysis, can help define trophic linkages, and hence food web structure, in many ecosystems.
As a postdoctoral fellow in Andrew Derocher’s lab, I was interested in developing and applying new methods of examining predator diets and foraging ecology with the ultimate goal of conserving of arctic wildlife.
Thiemann, G.W., S.M. Budge, S.J. Iverson, and I. Stirling. 2007. Unusual fatty acid biomarkers reveal age- and sex-specific foraging in polar bears (Ursus maritimus). Canadian Journal of Zoology 85: 505-517.
Thiemann, G.W., S.J. Iverson, and I. Stirling. 2007. Variability in the blubber fatty acid composition of ringed seals (Phoca hispida) across the Canadian Arctic. Marine Mammal Science 23: 241-261.
Amstrup, S.C., I. Stirling, T.S. Smith, C. Perham, and G.W. Thiemann. 2006. Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea. Polar Biology 29: 997-1002.
Thiemann, G.W., S.J. Iverson, and I. Stirling. 2006. Seasonal, sexual and anatomical variability in the adipose tissue of polar bears (Ursus maritimus). Journal of Zoology, London 269: 65-76.
Thiemann, G.W. 2005. Evolution, blood types, and weight-loss: A critical examination of a popular diet. Proceedings of the Nova Scotian Institute of Science 43: 57-68.
Thiemann, G.W., S.M. Budge, W.D. Bowen, and S.J. Iverson. 2004. Comment on Grahl-Nielsen et al. (2003) ‘Fatty acid composition of the adipose tissue of polar bears and of their prey: ringed seals, bearded seals and harp seals’. Marine Ecology Progress Series 281: 297-301.
Thiemann, G.W., S.M. Budge, and S.J. Iverson. 2004. Determining blubber fatty acid composition: a comparison of in situ direct and traditional methods. Marine Mammal Science 20: 284-295.
NSERC and Killam Postdoctoral Fellow
BSc: McMaster University, 1997
MSc: Dalhousie University, 1999
PhD: Dalhousie University, 2006