A newly documented but poorly understood correlate of anthropogenic climate change involves reductions in the body size of a diverse range of organisms. This phenomenon has been interpreted as a response to rising temperatures in the context of Bergmann’s Rule, originally proposed to explain geographical variation in body size. Changes in body size have important implications for the thermal tolerances and energetics of species because body size directly affects energy and water requirements for thermoregulation, energy budgets and life history traits. Thus, changing body size will have implications for individual fitness and population persistence. We are currently quantifying the nature and extent of recent size responses to environmental change and investigating underlying mechanisms at a continental scale in Australian birds.

Key publications:

• Gardner, J.L., Amano, T., Sutherland, W.J., Clayton, M., Peters, A. (2016). Individual and demographic consequences of reduced body condition following repeated exposure to high temperatures. Ecology, 97: 786-795
• Gardner, J.L., Amano, T., Mackey, B.G., Sutherland, W.J., Clayton, M., Peters, A. (2014). Dynamic size responses to climate change: prevailing effects of rising temperature drive long-term body size increases in a semi-arid passerine. Global Change Biology, 20: 2062-2075
• Gardner, J.L., Peters, A, Kearney, M.R., Joseph, L., Heinsohn, R. (2011). Declining body size: a third universal response to warming? Trends in Ecology & Evolution 26: 285-291
• Gardner, J.L., Heinsohn, R., and Joseph, L. (2009). Shifting latitudinal clines in avian body size correlate with global warming in Australian passerines. Proceedings of the Royal Society London B276: 3845-3852