Climate change impacts on frogs of Eastern Ontario.

by Stephen C. Lougheed

Leopard frog male.
Leopard frog male. Click on image to make larger. Photo by S.C. Lougheed.

Global climate change is anticipated to impact the natural world in myriad ways potentially causing shifting geographical ranges, and local or even global extinctions of species (Parmesan 2006, 2007). One possible manifestation of climate change is altered breeding or flowering phenology (e.g. Beebee 1995, Dunn and Winkler 1999, Chmielewski and Rötzer 2001, Kearney et al. 2010). My recently graduated M.Sc. student and QUBS alumna, Samantha Klaus, and I used historical “citizen science” data from the Natural Heritage Information Centre of Ontario and the Ontario Herpetofaunal Summary Atlas ( to test whether there have been detectable shifts in the breeding phenology of Eastern Ontario frogs (Klaus & Lougheed 2013). We quantified both the timing of spring emergence and key aspects of the calling phenology of eight anuran species in southeastern Ontario, Canada, using an approximately 40-year data set. The leopard frog (Lithobates pipiens) was the only species out of eight considered that we found to emerge significantly earlier, by an estimated 22 days over the considered 4-decade span. Both L. pipiens and American toads (Anaxyrus americanus) seem to have advanced onset of calling significantly earlier by an estimated 37.2 and 19.2 days, respectively. Wood frogs (Lithobates sylvaticus) showed a trend towards earlier emergence by 19 days (although marginally insignificant in statistical analyses), whereas we detected no shifts in emergence phenology for the remaining five species. We also evaluated long-term climatic trends in Eastern Ontario based on data from three weather stations within our study area for 1970–2010. We found marked and significant increases in spring and summer average maximum temperatures. For example, mean maximum monthly March increased by approximately 0.07°C per annum for a total of 2.8°C over four decades. We also found evidence for changes to precipitation patterns. For example, there has been a significant decrease in average total precipitation in March (approximately 0.71 mm per annum, 2.84 cm total diminution over 40 years) and a significant increase for the summer month of June (0.89 mm per annum, for a 3.56 cm total over four decades). These observations are borne out anecdotally by the dismally wet June that we have had in 2013.

Amplecting American toads. Click on image to make larger. Photo by S.C. Lougheed.
Amplecting American toads. Click on image to make larger. Photo by S.C. Lougheed.

Our study illustrates that temperate zones such as ours are not isolated from the impacts of global climate change, and indeed shows that Eastern Ontario has already experienced marked shifts in local climate that are impacting local diversity in profound ways.

Literature cited.

  • Beebee, T.J.C. 1995. Amphibian breeding and climate. Nature 374: 219–220.
  • Chmielewski, F.M., & T. Rötzer. 2001. Response of tree phenology to climate change across Europe. Agric. For. Meteorol. 108: 101–112.
  • Dunn, P.O., & D.W. Winkler. 1999. Climate change has affected the breeding date of tree swallows throughout North America. Proc. Roy. Soc. B 266: 2487–2490.
  • Kearney, M.R., N.J. Briscoe, D. J. Karoly, W. P. Porter, M. Norgate, & P. Sunnucks. 2010. Early emergence in a butterfly causally linked to anthropogenic warming. Biol. Lett. 6: 674–677.
  • Klaus, S.P. & S.C. Lougheed. 2013. Changes in breeding phenology of eastern Ontario frogs over four decades. Ecol. Evol. 3.4
  • Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annu. Rev. Ecol. Evol. Syst. 37: 637–669.
  • Parmesan, C. 2007. Influences of species, latitudes and methodologies on estimates of phenological response to global warming. Glob. Change Biol. 13: 1860–1872.