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Canada Geese Plastically Adjust Their Egg Laying Date to Spring Temperature

Paper Reviewed
Clermont, J., Réale, D. and Giroux, J.-F. 2018. Plasticity in laying dates of Canada Geese in response to spring phenology. Ibis 160: 597-607.

CO2-induced climate change has been projected to negatively impact animals by causing temperature-induced mismatches between breeding (birth/hatching) and the availability of food resources, ultimately leading to lower rates of animal survival. Yet the validity of such projections remains an open topic for debate; for it has also been projected that animals have inherent phenotypic plasticity that can minimize or nullify the predicted mismatches arising from climate change.

A test of such plasticity was recently performed by Clermont et al. (2018), who "examined the consequences of climatic conditions on the nesting phenology of temperate breeding Canada Geese Branta canadensis maxima, which rely on a continuous food supply, during a 14-year period (2003-2016)." The data utilized in the study came from a Canada Goose population nesting on the Varennes Islands (45.67°N, 73.45°W), located on the St. Lawrence River northeast of Montreal, Quebec, Canada. Each year, three complete nest searches were conducted on the islands, providing data on egg laying date that were then compared with various environmental variables (temperature, rainfall, snowfall and spring ice breakup date) so that the authors could test "whether laying dates shifted towards earlier reproduction over time and whether these changes were related to spring environmental conditions." In all, an average of 82 nests were examined each year, providing a total of 1145 laying dates for 500 different females.

In discussing their findings, Clermont et al. report that "Canada Geese responded to changing spring maximum temperature by plastically adjusting their breeding phenology: when springs were warmer than those that the Geese had experienced, individuals responded by laying their eggs earlier." Consequently, the three researchers state that "plasticity exists in that population, and that it allows laying date adjustments as a function of changes in temperature." Thus, they conclude by writing that "even a precocial, short-distance migrant bird species that relies on a continuous food supply can respond to external climate factors and plastically adjust laying dates to temperature, which may further be beneficial to nesting success."

Posted 7 December 2018