The cold, harsh Arctic environment imposes major limits on life. But warming could also create problems and even affect the population dynamics of greater snow geese, Chen caurelescens atlantica, one of North America’s most northerly breeding geese.
Greater snow geese, which breed in wet meadows in Canada’s eastern Arctic, may be the first plant-eating birds to demonstrate the effects of mismatch due to warming. Their young are among the relatively small number of birds whose chicks eat only plants. Breeding success hinges on matching the brief spring flush of protein-rich vegetation with goslings’ most dramatic and sensitive phase of development, 11 and 25 days after hatching. Plant growth is starting earlier, and advancing faster than this birds’ laying date, however.
Researchers tested the effect of warming on the plant food by covering patches of tundra with plexiglas chambers. They found that warming significantly decreased the nutritive quality later in the growing season (July), compared to unwarmed plots. “This suggests that warming speeds up plant phenology and the seasonal decline in nutritive quality,” write Madeleine Doiron of Laval University and her colleagues.
Hatching even a few days too late can greatly reduce goslings’ growth, and is one possible reason that in warmer years these geese produce smaller, lighter goslings less likely to survive their 4,000-kilometre southward autumn migration.
Using a decade-long database of gosling hatch dates and body size measurements, and nutritive sampling of local plants, Doiron and her colleagues found goslings’ weight and size near fledging time decreased with increased mismatch between their hatching date and the peak time for nitrogen content in plants. “These results suggest that an accelerated decline in plant nutritive quality due to increased temperatures could have significant negative impacts on the population dynamic of Arctic geese,” write Doiron and her colleagues.
Dickey M.H et al. (2008) Climatic effects on the breeding phenology and reproductive success of an arctic-nesting goose species. Global Change Biology 14(9):1973-1985.
Doiron M. et al. (2011) Climate change and the ecological mismatch between greater snow goose breeding and plant phenology. North American Arctic Goose Conference.