Data and code from: Opposite, but insufficient, phenological responses to climate in two circumpolar seabirds: relative roles of phenotypic plasticity and selection

The magnitude of climate change has been greatest in the Arctic, accelerating climate-induced shifts in phenology, but wildlife responses vary. Variation may be due to the relative importance of phenotypic plasticity or phenotypic selection.
Here, we examine and contrast the environmental drivers of plasticity in breeding phenology of two circumpolar seabirds at their receding summer range limit using unique datasets of marked individuals covering 25 and 30 years. Based on prior knowledge of the local ecosystems, we predicted that climate would generate opposing patterns of plasticity in the two populations.
Laying phenology of kittiwakes in the Gulf of Alaska was associated with a large-scale climate oscillation (Pacific Decadal Oscillation) while the Arctic-breeding murres adjusted laying to sea-ice conditions. Kittiwakes laid earlier after experiencing colder climate about two years prior and laying dates did not advance over the study, but murres laid earlier when warmer climate led...