Influence of climatic fluctuations on Common Eider life history and population dynamics: variation in and between populations.

Arctic ecosystems are among the most severely affected under a warming climate. A good understanding of the consequences of climate change on Arctic species demography and populations dynamics is thus of paramount importance and urgently needed. Using lon g-term data sets on Common Eider population life-histories and biodemography in the Southampton Island (Canada), the Svalbard archipelago (Norway) and northern Norway, we will study the response of Arctic avifauna to environmental fluctuations. We will co mbine the complementary expertise of several research teams 1) to assess and understand wildlife responses to changing climatic conditions at the individual and population levels, and 2) to compare the responses among three populations of an Arctic breedi ng seabird (Svalbard-Kongsfjorden in Norway; Grindøya in Norway; Southampton Island, Nunavut Canada). To understand and predict wildlife response to ongoing climate change, it is necessary to study and take both differences among populations and among ind ividuals into account. Among differences existing between individuals, we will study mainly the reproductive effort as an individual variable. The reproductive effort usually varies among individuals and the associated reproduction costs (i.e. on survival or breeding success) may influence individual responses to climate fluctuations. Our work will thus aim at linking climate to individual demography depending on their reproductive status, and assessing whether it could affect bird response to climate cha nge. Then depending on the proportion of birds investing a lot or not in the reproduction, we will study if individual responses can lead to different responses between three populations breeding and wintering under different conditions. Overall, the prop osed collaboration should thus yield significant and highly relevant insight into our understanding of, and ability to predict bird responses to climate change in some of the most threatened ecosystems.