Mapping threats to arctic bird populations. The effect of infectious organisms and pollution on bird health.
The arctic environment and its unique wildlife are currently being threatened on several levels; from climate change, from pollution and from infectious diseases. Health (infection levels and immune responsiveness) in wildlife is regulating population numbers through individual survival and reproduction. Little is known about the combined impact of infectious organisms and pollution on the health of arctic organisms. Due to the short arctic summer and limited food resources arctic birds typically have an exhausting breeding season were they rely upon accumulated body reserves for breeding. This leaves arctic animals very vulnerable to environmental stressors during breeding. This study proposes to (i) experimentally test how infectious organisms and (ii) how exposure from persistent organic pollutants (POPs); both legacy and new compounds and selected heavy metals (HMs), affect the health, reproduction and survival of breeding female common eiders Somateria mollissima. Moreover, (iii) by comparing health and infectious organisms of eider populations from three areas differing in migration patterns (wintering and breeding areas) we will assess the potential large scale effects of avian migration and climatic zones for distribution of infectious organisms. Also, (iv) waterfowl is considered the main source of avian influenza (AI) viruses, and may thus constitute a possible source for infection with bird flu to humans. We will thus identify previous exposure to, and current infection of, the different AI viruses in eider females from different populations to establish which individuals are most susceptible and also the geographical distribution of AI in the arctic. The eider is the most numerous sea-duck with a wide circumpolar distribution. Northern eider populations have been declining in recent years without any clear explanation. The arctic breeding strategy is extreme in the eider as the female does not eat for ~30 days while incubating eggs. This study will quantify geographic variation in individual levels of POPs and HMs, and in the prevalence of selected pathogens. The effect of these stressors on parameters related to individual fitness like immune function, survival and reproduction will be assessed through individual health monitoring, experiments and large scale comparisons of different eider populations from different climatic zones with different pollution levels.