Arctic terns Sterna paradisaea are noted for their extraordinary migration between Arctic and sub-Arctic breeding grounds and Antarctic wintering areas. Until recently, few data existed to document this migration, and none existed for North Pacific breeders. In this study, we tracked 6 Alaskan Arctic terns tagged with combined light geolocation and saltwater immersion tags through their fall migration. During fall 2007, these birds used several highly productive stopover locations to refuel during their southward migration: the California Current, the northern and southern Humboldt Current, and the Patagonian Shelf. At least 3 of the birds went on to winter in the Weddell Sea region of Antarctica, where Arctic terns from several Atlantic populations are also known to winter. Analysis of the first ever post-breeding behavioral data collected on this species showed that the birds foraged extensively in these staging areas, spending more time foraging on days when they were located within staging areas during the fall migration. We also found that the birds were exclusively diurnal foragers, spending their nights standing out of the water and/or flying. Arctic terns likely face strict time constraints throughout the migration, timing stopovers to match production while simultaneously aiming to arrive at the wintering grounds with sufficient time remaining to complete the winter molt before returning north. Ecological disturbance at any of these locations could have serious consequences for many birds. Further, predicted effects of climate change in the Weddell Sea region could have repercussions throughout the global Arctic tern population.

As colony-specific wintering ecology of small and medium-sized seabirds is poorly understood, it has been generally assumed that winter conditions have the same effect on all individuals from any given colony. However, advances in global positioning technology now allow researchers to investigate movements of smaller seabirds. We tracked black-legged kittiwakes Rissa tridactyla using geolocator tags during the non-breeding season. Although kittiwakes as a group appear to be generalists with respect to overwintering strategy, our data indicate that individual birds are more specialized in their use of wintering habitat. Among birds tagged in the Gulf of Alaska, we identified 3 groups employing different wintering strategies: (1) resident birds that remain in the northern Gulf of Alaska; (2) coastal birds that remain within coastal and shelf waters but move as far south as California; and (3) pelagic birds that travel up to 1700 km offshore. Given that wintering conditions differ in widely spaced areas, the effects of winter on bird survival and body condition are likely not the same on all birds in a colony, as is often assumed. Activity data revealed that kittiwakes are almost entirely diurnal during the non-breeding season. We found significant differences in time allocation among wintering groups: birds that remained in the colony region spent less time loafing during the day and engaged in longer daytime flying and foraging bouts than birds that wintered farther from the colony. These differences suggest that wintering birds make trade-offs among travel distance, metabolic demands, and foraging quality.

Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of Black-legged Kittiwakes (Rissa tridactyla) from Shoup Bay in Prince William Sound, Alaska to determine if there were age-related differences in metal levels, and in Black Oystercatchers (Haematopus bachmani)) from the same region to determine if there were differences in oiled and unoiled birds. Except for mercury, there were no age-related differences in metals levels in the feathers of kittiwakes. Kittiwakes over 13 years of age had the highest levels of mercury. There were no differences in levels of metals in the feathers of oystercatchers from oiled and unoiled regions of Prince William Sound. Except for mercury, the feathers of oystercatchers had significantly higher levels of all metals than those of kittiwakes. Levels of mercury in kittiwake feathers (mean of 2910 ng/g [ppb]) were within the range of many species of seabirds reported for other studies, and were generally below adverse effects levels.

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