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We tested the hypothesis that segregation in wintering areas is associated with population differentiation in a sentinel North Pacific seabird, the rhinoceros auklet (Cerorhinca monocerata). We collected tissue samples for genetic analyses on five breeding colonies in the western Pacific Ocean (Japan) and on 13 colonies in the eastern Pacific Ocean (California to Alaska), and deployed light-level geolocator tags on 12 eastern Pacific colonies to delineate wintering areas. Geolocator tags were deployed previously on one colony in Japan. There was strong genetic differentiation between populations in the eastern vs. western Pacific Ocean, likely due to two factors. First, glaciation over the North Pacific in the late Pleistocene might have forced a southward range shift that historically isolated the eastern and western populations. And second, deep-ocean habitat along the northern continental shelf appears to act as a barrier to movement; abundant on both sides of the North Pacific, the rhinoceros auklet is virtually absent as a breeder in the Aleutian Islands and Bering Sea, and no tagged birds crossed the North Pacific in the non-breeding season. While genetic differentiation was strongest between the eastern vs. western Pacific, there was also extensive differentiation within both regional groups. In pairwise comparisons among the eastern Pacific colonies, the standardized measure of genetic differentiation (FꞌST) was negatively correlated with the extent of spatial overlap in wintering areas. That result supports the hypothesis that segregation in the non-breeding season is linked to genetic structure. Philopatry and a neritic foraging habit probably also contribute to the structuring. Widely distributed, vulnerable to anthropogenic stressors, and exhibiting extensive genetic structure, the rhinoceros auklet is fully indicative of the scope of the conservation challenges posed by seabirds. [ABSTRACT FROM AUTHOR]

We compiled present-day observations and survey data of the avian and mammal fauna in the Islands of Four Mountains, Alaska, which primarily consist of marine-adapted species, to provide insight into the prehistoric fauna found in the archaeological record. We documented 63 bird species, mainly seabirds (67%). The majority (71%) of the estimated number of breeding birds are ledge nesters, predominately murres, and most (68%) spend the majority of their lives in the offshore environment. We lack good estimates for burrow and crevice nesters, which were impacted by and are still recovering from a period of arctic fox farming in the twentieth century. Marine mammals, predominately Steller sea lion, harbor seal, and sea otter, primarily use accessible land as haul-outs and are found in low numbers compared with the rest of the Aleutians. Red fox, the only land mammal, presently only reside on Chuginadak Island. While the present-day fauna is similar to the fauna recorded in the archaeological record, we found no indication of nesting by ancient murrelets and northern fulmars in the Island of Four Mountains, whereas both species were present in midden sites on Carlisle and Chuginadak Islands, with the possibility of prehistoric breeding colonies on Carlisle Island. [ABSTRACT FROM AUTHOR]

The article discusses a study of the status, distribution and population of the Kittlitz's Murrelet Brachyramphus brevirostris in northern Alaska from 1978 to 2009. Land-cover classes were used to map the locations of Kittlitz's Murrelet nests and to examine habitat relationships. Data from boat-based surveys were instrumental in the assessment of seasonal variation in the abundance of the species in the region. Results indicate that Kittlitz's Murrelets prefer to locate their nests in areas of barren land or dwarf shrub habitat. One of the environmental factors that may serve as hindrances to its breeding range is the oceanography of adjacent marine waters.

The article discusses a study which investigated Rusty Blackbirds nesting in Alaska and Canada to determine nesting habitats and to asses whether low success rates of nesting contribute to the decline of population in Alaska. The study found that nest survival in Alaska improved due to black spruce density and nest success with spruce was more than the nests in deciduous vegetation. The study noted the need to confirm the increase of nest survival in Canada.

• Currents and temperature affect ecosystem productivity in Unimak Pass, Alaska. • Seabirds showed stronger responses to environmental variability than responses at lower trophic levels. • Linkages between productivity at lower trophic levels and seabirds were variable. • Breeding success of murres and storm-petrels may be used to monitor some aspects of ecosystem productivity. Understanding bio-physical relationships for areas of high biodiversity in marine systems can illuminate potential impacts of environmental change on concentrations of marine life. A biodiversity hotspot of singular significance in the North Pacific Ocean is Unimak Pass, Alaska, where millions of seabirds, hundreds of cetaceans, and thousands of pinnipeds concentrate each summer to forage on rich zooplankton and forage fish resources. We synthesized a large number of disparate datasets from different sources to examine the effect of current flows and temperature on productivity across trophic levels in Unimak Pass on the seasonal time scale. Our results verify the importance of these factors. This study is one of few to investigate how seabird reproductive success may vary relative to ocean currents, and corroborates other studies showing trait-mediated responses of seabirds to variation in oceanographic conditions, but at the local scale of an Aleutian pass. Somewhat surprisingly, seabird species with larger foraging ranges appeared to respond most to variability in ocean parameters at the seasonal scale. Our hypothesis that spring conditions promote summer productivity was not supported. Instead, contemporaneous conditions in summer had more and stronger effects on seabird production and foraging density. An important caveat of our study is that these relationships remain mechanistically poorly understood due to a lack of data on lower trophic levels and corresponding information on prey use and other aspects of trophic ecology across species. Nonetheless, we have shown that the breeding success of some seabird species on Aiktak Island, as well as seasonal average foraging densities of migratory shearwaters and other species, track currents and temperature variability in Unimak Pass, and may thus be useful as ecological indicators to the robustness of local pelagic food webs, and therefore ecosystem status assessments, in the region. [ABSTRACT FROM AUTHOR]