In seasonal environments subject to climate change, organisms typically show phenological changes. As these changes are usually stronger in organisms at lower trophic levels than those at higher trophic levels, mismatches between consumers and their prey may occur during the consumers' reproduction period. While in some species a trophic mismatch induces reductions in offspring growth, this is not always the case. F I G U R E 2 Study locations for Red Knot ssp. islandica (yellow dots), canutus (orange dots), rogersi (purple dot) and roselaari (red dot), Great Knot (blue square) and Surfbird (green diamond) [Colour figure can be viewed at wileyonlinelibrary.com]

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Migration studies at Middleton island, Gulf of alaska, over four decades documented the regular autumn occurrences of over 100 species of birds (35+ passerines and 65+ nonpasserines), most of them apparently departing across the Gulf of alaska for the Pacific coast to the east and south. With a focus on fall migration, we discuss here 261 species and 16 additional subspecies recorded at Middleton. We present much new information on the status of bird species and subspecies in the Gulf of alaska and highlight the regular and predictable use of a route of migration across the Gulf of alaska by large numbers of passerines, including species associated with the central Flyway.

ABSTRACT:Prevalence of avian influenza virus (AIV) antibodies in the western Atlantic subspecies of Red Knot (Calidris canutus rufa) is among the highest for any shorebird. To assess whether the frequency of detection of AIV antibodies is high for the species in general or restricted only to C. c. rufa, we sampled the northeastern Pacific Coast subspecies of Red Knot (Calidris canutus roselaari) breeding in northwestern Alaska. Antibodies were detected in 90% of adults and none of the chicks sampled. Viral shedding was not detected in adults or chicks. These results suggest a predisposition of Red Knots to AIV infection. High antibody titers to subtypes H3 and H4 were detected, whereas low to intermediate antibody levels were found for subtypes H10 and H11. These four subtypes have previously been detected in shorebirds at Delaware Bay (at the border of New Jersey and Delaware) and in waterfowl along the Pacific Coast of North America.

The Short-eared Owl (Asio flammeus) is a widespread raptor whose abundance and distribution fluctuates in response to the varying amplitudes of its prey, which are predominately microtines. Previous efforts to describe the seasonal movements of Short-eared Owls have been hindered by few band recoveries and the species' cryptic and irruptive behavior. We attached satellite transmitters to adult Short-eared Owls at breeding areas in western and interior Alaska in June 2009 and July 2010, and tracked their movements for up to 19 mo. Owls initiated long-distance southward movements from Alaska and most followed a corridor east of the Rocky Mountains into the Prairie provinces and Great Plains states. Four owls followed a coastal route west of the Rocky Mountains, including one owl that crossed the Gulf of Alaska. Completed autumn migration distances ranged from 3205-6886 km (mean ¼ 4722 6 1156 km [SD]). Wintering areas spanned 218 of latitude from central Montana to southern Texas, and 248 of longitude from central California to western Kansas. Subsequent seasonal migrations were generally northward in spring and southward in autumn; these movements were comparatively short-distance (mean ¼ 767.5 6 517.4 km [SD]) and the owls exhibited low site fidelity. The Short-eared Owls we tracked from two relatively local breeding areas in Alaska used a patchwork of diverse open habitats across a large area of North America, which highlights that effective conservation of this species requires a collaborative, continental-scale focus.