Volume 9, Issue 1

Black Turnstone is an obligate Pacific coast shorebird that is included as a “Species of High Concern” in both the U.S. and Alaska Shorebird Conservation Plans. Specific migration routes for this species are not well understood, which makes its recent disappearance at a major spring stopover site, northern Montague Island in Prince William Sound, Alaska, difficult to interpret. We tracked 23 Black Turnstones between breeding and wintering areas and examined migration timing, duration, and routes used. We identified two high-use regions during migration: 1) Cook Inlet/Shelikof Strait, Alaska, and 2) the Haida Gwaii Archipelago in British Columbia/Alexander Archipelago in southeastern Alaska. This second region was also an important wintering area. We found that northbound migration was longer than southbound (the reverse of what is often observed in shorebirds) and that staging behavior was primarily seen during northbound migration. No birds were tracked to northern Montague Island, and only a few individuals stopped anywhere in Prince William Sound. Alterations in patterns of spring herring spawn in Prince William Sound may be affecting the routes and stopovers used by Black Turnstones, and birds may be wintering farther north in recent decades due to warmer winter conditions. Additionally, the increasing availability and popularity of citizen science efforts like eBird has created a mechanism for disseminating observations from less accessible parts of the Black Turnstone range, a fact which may confound our understanding of whether migration routes for this species have changed over the last 30 years.

Hundreds of millions of birds reach the Mediterranean islands or Mediterranean coast of Europe every spring after having crossed the Sahara Desert and the Mediterranean Sea. Using data from three small insular stopover sites, we calculated body mass without fuel for 18 trans-Saharan passerine migrants. We subsequently used arrival fuel loads coupled with potential flight range estimates to assess the percentage of birds that are forced to perform an obligatory stopover after crossing the Mediterranean Sea due to fuel depletion. Average arrival fuel loads were among the lowest ever recorded in the Mediterranean region and minimum body mass values recorded for several species were lower than any other individual value reported. The percentage of birds that needed to replenish their energy stores before resuming their northward migration journey varied from 0% to 50% depending on the species and locality studied. Based on conservative estimates at least 180 million birds of our study species are expected to migrate through Greece, 14% of which would not be able to resume their migration without refueling. The significance of small islands and coastal sites in the Mediterranean as obligatory refuelling sites is discussed and their conservation value for migratory birds is highlighted under the perspective of climate change.

Extrinsic and intrinsic factors operating during and prior to the passerine spring migratory period have been associated with both migratory timing and condition. Here we take advantage of a long-term data set to answer questions about how extrinsic factors encountered on the wintering grounds (El Niño Southern Oscillation, ENSO) and en route (temperatures south of our study site) along with intrinsic factors (age, sex if possible) influenced both arrival timing and condition at our site in northeastern Pennsylvania. Older birds preceded younger, male Common Yellowthroats ( Geothlypis trichas ) preceded females and within a year later arriving Gray Cat-birds ( Dumetella carolinensis ) and Common Yellowthroats were in better condition. We found that Gray Catbirds and Common Yellowthroats migrating during warmer years arrived in better condition. Finally, we found evidence that ENSO, likely via influencing weather and food availability during the winter, was associated with arrival timing in Veery ( Catharus fuscescens ), Common Yellowthroats and possibly Gray Catbirds. Our results support the hypothesis that events experienced earlier, either between (wintering to migratory periods) or within (earlier vs. later in migration) phases of the avian annual cycle may carry over, influencing fitness later in time or in subsequent phases of the annual cycle.