Title
Migratory connectivity of Semipalmated Sandpipers and implications for conservation
Author(s)
Brown, Stephen;Gratto-Trevor, Cheri;Porter, Ron;Weiser, Emily L.;Mizrahi, David;Bentzen, Rebecca;Boldenow, Megan;Clay, Rob;Freeman, Scott;Giroux, Marie-Andrée;Kwon, Eunbi;Lank, David B.;Lecomte, Nicolas;Liebezeit, Joe;Loverti, Vanessa;Rausch, Jennie;Sandercock, Brett K.;Schulte, Shiloh;Smith, Paul;Taylor, Audrey;Winn, Brad;Yezerinac, Stephen;Lanctot, Richard B.
Published
2017
Publisher
The Condor
Abstract
Semipalmated Sandpiper (Calidris pusilla) populations have undergone significant declines at core nonbreeding sites in northeastern South America. Breeding populations have also declined in the eastern North American Arctic, but appear to be stable or increasing in the central and western Arctic. To identify vulnerable populations and sites, we documented the migratory connectivity of Semipalmated Sandpipers using light-level geolocators, deploying 250 at 8 Arctic sites across the species' breeding range from 2011 to 2015, plus 87 at a single wintering site in northeastern Brazil in 2013 and 2014. We recovered 59 units and resighted 7 more (26% return rate) on the breeding grounds, but none at the nonbreeding site. We recovered only ?3% of units deployed in 2013 at eastern Arctic breeding sites, but recovered 33% of those deployed in 2015. Overall, birds with geolocators were 57% as likely to return as those carrying alphanumeric flags. Stopover durations at prairie sites (mean: 8.7 days southbound, 6.7 days northbound) were comparable with durations estimated by local banding studies, but geolocator-tagged birds had longer stopovers than previously estimated at James and Hudson Bay, the Bay of Fundy, and the Gulf of Mexico. Migration routes confirmed an eastern Arctic connection with northeastern South America. Birds from eastern Alaska, USA, and far western Canada wintered from Venezuela to French Guiana. Central Alaskan breeders wintered across a wider range from Ecuador to French Guiana. Birds that bred in western Alaska wintered mainly on the west coasts of Central America and northwestern South America, outside the nonbreeding region in which population declines have been observed. Birds that bred in the eastern Arctic and used the Atlantic Flyway wintered in the areas in South America where declines have been reported, whereas central Arctic?breeding populations were apparently stable. This suggests that declines may be occurring on the Atlantic Flyway and in the eastern Arctic region. Populations of Calidris pusilla have shown significant declines at major wintering sites in northeastern South America. Breeding populations have declined in the eastern North American Arctic, but appear stable or increasing in the central and western Arctic. To identify vulnerable populations and sites we documented the migratory connectivity of C. pusilla using light-level geolocators, deploying 250 of them at eight sites in the species' Arctic breeding range between 2011 and 2015, and 87 more at a wintering site in northeastern Brazil in 2013 and 2014. We recovered 59 units and re-observed 7 more (26% return rate) in the breeding areas, but none at the wintering site. We only recovered ∼3% of the units deployed in 2013 at breeding sites in the eastern Arctic, but recovered 33% of those deployed in 2015. Overall, birds with geolocators were only 57% more likely to return than birds carrying alphanumeric tags. The duration of migratory stopovers at sites in the Prairies (mean: 8.7 days migrating south, 6.6 north) was comparable to the duration estimated by local banding studies, but birds marked with geolocators had longer stopovers than previously estimated in the James and Hudson Bays and Bays of Fundy, and the Gulf of Mexico. Migratory routes confirmed a connection between the eastern Arctic and northeastern South America. Birds from eastern Alaska and western Canada wintered between Venezuela and French Guiana. Birds breeding in central Alaska overwintered in a wider geographic area between Ecuador and French Guiana. Birds breeding in western Alaska wintered primarily on the west coast of Central America and northwestern South America, outside the wintering area where population declines have been observed. Birds breeding in the eastern Arctic and using the Atlantic flyway winter in the areas in South America where population declines have been reported, while central Arctic populations are apparently stable. This suggests that declines may be occurring in the Atlantic Flyway and in the eastern Arctic region.
Keywords
geolocators;Arctic;migration;movements;nonbreeding;shorebirds;tag effects;Calidris pusilla;Arctic;shorebirds;tagging effects;site fidelity;geolocators;migration;movements;migration stopover sites

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PUB22242