Abstract
Migratory seabirds face threats from climate change and a variety of anthropogenic disturbances. Although most seabird research has focused on the ecology of individuals at the colony, technological advances now allow researchers to track seabird movements at sea and during migration. We combined telemetry data on Onychoprion fuscatus (sooty terns) with a long-term capture-mark-recapture dataset from the Dry Tortugas National Park to map the movements at sea for this species, calculate estimates of mortality, and investigate the impact of hurricanes on a migratory seabird. Included in the latter analysis is information on the locations of recovered bands from deceased individuals wrecked by tropical storms. We present the first known map of sooty tern migration in the Atlantic Ocean. Our results indicate that the birds had minor overlaps with areas affected by the major 2010 oil spill and a major shrimp fishery. Indices of hurricane strength and occurrence are positively correlated with annual mortality and indices of numbers of wrecked birds. As climate change may lead to an increase in severity and frequency of major hurricanes, this may pose a long-term problem for this colony.
Highlights
Given a variety of threats to ocean health, ranging from climate change to pollution and overfishing (Campagna et al, 2011; Sissenwine, Mace & Lassen, 2014; Boonstra et al, 2015), assessing ocean conditions is vital (Knap et al, 2002; Samhouri et al, 2012)
We have defined a ‘‘wrecked’’ individual as a recovered, deceased sooty tern found in a location that we considered unlikely to have been a part of their normal migration route
The first was that for any year where wrecked birds were recovered, we identified hurricanes whose paths both overlapped with the wrecked locations and took place before the recovery
Summary
Given a variety of threats to ocean health, ranging from climate change to pollution and overfishing (Campagna et al, 2011; Sissenwine, Mace & Lassen, 2014; Boonstra et al, 2015), assessing ocean conditions is vital (Knap et al, 2002; Samhouri et al, 2012). Monitoring colonial seabirds has provided a method of ocean threat assessment (Le Corre & Jaquemet, 2005). While what happens in the nesting colonies may be understood in exceptional detail, what happens at sea has generally only been known indirectly from year-to-year changes in the nesting birds or from the locations of banded individuals found wrecked and deceased away from the colony (Piatt & Van Pelt, 1997; Schreiber, 2002). Even where the birds feed—both when at the colony and during the rest of the year—has often been poorly known
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