August 11, 2018: Field report
Hatching is finally over with one very late egg hatching today after having been incubated for 34 days; 28 days is normal. The oldest nestling is 16 days old; the chick is gaining weight and doing well like all of the other 45 nestlings.
While the main pack ice is well offshore, the Marginal Ice Zone, where ice covers from 18 to 80 percent of the ocean’s surface, extends south to the entire Alaskan Beaufort Sea coast, including Cooper Island. The seascape visible from the north beach now has widely scattered floes, some with rather high vertical relief breaking the horizon, in a nearly flat calm sea. This differs greatly from what was present last year when the first week in August had no ice visible with large swells breaking on north beach. More importantly, last year at this time the sea surface temperature was well above 4 degrees Celsius while this year it is less than 2 degrees Celsius. The guillemot’s preferred prey, Arctic Cod, are typically found in waters from -2 to 4 degrees.
The ice and water temperature conditions are ideal for the parent birds provisioning. Arctic Cod has comprised well over 90 percent of the prey being fed to chicks this year. The two oldest chicks, hatched on July 21, weighed 35 grams at hatching and now weigh 275 grams and 245 grams – the larger of the two experiencing an almost seven-fold weight increase in a 15-day period. A growth rate that rapid requires readily available prey that is both abundant and high energy, as well as two dedicated parents to return to the nest site with a fish every hour. Similar high growth rates are occurring at other nests.
Read the rest of the field report at Proteus.
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Science writer Jenny Woodman of Proteus writes about Cooper Island research and the current field season.
George Divoky frets–with good reason. In 2016, CNN Correspondent John D. Sutter called him the man who is watching the world melt. The description is as distressing as it is apt.
George sends us regular dispatches from a small field camp on Cooper Island, about 25 miles east of Utqiaġvik, where he has studied a colony of nesting Mandt’s Black Guillemots for the last 44 years. Since his work began in 1975, the research has morphed into one of the longest-running studies of seabirds, sea ice, and climate change.
Read the full post and latest update on the 2018 field season here.
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Over most of its range the Black Guillemot is a nearshore seabird, occupying coastal waters during both the breeding and nonbreeding seasons, as do other members of the genus Cepphus. Pelagic or open ocean waters can offer abundant prey resources, but these options are often distant, patchy and unpredictable.
The nearshore typically offers seabirds a smaller but more reliable source prey base consisting of forage fish and benthic fauna from the ocean floor such as crustaceans or mussels.
The Arctic Ocean has extensive sea ice cover in the nearshore for the majority of the year; this presents a number of challenges to a nearshore species. Our work on the Cooper Island Black Guillemots has revealed a number of ways in which the species has met these challenges.
The current view from my cabin window illustrates one of the major problems guillemots face in the Arctic. Sea ice extends from the north beach of the island to the horizon and covers Elson Lagoon to the south. The only water available to the guillemots is a brackish pond in the center of the colony that provides no prey but is deep enough to provide sanctuary if the guillemots need to dive when pursued by an owl or falcon — regular visitors to the island.
Read George’s latest field report at Proteus.
MODIS image from July 9; snow and ice have blue/cyan color, while clouds will be lighter gray/white. Image Credit: David Douglass/USGS
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