On the move: Migration in the Arctic
© George Divoky
Is this Arctic seabird the “canary in the coalmine”?

Cooper Island, a 4-mile slice of sand and gravel off the coast of the northern tip of Alaska, is home to the region’s biggest colony of Mandt’s black guillemots. The pigeon-sized seabird feeds on Arctic cod and breeds near sea ice off the island from June to September.

But the Cooper Island colony would probably not exist if not for George Divoky.

For nearly half a century, the American ornithologist and founder of the Friends of Cooper Island has spent his summers studying these Arctic seabirds. Now he’s documenting what could be the last days of this once-thriving colony.

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A study that’s lasted more than 45 years

Shedding light on more than just seabirds

Divoky first visited Cooper Island back in the summer of 1972 as part of a seabird survey. At that time, he discovered 10 Mandt’s black guillemot pairs nesting under scattered debris—such as ammo boxes, floorboards and wooden planks. It was the beginning of his love affair with the Arctic and the guillemot colony that make it their home every summer.

In 1975, Divoky began an annual trek to Cooper Island to study the guillemot. Each summer, he returned to collect meticulous data on every nesting pair and chick. He also banded every bird.

In 1975, Divoky began an annual trek to Cooper Island to study the guillemot. Each summer, he returned to collect meticulous data on every nesting pair and chick. He also banded every bird.

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For the first two decades of his study, summer sea ice remained near the island during the guillemots’ breeding season. Parent birds were able to feed their chicks Arctic cod—the main fish found near sea ice—and most were able to successfully fledge the normal brood of two. In fact, by 1989, the colony had grown to 200 breeding pairs.

For the first two decades of his study, summer sea ice remained near the island during the guillemots’ breeding season. Parent birds were able to feed their chicks Arctic cod—the main fish found near sea ice—and most were able to successfully fledge the normal brood of two. In fact, by 1989, the colony had grown to 200 breeding pairs.

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But since the early 1990

But since the early 1990's, the colony’s numbers have been in free fall. As summer sea ice began to diminish, so did the numbers of Arctic cod that the guillemot depended on to raise their young.

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Although the Cooper Island guillemot research began as a way to examine seabird life history, the project’s duration—and the pace of climate change in the Arctic—resulted in it becoming a climate change study.

George Divoky
Founder, Friends of Cooper Island (a nonprofit organization)

A unique ecosystem in decline

Decreasing sea ice means fewer birds

As Artic cod disappeared from the waters around Cooper Island, the seabirds were forced to find other fish species to feed their chicks. But these were neither as abundant nor as nourishing. This led to a dramatic decrease in chicks’ growth and survival. Parent birds were often able to raise only a single chick—and sometimes none at all.

The problem is being made worse by the recent lack of ice in the Bering Sea—the birds’ traditional wintering area. Divoky believes this is playing a role in the decrease in adult birds’ ability to survive the winter, and may be preventing many adults from incubating or laying eggs.

Less sea ice also means polar bears can regularly visit the Cooper Island colony during the summer, consuming large numbers of chicks. In 2011, in an effort to prevent further decline in numbers, Divoky and his team began providing bear-proof cases for the birds to nest in.

A colony headed for extinction

Diminishing sea ice is hurting survival rates

By 2018, the guillemots’ population had dropped to just 75 pairs. As the number of breeding pairs decreases, the colony is much less attractive to new birds. And without new birds to replace those that die, numbers could plummet even further. If recent trends continue, Divoky fears that this colony of Mandt’s black guillemots could be heading to near-time extinction.

But Divoky plans to continue his annual summer visits to Cooper Island to assess changes in the ecosystem that supports the birds—and help determine whether the colony can avoid extinction as the Arctic continues to melt.

Learn more about Friends of Cooper Island.