Black Guillemot
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Guillemots impacted by ice melt

A small colony of black guillemots living on a gravel spit off Point Barrow is providing a unique insight into the changing Arctic environment.

The Cooper Island birds feed their young on cod that hug the underside and edges of the polar pack ice.

But their access to this prey source is being limited by the big retreat in seasonal ice cover now under way.

How the guillemots respond will turn a lens on the wider changes taking place in Arctic ecosystems, says biologist George Divoky.

He told the BBC's Jonathan Amos about his history with the birds.