Polar Bears on a collision course with seabirds?

22 04 2010

As if Murres don't have enough to worry about: Polar Bears?!

A new study in the journal Polar Biology has described  seemingly unprecedented predation on seabirds by an unusual perpetrator: the Polar Bear. Poster child for the plight of all Arctic animals as climate change melts the polar ice, the bears usually rely almost solely on seals for sustenance. When the ice breaks up every Spring, the bears usually enter a prolonged fast, consuming very few terrestrial organisms and relying on stored fat for survival. In Hudson Bay, scientists have documented progressively earlier ice break up, meaning longer and longer fasts for the bears.

Historically, Arctic seabirds have had little to fear from Polar Bears since the bears were still feeding on seals out on the ice during the birds’ nesting periods. By the time the bears were driven onto land, the young birds had already fledged and were out of danger. Now that the bears are coming onto land earlier, their arrival coincides with seabird nesting. In a spectacular slideshow, the scientists show the bears scaling almost vertical cliffs to feed on murre chicks and eggs. Locally, one bear can completely decimate a seabird population. It is still unclear if this will become an Arctic-wide phenomenon threatening seabird survival. Also unknown is whether the seabirds may somehow adapt to warming temperatures by altering their nesting periods. So far, the birds are lagging behind shifting temperatures, leading to food scarcity for their chicks.

With that uplifting story, the SEANET blogger wishes you all a Happy Earth Day.

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