The Antarctic has its penguins, but the Arctic is home to a small black-and-white tuxedoed bird that can fly as well as swim. And the little auk, also known as the dovekie, is serving as sentinel of global warming.

Adult body mass fell 4 percent – a potential problem for a bird about the size of a quail.

Marked sea-ice retreat has profoundly altered the feeding habits of little auks in Russia’s Franz-Josef Land, an archipelago is their northernmost breeding ground, a research team reported today in Global Change Biology. The islands have been virtually ice-free each summer since 2005.

Using miniature electronic tags, the scientists showed that the smallest of the European auks, members of the puffin family, were losing their main prey, lipid-rich zooplankton. The birds adapted by shifting to new foraging spots at the front of melting glaciers, where zooplankton become stunned by cold and osmotic shock. Little auk chick growth rates thus stayed steady, but adult body mass fell 4 percent compared to 21 years ago – a potential problem for a bird about the size of a quail.

The international team of researchers, including scientists from CEFE, France’s largest ecological research institute, and from National Geographic, say their study underscores the difficulty of predicting the impact of the rapid climate change underway in the complex ecosystems at the world’s poles.