Great mountains of ice are melting in Antarctica, vast plains of frozen water continue to collapse into the Southern Ocean. That's bad news for penguins, which rely on the ice for hunting, among other things. To find out how bad, some scientists had been affixing bands to penguin's flippers.

The bands allow tracking of the changes in penguins' lifestyle. And they didn't seem to be hurting the birds: Several banded Adelie penguins that were taken thousands of miles from their home in eastern Antarctica swam all the way back in less than a year.

But a new 10-year study of king penguins shows that bands kill. Banded birds died more frequently than their unencumbered cousins and produced fewer chicks between 1998 and 2008. The exact reason is unclear but it may be that the bands drag on the penguins during their swimming flights through Antarctic waters. In fact, such bands force Adelie penguins to exert nearly a quarter more energy to swim.

What's worse from a scientific standpoint: banded and unbanded penguins respond differently to climate changes, with the banded birds showing up even later to breed when food is scarce. That makes the case for banding them even more suspect, especially when sensors implanted beneath the skin can deliver the same information. One thing remains clear, however, bands may be bad for the Antarctic birds but climate change will be even worse.

—David Biello