Although Emperor Penguins are abundant, their reliance on sea ice for breeding makes them potentially highly vulnerable to climate change. Estimates of projected changes in sea ice around the Antarctic coastline suggest that populations could be halved by the 2050s.
Populations of these penguins are remote and frequently inaccessible, but they are amenable to satellite monitoring. Using this approach, Peter Fretwell, from the British Antarctic Survey, and co-workers have identified a number of colonies using glacial ice shelves, rather than sea ice, as their breeding sites. Two of these colonies were particularly interesting because they were found to switch between breeding sites, sometimes occupying the ice shelf and sometimes the sea ice. The choice, at least for the largest colony, seemed to reflect the timing of sea ice formation with relocation to the ice shelf occurring in years when sea ice formation was late. The authors note that the discovery of this new breeding behaviour at climatically marginal sites could mitigate some of the consequences of sea ice loss for these enigmatic birds.