Some penguin colonies live off the ice. Emperor penguins depend on the sea ice.
In the autum, they congregate on the frozen expanses for breeding season, coming back to the same places each year.
But in recent decades the extent of autum sea ice has ebbed and flowed, and over the long term researchers expect Antarctic sea ice extent to decline because of regional warming.
Because of this anticipated habitat loss, the International Union for Conservation of Nature has been worried about the fate of emperor penguins. Emperor penguins crucially depend on the sea ice, some researchers think, so without it, penguin populations will crumble.
In a new study, however, a team of scientists led by the British Antarctic Survey’s Peter Fretwell found that some emperor penguins live without the sea ice—an indication that other penguins might be able to adapt to changing conditions.
Using satellite images the scientists surveyed 46 emperor penguin colonies. While most of them lived on the sea ice, just as we thought, a few have taken up different turf:
Here we report on newly discovered breeding behaviour in emperor penguins seen from satellite and aerial surveys. Four emperor colonies have been observed breeding on ice-shelves not sea-ice
The first, discovered in 2009 on the West Ice Shelf at the edge of Barrier Bay was a small colony of that could have been judged an anomaly or a break off group from the larger West Ice shelf colony located ~110 km to the north.
However, since the discovery of the colonies on the West Ice Shelf, three other, large colonies, have been found that are either permanently, or annually located on ice shelves rather than on sea-ice.
… It is at present unclear whether this behaviour of breeding on ice shelves is a new phenomenon associated with recent climate change, or one that has always existed but has not yet been documented.
Sea ice and shelf ice are very different things: sea ice is usually relatively thin, and forms when the sea water freezes in the fall. Shelf ice, however, is made as glaciers flow out into the sea, and can have sharp cliff faces hundreds of feet high.
The realization that emperor penguins don’t necessarily live and die by the ice, the researchers say, means we need to rethink how they might cope with climate change:
That emperor penguins can move their breeding site depending upon ice conditions to a more stable location, including onto the top of the ice-shelf itself, means new factors should be incorporated into modelled population trajectories for this species. Whether such factors will provide temporary or permanent relief from the impacts of climate change remains uncertain.
The fact that emperors exhibit a previously unknown breeding behaviour, intimates that other less-well known species may also have similar unknown adaptive behaviours that may also offer temporary or permanent relief to the challenges of climate change.
That being said, just because the penguins seem to be able to adjust to the loss of sea ice doesn’t mean they’re home free from the effects of warming. The scientists note that warming will also affect the organization of the food web as some species die out and as invasive species move in.
By Colin Schultz | http://www.smithsonianmag.com