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Emperor of the Ice
You are currently viewing the summary. View Full Text. Log in to view the full text via AAAS login. Log in through your institution Log in via OpenAthens. Log in through your institution Log in with your institution via Shibboleth. More options Purchase digital access to this article Download and print this article for your personal scholarly, research, and educational use. Search the site. Emperors on thin ice: three years of breeding failure at Halley Bay Satellite imagery is used to show that the world's second largest emperor penguin colony, at Halley Bay, has suffered three years of almost total breeding failure.
Although, like all emperor colonies, there has been large inter-annual variability in the breeding success at this site, the prolonged period of failure is unprecedented in the historical record. The observed events followed the early breakup of the fast ice in the ice creeks that the birds habitually used for breeding.
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But the kings breed in warmer latitudes, and this allows a different approach. By late february, the sun is circling low around the sky, and starts dipping below the horizon at midnight. The sun gives less and less heat until, in late April, it skims the horizon for the last time. Their first filming trip to Cape Crozier was in the last days of March. But there were none at Crozier, just some late-developing Ad4lie chicks that had probably left their run too late.
The predatory skuas would mop them up and then fly north. Antarctica in late summer is a huge ship of ice being deserted by its summer crew. Its skeleton winter crew is small, widely scattered, and very hardy. Out in the pack ice, as in the open sea, there are few obvious clues to navigate by, other than the sun wheeling around the sky. For a bird standing a metre high the horizon is only two nautical miles away. Even what looks real often vanishes when approached. Mirages hover over the flat horizon, creating coastlines and mountain ranges where none exist.
Spirit kingdoms in the air. Courtship is a stately blend of body movements and song. Emperors are the only penguins which do not defend territories—winter cold demands they huddle together, not stay apart—so noise is not used to assert territorial claims. However, in larger colonies partners need to find each other among tens of thousands of other birds, all of which are continually moving around and calling to each other.
There are also distinct differences between the calls of males and females. Emperor penguins are the only birds in the world that may spend their entire life without touching land. All but two of the 40 or so known colonies are on fast sea ice—ice anchored to sheltering coastline or grounded icebergs. Emperors need open, flat space for huddling, and they need to huddle to make it through winter.
The emperor breeding cycle is closely tied to the sea ice cycle, the colonies assembling as soon as the newly formed autumn ice is thick enough to support their weight. But those feet are not designed solely for egg holding, and are smaller than ideal.
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Larger feet might hold the egg more securely, but would lose more heat, too. Compromise again. So the father shuffles, not walks, slowly and awkwardly. The to gram emperor egg is the smallest laid by any bird, relative to body size. It weighs a mere 1. She has lost 20 per cent of her body weight, and needs to fatten up again before the egg hatches. They are large and rounded—factors which reduce heat loss.
The layer of fat under the skin provides the other 15 per cent, and doubles as a food reserve. Their extremities—feet, flippers, head and bill—are all small, relative to body size; another heat-saving adaptation. But the strangest adaptation of all is huddling. Huddles are remarkable acts of cooperation and nonaggression on a level rarely met in either animal or human societies. Individuals take their turn acting as windbreaks on the coldest, windward side, before shuffling around the huddle to the sheltered side.
The continual stream of birds moving from windward to leeward shifts the whole huddle slowly downwind, as much as a hundred metres per day of blizzard. If their body weight drops to about 22 kilograms they have no choice but to leave the egg or chick to its fate and head for the sea. And the male is the logical choice for the long winter watch, both by virtue of his greater fat reserves and by the fact that he has not burnt up energy producing the egg.
For four months the sun stays firmly below the horizon. During August, the midday twilight gradually grows longer and brighter until, on August 19, the sun makes a much-awaited reappearance. Each following day its low, flat path sweeps higher and wider across the sky until, by late October, it will no longer set, but freewheel for four months around the bright summer sky.
Emperors On Thin Ice | Common Dreams Further
The Cape Crozier eggs hatch in late August or early September, up to a month later than in northern colonies. For the first few days, the males feed their silver-grey bundles with a milky secretion from the crop. The reunion between partners is not without some awkwardness. HIS chick.
But finally he wanders off, thin and scruffy, to look for the sea, possibly still several days away. From then on, the pair run a shuttle service, delivering meals at intervals determined by the distance to open water. Eggs and chicks are blown away in storms or abandoned by parents. Storms may do more than just buffet the birds. On occasions, they may break out the sea ice from under the colony. During winter, while most males are incubating healthy, fertile eggs, a small number may be sitting on abandoned frozen eggs which then thaw, go rotten, and burst or even lumps of ice or rock about the right size.
Less harmless, however, is the chicknapping that starts once the chicks are born. This leaves fewer males than females, so next season, some females will not find mates.
These would-be foster parents often roam in groups—unruly street gangs ready for action, and violence if necessary. Many chicks are injured, and some are killed in these mauls as up to a dozen adults try to push the chick under their belly feathers with their pointed bills. Once a chick is tucked under an adult any adult the scrum immediately breaks up—until the next skirmish.
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I watched dozens of chicknapping attempts at Crozier, one of them resulting in much blood on both chick and a dozen would-be foster parents.