Huddle or Die!
Bird On! News
30th March 1997
The Emperor Penguin is daft. It breeds on the Antarctic ice during the Southern winter and enjoys (possibly one should say endures) extremes of temperature. The only thing that can be said for it as a strategy is that there are few predators!
A recent paper in Nature (385: 304-305) by Andre Ancel, Henk Visser, Yvbes Handrich, Dirkjan Masman and Yvon Le Maho reports on the metabolism of these birds. The males incubate for the whole time with a spell of fasting of 105-115 days. They carefully monitored tow groups of five birds they kept away from the big huddles of birds and were able to find eight of the experimental birds that were allowed to huddle naturally. Water flux in the natural birds was less than in the experimental ones not able to huddle and their weight loss was about 20% per day less. Huddling is absolutely crucial for the males to be able to survive and incubate the egg. As they say it is a key adaptation for this species to be able to survive.
What they do not mention is that there is clearly a critical number of Emperors which need to come together to form a viable huddle. Several may occur at a colony but how does a new colony from? Are the existing colonies in the same places they have been for centuries or longer? Most are on sea ice but carbon-14 dating of remains at stratigraphically low levels of any colnies on land would be very interesting.