Now that's a warm hug!
- Researchers studied Antarctica's Pointe Géologie Archipelago colony
- They found the huddles only last for an average of 50 minutes
- Some penguins get too hot and even eat fresh snow to cool down rapidly
- Air inside the huddles can reach an uncomfortable 37.5°C (99.5°F)
You might think penguins would only just be warm enough when huddled together to survive the harsh winds of an Antarctic storm.
But now researchers have found some Emperor penguins get so hot in the tight bundle of bodies that they have to eat snow to cool down.
The experts also discovered that huddles are more complicated and temporary than previously thought – lasting on average 50 minutes at a time.
You might think penguins would only just be warm enough when huddled together to survive the harsh winds of an Antarctic storm. But now researchers have found some Emperor penguins get so hot in the tight bundle of bodies that they have to eat snow to cool down (stock image)
Previous estimates suggested the penguins hunkered down for as long as the storms lasted, which could be hours and hours.
It was popularly thought Emperor penguins stay warm by rotating from the inside of a huddle to the outside to make sure no individual gets too cold.
But scientists at the University of Strasbourg in France have found the huddles regulate the birds' temperatures in a more complicated way, with some members breaking free to cool down.
The researchers studied Antarctica's Pointe Géologie Archipelago colony, which comprises approximately 3,000 breeding pairs during the 2005, 2006 and 2008 breeding seasons.
The experts counted the birds and filmed their actions.
The study revealed some Emperor penguins get so hot in the tight bundle of bodies that they have to eat snow to cool down. A stock image of two chicks eating snow is shown
THE MAJESTIC EMPEROR PENGUIN
The Emperor Penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguin species and is endemic to Antarctica.
The male and female are similar in plumage and size, reaching 48 inches (122cm) in height and weighing anywhere from 49 to 99lbs (22 to 45 kg).
Like all penguins, the Emperor is flightless, but has a streamlined body and wings stiffened and flattened into flippers for a marine habitat.
Its diet consists primarily of fish, but can also include crustaceans, such as krill, and cephalopods, such as squid.
In hunting, the species can remain submerged for up to 18 minutes, diving to a depth of 1,755 ft (535 metres).
It has several adaptations to facilitate this, including an unusually structured hemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma and the ability to reduce its metabolism and shut down non-essential organ functions.
The Emperor is the only penguin species that breeds during the Antarctic winter.
It treks up to 75 miles (120 km) over the ice to breeding colonies which may include thousands of individuals.
Their lifespan is typically 20 years in the wild, although observations suggest that some individuals may live to 50 years of age.
They found that as the temperature drops, the birds huddle so tightly that 10 penguins squeeze into a square metre of space, helping them to survive conditions as cold as -89.2°C by conserving energy.
In particularly chilly conditions, they form a large huddle, but it may not last long - breaking up after an average of 50 minutes.
The experts think the huddles disband regularly because penguins get too hot.
'The regular growth and decay of huddles operates as pulses through which birds gain, conserve or lose heat', they wrote.
'Originally proposed to account for reducing energy expenditure, the concept of social thermoregulation appears to cover a highly dynamic phenomenon that fulfils a genuine regulatory function in emperor penguins.'
The birds can get too hot in a huddle, with the air reaching 37.5°C (99.5°F) as they breathe out - much higher than the 20°C (68°F) the birds can comfortably tolerate.
If this happens, penguins seek to break free to become cooler again and regulate their body temperature.
Some birds leaving a huddle have even been seen eating snow, perhaps to lower their body temperature more rapidly.
Study author André Ancel said: 'The breakup of huddles is sometimes accompanied by a haze of warm air rising over the colony, which indicates a significant dissipation of heat.'
While the experts predicted the huddles would be disbanded by individuals at the centre, where temperatures are highest, they found those near the edge were more often the cause.
The researchers studied Antarctica's Pointe Géologie Archipelago colony (pictured) which comprises approximately 3,000 breeding pairs during the 2005, 2006 and 2008 breeding seasons
Starting at the edge of the huddle, groups were broken up in as little as two minutes, according to the study, published in the journal Animal Behaviour.
The behaviour could mean that the centre of the huddle is not dramatically hotter than areas towards the edge of the group, or that those in the middle are simply trapped and forced to bear the uncomfortable heat.
The researchers added they have only observed the behaviour in Emperor penguins and further work is needed to see whether it's true of all penguin species.
CLIMATE CHANGE MAY BE GOOD NEWS FOR PENGUINS
Melting ice caps and shrinking glaciers are often seen as a negative side effect of global warming, but at least one species is benefiting from these changes in temperature.
In East Antarctica, the population of Adélie penguins has increased 135-fold over the past 14,000 years, despite the decrease of ice in the region.
Experts at the University of Tasmania believe this is due to the fact that as glaciers retreat, the number of potential breeding sites for the birds increases.
East Antarctica is currently home to 30 per cent of the global population of Adélie penguins, with an estimated abundance of 1.14 million breeding pairs.
Adélie penguins are sensitive to changes in sea ice because they form breeding colonies on ice-free land along the Antarctic coastline. They also forage in the pack ice zone during the breeding season.
An increase in sea ice can be detrimental to the birds, as adults have to forage for longer, which reduces the frequency at which they can feed their chicks.