Model Reveals How Huddling Penguins Share Heat

Ever wondered what characteristics help a penguin survive the coldest and harshest climates on earth because being warm-blooded animals they can ill-afford to let their body temperature fall.

It has been found that it is their self-centered behaviour that keeps them toastier.  This is the reason we often spot penguins huddled together in large groups for warmth during storm.

Mathematicians at the University of California, Merced, created a model of penguin huddles that assumes each penguin aims solely to minimize its own heat loss. Their self-centered behavior leads to equitable sharing of heat.

Francois Blanchette, an applied mathematician at UC Merced, developed an interest in penguin huddles after watching "The March of Penguins". Along with his fellow researchers, Arnold Kim and Aaron Waters, he created a mathematical model of penguin huddles that varies with wind strength and turbulence.

Their modeled huddles packed so tightly that only the penguins on the outside could move.  Each penguin in the huddle generated heat that the wind blew away. By considering such factors as the number of penguins in the huddle and the strength and turbulence of the wind, the model calculated which penguin on the outside of the huddle was coldest. 

It was noticed that the coldest penguin moved to the most sheltered spot available in an attempt to relocate from a windward to a leeward position. Again the heat distribution around the huddle was recalculated. Repeated iterations showed the huddle gradually elongating and creeping downwind over time.

The researchers were surprised to know that the model showed the penguins shared warmth nearly equally among themselves

"Even if penguins are only selfish, only trying to find the best spot for themselves and not thinking about their community, there is still equality in the amount of time that each penguin spends exposed to the wind," says Blanchette. Not all instances of selfish behavior result in such fair outcomes, he notes. "A penguin huddle is a self-sufficient system in which the animals rely on each other for shelter, and I think that is what makes it fair. If you have some kind of obstacle, like a wall, then I think it would stop being fair," Blanchette says.

"Penguins huddle during blizzards, when the conditions are horrible, and if you're going to collect data you're also going to be in a blizzard in horrible conditions," Blanchette points out. 

According to Blanchette the group investigates how to adapt the model to describe other biological organisms, such as certain bacteria, that move as a group in response to an outside stimulus like food or the presence of a toxin. 

"Nearly everybody seems to love penguins and not enough people love math," he says. "If we use math to study penguins we could potentially teach more people to love math too!"

he results are published in the online journal PLOS ONE and the researchers will discuss their findings at the annual meeting of the American Physical Society's (APS) Division of Fluid Dynamics (DFD) held Nov. 18 - 20 in San Diego, Calif.