# Penguin Huddles Move Like Waves

## Maintaining a massive huddle of thousands of penguins may sound simple, but sticking together in a pack so large turns out to be quite complicated.

When male emperor penguins face the minus-58-degrees-Fahrenheit (minus 50 degrees Celsius), 120-mph (200 km/h) winds of Antarctic winters, the birds rely on their neighbors' bodies to keep themselves - and the eggs that they protect in a pouch near their feet - alive and warm.

Maintaining a massive huddle of thousands of penguins may sound fairly simple, but sticking together in a pack so large turns out to be quite complicated: When one penguin moves a single step, the rest must also move to accommodate the open space and stay warm. In this particular species of penguin, males play the unusual gender role of incubating eggs, so it is especially crucial that they maintain warmth during cold winters.

## Top 10 Weird Ways Animals Stay Warm in Winter

Previous research has suggested that individual penguins within a huddle regularly make small movements roughly every 30 to 60 seconds, travelling between 2 and 4 inches (5 and 10 centimeters) with each step. But researchers haven't understood the physics behind how all of these moving parts stick together as a single unit.

Now, biologists and physicists based at the University of Erlangen-Nuremberg in Germany have collaborated to create mathematical models based on time-lapse camera footage of emperor penguins to try to understand the physics behind the huddles. (Video: Watch Massive Emperor Penguin Huddle Shuffle as a Wave)

"If you look at the huddle in real-time, it seems very steady - every penguin seems to stay at a fixed location," study co-author Richard Gerum told LiveScience. "We tried with our research to investigate what reorganization processes are going on inside the huddle and how they can merge between simple interactions between penguins."

The team's mathematical models showed that the huddles behave as waves instigated by any individual in the pack, no matter that individual's location. If two waves travel toward each other, they merge, rather than passing one another. Gaps just 2 centimeters wide (0.8 inches) appear to instigate a reorganization, in order for the penguins to stay warm, the team reports today (Dec. 16) in the New Journal of Physics.

## NEWS: How Penguins Lost Their Ability to Fly

Why penguins move so frequently and in such small steps remains unclear, though the researchers think the shuffles may help the birds rotate their eggs to keep them warm.

"It might be that the egg can get cold at the bottom and so the penguins have to rotate the egg every now and then," Gerum said. "This is just a speculation."

Emperor penguins are the only vertebrates on the Antarctic continent that breed during the coldest months of the year.

While the model that the researchers created has the penguins moving in a straight line, the natural formation of the huddles often moves more in a spiral rotation, Gerum said. Next, the team hopes to create a mathematical model that recreates this more complicated rotational movement.

More from LiveScience:

Happy Feet: A Gallery of Pudgy Penguins The Mysterious Physics of 7 Everyday Things Photos of Flightless Birds: All 18 Penguin Species Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

This story originally appeared on LiveScience.com.

Emperor penguins, standing very close, form a huddle against the cold temperatures.

Arctic animals have developed amazing adaptations to be able to survive in the tundra. The arctic fox has fur that changes from brown to white in September.

Three Japanese macaques -- also known as snow monkeys -- take a relaxing soak in Jigokudani, Japan.

A deer doesn't seem to mind the snowfall as it munches vegetation. Young deer are covered with white spots that disappear, in most species, when a new coat of fur is grown.

Snow leopards are found in the mountains of Central Asia. Fun fact: The snow Leopard is Packistan's "national predator." Keep your head on a swivel,

bharals

.

Polar bear cubs emerge for the first time from their den.

Barn owls can pinpoint and capture prey without even being able to see it. They've been documented to catch prey with absolutely no light at all using nothing but their hearing.

A young emperor penguin chick explores the sea ice all by itself, with a large iceberg in the background.

This llama seems to think an abandoned school bus would make a good shelter, as snow falls in Centreville, Va.

The fur of the ermine, a species of weasel, is partly brown in summer. It turns completely white in winter. Ermine fur is valuable and was once reserved for royalty. As a symbol of purity and honor, the fur was used to line the robes of judges.

A snowshoe hare's large feet allow them to get around in several feet of the snow without sinking. The hare's coat turns from brown to white, providing excellent camouflage in North American winters.