It Takes One Penguin to Break Up a Huddle

In nature documentaries, the huddles performed by penguins are often portrayed as astonishing acts of cooperation. And while watching thousands of penguins rotate through a crowd is impressive, this behavior doesn’t always end so gracefully once the camera cuts away.

During the 2005, 2006, and 2008 breeding seasons, André Ancel of the University of Strasbourg in France and his colleagues studied about 3000 breeding pairs of the emperor penguin colony of Antarctica’s Pointe Géologie Archipelago. In the December issue of Animal Behavior, the researchers report that the huddles they observed are much more complicated than they appear. The arrangements lasted a few hours at the most, and all it took was one penguin to break up the group in less than two minutes. 

In penguin huddles, the birds in the center are always depicted as having the sweetest set-ups while it's the ones around the perimeter that are thought to be taking one for the team. But when penguins decide to give up their prime interior spot, it's not necessarily out of altruism. The heat-conserving strategy works so well that the center of a huddle can reach temperatures of nearly 100°F, which is well past the point of comfort for penguins. Penguins shift towards the outside of the group not just to give other penguins a chance to get in, but because they're looking for some relief for themselves. After leaving a huddle, Ancel and his team observed some penguins eating snow, possibly as a way to cool down.

It was for this reason that the team of researchers hypothesized that most huddle breakups would begin at the center, but they only observed this happening once. Most of the time it was started by penguins on the exterior, and within two minutes of departure the huddle would be complete broken up. The huddles lasted anywhere from a dozen minutes to several hours, but the average length was 50 minutes. After they dispersed, a haze of warm air could sometimes be seen rising over the colony. The researchers think that while huddles begin as a way to conserve heat, the sudden breakups help to dissipate it. Consider that the next time you're watching footage of a penguin huddle—you should probably save some sympathy for the guys in the middle. 

[h/t: Science News]

Big Questions
What Makes a Cat's Tail Puff Up When It's Scared?

Cats wear their emotions on their tails, not their sleeves. They tap their fluffy rear appendages during relaxing naps, thrash them while tense, and hold them stiff and aloft when they’re feeling aggressive, among other behaviors. And in some scary situations (like, say, being surprised by a cucumber), a cat’s tail will actually expand, puffing up to nearly twice its volume as its owner hisses, arches its back, and flattens its ears. What does a super-sized tail signify, and how does it occur naturally without help from hairspray?

Cats with puffed tails are “basically trying to make themselves look as big as possible, and that’s because they detect a threat in the environment," Dr. Mikel Delgado, a certified cat behavior consultant who studied animal behavior and human-pet relationships as a PhD student at the University of California, Berkeley, tells Mental Floss. The “threat” in question can be as major as an approaching dog or as minor as an unexpected noise. Even if a cat isn't technically in any real danger, it's still biologically wired to spring to the offensive at a moment’s notice, as it's "not quite at the top of the food chain,” Delgado says. And a big tail is reflexive feline body language for “I’m big and scary, and you wouldn't want to mess with me,” she adds.

A cat’s tail puffs when muscles in its skin (where the hair base is) contract in response to hormone signals from the stress/fight or flight system, or sympathetic nervous system. Occasionally, the hairs on a cat’s back will also puff up along with the tail. That said, not all cats swell up when a startling situation strikes. “I’ve seen some cats that seem unflappable, and they never get poofed up,” Delgado says. “My cats get puffed up pretty easily.”

In addition to cats, other animals also experience piloerection, as this phenomenon is technically called. For example, “some birds puff up when they're encountering an enemy or a threat,” Delgado says. “I think it is a universal response among animals to try to get themselves out of a [potentially dangerous] situation. Really, the idea is that you don't have to fight because if you fight, you might lose an ear or you might get an injury that could be fatal. For most animals, they’re trying to figure out how to scare another animal off without actually going fisticuffs.” In other words, hiss softly, but carry a big tail.

10 Notable Gestation Periods in the Animal Kingdom

The gestation periods of the animal kingdom are varied and fascinating. Some clock in at just a few weeks, making any human green with envy, while others can last more than a year. Here are 10 notable gestation times for animals around the globe. The lesson? Be thankful that you’re not a pregnant elephant.

1. ELEPHANTS: 640-660 DAYS

Elephants are pregnant for a long time. Like really, really long. At an average of 95 weeks, the gestation period is more than double the length of a human pregnancy, so it shouldn't come as a shock that female elephants don't often have more than four offspring during their lifetimes. Who has the time?


A photo of a mother hippo and her baby in Uganda

Yes, it takes less time to make a hippopotamus than it takes to make a human.


Baby giraffes can weigh more than 150 pounds and can be around 6 feet tall. Another fascinating tidbit: giraffes give birth standing up, so it's pretty normal for a baby to fall 6 feet to the ground.


There’s a reason for the long wait: after that 17 months, Baby Shamu emerges weighing anywhere from 265 to 353 pounds and measuring about 8.5 feet long. Yikes.

5. OPOSSUM: 12-13 DAYS

A baby opossum wrapped up in a blanket

Blink and you'll miss it: This is the shortest gestation period of any mammal in North America. But since the lifespan of an opossum is only two to four years, it makes sense.


Hey, they get off pretty easy.


It's not a huge surprise that their gestational periods are pretty similar to ours, right?


A pair of black bear cubs

Also less than a human. Interestingly, cubs might only be 6 to 8 inches in length at birth and are completely hairless. 


This is the longest gestation period of any rodent. Thankfully for the mother, porcupine babies (a.k.a. porcupettes) are actually born with soft quills, and it's not until after birth that they harden up.


Baby walruses? Kind of adorable. They certainly take their sweet time coming out, though.


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