Why Are Some Birds So Smart? Their Brains Are Neurally Dense

Alastair Rae via Wikimedia Commons // CC BY-SA 2.0
Alastair Rae via Wikimedia Commons // CC BY-SA 2.0

Little by little, the well-established myth of the stupid bird is crumbling. Just a few months ago, researchers reported that some birds are as smart as apes. Now another team of scientists say that bird brains pack way more brain cells per square inch than those of primates and other mammals. They published their findings in the Proceedings of the National Academy of Sciences.

The brains of humans and apes include a structure called the neocortex, which houses some of our most sophisticated thought processes and mental tasks. Birds don’t have neocortices at all, and so for years, scientists assumed that meant they were unintelligent. As it turns out, we were just being self-centered. Birds don’t need neocortices; a similar structure called a pallium does their mental heavy lifting.

One bird stereotype is accurate: Compared to, say, a human or a chimpanzee, birds do have little brains. Yet “corvids and some parrots are capable of cognitive feats comparable to those of great apes,” the authors write. “How do birds achieve impressive cognitive prowess with walnut-sized brains?”

To find out, the researchers examined the brains of 28 different bird species, from tiny zebra finches to towering emus. They examined the birds’ brain tissue at a cellular level, measuring the number and distribution of neurons in each region. They compared the neural density to that found in the brains of mice, rats, primates, and artiodactyls (even-toed ungulates).

As it turns out, when it comes to brain cell density, birds have them all beat. The pallium was crammed wall-to-wall with brain cells. Parrot and songbird brains contained twice as many neurons as similar-sized primate brains, and two to four times as many neurons as those of rodents. Birds also dedicate way more brainpower to their pallia than we do to our neocortices. The pallium houses 33 to 55 percent of a songbird’s brain cells, and 46 to 61 percent of a parrot’s. By comparison, the human neocortex hosts only 19 percent of our brain cells.

Senior author Suzana Herculano-Houzel, a neuroscientist at Vanderbilt University, said in a press statement: “In designing brains, nature has two parameters it can play with: the size and number of neurons and the distribution of neurons across different brain centers, and in birds we find that nature has used both of them.”

These findings open a new pathway in understanding how brains evolve. Generally speaking, in order to advance, brains have had to get bigger, and bigger brains are linked to more cognitive capacity. But, Herculano-Houzel said, “bird brains show that there are other ways to add neurons: keep most neurons small and locally connected and only allow a small percentage to grow large enough to make the longer connections."

But no evolutionary advantage is truly free. Does a denser bird brain require more energy to run than ours, which are spacious by comparison? If so, where is that energy coming from?

“Something I love about science is that when you answer one question, it raises a number of new questions,” said Herculano-Houzel.

Meet Gracie: The Resident 'Bark Ranger' at Montana's Glacier National Park

NPS/A.W. Biel
NPS/A.W. Biel

Gracie isn't like the other park rangers at Glacier National Park in Montana: She’s not afraid to run after bighorn sheep and mountain goats in order to keep them at a safe distance from visitors. And while she doesn’t earn a salary, she’s content to work for belly rubs.

That’s because Gracie is a trained border collie who became the first employee-owned dog to become a “bark ranger” at a U.S. national park. She was accepted into Glacier’s wildlife shepherding program in July 2016 and has been protecting both humans and wildlife alike ever since.

One of Gracie's main duties is to keep sheep and goats away from areas with high foot traffic, like the Logan Pass parking lot. Through habituation, many of the park’s native species have begun to feel comfortable around humans, and sometimes even approach them. This is problematic for a couple of reasons.

“When closely approached or provided with human food, bighorn sheep and mountain goats can become aggressive; each has the ability to kick, bite, gore, or trample when feeling threatened,” the National Park Service (NPS) writes on its website. “This can cause injury—or in rare cases, death—to people and can cause the animal to be lethally removed from the population.”

In the winter, Gracie also helps shepherd deer out of highly populated areas in an effort to keep predators—namely mountain lions—away from people. Gracie completed a 10-week training program in Florence, Montana, where she learned how to control her direction and speed. She also knows when to retreat at the command of her owner, Mark Biel, who works as the park's natural resources program manager.

Gracie’s hard work has not gone unnoticed either. Her Instagram account, which chronicles the life of a #WorkingDog, has more than 17,000 followers. Check out some of the photos and videos below to see this very good girl in action.

Every time Gracie moves wildlife, Ranger Mark records how many animals were moved, how long it took to move them, where they went, and how long they stayed out of the area. This helps us evaluate the effectiveness of the program and learn about wildlife habits. The data show that in the park headquarters area, the deer have four established “escape routes” they favor when heading into the woods. Watch as this deer stops to decide which way to go, then heads to the left, toward the woods and one of those routes. Turning to the right would have taken it away from Gracie, but further into the housing area. This is an example of the program working as it’s intended. When pressured from a distance, the deer decides that the more comfortable place to be is in the woods, instead of further inside the populated area. 🐾🦌 #parkscience #barkrangergracie #barkranger #whitetail #keepwildlifewild​ @glaciernps @glacierconservancy @wind_river_bear_institute #workingbordercollie #workingdogsofig #glaciernationalpark #glacier

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What's the Difference Between a Rabbit and a Hare?

iStock.com/Carmen Romero
iStock.com/Carmen Romero

Hippity, hoppity, Easter's on its way—and so is the eponymous Easter bunny. But aside from being a magical, candy-carrying creature, what exactly is Peter Cottontail: bunny, rabbit, or hare? Or are they all just synonyms for the same adorable animal?

In case you've been getting your fluffy, long-eared mammals mixed up, we've traveled down the rabbit hole to set the record straight. Although rabbits and hares belong to the same grass-munching family—called Leporidae—they're entirely different species with unique characteristics. It would be like comparing sheep and goats, geneticist Steven Lukefahr of Texas A&M University told National Geographic.

If you aren't sure which animal has been hopping around and helping themselves to the goodies in your vegetable garden, take a closer look at their ears. In general, hares have longer ears and larger bodies than rabbits. Rabbits also tend to be more social creatures, while hares prefer to keep to themselves.

As for the baby animals, they go by different names as well. Baby hares are called leverets, while newborn rabbits are called kittens or kits. So where exactly do bunnies fit into this narrative? Originally, the word bunny was used as a term of endearment for a young girl, but its meaning has evolved over time. Bunny is now a cutesy, childlike way to refer to both rabbits and hares—although it's more commonly associated with rabbits these days. With that said, the Easter bunny is usually depicted as a rabbit, but the tradition is thought to have originated with German immigrants who brought their legend of an egg-laying hare called "Osterhase" to America.

In other ambiguous animal news, the case of Bugs Bunny is a little more complicated. According to scientist and YouTuber Nick Uhas, the character's long ears, fast speed, and solitary nature seem to suggest he's a hare. However, in the cartoon, Bugs is shown burrowing underground, which doesn't jive with the fact that hares—unlike most rabbits—live aboveground. "We can draw the conclusion that Bugs may be a rabbit with hare-like behavior or a hare with rabbit nesting habits," Uhas says.

The conversation gets even more confusing when you throw jackrabbits into the mix, which aren't actually rabbits at all. Jackrabbits are various species of large hare that are native to western North America; the name itself is a shortened version of "jackass rabbit," which refers to the fact that the animal's ears look a little like a donkey's.

A jackrabbit
Connor Mah, Flickr // CC BY-SA 2.0

As Mark Twain once famously wrote about the creature, "He is just like any other rabbit, except that he is from one-third to twice as large, has longer legs in proportion to his size, and has the most preposterous ears that ever were mounted on any creature but the jackass." (Fun fact: Black-tailed jackrabbits' extra-long ears actually help them stay cool in the desert. The blood vessels in their ears enlarge when it gets hot, causing blood to flow to their ears and ridding their bodies of excess heat.)

Rabbits, hares, and jackrabbits all have one thing in common, though: They love a good salad. So if you happen across one of these hopping creatures, give them some grass or weeds—and skip the carrots. Bugs Bunny may have loved the orange vegetable, but most hares and rabbits would prefer leafy greens.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

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