This Crow’s Beak Evolved to Wield Tools

Sometimes we adapt tools to suit our purposes. Sometimes nature adapts us to suit our tools. For example: ornithologists say the bills of some crows have evolved to help them hold and manipulate their tools. The researchers published their findings in the journal Scientific Reports.

Scientists are beginning to realize that birds are much sharper than we previously realized, but even by bird-smarts standards, the New Caledonian crow (Corvus moneduloides, also known as the NCC) is special. The NCC’s ingenuity is exclusively food-driven, although their foods of choice are bugs and grubs that live in tree trunks. To extract their prey, NCCs make fishing rods and hooks by trimming excess pieces from slender sticks and barbed leaves. There’s only one other animal on Earth that makes fishing hooks: humans.

Scientists say these sophisticated behaviors are made possible by two of the crow's features: its brain and its beak. The latter's uniqueness is a new discovery, but the epiphany that inspired it is nearly 20 years old.

Ornithologist Kevin McGowan was looking at stuffed bird specimens one day in the late '90s when he noticed the NCCs. "I remember saying to a student, 'I don't know what this bird does, but it does something different from any other corvid on Earth because its bill is so weird,'" McGowan recalled in a press statement.

A few years later, in 2000, a researcher named Gavin Hunt published a paper on the NCC’s extraordinary tool use. As McGowan read the paper, a light bulb went on in his head.

Then, McGowan, Hunt, and seven of their colleagues in New Zealand and Japan decided to find out if their suspicions were right. They used computed tomography, better known as CT scanning, to make 3D images of the beaks of 11 species: NCCs, nine of their relatives, and black woodpeckers, which feed on the same in-tree grubs and bugs as the NCCs. The researchers created 11 reference points, or landmarks, so they could compare the beaks’ proportions and dimensions.

Image Credit: Matsui et al. 2016

The researchers found that McGowan was right—the shape of the NCC’s beak is completely unique. "Their bill is shorter than a regular crow's," McGowan said. "It's blunter, and it doesn't curve down like nearly all bird bills do.”

There’s a reason for that. NCCs hold their tools in their beaks, and they have perfected a technique that requires holding the stick or leaf at a specific angle. Over generations, the NCC’s beaks have obligingly curved to make this possible.

“The lower mandible actually curves slightly up, which likely gives it the strength it needs to hold the tool," McGowan said. "And because the bill doesn't curve downward it brings the tool into the narrow range of the bird's binocular vision so it can better see what it is doing."

Just like a left- or right-handed human holding a tool, each crow has a dominant side. "They hold the stick tool so that it goes up along the side of their head along the length of the bill," McGowan said. "Apparently there are birds that favor one side of the head over the other—left-sticked or right-sticked, you could call it—it’s really cool."

Slow Motion Is the Only Way to Appreciate a Chameleon’s Lightning-Fast Tongue

From the unusual way they walk, to their ability to change color, the evolutionary adaptations of chameleons are pretty bizarre, and some of them remain mysterious even to scientists. Their super-powered tongues, for instance, can dart out so quickly that the movement can barely be seen with the naked eye. But modern high-speed cameras have enabled researchers at the University of South Dakota to observe this appendage at work like never before. The video below, shared over at The Kid Should See This, includes some of that groundbreaking footage, and it's pretty amazing to watch.

Shooting at 3000 frames per second, the camera was able to capture every split-second aspect of the chameleon's tongue strike. Slowed down, the video allows you to see how every component of the process works in harmony: First, muscles in the lizard’s tongue contract like the string of a bow. Then, when that tension is released, the bony base of the tongue shoots forward, pushing the sticky, elastic part toward the chameleon’s prey.

According to Christopher Anderson, one of the scientists who conducted the high-speed camera research, larger chameleons can catapult their tongues forward at distances of one to two times their body length. For smaller chameleons, this distance can reach up to two and a half times their body length. “Small chameleons need to be able to eat more food for their body size than large chameleons,” he tells bioGraphic in the video, “and so by being able to project their tongues proportionately further than these large species, they basically are opening up additional feeding opportunities to themselves that they wouldn’t have if they had a shorter tongue.”

To see one of nature’s greatest hunting tools in action, check out the full video below.

[h/t The Kid Should See This]

There May Be an Ancient Reason Why Your Dog Eats Poop

Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]


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