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Can Birds Smell?

Legendary birdman John James Audubon would tell you decisively that, no, birds can't smell. In the 1820s, Audubon designed two experiments to prove that turkey vultures followed their eyes, not their noses, to carrion. First, the naturalist left a stuffed deer in a meadow with its legs in the air. Before long, the deer attracted the attention of a vulture, who dropped out of the sky to investigate. Finding nothing but grass inside the fake deer, the vulture took off.

The second experiment took place in the sweltering heat of July. Audubon dragged a decaying pig carcass into a ravine and covered the body with brush. The vultures spotted it, but they weren’t interested. That was that, said Audubon. No smell.

For more than a century, scientists took him at his word. Then, in the 1960s, an ornithologist at the Los Angeles County Natural History Museum named Kenneth Stager realized why vultures ignored Audubon’s carcass in the woods: it was just too gross. Like any discriminating diner, a turkey vulture prefers a fresh carcass [PDF], no more than four days old.

Through rather odd means, Stager learned that vultures actually do use smell. A gas company worker mentioned to him that turkey vultures would congregate around leaks in the pipeline, showing up so reliably that they began to use the birds as leak detectors.

This behavior occurred because the company had added a smelly chemical called ethyl mercaptan to the gas. You know what else gives off ethyl mercaptan? Carrion. Stager was able to tie the two together to suggest that vultures do in fact sniff their way to supper.

Stager wasn’t the only scientist interested in bird olfaction. In 1965, physiologist Bernice Wenzel of UCLA hooked pigeons up to heart monitors and exposed them to strong smells. The pigeons’ heart rates spiked each time a scent wafted their way. Then she attached electrodes to the pigeons’ olfactory bulbs (the smell centers of the brain) and started again. The results were just as dramatic.

In the half-century since, scientists have tested more than a hundred bird species, and all of them have had at least some sense of smell.

At times, their experiments have swerved into the realm of the bizarre. Sensory ecologist Gabrielle Nevitt once soaked super-absorbent tampons in fish-scented oil and tied the tampons to kites, launching them over the sea. The experiment worked a little too well: after a short while, the swarming seabirds were so intense that Nevitt had to bring the kites down in order to keep them from getting tangled in the strings.

Just how much a bird can smell depends on its species. The humble kiwi has one of the strongest senses of smell in the bird family, and it’s the only bird with nostrils at the end of its beak. At night, the kiwis sweep their beak tips along the ground like metal detectors, sniffing out earthworms and grubs.

Eurasian rollers, on the other hand, use scent in self-defense. When threatened, roller chicks vomit up an awful-smelling orange liquid. The stink not only deters potential predators, but it also acts as a warning. When the adult birds return to the nest, the scent tells them that a predator has been, and may still be, near.

Other birds use scent as an instrument of seduction. Crested auklets produce a tangerine-scented oil, which they dab all over their feathers like perfume. The better a bird smells, the better its chances of mating.

The same goes for the pudgy, flightless parrot known as the kakapo, which is said to emit a smell like lavender and honey. The kakapo is extremely endangered—there are only 124 left in the wild—so mating is of dire importance. One researcher even considered creating a synthetic kakapo perfume and applying it to unattractive males in the hopes of boosting their chances.

As for Toucan Sam, the jury's still out.

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holidays
Bleat Along to Classic Holiday Tunes With This Goat Christmas Album
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Feeling a little Grinchy this month? The Sweden branch of ActionAid, an international charity dedicated to fighting global poverty, wants to goat—errr ... goad—you into the Christmas spirit with their animal-focused holiday album: All I Want for Christmas is a Goat.

Fittingly, it features the shriek-filled vocal stylings of a group of festive farm animals bleating out classics like “Jingle Bells,” “Rudolph the Red-Nosed Reindeer,” and “O Come All Ye Faithful.” The recording may sound like a silly novelty release, but there's a serious cause behind it: It’s intended to remind listeners how the animals benefit impoverished communities. Goats can live in arid nations that are too dry for farming, and they provide their owners with milk and wool. In fact, the only thing they can't seem to do is, well, sing. 

You can purchase All I Want for Christmas is a Goat on iTunes and Spotify, or listen to a few songs from its eight-track selection below.

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Animals
If You Want Your Cat to Poop Out More Hairballs, Try Feeding It Beets
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Have you ever wondered if there’s a way to get your cat to poop out its hairballs instead of hacking them up? If so, you’re likely a seasoned cat owner whose tolerance for gross stuff has reached the point of no return. Luckily, there may be an easy way to get your cat to dispose of hairballs in the litter box instead of on your carpet, according to one study.

The paper, published in the Journal of Physiology and Animal Nutrition, followed the diets of 18 mixed-breed short-haired cats over a month. Some cats were fed straight kibble, while others were given helpings of beet pulp along with their regular meals. The researchers suspected that beets, a good source of fiber, would help move any ingested hair through the cats’ digestive systems, thus preventing it from coming back up the way it went in. Following the experiment, they found that the cats with the beet diet did indeed poop more.

The scientists didn’t measure how many hairballs the cats were coughing up during this period, so it's possible that pooping out more of them didn’t stop cats from puking them up at the same rate. But considering hairballs are a matter of digestive health, more regular bowel movements likely reduced the chance that cats would barf them up. The cat body is equipped to process large amounts of hair: According to experts, healthy cats should only be hacking hairballs once or twice a year.

If you find them around your home more frequently than that, it's a good idea to up your cat's fiber intake. Raw beet pulp is just one way to introduce fiber into your pet's diet; certain supplements for cats work just as well and actually contain beet pulp as a fiber source. Stephanie Liff, a veterinarian at Pure Paws Veterinary Care in New York, recommends psyllium powder to her patients. Another option for dealing with hairballs is the vegetable-oil based digestive lubricant Laxatone: According to Dr. Liff, this can "help to move hairballs in the correct direction."

[h/t Discover]

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