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Sarah Knutie, University of Utah

Galapagos Birds Beat Bloodsuckers with Pesticide-Lined Homes

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Sarah Knutie, University of Utah

In the 1990s, the fly Philornis downsi was accidentally introduced to the Galapagos Islands, probably in a shipment of fruit. The adult flies are harmless enough as invaders go, but their kids are a real problem for the islands’ native birds, some of which are found nowhere else in the world and a few of which are endangered.

The flies lay their eggs in birds’ nests just as the chicks are emerging from their own eggs, and once the larvae hatch, they begin to eat their hosts from both inside and out. No larger than grains of rice, the maggots wriggle their way into the baby birds’ nostrils and eat away at their nasal cavities. As they get larger, the parasites burst back out and continue to live in the nest, hiding by day and emerging each night to suck blood from the chicks. This is often too much for the birds to bear. In some years, the parasites have killed every single chick in a given area and caused every nest to fail. Even if the birds survive, they often have difficulty eating because their beaks are deformed from the larvae that crawled around inside.

Among the birds that the flies maim and kill are Darwin’s finches, a group of 15 related species whose beaks diverged in form as adaptations to their function and were a key piece of evidence for Charles Darwin when he was developing his idea of evolution by natural selection. And even though they’re textbook examples of adaptation, the birds haven’t adapted to the parasites yet because they don’t have a long evolutionary history with them. For now, it falls to scientists to protect them. Conservation biologists have tried treating the nests with insecticides, which increases the number of chicks that survive long enough to fly on their own, and also removing chicks of the most vulnerable species from their nests and raising them in incubators.

Neither of these strategies is inexpensive or easy. Treating the nests is particularly tricky because they’re often hard to find or placed too high in the trees to reach. Now a team of biologists thinks they’ve found a new, more efficient way to do it: lend the birds the insecticides and let them be their own exterminators.

The idea came to University of Utah doctoral student Sarah Knutie as she watched finches come to the laundry lines outside her island dorm and pull threads from clothes and towels to add to their nests. She wondered if the birds would also take fibers that had been treated with permethrin—an insecticide often used in flea collars and lice shampoos—and work them into the nests to “self-fumigate” them.

To find out, Knutie, other students and their advisor Dale Clayton fashioned 30 dispensers out of wire mesh, filled them with either permethrin- or water-soaked cotton, and placed them along a road near nesting sites on Santa Cruz Island.

When the breeding season was over and the baby birds left home, the researchers collected and dissected 26 empty nests built by four different finch species. Twenty-two of the nests contained cotton from the dispensers, and more than half of those contained the insecticide-laced cotton.

The birds were apparently happy to take the dosed cotton, and it paid off for them. The nests with the permethrin cotton in them contained about half as many parasites as the ones that had plain cotton or no cotton at all, and all but one of the nests with a least of a gram of treated cotton—about a thimble's worth—were parasite-free. 

If more cotton dispensers can be installed and maintained, they could make a huge difference for some of the islands’ birds. One of Darwin’s finches, the mangrove finch, has a population of less than 100 birds confined to about a square kilometer of land. It would only take 60 dispensers, Knutie says, to protect the whole population from the flies.

The researchers hope that the same method could be used to protect other birds and nest-building animals against parasites and pests, from Hawaiian honeycreepers dealing with feather lice to prairie dogs that are literally plagued by Yersinia pestis-carrying fleas. Just a little puff of cotton could go a long way in helping these animals help themselves. 

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Big Questions
Why Can't Dogs Eat Chocolate?
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Even if you don’t have a dog, you probably know that they can’t eat chocolate; it’s one of the most well-known toxic substances for canines (and felines, for that matter). But just what is it about chocolate that is so toxic to dogs? Why can't dogs eat chocolate when we eat it all the time without incident?

It comes down to theobromine, a chemical in chocolate that humans can metabolize easily, but dogs cannot. “They just can’t break it down as fast as humans and so therefore, when they consume it, it can cause illness,” Mike Topper, president of the American Veterinary Medical Association, tells Mental Floss.

The toxic effects of this slow metabolization can range from a mild upset stomach to seizures, heart failure, and even death. If your dog does eat chocolate, they may get thirsty, have diarrhea, and become hyperactive and shaky. If things get really bad, that hyperactivity could turn into seizures, and they could develop an arrhythmia and have a heart attack.

While cats are even more sensitive to theobromine, they’re less likely to eat chocolate in the first place. They’re much more picky eaters, and some research has found that they can’t taste sweetness. Dogs, on the other hand, are much more likely to sit at your feet with those big, mournful eyes begging for a taste of whatever you're eating, including chocolate. (They've also been known to just swipe it off the counter when you’re not looking.)

If your dog gets a hold of your favorite candy bar, it’s best to get them to the vet within two hours. The theobromine is metabolized slowly, “therefore, if we can get it out of the stomach there will be less there to metabolize,” Topper says. Your vet might be able to induce vomiting and give your dog activated charcoal to block the absorption of the theobromine. Intravenous fluids can also help flush it out of your dog’s system before it becomes lethal.

The toxicity varies based on what kind of chocolate it is (milk chocolate has a lower dose of theobromine than dark chocolate, and baking chocolate has an especially concentrated dose), the size of your dog, and whether or not the dog has preexisting health problems, like kidney or heart issues. While any dog is going to get sick, a small, old, or unhealthy dog won't be able to handle the toxic effects as well as a large, young, healthy dog could. “A Great Dane who eats two Hershey’s kisses may not have the same [reaction] that a miniature Chihuahua that eats four Hershey’s kisses has,” Topper explains. The former might only get diarrhea, while the latter probably needs veterinary attention.

Even if you have a big dog, you shouldn’t just play it by ear, though. PetMD has a handy calculator to see just what risk levels your dog faces if he or she eats chocolate, based on the dog’s size and the amount eaten. But if your dog has already ingested chocolate, petMD shouldn’t be your go-to source. Call your vet's office, where they are already familiar with your dog’s size, age, and condition. They can give you the best advice on how toxic the dose might be and how urgent the situation is.

So if your dog eats chocolate, you’re better off paying a few hundred dollars at the vet to make your dog puke than waiting until it’s too late.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
7 Fun Facts for World Elephant Day
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Happy World Elephant Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.

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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.

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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit low-frequency sound, inaudible to humans, that warns other elephants. "It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told the Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.

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Human adults and babies often use pointing as a way to nonverbally get a message across, but not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 

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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.

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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.

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If you thought being pregnant for nine months was bad, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herds’ complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.

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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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