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BS Thurner Hof via Wikimedia Commons // CC BY-SA 3.0
BS Thurner Hof via Wikimedia Commons // CC BY-SA 3.0

Noise Keeps Animals From Recognizing the Scent of Danger

BS Thurner Hof via Wikimedia Commons // CC BY-SA 3.0
BS Thurner Hof via Wikimedia Commons // CC BY-SA 3.0

Picture this: you’re driving somewhere you’ve never been before, blasting your favorite tunes. As you approach your destination and start checking house numbers, your hand reaches for the dial and turns the radio down. Without even realizing it, you’ve decided to redirect your attention from sounds to sights. Now imagine that your passenger has interfered. They’ve turned the radio all the way up and opened all the windows, filling the car with the roar of traffic and wind as you’re trying to focus. Harder now, isn’t it? And it isn’t just us; scientists say mongooses exposed to traffic noise overlook crucial clues from their other senses—clues that could mean the difference between life and death. Their findings were published today in the journal Current Biology.

We’ve known for a long time that pollution and urbanization are bad news for everyone. Much of our research has focused on the physical effects like smog, water contamination, and habitat destruction. We haven’t paid too much attention to the toxic effects of too much noise until recently, but what we’ve learned is troubling.

Studies have shown that exposure to anthropogenic, or human-made, noise causes intense stress for animals, can interfere with their communication, and may even keep them from migrating and having sex. All of these issues could mess with a species’ chances of survival in the long run.

The short-term effects have been less understood, says biologist Amy Morris-Drake of the University of Bristol. She and her colleagues decided to test the immediate consequences of noise on one species, the dwarf mongoose (Helogale parvula), whose South African habitat is increasingly bounded by cities and roads.

The dwarf mongoose has many predators, including jackals, hyenas, civets, servals, honey badgers, wildcats, bigger mongooses, and an assortment of reptiles. The key to survival, consequently, is constant olfactory vigilance: sniffing the air for the scent of predator poop.

The research team headed into mongoose territory with audio recordings of traffic noise and Ziploc baggies of poop from servals, wildcats, and giraffes. (Because giraffes present no threat to mongooses, their poop was used as a control group.) The researchers set out the poop and played their road sounds, watching the mongooses to see how they would respond.

The results were not encouraging. Exposure to traffic noises significantly decreased the mongooses’ vigilance. They spent less time investigating the predator poop; they were less likely to scan the area for potential threats; and they were less likely to retreat to the entrance of their burrow to prepare for an attack. If the scientist-provided poop, and therefore the threat, had been real, those mongooses would have found themselves in significant danger.

"Our study suggests that noise pollution can have a negative effect in terms of information use,” said co-author Andy Radford. “Given the demonstrated effects, considering the interactions among multiple sensory channels is critically important if we are to understand fully the consequences of human-induced environmental change."
 
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Slow Motion Is the Only Way to Appreciate a Chameleon’s Lightning-Fast Tongue
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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]

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There May Be an Ancient Reason Why Your Dog Eats Poop
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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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