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Birds Steer Clear of Invisible Roads

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Forget about whether the chicken crossed the road or not. The question for some scientists is why other birds won’t even come near a roadway. 

Wherever wildlife and automobile traffic meet, it’s usually bad news for the animals. More than just making roadkill, roads use up land, create noise and pollution, and act as barriers that cut animals off from resources, mates, and territory. Because of all these problems, bird populations tend to decline sharply within a kilometer of a road or other human infrastructure, and mammals begin declining within five kilometers. 

You’re within about a kilometer away from a road in more than 80 percent of the USA. That’s a whole lot of country covered in things that bug birds. But what bothers them most? The trash? Close calls with windshields? A lot of research has suggested that it's the level of noise around a busy roadway, but most of these studies have been done along actual roads. When all the potential bird-deterring effects are there at the same time, it’s hard to pin down the strength of any single one. 

To isolate the noise factor and see how much it matters to birds, biologists from Boise State University in Idaho wanted a way to create traffic noise without actual traffic. They decided to hide speakers in the trees of a southern Idaho forest that migrating birds use as a rest stop. When they piped recordings of traffic sounds through the speakers, they had a half-kilometer-long “phantom road” that wouldn’t bother the birds any way but through their ears. 

The Road Not Taken

Alternating between four days of noise and four days of quiet throughout the fall migration season, the researchers recorded visits of more than 8000 individual birds from 59 species to their phantom road and a noise-less control site. Whenever they turned the speakers on, the total bird abundance at the phantom road declined by more than a quarter. Some species avoided the area in even greater proportions, and a few, like the cedar waxwing, avoided it almost entirely.

Scaring away that many birds with only traffic noise is a startling demonstration of how man-made noise can alter the way animals use space. Because of the sheer amount of land that roads cover in the U.S., particularly noise-sensitive species like the waxwings and yellow warblers are pushed away from a whole lot of otherwise useable habitat because it’s too loud for them. 

Even within national parks and other protected areas, the researchers say, roads can produce noise levels similar to their phantom road, and man-made noise needs to be taken into account when preserving and managing land and wildlife. The next step is figuring out why noise is such a big deterrent for birds. It could be that noise masks birds’ songs and calls and keeps them from finding or communicating with one another. Other scientists have found that birds with high-frequency songs aren’t as bothered by roads and certain industrial sites because these low-frequency noises don’t drown out their songs as much as they do some other species. 

Road noise might also turn birds away because it keeps them from hearing predators. Some birds, like chaffinches, and other animals are more vigilant in noisy areas so other animals don’t get the drop on them, often at the expense of eating or other normal behaviors. If more noise means less eating, then roads are especially lousy places to be when a bird is migrating and needs fuel to keep going. 

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Big Questions
Why Do Dogs Howl at Sirens?
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A dog's behavior can often prove confusing to their human colleagues. We know they like to eat their own poop, but puzzle at their motivations. We're surprised when dogs give a ladybug the same greeting as a home intruder.

Topping the list of eccentric canine behavior: Why do dogs howl at sirens? Is there some genetic predisposition to responding to a high-pitched alarm from passing ambulances or police vehicles?

As it turns out, the reason dogs howl at sirens is because of their ancestry—namely, the wolf. When members of a pack are fractured and spread out, their companions will howl to provide a way of locating them. Think of it as nature’s GPS: By howling, dogs are able to communicate their respective locations to one another, even across long distances.

Since dogs really don’t know what a cop car is supposed to sound like, they’ll often interpret a siren as an animal’s howl. It’s also possible that dogs consider sirens to be a sign that something is abnormal in their environment, and that they want you, the pack leader, to be aware of it.

Contrary to belief, a dog is rarely howling because the noise hurts their delicate ears. If that were the case, some experts say, then they would display other behaviors, like running and hiding.

The more a dog hears and responds to a siren, the more they might be compelled to continue the behavior. That’s because dogs who howl and then notice the sound drifting away might begin to associate their vocalizing with the disappearance of the noise. In the future, they’ll probably recall that they “drove” the interloper away with their warbling and repeat the process.

While howling is usually harmless, sometimes it can be a sign that your pet is feeling separation anxiety from an owner or that they’re feeling unwell. If howling persists even without a screaming siren within earshot, you might consider taking them in for a check-up.

If you’ve wondered why dogs howl at sirens, now you know. It’s simply a way of signaling their location and not because it pains them. Owners, on the other hand, might feel differently.

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
5 Ways to Keep Your Dog Calm on the Fourth of July

The Fourth of July can be rough for dogs. Fireworks displays light up their senses with unfamiliar noises, flashes, and smells, and parties flood their homes with strange guests who may invade the rooms they usually have as private retreats. And when distressed dogs escape, howl, or thrash around the house, Independence Day can quickly become a nightmare for their owners, too. To minimize Fido's stress this holiday, we spoke to some dog experts to discover the best ways to keep your canine calm on the Fourth of July.

1. EXERCISE

Anthony Newman, the dog whisperer who runs New York City's Calm Energy Dog Training, says that exercise is a great way to help your dog let off some nervous energy. “Whenever Fido is going to be neglected for an extended period of time, or around any stressful stimuli, it always helps to tire him out just before—and even during the night if you can,” Newman says. “As the saying goes, a tired dog is a good dog! He’ll be calmer, happier, and more peaceful.”

2. STAY INDOORS

Dr. Stephanie Liff, head veterinarian at Pure Paws Veterinary Care, says the best place to keep your pet during a fireworks show is inside and away from the windows. “If the pet is very scared, an escape-proof crate or a sound-insulated room, such as an internal bathroom, may help the pet to feel more secure,” Liff tells us. “If you cannot keep your pet inside, make sure that the pet is prevented from escape (monitor all exits and tell guests to monitor your pet).”

3. SOCIALIZE

While your dog may feel more secure in a room away from all the noise, Newman points out that keeping your dog isolated in another room for too long can be stressful for your pet. “Release his curiosity and let him in on the fun, to run around and play with both two-legged as well as four-legged guests,” Newman says. “Then back to his obedient room, bed, car, crate, or spot. Rinse and repeat as needed throughout the night."

4. TAKE CONTROL

According to Newman, the best way to keep your dog calm during the chaos of July 4th is to stay in charge. “If your dog winces, shivers, and runs away at loud noises, the last thing he wants is to feel like nobody else is looking out for him,” Newman says. Don’t let your dog run rampant around the house or follow him around trying to soothe him. Instead, Newman says it's important to “take control by attaching a super-light leash that you can grab and lead him whenever you need.”

5. MEDICATE

In extreme cases of nervousness, Liff says that you should talk to your vet about medication to sedate your dog.

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