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Wikimedia Commons

Birds Steer Clear of Invisible Roads

Wikimedia Commons
Wikimedia Commons

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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Animals
10 Notable Gestation Periods in the Animal Kingdom
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The gestation periods of the animal kingdom are varied and fascinating. Some clock in at just a few weeks, making any human green with envy, while others can last more than a year. Here are 10 notable gestation times for animals around the globe. The lesson? Be thankful that you’re not a pregnant elephant.

1. ELEPHANTS: 640-660 DAYS

Elephants are pregnant for a long time. Like really, really long. At an average of 95 weeks, the gestation period is more than double the length of a human pregnancy, so it shouldn't come as a shock that female elephants don't often have more than four offspring during their lifetimes. Who has the time?

2. HIPPOS: 8 MONTHS

A photo of a mother hippo and her baby in Uganda

Yes, it takes less time to make a hippopotamus than it takes to make a human.

3. GIRAFFE: 14-15 MONTHS

Baby giraffes can weigh more than 150 pounds and can be around 6 feet tall. Another fascinating tidbit: giraffes give birth standing up, so it's pretty normal for a baby to fall 6 feet to the ground.

4. KILLER WHALE: 17 MONTHS

There’s a reason for the long wait: after that 17 months, Baby Shamu emerges weighing anywhere from 265 to 353 pounds and measuring about 8.5 feet long. Yikes.

5. OPOSSUM: 12-13 DAYS

A baby opossum wrapped up in a blanket

Blink and you'll miss it: This is the shortest gestation period of any mammal in North America. But since the lifespan of an opossum is only two to four years, it makes sense.

6. GERBILS: 25 DAYS

Hey, they get off pretty easy.

7. GORILLAS: 8.5 MONTHS

It's not a huge surprise that their gestational periods are pretty similar to ours, right?

8. BLACK BEAR: 220 DAYS

A pair of black bear cubs

Also less than a human. Interestingly, cubs might only be 6 to 8 inches in length at birth and are completely hairless. 

9. PORCUPINE: 112 DAYS

This is the longest gestation period of any rodent. Thankfully for the mother, porcupine babies (a.k.a. porcupettes) are actually born with soft quills, and it's not until after birth that they harden up.

10. WALRUS: 15 MONTHS

Baby walruses? Kind of adorable. They certainly take their sweet time coming out, though.

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Goldfish Can Get Depressed, Too
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Don’t believe what Pixar is trying to sell you: Fish are not exactly brimming with personality. In aquariums, they tend to swim in circles, sucking up fragments of food and ducking around miniature treasure chests. To a layperson, fish don’t appear to possess concepts of happy, or sad, or anything in between—they just seem to exist.

This, researchers say, is not quite accurate. Speaking with The New York Times, Julian Pittman, a professor at the Department of Biological and Environmental Sciences at Troy University, says that fish not only suffer from depression, they can be easily diagnosed. Zebrafish dropped into a new tank who linger at the bottom are probably sad; those who enthusiastically explore the upper half are not.

In Pittman’s studies, fish depression can be induced by getting them “drunk” on ethanol, then cutting off the supply, resulting in withdrawal. These fish mope around the tank floor until they’re given antidepressants, at which point they begin happily swimming near the surface again.

It’s impossible to correlate fish depression with that of a human, but Pittman believes the symptoms in fish—losing interest in exploring and eating—makes them viable candidates for exploring neuroscience and perhaps drawing conclusions that will be beneficial in the land-dwelling population.

In the meantime, you can help ward off fish blues by keeping them busy—having obstacles to swim through and intriguing areas of a tank to explore. Just like humans, staying active and engaged can boost their mental health.

[h/t The New York Times]

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