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How Can Owls Rotate Their Heads 270 Degrees Without Dying?

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For humans, sudden gyrations of the head and neck—whether they’re from car accidents, rollercoaster rides, or chiropracty gone awry—can tear blood vessel linings in the neck, leading to clots that can cause stroke. Not so in owls, which can quickly rotate their heads 270 degrees in either direction without damaging blood vessels or cutting off blood flow to the brain. How do they do it?

To solve the mystery, scientists at Johns Hopkins—led by medical illustrator Fabian de Kok-Mercado and neuroradiologist Philippe Gailloud—used angiography and CT scans to examine the anatomy of a dozen snowy, barred, and great horned owls that died from natural causes. They discovered that the birds are equipped with four biological adaptations that prevent injury from rapid rotational movement; their study appears in the latest issue of Science.

“Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke," Gailloud said in a press release announcing the results of the study. "The carotid and vertebral arteries in the neck of most animals—including owls and humans—are very fragile and highly susceptible to even minor tears of the vessel lining.”

After x-raying, dissecting and analyzing blood vessels from the dead birds’ necks, the researchers injected dye into the dead owls’ arteries to mimic blood flow and manually turned their heads. What they found was surprising: Unlike in humans, whose arteries shrink as the head turns, the blood vessels just under the jaw at the base of the owls’ heads got increasingly larger as more of the dye entered, but before the fluid pooled into reservoirs. These contractile reservoirs, scientists say, are what allow owls to turn their heads so radically while still having enough blood to feed the eyes and the brain. What's more, a complex supporting vasular network minimizes interruptions in blood flow; the scientists discovered that owls have small vessel connections between the carotid and vertebral arteries that allow blood to flow between the two vessels—so even if one route is blocked by an extreme neck rotation, another can provide an uninterrupted blood flow to the brain.


Click to enlarge.

Bones in owls’ necks also have adaptations designed to facilitate extreme rotation. One of the major arteries feeding the birds' brains passes through holes in the vertebrae, called transverse foramine; the team found that these holes were 10 times larger in diameter than the artery. This extra space creates air pockets that allow the artery to move around when twisted; 12 of the vertebrae in the owls’ necks had this adaptation. "In humans, the vertebral artery really hugs the hollow cavities in the neck. But this is not the case in owls, whose structures are specially adapted to allow for greater arterial flexibility and movement," said de Kok-Mercado. Plus, the owls’ vertebral artery enters the neck higher than it does in other birds’—going in at the 12th cervical vertebrae, rather than the 14th—allowing for more slack.

"Our new study results show precisely what morphological adaptations are needed to handle such head gyrations and why humans are so vulnerable to osteopathic injury from chiropractic therapy," Gailloud said. "Extreme manipulations of the human head are really dangerous because we lack so many of the vessel-protecting features seen in owls." The team created a poster (above) that details their findings, and next plans to study hawk anatomy to see if those birds have similar adaptations for head rotation.

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Animals
Elusive Butterfly Sighted in Scotland for the First Time in 133 Years

Conditions weren’t looking too promising for the white-letter hairstreak, an elusive butterfly that’s native to the UK. Threatened by habitat loss, the butterfly's numbers have dwindled by 96 percent since the 1970s, and the insect hasn’t even been spotted in Scotland since 1884. So you can imagine the surprise lepidopterists felt when a white-letter hairstreak was seen feeding in a field in Berwickshire, Scotland earlier in August, according to The Guardian.

A man named Iain Cowe noticed the butterfly and managed to capture it on camera. “It is not every day that something as special as this is found when out and about on a regular butterfly foray,” Cowe said in a statement provided by the UK's Butterfly Conservation. “It was a very ragged and worn individual found feeding on ragwort in the grassy edge of an arable field.”

The white-letter hairstreak is a small brown butterfly with a white “W”-shaped streak on the underside of its wings and a small orange spot on its hindwings. It’s not easily sighted, as it tends to spend most of its life feeding and breeding in treetops.

The butterfly’s preferred habitat is the elm tree, but an outbreak of Dutch elm disease—first noted the 1970s—forced the white-letter hairstreak to find new homes and food sources as millions of Britain's elm trees died. The threatened species has slowly spread north, and experts are now hopeful that Scotland could be a good home for the insect. (Dutch elm disease does exist in Scotland, but the nation also has a good amount of disease-resistant Wych elms.)

If a breeding colony is confirmed, the white-letter hairstreak will bump Scotland’s number of butterfly species that live and breed in the country up to 34. “We don’t have many butterfly species in Scotland so one more is very nice to have,” Paul Kirkland, director of Butterfly Conservation Scotland, said in a statement.

Prior to 1884, the only confirmed sighting of a white-letter hairstreak in Scotland was in 1859. However, the insect’s newfound presence in Scotland comes at a cost: The UK’s butterflies are moving north due to climate change, and the white-letter hairstreak’s arrival is “almost certainly due to the warming climate,” Kirkland said.

[h/t The Guardian]

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Plagued with Rodents, Members of the UK Parliament Demand a Cat
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Members of the United Kingdom’s Parliament want a cat, but not just for office cuddles: As The Telegraph reports, the Palace of Westminster—the meeting place of Parliament’s two houses, the House of Commons and the House of Lords—is overrun with vermin, and officials have had enough. They think an in-house feline would keep the rodents at bay and defray skyrocketing pest control costs.

Taxpayers in the UK recently had to bear the brunt of a $167,000 pest control bill after palace maintenance projects and office renovations disturbed mice and moths from their slumber. The bill—which was nearly one-third higher than the previous year’s—covered the cost of a full-time pest control technician and 1700 bait stations. That said, some Members of Parliament (MPs) think their problem could be solved the old-fashioned way: by deploying a talented mouser.

MP Penny Mordaunt tried taking matters into her own hands by bringing four cats—including her own pet kitty, Titania—to work. (“A great believer in credible deterrence, I’m applying the principle to the lower ministerial corridor mouse problem,” she tweeted.) This solution didn’t last long, however, as health and safety officials banned the cats from Parliament.

While cats aren’t allowed in Parliament, other government offices reportedly have in-house felines. And now, MPs—who are sick of mice getting into their food, running across desks, and scurrying around in the tearoom—are petitioning for the same luxury.

"This is so UNFAIR,” MP Stella Creasy said recently, according to The Telegraph. “When does Parliament get its own cats? We’ve got loads of mice (and some rats!) after all!" Plus, Creasy points out, a cat in Parliament is “YouTube gold in waiting!"

Animal charity Battersea Dogs & Cats Home wants to help, and says it’s been trying to convince Parliament to adopt a cat since 2014. "Battersea has over 130 years [experience] in re-homing rescue cats, and was the first choice for Downing Street, the Foreign and Commonwealth Office, and the Cabinet Office when they sought our mousers to help with their own rogue rodents,” charity head Lindsey Quinlan said in a statement quoted by The Telegraph. “We'd be more than happy to help the Houses of Parliament recruit their own chief mousers to eliminate their pest problem and restore order in the historic corridors of power."

As of now, only assistance and security dogs are allowed on palace premises—but considering that MPs spotted 217 mice alone in the first six months of 2017 alone, top brass may have to reconsider their rules and give elected officials purr-mission to get their own feline office companions.

[h/t The Telegraph]

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