Science news in brief: From blinking birds to the loudest crickets

And other stories from around the world

Wednesday 06 January 2021 12:05 GMT
Great-tailed grackle (Quiscalus mexicanus)
Great-tailed grackle (Quiscalus mexicanus) (US Fish and Wildlife Service/Public Domain)

To study blinking, a scientist needed a real bird’s-eye view

When Jessica Yorzinski chased great-tailed grackles across a field, it wasn’t a contest to see who blinked first. But she did want the birds to blink.

Yorzinski had outfitted 10 great-tailed grackles with head-mounted cameras pointing back at their faces. Like other birds, grackles blink sideways, flicking a semitransparent membrane across the eye. Recordings showed that the birds spent less time blinking during the riskiest parts of a flight. The finding was published last week in Biology Letters.

Yorzinski, a sensory ecologist at Texas A&M, had been wondering how animals balance a need to blink with the need to get visual information about their environments.

She worked with a company that builds eye-tracking equipment to make a custom bird-size headpiece. Because a bird’s eyes are on the sides of its head, the contraption held one video camera pointed at the left eye and one at the right, making the bird resemble a sports fan in a beer helmet. The headpiece was connected to a backpack holding a battery and transmitter. Each bird wore the camera helmet and backpack while Yorzinski encouraged it to fly by chasing it across an outdoor enclosure.

Afterwards, she broke down the flight videos into stages, from standing and taking off to landing again. While the birds were in flight, their blinks were quicker than when they were on the ground. And just before landing, they barely blinked.

“Maximizing the visual input they get during these critical stages of being in flight and landing makes a lot of sense,” she said. The birds blinked most often at the moment they hit the ground, perhaps because they needed to blink after holding their eyes open, or to protect their eyes from debris.

Yorzinski plans to do further experiments with birds navigating different environments, such as a forest setting with more obstacles.

Graham Martin, an emeritus professor of avian sensory science at the University of Birmingham in England, said the study is “an interesting piece of work”. But he pointed out that the flights Dr Yorzinski observed were only a few seconds long. He doesn’t think there’s enough evidence yet to say anything broadly about how birds alter their blinks in flight.

“I think we need to see samples of blinking behaviour during longer flights and in other species before any general conclusions are possible,” he said.

Elizabeth Preston


Before coiling around the world, pythons slithered through Europe

From 20ft anacondas to species that can comfortably fit on a coin, snakes slither across much of the world today. That’s in part because they’re remarkably good at adapting to new environments – for instance, the Burmese python, native to southeast Asia, is thriving in Florida’s Everglades National Park. Now, researchers have analysed four fossilised python skeletons unearthed in Germany – part of a region that’s currently free of the scaly creatures – and rewritten the snake family trees.

These results were published this month in Biology Letters.

Last year during a sabbatical at the French National Museum of Natural History, Hussam Zaher, a paleontologist, pored over a 52-page manuscript written in German that contained an illustration of a skull of an unnamed snake species. Zaher was intrigued – he was studying ancient snakes, and this skull had some but not all of the characteristics of modern pythons.

Zaher tracked down the specimen, which measured just over 38in long, in the State Museum of Natural History Karlsruhe in southwestern Germany. With the help of Krister T Smith, a vertebrate paleontologist at the Senckenberg Research Institute in Frankfurt, he set off looking for more like it.

Zaher and Smith located four similar skeletons in the collections of history museums and paleontological institutions across Germany. The skeletons, all remarkably intact, had been excavated from the country’s Messel Pit, a Unesco World Heritage Site. The research team found that the four skeletons belonged to a new species of python, which they named Messelopython freyi.

“The fossils there are exquisite,” said Dr Zaher, who is now at the University of São Paulo in Brazil.

Based on where the fossils were excavated relative to volcanic rock of a known age, the researchers estimated that the skeletons were at least 47 million years old. That places them squarely in the geological epoch known as the Eocene. But the discovery pushes the snake’s origins back 20 million years.

Finding this species also sheds light on the geographic origin of pythons. It now looks like pythons originated instead in the supercontinent known as Laurasia, which was composed of North America, Europe and Asia.

That’s a bit of a surprise, the researchers said, given that pythons aren’t currently found in Europe.

Katherine Kornei

(Getty Images/iStockphoto)

More mammals are hiding their secret glow

Were platypuses just the beginning?

In October, researchers reported that the already perplexing animals fluoresce a psychedelic blue-green color under black light. The species joined a short list of mammals known to do this, including opossums and flying squirrels.

Since the study came out, others have begun their own investigations, mostly in Australian mammals. Although results are preliminary, the findings suggest we may have to book a larger venue for the mammal rave.

When he heard about the platypus discovery, Kenny Travouillon, curator of mammals at the Western Australian Museum, borrowed a black light lamp and, after confirming that their preserved platypuses glowed, he and his colleagues moved on to the rest of the collection.

But what they saw was encouraging. Bilbies – endangered marsupials with long snouts and rabbit-like ears – had orange and green accents. The quills of hedgehogs, porcupines and echidnas shone bright white, as if dipped in correction fluid.

Some specimens were more reserved: of two wombat species they examined, only one fluoresced, and “kangaroos didn’t seem to do very much at all”, Travouillon said. The museum plans to team up with a nearby university to do a more systematic study early next year.

Live animals are also being tested.

When a co-worker told Jake Schoen, a conservation technician at the Toledo Zoo, the platypus news, “we got pretty excited about it”, he said. Schoen turned his lens on the zoo’s Tasmanian devils, Spiderman and Bubbles. “The tricky part was having them sit still for a fraction of a second,” he said. Eventually, Bubbles cooperated. When the UV flash went off, voilá: a cool blue glow emerged around her eyes, at the bases of her whiskers and inside the cups of her ears.

Cara Giaimo


Neptune’s weird dark spot just got weirder

Neptune boasts some of the strangest weather in the solar system. The sun’s eighth planet holds the record for the fastest winds observed on any world, with speeds cutting through the atmosphere upward of 1,100mph, or 1.5 times the speed of sound. Scientists still don’t know exactly why its atmosphere is so tumultuous. Their latest glimpse of Neptune provided even more reason to be confused.

The Hubble Space Telescope identified a storm in 2018, a dark spot some 4,600 miles across. Since that time, it appears to have drifted toward the equator but then swooped back up north, according to the latest Hubble observations. It also has a smaller companion storm, nicknamed Dark Spot Jr, that scientists think might be a chunk that broke off the main storm. These inky vortexes stand out against the dizzying cerulean blue of the planet, but while they’re dazzling to see, their life spans are short, making them even more challenging to study.

This is not the first time Neptune’s dark spots have behaved so strangely. When the Voyager 2 spacecraft flew past the planet in 1989, (still the only spacecraft to do so) it observed two storms. One was the original dark spot, a large vortex about the size of the Earth. It too had a companion, a smaller, fast moving storm nicknamed Scooter. The first observed dark spot also seemed to move south and then back to the north.

“When we were tracking the great dark spot with Voyager, we saw it oscillating up and down in longitude,” said Heidi Hammel, a member of the imaging team of the Voyager 2 space probe and currently the vice president for science at the Association of Universities for Research in Astronomy. “We had enough time on Voyager, that we were able to track the feature for something like four to five months leading up to the flyby. That storm was huge, a big monster” – as big as planet Earth.

But by the time the Voyager team were able to get time with the Hubble telescope to observe the storms again, some four years later, they were gone. Astronomers estimate the average life span of a Neptune storm is anywhere from two to five years, and its longevity might also depend on its size. That’s a contrast with the Great Red Spot of Jupiter, our outer solar system’s other best known storm, which shrinks at times, but has been churning consistently for at least hundreds of years.

Shannon Stirone

(Getty Images/iStockphoto)

He’s too quiet for his mate to hear him. So he makes a megaphone

For better or for worse, female tree crickets tend to prioritise two traits in their mates: loudness and size. The louder the boy cricket, the more likely a lady is to be wooed by his serenade. The larger he is when she finds him, the more time she will stay locked in a sexual tryst.

But a few of these punier males can deploy a clever ruse to make themselves heard, research shows. To stay competitive, crickets with quieter voices or tiny bodies will fashion mini-megaphones out of leaves to amplify their calls, coaxing females into mating with them longer and more frequently than they otherwise would.

Rittik Deb, a biologist at the National Center for Biological Sciences in Bangalore, India, can still vividly recall the first time he observed the behavior – called “baffling” – in 2008. Then a graduate student, he watched in awe as a male cricket, no bigger than a kernel of corn, scurried up a large leaf of a pignut plant and munched a hole into its fleshy center. The little lothario then shoved his head and forelegs through the opening, as if at a carnival’s photo stand-in, and began to trill a surprisingly loud tune.

“We humans boast about loudspeakers, but they have evolved to make such a simple structure,” said Deb, a co-author of a paper on baffling that was published this month in the journal Proceedings of the Royal Society B. “I don’t have exact words for the joy that I felt.”

Tree cricket baffling was initially described by scientists in the 1970s. Since then, a smattering of reports have looked at the ways in which males will chew leaves into botanical speaker systems. But little was known about how or why the behaviour came to be, Deb said.

To pinpoint baffling’s evolutionary origins, Deb and his colleagues at the Indian Institute of Science in Bangalore, where he earned his doctorate, eavesdropped on tree crickets of the species Oecanthus henryi. Baffling males, the researchers found, tended to be more petite than their unmic’d counterparts.

When warbling without a leaf, smaller males chirped at about 60 decibels — akin to noisy restaurant chatter. But once outfitted with foliage, the crickets were able to amp up their serenades substantially, “at least double or triple the volume”, Deb said. The bigger the leaf, the more the crickets were able to broadcast their bravado, on occasion achieving sound pressures around 70 decibels, about the roar of a vacuum cleaner.

In the lab, the researchers found that females naturally gravitated toward louder cricket calls. The crickets even eagerly approached quiet chirps when they were played from speakers at a higher volume – the scientists’ synthetic take on baffling.

Katherine J Wu

© The New York Times

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