Category Archives: International

Meet the Woodpecker That Impersonates a Snake

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( National Geographics; 19 september 2018)

The Eurasian wryneck can’t put a spell on you, as people once believed, but it does have a few tricks up its sleeve.

This bird’s motto is fake it till you make it. Or in this case, fake it until the threat of being eaten has passed.

That’s the strategy of Eurasian wrynecks, small brown woodpeckers native to Europe, Africa, and Asia. When spooked, they bend and twist their head from side to side, often while hissing, to imitate a forest snake.

“Whenever you catch a wryneck, they usually wiggle with their neck to imitate some kind of snake,” says Anders Nielsen, a student at the University of Copenhagen, who shot the video at Denmark’s Gedser observatory, where scientists capture wrynecks each summer and apply leg bands to monitor their population.

“Moving its head and throat from side to side … it looks pretty strange.”

Once considered otherworldly and a sign of magical powers, the odd behavior is now known to be a form of self-defense, he says. And it’s something of a genius strategy: If you’re not scary yourself—perhaps, you don’t have sharp talons, quick speed, or a powerful bite—impersonate an animal that’s more terrifying. Why not a snake? (See how snakes, spiders, and other animals fool their prey.)

In the hand of a bird bander, the display might not be so convincing. But shrouded in the shadows of a dark tree cavity, where these birds nest, the disguise is sure to trick stoats, goshawks, and other feather-hungry predators, says Kenn Kaufman, a renowned bird expert and field editor at Audubon magazine.

“If you’re a wryneck sitting inside a cavity, writhing around and looking and sounding like a snake is likely to make just about any predator retreat,” he says. “The more snakelike it looks and sounds, the more effective the defense could be.”

One Weird Woodpecker

Wrynecks are in the woodpecker family, but they don’t exactly fit in—at least at first glance.

For one, they don’t peck wood. Instead, they nest in holes that other species have laboriously excavated for themselves. And unlike their tree-drilling brethren, wrynecks forage on the ground, using exceedingly long tongues to slurp up fat-rich ants. (Related: How woodpeckers can thrive in leafy suburbs.)

 

But while they don’t look or act like your typical backyard woodpecker, wrynecks share important features with them, including a long, flexible neck packed with muscles. (Related: Why woodpeckers don’t get headaches.)

It’s these underlying woodpecker features that make snake mimicry possible, Kaufman says.

“Even though the wrynecks are not digging holes, they’ve got the woodpecker family characteristics, such as really complex vertebrae,” he says. “Since they’re not pounding on trees, they can put those morphological traits to use in other ways, such as by being contortionists and moving their head in every which way.”

In other words, wrynecks have repurposed their family strengths—which most species use for hammering out homes and digging up grubs—to imitate a snake when they feel threatened. And they did so over thousands of years of evolution that selected for “accidental” snake-like traits, Kaufman says.

“There wasn’t any conscious attempt at the start, like ‘gee, I’ll try to look like this other species,” he says. “Selection is likely favoring wrynecks becoming more and more snake-like, just like in other cases of mimicry.”

And there are plenty of other snake mimics in the animal kingdom. The hawkmoth caterpillar can inflate a serpent head, the mimic octopus has eight limbs that each double as sea snakes, and burrowing owls are known to produce a long, hissing noise. Heck, there are even snakes that imitate snakes.

A Bird for Bewitching

Today, you’d be lucky to spot a wryneck in the woods. They’re elusive, well-camouflaged, and in decline. But centuries ago, its shrill cry might have sent you running.

Due to its odd movements, this humble-looking woodpecker—known then as the jynx bird—was once thought to wield magical, perhaps even evil powers. In fact, that’s where our modern word jinx (“one that brings bad luck”) comes from.

Other sources suggest it was also used for love spells. According to the book Birds: Myth, Lore and Legend, hopeless romantics would nail an open-winged wryneck to a spinning top called an iynx, which they would twirl “amid incantations to excite sexual love.”

Thankfully, that practice has long been retired. But the wryneck’s scientific name, Jynx torquilla (from the Latin torqueo, “to twist”) has forever preserved its spellbinding past and head-turning talent.

 

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Woodpeckers show signs of possible brain damage, but that might not be a bad thing

(Field Museum, ScienceDaily 2 February 2018; Photo:Arlene Koziol)

With woodpeckers, the answer’s in the question—true to their name, they peck wood. And when they do, they peck hard—with each peck, the bird undergoes a force of 1,200 to 1,400 g’s. By comparison, a measly force of 60-100 g’s can give a human a concussion. The fact that a woodpecker can undergo fourteen times that without getting hurt has led helmet makers to model their designs around these birds’ skulls. However, a new study in PLOS ONE complicates this story by showing that woodpecker brains contain build-ups of a protein associated with brain damage in humans.

“There have been all kinds of safety and technological advances in sports equipment based on the anatomic adaptations and biophysics of the woodpecker assuming they king. The weird thing is, nobody’s ever looked at a woodpecker brain to see if there is any damage,” says Peter Cummings of the Boston University School of Medicine, one of the new study’s authors.

To find the answer to this question, researchers used bird brains from the collections of The Field Museum and the Harvard Museum of Natural History and examined them for accumulation of a specific protein, called tau.

“The basic cells of the brain are neurons, which are the cell bodies, and axons, which are like telephone lines that communicate between the neurons. The tau protein wraps around the telephone lines—it gives them protection and stability while still letting them remain flexible,” explains lead author George Farah, who worked on the study as a graduate student at the Boston University School of Medicine.

In moderation, tau proteins can be helpful in stabilizing brain cells, but too much tau build-up can disrupt communication from one neuron to another. “When the brain is damaged, tau collects and disrupts nerve function—cognitive, emotional, and motor function can be compromised,” says Cummings.

Since excessive tau can be a sign of brain damage in humans, Farah and his team decided to examine woodpecker brains for tau build-up. The Field Museum and Harvard loaned the researchers bird specimens pickled in alcohol—Downy Woodpeckers for the experimental data and non-head-injury-prone Red-winged Blackbirds as a control. The researchers then removed the birds’ brains—“The brains themselves were well-preserved, they had a texture almost like modeling clay,” says Farah—and took incredibly thin slices, less than a fifth the thickness of a sheet of paper. The slices of brain tissue were then stained with silver ions to highlight the tau proteins present.

The verdict: the woodpeckers’ brains had far more tau protein accumulation than the blackbirds’ brains. However, while excessive tau buildup can be a sign of brain damage in humans, the researchers note that this might not be the case for woodpeckers. “We can’t say that these woodpeckers definitely sustained brain injuries, but there is extra tau present in the woodpecker brains, which previous research has discovered is indicative of brain injury,” says Farah.

“The earliest woodpeckers date back 25 million years—these birds have been around for a long time,” says Cummings. “If pecking was going to cause brain injury, why would you still see this behavior? Why would evolutionary adaptations stop at the brain? There’s possibility that the tau in woodpeckers is a protective adaptation and maybe not pathological at all.”

So, woodpeckers show signs of what looks like brain damage in humans, but it might not be a bad thing. Either way, the researchers believe that the study’s results could help us humans. For example, the knowledge about woodpecker brains that could help make football equipment safer for kds, says Cummings. On the other hand, he notes, “If the tau accumulation is a protective adaptation, is there something we can pick out to help humans with neurodegenerative diseases? The door’s wide open to find out what’s going on and how we can apply this to humans.”

Farah notes that the study relied heavily upon the museum collections that the bird brains came from. “Museums are gateways to the past and a source of new innovation,” he says. “The role of museums in this project was immense—we couldn’t have done our study with just one woodpecker.”

Ben Marks, The Field Museum’s Collections Manager of Birds, said of the researchers’ request to use the Museum’s bird brains, “With one of the world’s best bird collections, we’re always trying to let people know what we have, why we have it, and what it can be used for. We get over a hundred requests for specimen loans every year—this one stood out because it was a novel approach that had real world applications. Some of the specimens used in this study were collected in the 1960s. Our staff cared for them for over 50 years before until they were requested for this study and used in a way the original collector couldn’t even envision.”

Snowy owl numbers far lower than once thought

Snowy owl migration gives scientists chance to study them
(Tammy Webber 21 Dec 2017)

Scott Judd trained his camera lens on the white dot in the distance. As he moved up the Lake Michigan shoreline, the speck on a breakwater came into view and took his breath away: it was a snowy owl, thousands of miles from its Arctic home.

“It was an amazing sight,” said Judd, a Chicago IT consultant. “It’s almost like they’re from another world. They captivate people in a way that other birds don’t.”

The large white raptors have descended on the Great Lakes region and northeastern U.S. in huge numbers in recent weeks, hanging out at airports, in farm fields, on light poles and along beaches, to the delight of bird lovers.

But for researchers, this winter’s mass migration of the owls from their breeding grounds above the Arctic Circle is serious business.

It’s a chance to trap and fit some of the visitors with tiny transmitters to help track them around the globe and study a long-misunderstood species whose numbers likely are far fewer than previously thought, researchers say.

“There is still a lot that we don’t know about them … but we aim to answer the questions in the next few years,” said Canadian biologist Jean-Francois Therrien, a senior researcher at Hawk Mountain Sanctuary in Pennsylvania.

The solar-powered transmitters can last for years, collecting information such as latitude, longitude, flight speed and air temperature that is downloaded to a server when the birds fly into range of a cell tower.

The use of transmitters, which intensified during the last North American mass migration in winter 2013-14, already has yielded big surprises.

Instead of 300,000 snowy owls worldwide, as long believed, researchers say the population likely is closer to 30,000 or fewer. The previous estimate was based on how many might be able to breed in a given area.

That calculation was made assuming snowy owls acted like other birds, favoring fixed nesting and wintering sites. But researchers discovered the owls are nomads, often nesting or wintering thousands of miles from previous locations.

The miscalculation doesn’t necessarily mean snowy owls, which can grow to about 2 feet long with 5-foot wingspans, are in decline. Scientists simply don’t know because they never had an accurate starting point.

This month, snowy owls were listed as vulnerable—one step away from endangered—by the International Union for Conservation of Nature. They’re protected in the U.S. under the Migratory Bird Act.

This year’s mass migration is a bit of good news. Researchers once thought these so-called “irruptions” signaled a lack of prey in the Arctic, but now believe the opposite: Breeding owls feed on lemmings, a rodent that lives under Arctic snowpack and whose population surges about every three or four years. More lemmings means the owl population explodes— and that more birds than usual will winter in places people can see them.

 But researchers worry that climate change will affect the owl population because lemmings are exceptionally sensitive to even small temperature changes.

Lemmings “depend on deep, fluffy, thick layers of insulating snow” to breed successfully, said Scott Weidensaul, director at Project SNOWstorm, an owl-tracking group whose volunteers have put transmitters on more than 50 snowy owls in the past four years .

The snowy owl population collapsed in Norway and Sweden in the mid-1990s, all but vanishing there for almost two decades before reappearing at lower numbers, experts said. In Greenland, where the population collapsed in the late 1990s, researchers found a few nests in 2011 and 2012 after six years with no recorded nests, but owls didn’t come back in 2016 or 2017, when lemmings should have been peaking.

The National Oceanic and Atmospheric Administration reported this month that the far northern Arctic is warming twice as fast as the rest of the globe.

But it’s tough to assess lemming population trends in remote areas. Although researchers hope to enlist native villagers to help, it’s mostly up to owls with transmitters for now.

Snowy owls somehow seem to find lemmings even if they are thousands of miles from where their population last peaked, Therrien said.

“They look around the Arctic,” he said. “The movement is amazing to watch on a map: There are no straight lines. They’re zigzagging.”

Norman Smith, a snowy owl expert with Mass Audubon in Massachusetts, said he’s heartened that many independent researchers worldwide joined forces to share information on snowy owls.

“It’s amazing what we’ve learned, but we need a bigger database of birds,” said Smith, who has been trapping owls at Boston’s Logan International Airport for more than 35 years and fits them with a leg band or transmitter before letting them go. He put a satellite tracker on an owl for the first time in 2000, proving that they could make it back to the Arctic.

Last week, Smith released a young female on a barrier beach along the Atlantic Ocean. It flew south, then circled back and flew overhead. As he drove over a bridge to the mainland, the owl was sitting on a post, surveying its new winter home.

Snowy owl migration gives scientists chance to study them

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Social interactions override genetics when birds learn new songs

(Nicholas Weiler, 26 Dec 2017)

New UC San Francisco research finds that although young male songbirds are genetically predisposed to sound like their fathers, enriched early experience with a foster-father can overcome this genetic destiny. This finding has striking implications for our thinking about how experience influences the genetics of complex human traits like learning ability or even psychiatric disease, the authors say.

Neuroscientists like UCSF’s Michael Brainard, Ph.D., have long studied songbirds like the Bengalese finch (Lonchura striata domestica) as a model of how complex behaviors like human language are shaped by early experience. Like human language, a male finch’s unique mating song is learned early in life by listening to and mimicking adult “tutors.” In nature, this is usually the bird’s father, but young birds raised by unrelated adults in the lab will learn to sing their foster-father’s song instead.

Now Brainard’s lab has shown that not all early experiences are equal in their influence over impressionable young birds: exposed only to a computerized “synthetic tutor,” young birds will revert to singing like a biological father they’ve never known or heard. The research—published the week of December 25, 2017 in PNAS—suggests that finch song has a stronger genetic component than had previously been realized, but also that this genetic drive can be suppressed by the right kind of early life experience.

“What we saw is that the genetic contribution to a bird’s song depends on the specifics of that bird’s experience. This is a striking demonstration that heritability for complex behaviors like birdsong is not fixed, as is often assumed, but instead can vary dramatically depending on the experience of an individual,” said Brainard, a professor of physiology and of psychiatry at UCSF, Howard Hughes Medical Institute investigator, and member of the UCSF Weill Institute for Neurosciences.

As noted, researchers have long considered the structure of adult birdsong to be dominated by the influence of whatever song a bird hears as a chick. However, David Mets, Ph.D., a postdoctoral scholar in the Brainard lab and the new paper’s first author, noticed a surprising amount of variation between the songs of individual Bengalese finches in the lab, even when all birds were exposed to the same experimentally controlled tutor song early in life.

To determine whether these differences might be caused by a previously overlooked genetic contribution to the birds’ song, Mets developed a careful set of experiments to control the contribution of genetics and experience. He removed eggs from their nests shortly after they were laid to ensure chicks never heard their fathers’ song, even in the egg. He then exposed the hatchlings only to carefully controlled computer-generated songs, which he varied in tempo in an attempt to influence the tempo of the song the young birds would learn.

To the researchers’ surprise, they found that these birds largely ignored the tempo of the synthetic songs, and developed adult songs with tempos much closer to their fathers’ songs—which they had never heard. The researchers quantified this observation, showing that 55 percent of variability in the experimental birds’ songs could be explained by differences in their fathers’ songs, but only 21 percent was driven by differences in the synthetic song they heard as chicks.

In a second set of experiments, Mets got rid of the synthetic tutor and instead exposed finch chicks—which also had never heard their fathers’ songs—to unrelated live adult males. The researchers were again surprised to discover a complete reversal of the results seen with synthetic tutoring: the live tutor’s song contributed 53 percent to the tempo of the young birds’ adult songs, with differences in their fathers’ songs contributing only 16 percent.

“This was really exciting because it showed that the experience provided by a live tutor can actually reduce the contribution of genetics to complex behavior like birdsong,” Mets said. “We knew before that live tutors helped birds learn better and faster, but we were surprised to find that this experience can actually override the bird’s genetics.”

“We’ve gotten used to the idea that complex traits and behaviors can have a big genetic component,” Brainard added, citing human studies of identical twins separated at birth who nonetheless share surprising similarities in things like their sense of humor, fashion sense, and so on. “But those stories tend to assume that the genetic component is fixed—academic achievement is either 20 percent genetic or 80 percent genetic. We’re showing here that the contribution of genetics is anything but fixed—in the case of academic achievement, the school you go to may well overcome any contribution of genetics.”

The findings raise the possibility that human genetic studies that fail to account for differences in individuals’ experience could be producing misleading conclusions about the genetic contributions to complex behaviors, Brainard said.

The researchers now hope to use the Bengalese finch as a model to explore how genetics and experience interact in the brain to influence complex behaviors like birdsong. “Where in the brain are the father’s genes and early life experience competing for control over song tempo?” Mets asked. “That’s the next really exciting question.”

The results also suggest a broader opportunity to understand the specific features of enriched early experiences that allows them to override genetic predispositions, Brainard said: “This is far into the future, of course, but it highlights the potential of early behavioral intervention to help mitigate negative genetic traits, such as a predisposition to psychiatric disease.”

Birds learn from each other’s ‘disgust,’ enabling insects to evolve bright colors

(University of Cambridge 18 Dev 2017)

Many animals have evolved to stand out. Bright colours are easy to spot, but they warn predators off by signalling toxicity or foul taste.

Yet if every individual predator has to eat colourful prey to learn this unappetising lesson, it’s a puzzle how conspicuous colours had the chance to evolve as a defensive strategy.

Now, a new study using the great tit species as a “model predator” has shown that if one bird observes another being repulsed by a new type of prey, then both birds learn the lesson to stay away.

By filming a great tit having a terrible dining experience with conspicuous prey, then showing it on a television to other tits before tracking their meal selection, researchers found that birds acquired a better idea of which prey to avoid: those that stand out.

The team behind the study, published in the journal Nature Ecology & Evolution, say the ability of great tits to learn bad food choices through observing others is an example of “social transmission.”

The scientists scaled up data from their experiments through mathematical modelling to reveal a tipping point: where social transmission has occurred sufficiently in a predator species for its potential prey to stand a better chance with bright colours over camouflage.

“Our study demonstrates that the social behaviour of predators needs to be considered to understand the evolution of their prey,” said lead author Dr Rose Thorogood, from the University of Cambridge’s Department of Zoology.

“Without social transmission taking place in predator species such as great tits, it becomes extremely difficult for conspicuously coloured prey to outlast and outcompete alternative prey, even if they are distasteful or toxic.

“There is mounting evidence that learning by observing others occurs throughout the animal kingdom. Species ranging from fruit flies to trout can learn about food using social transmission.

“We suspect our findings apply over a wide range of predators and prey. Social information may have evolutionary consequences right across ecological communities.”

Thorogood (also based at the Helsinki Institute of Life Science) and colleagues from the University of Jyväskylä and University of Zurich captured wild great tits in the Finnish winter. At Konnevesi Research Station, they trained the birds to open white paper packages with pieces of almond inside as artificial prey.

The birds were given access to aviaries covered in white paper dotted with small black crosses. These crosses were also marked on some of the paper packages: the camouflaged prey.

One bird was filmed unwrapping a package stamped with a square instead of a cross: the conspicuous prey. As such, its contents were unpalatable — an almond soaked with bitter-tasting fluid.

The bird’s reaction was played on a TV in front of some great tits but not others (a control group). When foraging in the cross-covered aviaries containing both cross and square packages, the birds exposed to the video were quicker to select their first item, and 32% less likely to choose the ‘conspicuous’ square prey.

“Just as we might learn to avoid certain foods by seeing a facial expression of disgust, observing another individual headshake and wipe its beak encouraged the great tits to avoid that type of prey,” said Thorogood.

“By modelling the social spread of information from our experimental data, we worked out that predator avoidance of more vividly conspicuous species would become enough for them to survive, spread, and evolve.”

Great tits — a close relation of North America’s chickadee — make a good study species as they are “generalist insectivores” that forage in flocks, and are known to spread other forms of information through observation.

Famously, species of tit learned how to pierce milk bottle lids and siphon the cream during the middle of last century — a phenomenon that spread rapidly through flocks across the UK.

Something great tits don’t eat, however, is a seven-spotted ladybird. “One of the most common ladybird species is bright red, and goes untouched by great tits. Other insects that are camouflaged, such as the brown larch ladybird or green winter moth caterpillar, are fed on by great tits and their young,” said Thorogood.

“The seven-spotted ladybird is so easy to see that if every predator had to eat one before they discovered its foul taste, it would have struggled to survive and reproduce.

“We think it may be the social information of their unpalatable nature spreading through predator species such as great tits that makes the paradox of conspicuous insects such as seven-spotted ladybirds possible.”

Video: https://www.youtube.com/watch?v=87l0Dyte_nQ

Complex, old-growth forests may protect some bird species in a warming climate

(Oregon State University 15 Dec 2017;Photo:Hankyu Kim)

Old forests that contain large trees and a diversity of tree sizes and species may offer refuge to some types of birds facing threats in a warming climate, scientists have found.

In a paper published in Diversity and Distributions, a professional journal, researchers in the College of Forestry at Oregon State University reported that the more sensitive a bird species is to rising temperatures during the breeding season, the more likely it is to be affected by being near old-growth forest.

Researchers studied 13 bird species that have been tracked annually in the U.S. Geological Survey’s annual Breeding Bird Survey, one of the most comprehensive efforts of its kind in North America. Only two — the Wilson’s warbler and hermit warbler — showed negative effects from rising temperatures over the past 30 years, but actual counts of both species show that their populations are stable or increasing in areas that contain high proportions of old-growth forest.

A team led by Matthew Betts, professor in the College of Forestry, reached their conclusions by analyzing data for bird populations, forest structure and climate across northwestern North America. The researchers used satellite imagery to determine the amount of old-growth forest within about 450 yards of each 25-mile-long bird survey route.

The findings provide an additional reason for old-growth forest conservation, said Betts. “Managers hoping to combat the effects of climate change on species’ populations may now have an additional tool — maintaining and restoring old-growth forest.” He noted that this is important because management recommendations from biodiversity and climate studies have traditionally been sparse. Such studies have tended to focus on moving species to cooler climates or simply reducing carbon emissions.

Wilson’s warbler winters in Mexico and breeds during the late spring and early summer along the West Coast and across northern North America from Alaska to New England and the Canadian Maritimes. Although it occurs in early-stage as well as mature forests, it is declining at a rate of about 2 percent per year in the Pacific Northwest.

The hermit warbler also winters in Mexico but breeds exclusively along the West Coast as far north as Washington. Its populations are relatively stable but declining in landscapes with low amounts of old-growth forest.

Additional research will be needed to identify the specific features of mature forests that buffer the effects of warming temperatures on birds. One possibility, the researchers said, is that the large trees themselves function as “heat sinks” during warm periods and thus moderate temperatures. Multiple canopy layers may also provide climate buffering effects.

For the love of birds

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From the glorious crested guinea fowl to the adulterous African jacana to vultures that can pick a zebra carcass clean in 30 minutes, Washington Wachira wants us all to get to know the marvelous species of birds that share the planet with us. If you’re not already a fan of earth’s feathermakers — or concerned about their conservation — you will be after you watch this delightful talk.