Tag Archives: research

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.”

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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.”

Rooftop wiretap aims to learn what crows gossip about at dusk

(University of Washington 5 Dec 2017)

What are crows saying when their loud cawing fills a dark winter’s evening? Despite the inescapable ruckus, nobody knows for sure. Birds congregate daily before and after sleep, and they make some noise, but what might be happening in those brains is a mystery.

Curious about these raucous exchanges, researchers at the University of Washington Bothell are listening in. They are placing equipment on the roof of their building — a meeting place for some of the thousands of crows that sleep in nearby campus trees — and using a sort of computerized eavesdropping to study the relationship between calls and the birds’ behavior.

“With audio alone, our team is able to localize and record the birds remotely, and in dim light that makes this situation less suitable for video tracking,” said Shima Abadi, an assistant professor at UW Bothell’s School of Science, Technology, Engineering & Mathematics. “It’s still a challenging task, but we can use the audio signals to look for patterns and learn more about what the birds may be communicating.”

Abadi’s background is in ocean acoustics; some of her previous research tracks whales using underwater microphones in the ocean water. For this project she teamed up with a colleague in biology who studies the local crow population with his undergraduate students.

“They’re incredibly raucous, and make this cacophony every night, and people wonder: What are they saying? And that’s a great question to ask on this campus,” said Douglas Wacker, an assistant professor of biology at UW Bothell.

Wacker earned his UW doctorate studying song sparrows. After joining UW Bothell in 2012, it was only natural that he study the roughly 15,000 crows that migrate to the North Creek Wetlands on campus each evening in fall, winter and spring.

People walking through campus can’t fail to hear the not-always-melodious sound of the birds.

“Crows make a variety of different calls, some of which we understand the functions of fairly well, and others not as well,” Wacker said. “Their normal ‘caw’ calls are not necessarily well understood — we don’t know what information they might be conveying.”

He and Abadi have nearby offices. They decided last year to collaborate on an interdisciplinary project that blends his biology background with her acoustics expertise.

While the field site on the roof of the faculty members’ building is convenient, this project poses technical challenges. These crows call in a noisy environment, where it is tricky to separate their vocalizations from different birds and other surrounding sounds. What’s more, crows are intelligent. They will change their behavior if they think humans are watching, or even if unfamiliar equipment is nearby.

That’s why the high-tech approach, worthy of an avian CSI, is needed.

The team of mostly undergraduate students has been perfecting its audio recording technique. They placed four audio recorders in a 10-foot square in a parking lot, and then placed a speaker playing a crow call in one of the quadrants. The recorders have precise time stamps to calculate when the sound waves arrive, and then software compares the times to pinpoint where the sound was generated.

The students figured out a way to focus on the highest-quality audio to triple the accuracy of the source locations. They can now use the recordings to locate the source of the call to within 6-12 inches, or about the size of a bird.

About 50 to 100 crows might assemble in the pre-roost gathering at dusk on the roof of the science building. Their incessant cawing during flight quietens to just the occasional outburst while on the roof. With Abadi’s help, the team is working to develop a user interface and computer techniques that pick out particular calls, so they do not have to manually pick through hours of cawing but can focus on the most interesting events.

Derek Flett, a senior undergraduate student in mechanical engineering, will describe the team’s efforts Dec. 5 at the Acoustical Society of America’s annual meeting in New Orleans.

This winter they plan to use the equipment in the wild — that is, on the roof — to monitor real groups of crows. Eventually they hope to combine the audio surveillance with video, so they could study how birds might react to particular sounds.

They have also begun to test their theories by playing particular calls and then seeing whether the crows react in the predicted manner.

The idea that the calls contain meaning is plausible, Wacker said. The number of caws, or the length of the pauses between caws, could say something about food sources or possible dangers.

“If a bee can do a dance to tell other bees where food is located, then certainly a highly intelligent bird — in a family with other bird species that are capable of insight learning, recognizing themselves in a mirror, recognizing faces and passing that information on to subsequent generations — could be capable of communicating complex information,” Wacker said.

The other co-author on the work being presented in December is Virdie Guy, an undergraduate in mechanical engineering. The research was funded by a UW Royalty Research Fund.

A warbler’s flashy yellow throat? There are genes for that

warbler2.JPG

(University of British Columbia. 8 Oct 2017; Photo Alan Brelsford)

Birds get their bright red, orange and yellow plumage from carotenoid pigments—responsible for many of the same bright colours in plants. But how songbirds turn carotenoids into the spectacular variety of feathered patches found in nature has remained a mystery.

Now University of British Columbia (UBC) research might have pinpointed some of the genetic machinery responsible for the plumage colouration in Audubon’s and myrtle warblers, related but distinctly feathered North American songbirds.

“Audubon’s and myrtle warblers interbreed in a narrow band across British Columbia and Alberta,” says David Toews, co-author of a new Proceedings of the Royal Society paper exploring the birds’ colouration.

“Those hybrid warblers, while considered oddities to some birders, were key for this study because their plumage traits and genes are all jumbled and mixed, allowing us to link their differing colours to genetic markers and hopefully the genes responsible.”

Both types of warblers use colourful carotenoid pigments to make several yellow feather patches, including their yellow-rumps—the birds are colloquially referred to as ‘butter butts’.

But only Audubon’s also used carotenoids in their telltale yellow throats. Myrtles have white throats and the hybrids have a mix of white and yellow.

The study identified several genomic region s— one including a member of the scavenger receptor gene family that affects carotenoids in other animals—that might be involved in this selective distribution of yellow carotenoid colours.

“We found strong associations with several genomic regions across a handful of distinct plumage traits” explains co-author Alan Brelsford. “Now we can now dig even deeper into these regions to understand the mechanisms that make warblers so colourful and diverse.”

“This study is unusual in that it focused on variation in multiple colour patterning traits,” says co-author Darren Irwin, a professor of zoology at UBC. “Two of the plumage differences between the species, eye spot and eye line colouration, appear to be encoded by a single region in the genome.”

Migrating birds use a magnetic map to travel long distances

Migrating birds use a magnetic map to travel long distances
(Richard Holland 18 August 20017)

Birds have an impressive ability to navigate. They can fly long distances, to places that they may never have visited before, sometimes returning home after months away.

Though there has been a lot of research in this area, scientists are still trying to understand exactly how they manage to find their intended destinations.

Much of the research has focused on homing pigeons, which are famous for their ability to return to their lofts after long distance displacements. Evidence suggests that pigeons use a combination of olfactory cues to locate their position, and then the sun as a compass to head in the right direction.

We call this “map and compass navigation”, as it mirrors human orienteering strategies: we locate our position on a map, then use a compass to head in the right direction.

But pigeons navigate over relatively short distances, in the region of tens to hundreds of kilometres. Migratory birds, on the other hand, face a much bigger challenge. Every year, billions of small songbirds travel thousands of kilometres between their breeding areas in Europe and winter refuges in Africa.

This journey is one of the most dangerous things the birds will do, and if they cannot pinpoint the right habitat, they will not survive. We know from displacement experiments that these birds can also correct their path from places they have never been to, sometimes from across continents, such as in a study on white crowned sparrows in the US.

Over these vast distances, the cues that pigeons use may not work for migrating birds, and so scientists think they may require a more global mapping mechanism.

Navigation and location

To locate our position, we humans calculate latitude and longitude, that is our positon on the north-south and east-west axes of the earth. Human navigators have been able to calculate latitude from the height of the sun at midday for millennia, but it took us much longer to work out how to calculate longitude.

Eventually it was solved by having a highly accurate clock that could be used to tell the difference between local sunrise time and Greenwich meantime. Initially, scientists thought birds might use a similar mechanism, but so far no evidence suggests that shifting a migratory bird’s body clock effects its navigation ability.

There is another possibility, however, which has been proposed for some time, but never tested – until now.

The earth’s magnetic pole and the geographical north pole (true north) are not in the same place. This means that when using a magnetic compass, there is some angular difference between magnetic and true north, which varies depending on where you are on the earth. In Europe, this difference, known as declination, is consistent on an east west axis, and so can possibly be a clue to longitude.

To find out whether declination is used by migrating birds, we tested the orientation of migratory reed warblers. Migrating birds that are kept in a cage will show increased activity, and they tend to hop in the direction they migrate. We used this technique to measure their orientation after we had changed the declination of the magnetic field by eight degrees.

First, the birds were tested at the Courish spit in Russia, but the changed declination – in combination with unchanged magnetic intensity – indicated a location near Aberdeen in Scotland. All other cues were available and still told them they were in Russia.

If the birds were simply responding to the change in declination – like a magnetic compass would – they would have only shifted eight degrees. But we saw a dramatic reorientation: instead of facing their normal south-west, they turned to face south-east.

This was not consistent with a magnetic compass response, but was consistent with the birds thinking they had been displaced to Scotland, and correcting to return to their normal path. That is to say they were hopping towards the start of their migratory path as if they were near Aberdeen, not in Russia.

This means that it seems that declination is a cue to longitudinal position in these birds.

There are still some questions that need answering, however. We still don’t know for certain how birds detect the magnetic field, for example. And while declination varies consistently in Europe and the US, if you go east, it does not give such a clear picture of where the bird is, with many values potentially indicating more than one location.

There is definitely still more to learn about how birds navigate, but our findings could open up a whole new world of research.

Stress in the nest can have lifelong effect

(The Norwegian University of Science and Technology, Science Daily 16 August 2017)

Why do some sparrows hatch six chicks while others don’t hatch any? How does upbringing affect the remainder of their lives? Physiological stress in the nest can actually affect birds’ DNA and possibly their lifespan.

On average, a mere 10 to 20 per cent of sparrow nestlings survive until the next breeding season. But the survival rate varies between different parents, according to Thomas Kvalnes and Michael Pepke Pedersen at the Norwegian University of Science and Technology’s (NTNU) Centre for Biodiversity Dynamics (CBD).

In order to learn more about this variation, they’re studying birds by banding them.

Good conditions in NTNU birdhouse

At the NTNU Gløshaugen campus in Trondheim, Kvalnes and Pedersen have been following a pair of Eurasian blue tits, which eventually laid ten eggs and were incubated for two weeks. Then the real work started for the parents. No fewer than nine chicks hatched and they all wanted to eat — at the same time.

The blue tit chicks — which are part of the sparrow family — grew enormously fast during the nesting period, growing from less than one gram at hatching to 10 to 12 grams at around 15 days old. This requires a lot of food. The parents in the NTNU birdhouse seem to have access to good nutrition, because all nine young were alive and growing normally when they were 12 days old.

Banding for research

By the age of 12 days, the young had a lot of feathers and were able to regulate their body temperature well. They were also small enough not to get scared and fly out when the lid on the birdhouse was opened. This is important to think about when banding chicks, because the bands must not adversely affect the birds.

The researchers banded all nine baby birds with metal rings, each having a unique identity number. This allows researchers to recognize the individuals later and to follow their development throughout their lives.

Banding is a widely used method by researchers at the NTNU’s Centre for Biodiversity Dynamics.

How does upbringing affect the rest of a bird’s life?

New research suggests that the first days and weeks have a big impact on how the rest of a bird’s life unfolds. In some clutches, the young get a lot of food and grow fast, whereas in others the chicks face tougher competition or the nest is more exposed to the weather. However, conditions in the nest can actually leave a genetic impression in the birds, more specifically on the ends of the chromosomes that make up the DNA.

The telomeres (from Greek, meaning “end pieces”) that protect the DNA from breaking down are found here, say Kvalnes and Pedersen.

“Each time a cell divides, the DNA must be copied, but the entire DNA sequence cannot be copied, and that impacts the telomere structures, which get shorter after each copying. At the same time, the telomeres wear down if exposed to oxidative or physiological stress, the researchers say.

Molecular thread of fate?

When the telomeres become too short, cell function may become impaired and the entire organism may be affected by age-related illnesses. Some studies have shown that birds’ telomere length can predict how long they will live — a bit like the thread of fate that is clipped by the Norns in Norse mythology and decides the length of human lives.

The most rapid shortening of the telomeres in life occurs when the young chicks grow fast. At CBD, researchers are investigating the connection between sparrow telomeres and their life stories. The researchers follow them from their time in the nest until they become parents themselves — and perhaps grandparents — until their death.

Telomeres in birds and humans

Much of our understanding of telomeres comes from studies of animals in captivity or laboratories, but there’s a lot we don’t know about how these fundamental physiological processes work in typical natural circumstances. CBD researchers hope to help answer these questions.

“The telomeres in birds are identical to those found in humans and all other vertebrates, and they speak to our common origin. In fact, telomere mechanisms exist in all organisms except simple bacteria and archaea. So it’s conceivable that we’ll be able to transfer our knowledge of telomere dynamics in birds to many other organisms,” the researchers say.

New Government Report Contradicts Trump Administration Climate Claims

Common Loon with chicks. Photo: Richard D. Pick/Audubon Photography Awards(Andy McGlashen 8 August 2017)

The report, which paints a dire picture of the planetary changes caused by warming temperatures, is awaiting official White House approval. But scientists worry its findings will be downplayed or suppressed.

The White House has found itself in yet another tough spot: Will the president and cabinet officials approve a report that contradicts their own public statements about climate change, or face backlash for suppressing the report and its inconvenient conclusions? Either way, they only have until August 18 to make a decision, and a sudden frenzy of news coverage this week has increased pressure as the deadline looms.

As originally reported by The New York Times on Monday, the draft report from scientists at 13 federal agencies shows severe warming in recent years, projects continued, significant temperature increases, and says human activity is chiefly to blame. According to the Times, scientists involved in the study are concerned that the Trump administration will hide or downplay the findings of the report, which was publicly available during its review period in December but received little press coverage until now.

Trump infamously called climate change a Chinese hoax during his campaign for the White House, has since moved to undo domestic climate policies, and has pulled the United States out of the Paris climate accord signed by nearly 200 countries in 2015. He also made Scott Pruitt the administrator of the Environmental Protection Agency. Pruitt, who is a known climate change denier, would need to approve the report before it went public. Pruitt has spent much of his time in office weakening the EPA’s climate change research, and as the Times notes, in March, he said that carbon dioxide is not a “primary contributor” to global warming.

The draft report thoroughly undermines the Trump administration’s climate change claims and policies. “Evidence for a changing climate abounds, from the top of the atmosphere to the depths of the oceans,” it says. “Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate changes. There are no alternative explanations, and no natural cycles are found in the observational record that can explain the observed changes in climate.” You can read the full report here.

Our planet has warmed by 1.6 degrees Fahrenheit since 1880, and it is “extremely likely” that most of the 1.2 degrees of warming since 1951 is due to human activity, the report concludes. We could expect another half-degree of warming by the end of the century, even if humans stopped pumping greenhouses gases into the atmosphere today. And under more realistic emissions scenarios, “the temperatures of recent record-setting years will become relatively common in the near future,” the authors write.

Along with rising temperatures, the report paints an unsettling picture of other planetary changes already underway. In the northeastern U.S., for example, extreme precipitation events are 17 percent more frequent than they were in the first half of the 20th century. Global sea levels have risen 3 inches since 1990, and the oceans are becoming more acidic faster than at any period in the past 66 million years. Permafrost is thawing and sea ice is melting in the Arctic, which is warming more than twice as fast as the rest of the planet. “Residents of Alaska are on the front lines of climate change,” the report says. “Crumbling buildings, roads, bridges, and eroding shoreline are commonplace.” 

While most scientists have long been cautious about blaming climate change for specific weather events, the report notes that new tools and techniques are making it possible to detect its influence on specific extreme weather events.

In addition to being a danger to human life, especially the socioeconomically disadvantaged, the global changes documented in the report threaten birds and other wildlife. As Audubon has reported, warming oceans are changing seabird diets and possibly even causing die-offs, while rising seas threaten bird habitat. And Audubon’s 2014 Birds & Climate Change Report, published in peer-reviewed scientific journals, found that climate change is the biggest threat to 314 North American bird species. In South America, where many of these species migrate for the winter, climate change-related droughts also put birds at risk.

The draft Climate Change Special Report is part of the National Climate Assessment charged with reporting the latest climate science to Congress and the president every four years. The National Academy of Sciences has approved the draft, but it won’t be final until the White House signs off. If the administration did have plans to quietly scuttle the report or water down its urgent message, it will now have a much harder time doing so.