The comeback of the bald eagle has been one of America’s great environmental success stories. The mighty eagles nearly vanished from the continental United States in the 1970s due to habitat loss, hunting, and use of the pesticide DDT, which thins the birds’ eggshells. But bald eagle populations have rebounded in the decades since the federal government banned DDT and put strict protections in place, leading conservationists to reintroduce the eagles to historic habitats, like Southern California’s Channel Islands. But a new study in the Proceedings of the National Academy of Sciences suggests that the story’s happy ending may be more complicated than expected.
Conservation biologist Seth Newsome of the University of Wyoming reconstructed the eating habits of the bald eagles who lived on the islands until the late 1960s by analyzing old bones and feathers. He found evidence that resurgent eagles on the Channel Island may threaten another endangered species.
It’s not just that some birds can use tools, as primates can. Their smarts stretch even further: New research this week suggests that New Caledonian crows can solve a three-step problem, in which the three steps must be completed in succession to reach a tasty snack. Alex Taylor and colleagues document this discovery in the Proceedings of the Royal Society B.
Here’s the setup: There’s a short stick dangling from the bird’s perch on a string. That short stick isn’t long enough to grab the food that’s tucked inside a long and narrow box, but there’s a longer stick in a separate box. If the birds could figure out the first two steps—grabbing the short stick, and using it to get the longer stick—then voila, they could use the longer stick to reach the food.
When you see a flock of birds flying in formation, it might seem like their group dynamics are fairly simple: The one out front leads the way. But does the same birds always take the lead in a group? And do the birds in the back follow the overall leader, or rather the middle managers in front of them?
To find out, Tamás Vicsek and colleagues strapped backpacks equipped with GPS sensors to pigeons for a study out this week in Nature. The lightweight trackers recorded the birds on both solo flights and group flight and measured their positions five times per second. Indeed, Vicsek found, birds fly according to the group pecking order, with the leader out front. When it changed direction, its direct followers would do the same in less than a second, and then the more junior members of the group would respond to the direction of those middle managers.
But there were surprises, too. Sometimes the lead bird wouldn’t fly out front; it may have been tired from leading the pack and needed some time off. So perhaps birds are like cycling teams, occasionally trading off who carries the taxing burden of leading the group.
For more details about the study—including why it’s not as obvious as you might think that the leading bird flies in the front of the group, and why left and right matter so much to pigeons—check out DISCOVER blogger Ed Yong’s post at Not Exactly Rocket Science.
This week the federal government released its 2010 report, “The State of the Birds,” examining the health of the United States’ native fowl. According to Interior Secretary Ken Salazar, the state of our union’s birds is precarious.
The 2010 report focused on climate in particular. In it, scientists reviewed data for 800 species nationwide, and ranked their sensitivity to climate change based on factors including how many young they produce each year, how able they are to move to new habitats, and how unique their food and nesting needs are [San Jose Mercury News]. Each of the 800 then received a designation of low, medium, or high vulnerability. You can see the methods for scoring here.
The technical way to explain this odd-looking fowl is that it’s “gynandromorphous.” But if you just want to call it “one seriously confused chicken,” that works, too.
For a new study in Nature, Michael Clinton and colleagues investigated a few of these half-male, half-female chickens they obtained from chicken farms. Gynandropmorphs show up now and then not just in chickens, but also in parrots, pigeons, and some other kinds of animals. But scientists weren’t sure how the mix-up happens, since the standard idea for sex differentiation is that the sex hormones released by the gonads either masculinize or feminize the embryo. Clinton’s team discovered that bird cells don’t need to be programmed by hormones. Instead they are inherently male or female, and remain so even if they end up mixed together in the same chicken [BBC News].
The researchers had first assumed that the half-and-half chickens followed the hormone pattern, and that they were females with some sort of chromosomal problem on the male side (the lighter half of the bird in the image, which also sports a large wattle, sturdy breast musculature, and a leg spur on its male side). Instead, they found the chickens to be almost perfectly split between male and female. The hen half was, for the most part, made up of normal female cells with female chromosomes, whereas the cockerel side contained mostly normal male cells with male chromosomes [Nature News].
An international team of researchers has discovered how to extract DNA from fossilized bird eggs–including the eggshell of the enormous elephant bird that went extinct four centuries ago.
In a research breakthrough, scientists were able to isolate DNA from the eggshells of not just the extinct giant moa bird from New Zealand, but also a 19,000-year-old emu from Australia and the extinct elephant bird of Madagascar. The elephant bird’s egg is the largest known bird egg, with 160 times the volume of a chicken’s egg [New Scientist].
The discovery of these birds’ DNA could help scientists understand how they lived, and why they became extinct. The DNA was extracted from desiccated inner membranes in fossil eggshells, found in 13 locations in Australia, Madagascar and New Zealand [PhysOrg], and the work was published in the Proceedings of the Royal Society B.
For years scientists have been trying to extract DNA from old eggshells without success, because their approach, scientists admit, was faulty. Charlotte Oskam and Michael Bunce of Murdoch University in Perth, Western Australia, who isolated the DNA, say researchers (including themselves) were using techniques designed to extract DNA from bone, not eggshells. They even threw out the most DNA-hardy bits of eggshell [New Scientist]. Bunce explains that extracting DNA from bone involves sucking out the bone’s calcium and discarding it.
Last week, a study found that an early dinosaur had a red mohawk and striped tail, one of the first pieces of solid evidence regarding dinosaur coloration. But a new study forthcoming in Science goes one step further, mapping in full 3D the strange plumage of the earliest-known feathered dinosaur, Anchiornis huxleyi.
Richard O. Prum, leader of the new study, was among the first to document that pigment-giving structures called melanosomes could survive fossilized for millions of years. The shape and arrangement of melanosomes help produce the color of feathers, so the scientists were able to get clues about the color of fossil feathers from their melanosomes alone [The New York Times]. British and Chinese scientists used this technique to release last week’s color study of the 125-million-year-old Sinosauropteryx, and Prum’s team applied it to the 150-million-year-old Anchiornis.
Scientists knew that the Aztec people of pre-Columbian Mexico had domesticated the turkey by the time Europeans arrived, and that those birds are the forebears of the giant birds Americans devour in gut-busting volume every Thanksgiving. But a new study (pdf) in the Proceedings of the National Academy of Sciences suggests that the Aztecs weren’t the only early Americans to tame the turkey: People of what is now the Southwestern United States, including the Anasazi, separately domesticated the birds.
Two teams that had been separately studying the bones and the fossilized dung of ancient turkeys joined forces for this find. Studying 38 different sites, they found that the Aztec peoples accomplished the feat first. But later, perhaps around 200 B.C., they saw that the people of the Southwest United States duplicated the achievement. The two instances of domestication appear to have been separate, based on DNA analysis of ancient turkey remains. However, the different Native American groups could have been in contact with each other, sharing turkey-raising tips [Discovery News].
As much as paleontologists have sorted out about the dinosaurs, one of the main aspects of their appearance—what color they were—has remained mysterious. But in a new Naturestudy, a team of British and Chinese scientists report that they found a way to unlock the color patters of one of the earliest feathery dinosaurs—it had a red mohawk, they say, with a red and white striped tail.
The dino in question is called Sinosauropteryx, which lived about 125 million years ago. Looking at fossils found in China, the team led by Mike Benton found what they think are the remains of feathers. And they found something inside the feathers that matches modern birds: melanosomes. These structures provide the melanin pigment in bird feathers (and human hair), and what color they are depends on the shape. “A ginger-haired person would have more spherical melanosomes, and a black-haired or grey-haired person would have more of the sausage-shaped structures,” said Professor Benton [BBC News].
Alligators breathe like birds, with a one-way tube that flows all the way through their respiratory systems. While that might not seem earth-shattering at first, alligators and birds diverged 246 million years ago. And according to a new study in Science, that means this breathing technique goes way, way back, and could even explain how the ancestors of dinosaurs survived the great Permian-Triassic extinction.
Unlike a mammal’s breath, which exits the lungs from the same dead-end chambers it enters, a bird’s breath takes a loopy one-way street through its lungs [Science News]. This breathing technique allows birds to explore high altitudes where oxygen levels drop off significantly.
If you thought George Clooney’s character in “Up in the Air” racked up a lot of frequent flyer miles, you should meet his avian rival, which flies the equivalent of three round trips to the moon and back during its lifespan. For a study in the Proceedings of the National Academy of Sciences, researchers tracked the arduous migration of the tiny Arctic tern and found that it flies an average of 44,000 miles every year on its trip from Greenland to Antarctica and back. That’s a new world record.
Scientists suspected that this tern could best the previous world record of 39,000-mile migrations by the sooty shearwater, though they previously lacked tracking devices small enough for the bird to carry. But the team used a tiny tracker developed by the British Antarctic Survey, which weighs just a twentieth of an ounce (1.4 grams)—light enough for an Arctic tern to carry on a band around its leg [National Geographic]. This device reported the birds’ position twice daily.
For one species to diverge into two, you typically need physical separation so that two populations can breed independently and evolve in different ways. That may happening to the blackcap warblers of Central Europe, Martin Schaefer says in a new Current Biologystudy, thanks to … bird feeders.
The birds are native to Germany and Austria, and migrate in the winter. Blackcap migration routes are genetically determined, and the population studied by Schaefer has historically wintered in Spain. Those that flew north couldn’t find food in barren winter landscapes, and perished [Wired.com].
You’d think something with as much awesome power as the talons on birds of prey would be among the better-understood appendages in the animal kingdom. Not so, say the authors of a new in PLoS One, but they’ve rectified the situation by analyzing 24 different birds to reveal the evolution and use of talons by the owl, osprey, falcon, and more.
They describe how accipitrids, which include hawks and eagles, have two giant talons on their first and second toes [as in pictures A and B]. These give them a secure grip on struggling game that they like to eat alive, “so long as it does not protest too vigorously. In this prolonged and bloody scenario, prey eventually succumb to massive blood loss or organ failure, incurred during dismemberment” [Wired.com].
On the Galapagos Islands, where Charles Darwin’s observations led to his evolutionary theory, scientists are now reporting that they’re witnessing a single species splitting into two, according to a new paper in the Proceedings of the National Academy of Sciences.
A husband and wife team, Peter and Rosemary Grant of Princeton University, have spent the past 36 years studying Darwin’s finches, technically know as tanagers. Darwin‘s observations of the birds during his voyage to the Galapagos on the HMS Beagle helped him arrive at the idea of evolutionary divergence: when different populations of a single species become geographically isolated, and evolve in different directions. The Grants have pushed that work further, with decades of painstaking observations providing a real-time record of evolution in action. In the PNAS paper, they describe something Darwin could only have dreamed of watching: the birth of a new species [Wired.com].The process has been taking place with the help of a little bit of chance and a special song.
Some migratory birds that have to navigate across continents have an extremely useful tool at their disposal–an internal compass that points unerringly towards magnetic north. Researchers already knew that some birds possess these biological compasses, but their mechanism has been unclear. “This is basically the sixth sense of biology, but no one knows how it works…. The magnetic sense is by far the least understood sense in the natural world,” [Science News], says study coauthor Henrik Mouritsen.
Now, researchers have determined that light-sensing cells in the eye convey the crucial message to a special visual center of a robin’s brain, called cluster N. Special proteins called cryptochromes in the birds’ eyes may mediate this light-dependent magnetic sensing, Mouritsen says. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is [Science News].
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
The comeback of the bald eagle has been one of America’s great environmental success stories. The mighty eagles nearly vanished from the continental United States in the 1970s due to habitat loss, hunting, and use of the pesticide DDT, which thins the birds’ eggshells. But bald eagle populations have rebounded in the decades since the federal government banned DDT and put strict protections in place, leading conservationists to reintroduce the eagles to historic habitats, like Southern California’s Channel Islands. But a new study in the Proceedings of the National Academy of Sciences suggests that the story’s happy ending may be more complicated than expected.
When you see a flock of birds flying in formation, it might seem like their group dynamics are fairly simple: The one out front leads the way. But does the same birds always take the lead in a group? And do the birds in the back follow the overall leader, or rather the middle managers in front of them?
This week the federal government released its 2010 report, “
The technical way to explain this odd-looking fowl is that it’s “gynandromorphous.” But if you just want to call it “one seriously confused chicken,” that works, too.
An international team of researchers has discovered how to extract DNA from fossilized bird eggs–including the eggshell of the enormous elephant bird that went extinct four centuries ago.
Last week, 
Scientists knew that the Aztec people of pre-Columbian Mexico had domesticated the turkey by the time Europeans arrived, and that those birds are the forebears of the giant birds Americans devour in gut-busting volume every Thanksgiving. But a new 
As much as paleontologists have sorted out about the dinosaurs, one of the main aspects of their appearance—what color they were—has remained mysterious. But in a new Nature 
Alligators breathe like birds, with a one-way tube that flows all the way through their respiratory systems. While that might not seem earth-shattering at first, alligators and birds diverged 246 million years ago. And according to a new 
If you thought George Clooney’s character in “
For one species to diverge into two, you typically need physical separation so that two populations can breed independently and evolve in different ways. That may happening to the blackcap warblers of Central Europe, Martin Schaefer says in a new Current Biology 
On the 
Some 
