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].
A team of researchers recently discovered that Tamiflu, the leading flu-fighting drug, is accumulating in rivers downstream from sewage-treatment plants in Kyoto. How is this possible? Tamiflu’s active ingredient, oseltamivir phosphate, is excreted in the urine of people taking the medication. Concerns are now building that birds, which are natural influenza carriers, are being exposed to waterborne residues of Tamiflu’s active form and might develop and spread drug-resistant strains of seasonal and avian flu [Science News]. The resistant virus strains would be of the conventional seasonal or avian flu variety, not the H1N1 swine flu strain that is currently pandemic in humans. Seasonal flu, however, kills thousands of people each year.
Study coauthor Gopal Ghosh explains that the team took measurements during normal flu season, and found concentrations that seem “high enough to lead to antiviral resistance in waterfowl” [Science News]. Computer models show that oseltamivir phosphate will survive sewage treatment, but it should break down when exposed to sunlight and its concentrations should decrease by half every three weeks. The high concentrations were found during a period where 1,738 flu cases were reported in Kyoto, according to the study, published in the journal Environmental Health Perspectives. In the United States, Tamiflu is only recommended for the very sick or those with compromised immune system, while Japan has a more liberal policy.
A feathered dinosaur unearthed in a Chinese quarry has added another solid piece of evidence to the theory that birds descended from dinosaurs. The newly uncovered fossil of the species Anchiornis huxleyi dates from the Late Jurassic period, 151-161 million years ago, and therefore predates the earliest known bird, the Archaeopteryx. Paleontologists say this represents the final proof that dinosaurs were ancestral to birds. “Drawing the tree of life, it’s fairly obvious that feathers arose before Archaeopteryx appears in the fossil record” [BBC News], says paleontologist Michael Benton.
The creature, described in a paper [pdf] in Nature, was covered in the short feathers known as “dino-fuzz,” and had longer feathers on both its forelimbs and its back legs that formed primitive wings. The four-winged dinosaurs also had feathers on their feet and wing-like attachments on the arms and legs. But they could probably only glide, as their plumage was insufficient for powered flight [Nature News].
At some point in the first half of the 20th century, a couple of ants hitched a ride on a boat and ended up on Christmas Island, an Australian territory in the Indian Ocean. And so began the rampage of the “yellow crazy ants,” creatures that have been named one of the top 100 most invasive species in the world. On Christmas Island, scientists have now declared an “invasional meltdown” of the original ecosystem [Science News].
The latest evidence: The ants are so plentiful and bothersome that they’re preventing birds from feeding on berries, and the birds are therefore failing to disperse seeds around the island.
Researcher Dennis O’Dowd explains that the long-legged yellowish ants earned the named “crazy” because when they are disturbed they run around frenetically. O’Dowd says crazy ants form large super-colonies and cover ground and vegetation in densities of around 1000 ants per square metre. “These ants are three-dimensional foragers,” he says [ABC Science]. The ants can thickly cover the forest floor and swarm up vines and plants.
Pigeons alert their flockmates to impending danger not through vocalization, but by making a whistling sound with their wings as they take off in response to a threat, according to a study published in the journal Proceedings of the Royal Society B. Researchers say other birds may also have co-opted the basic mechanical sounds of flight for communication purposes.
Biologists were curious about how all the pigeons in a huge flock knew to launch themselves into the air at the same moment. Because the birds don’t use vocal calls to alert their peers, scientists hypothesized they convey the message using their wings. Researchers first recorded the sounds made by crested pigeons flying happily around a feeder, then sent in a decoy of a hawk, and recorded their flight from the faux predator. When the researchers later played the sound back for a flock of birds, they didn’t so much as twitch at the normal recording. But the rapid clap-clap-clap of the alarmed bird sent them fleeing. Similarly, when the volume or speed of the recording was manipulated, birds only reacted to emergency wing whistles [Discovery News]. Although it’s not yet known exactly how the birds make these sounds, the study’s results could do more than increase our understanding of bird communication. They could also help repel the pesky birds from places where they are annoying or even harmful, like public parks and airports.
In the first experiment linking cognitive ability to reproductive success, researchers found that the male bowerbirds with the best problem-solving capabilities also mated the most often, according to a study published in the journal Animal Behaviour.
The Australian bowerbird is known for its elaborate courtship behavior. During breeding season, males build a special platform, or bower, on the forest floor to lure females, and they decorate it with rare objects such as blue feathers and shiny bits of glass. They accompany this with varied vocalizations, hopping, and tail-bobbing [ScienceNOW Daily News]. To evaluate which males had the best problem-solving abilities, scientists placed a red object in the birds’ bowers–a color the birds disdain. In one experiment, three red objects were placed in the bower and covered by clear plastic that the bird had to take off in order to remove the noxious items. In the next, the red object was securely nailed to the nest, so the only way to make it less visible was to cover it with leaves and twigs.
Rising temperatures in Australia have caused birds on that continent to shrink–some by nearly 4 percent. The findings of a study published in the journal Proceedings of the Royal Society B are the first to show that birds’ sizes are affected by global warming, although this phenomenon previously has been shown in fish and Soay sheep. Scientists postulate that the relationship between a warmer climate and smaller animals may be true for the animal kingdom as a whole.
Temperature has a clear impact on body size; it’s old news among scientists that birds closer to the equator evolved to be smaller than their peers near the poles. One possible explanation for this, called Bergmann’s Rule, is that larger animals conserve heat more efficiently, and this trait is naturally selected for in colder climates, but not in warmer climates. On this basis, scientists have predicted that climate change will affect the way animals vary in size at different latitudes [ABC Science]. The recent research on sheep and fish has corroborated this hypothesis by showing that these animals have become smaller as temperatures have risen.
A quartet of clever rooks have provided evidence that one of Aesop’s fables could have a basis in fact. The tale in question tells the story of a thirsty crow. The bird comes across a pitcher with the water level too low for him to reach. The crow raises the water level by dropping stones into the pitcher. (Moral: Little by little does the trick, or in other retellings, necessity is the mother of invention) [AP]. In the new lab experiment, four rooks each dropped stones into a clear plastic tube, which raised the water level high enough to bring a floating worm within reach.
Rooks and crows are both in the corvid family, which researchers say rivals the great ape family for intelligence and tool use–the only other animal that has performed a comparable task was an orangutan, who spat into a tube to gain a floating peanut. Says study coauthor Nathan Emery: “We have performed a large number of studies on both corvids … and apes, and have found that the crow’s performance is on a par or often superior to apes. However, it is not particularly useful to say that one species is more or less intelligent than another because often the playing fields aren’t even” [The Independent].
Just when it seemed that there were no more mysteries left in the wild parts of the planet, scientists have turned up a new species of bird–an odd-looking creature that has been named the Barefaced Bulbul because of its mostly bald head. The never-before seen songbird was spotted in a remote forest in Laos, and the find provides a cheerful contrast to the steady drumbeat of endangered species news. Despite the ever-spreading imprint of humanity on this small planet, scientists keep discovering new species, even among relatively conspicuous classes of vertebrates like mammals and birds [The New York Times, blog].
The new bulbul is about the size of a thrush, and sports olive green feathers on most of its body. But it has a bald, pink face with just one line of feathers that ornaments its head like a mohawk. Hardly a shy and retiring bird, the bald-headed bulbul foraged and noisily moved about the researchers during the day, making them wonder how this eye-catching bird went undiscovered for so long. “Certainly one reason is that the bird appears to be truly restricted to some very harsh and inaccessible terrain in Indochina” [Discovery News], said Peter Clyne of the Widlife Conservation Society.
The toucan’s big beak has been an object of fascination for centuries: In the late 1700s a French naturalist called it a “grossly monstrous” appendage, and later Charles Darwin contemplated its possible purpose. Why should the bird have a beak that accounts for 40 percent or more of the total surface area of its body? Among the suggestions are that it is useful for peeling fruit, for attacking other nests or as sexual ornamentation [The New York Times]. Now a new study has revealed the beak’s true purpose: It serves as a giant air conditioner, helping the bird keep cool.
Animals have a range of ways including layers of fat in polar bears and large skin surfaces in elephants to stay cool or keep warm in harsh environments. [Lead researcher Glenn] Tatersall and colleagues found the toucan can lose up to four times as much heat from its beak than it produces at rest — the most reported for any animal [Bloomberg]. The researchers found that the toucan’s bill beats out the elephant’s ears in its ability to change the animal’s body temperature; it can rapidly adjust the internal thermostat by as much as 27 degrees Fahrenheit, Tattersall says.
To get inside the head of a homing pigeon as it navigates towards its roost, researchers turned a flock of pigeons into cutting-edge techno-birds. The scientists outfitted the birds with “neurologgers” consisting of an electroencephalograph (EEG) to read the bird’s brain waves and a GPS tracker to record its location; by matching a bird’s position to its brain activity, the researchers could determine the bird’s reaction to the landscape below it. They found that, just like humans, the pigeons use visual landmarks in their navigation.
How homing pigeons find their way back to a starting point is not completely known. Studies have shown that the birds variously use the position of the Sun and the Earth’s magnetic field as a compass, and sense of smell and visual cues as navigation aids. But the use of visual cues has been difficult to study, because if a bird flies over a landmark and doesn’t change its course, it’s impossible to know whether the bird has not perceived the cue or is ignoring it [The New York Times].
A husband and wife team that for 35 years has researched finches’ evolutionary responses to environmental changes have won the prestigious Kyoto Prize in the basic sciences category. Peter and Rosemary Grant, both emeritus professors at Princeton University, have studied finches that lives on the Galapagos Islands for decades and will share the $515,000 prize. The Kyoto Prize is a Japanese award similar to the Nobel Prize.
The two evolutionary biologists devoted their careers to furthering Charles Darwin‘s theory of evolution. Both 72, the Grants have been traveling regularly since 1973 to the Galápagos, the remote islands west of Ecuador. There, they have painstakingly recorded the characteristics of numerous varieties of finches [Philadelphia Inquirer]. Darwin stumbled upon these finches during his famous tour of the Galapagos Islands in 1835, later chronicled in his book The Voyage of the Beagle.
Most paleontologists believe that a group of dinosaurs evolved into today’s birds, but in trying to understand that gradual process they’ve been bedeviled by some details. Yesterday, researchers announced that they may have solved one of those small conundrums. A fossilized dinosaur found in China appears to settle the matter of exactly how the bones in dinosaurs’ feet evolved into the digits hidden in bird wings.
The newly discovered ceratosaur belonged to a group of dinosaurs called theropods, which are thought to have given rise to modern birds and which included the mighty Tyrannosaurus rex. But unlike its T. rex cousin, this ceratosaur appears to have been a vegetarian. Says study coauthor James Clark: “It’s a really weird animal – it’s got no teeth, had a beak and a very long neck, and very wimpy forelimbs…. Then when we looked closely at the hand, we noticed it was relevant to a very big question in palaeontology” [BBC News].
More than 220 years since a ship wrecked on the rocks surrounding a remote Aleutian island, biologists believe they may have finally cleaned up the resulting mess. Rats have ruled the island since 1780, when they jumped off a sinking Japanese ship and terrorized all but the largest birds on the island [Reuters]. The voracious rodents feed on bird eggs and even chicks and small adult birds, and they so dominated the tiny island that it was given the name Rat Island. Biologists embarked on an ambitious effort to wipe out the rats last year, and now say they may have accomplished their task–but the campaign may have resulted in some avian casualties.
Nine months after scattering poisoned pellets across the island, biologists say they haven’t spotted any remaining rats, but they have found the carcasses of 186 glaucous-winged gulls and 41 bald eagles. U.S. Fish and Wildlife spokesman Bruce Woods said it’s unlikely carnivorous eagles ate the Rodenticide grain pellets, but they may have devoured some dead rats that had consumed them. “Eagles are scavengers of opportunity,” he said. “Rats don’t make up a big part of their diet naturally, but if meat is available, they’re going to take it” [Anchorage Daily News].
A hummingbird in love can perform aerial stunts that put fighter pilots to shame. In a new study, researcher Christopher Clark captured the male hummingbird’s daring dives with cameras that can capture 500 frames per second. To get the footage, Clark set out a caged female, or even a stuffed female on a stick, to inspire birds to dive right in front of his video cameras [Science News].
In the study, published in the journal Proceedings of the Royal Society B, Clark observed the Anna’s hummingbird, a tiny bird native to the American southwest. In the male’s courtship display he dives down dramatically with his wings pressed to his sides, and then dramatically stretches out his wings and tail feathers to break his momentum and bring him swooping back up into the sky. Clark says that the maneuver sets some records. When measured relative to the length of their bodies, the birds’ top speed, he said, was “greater than [that] of a fighter jet with its afterburners on, or the space shuttle during atmospheric re-entry” [BBC 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].
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.
A team of researchers recently discovered that Tamiflu, the leading flu-fighting 
A feathered 
At some point in the first half of the 20th century, a couple of 
In the first experiment linking 
Rising temperatures in Australia have caused 
Just when it seemed that there were no more mysteries left in the wild parts of the planet, scientists have turned up a 
The toucan’s big beak has been an object of fascination for centuries: In the late 1700s a French naturalist called it a “grossly monstrous” appendage, and later Charles Darwin contemplated its possible purpose. Why should the bird have a beak that accounts for 40 percent or more of the total surface area of its body? Among the suggestions are that it is useful for peeling fruit, for attacking other nests or as sexual ornamentation [
To get inside the head of a homing pigeon as it navigates towards its roost, researchers turned a flock of pigeons into cutting-edge techno-birds. The scientists outfitted the 
A husband and wife team that for 35 years has researched finches’ 
Most paleontologists believe that a group of 
More than 220 years since a ship wrecked on the rocks surrounding a remote Aleutian island, biologists believe they may have finally cleaned up the resulting mess. Rats have ruled the island since 1780, when they jumped off a sinking Japanese ship and terrorized all but the largest birds on the island [
A hummingbird in love can perform aerial stunts that put fighter pilots to shame. In a new study, researcher Christopher Clark captured the male hummingbird’s daring dives with cameras that can capture 500 frames per second. To get the footage, Clark set out a caged female, or even a stuffed female on a stick, to inspire birds to dive right in front of his video cameras [
