Blogs / 80beats

If you get on a mockingbird’s enemy list, expect to be dive-bombed every time you come within the bird’s sight. That’s one lesson that can be taken from a new study which proved that mockingbirds can recognize individual people, and attack those who have bothered their nests in the past. While ornithologists knew that certain highly intelligent birds like parrots and crows can recognize humans in a lab setting, they were surprised to find similar behavior in a songbird living in the wild. This paper is “a beauty,” says John Fitzpatrick, an ornithologist at Cornell University. “It’s amazing what a bird brain can do” [ScienceNOW Daily News].

The study was prompted by a series of bird attacks. A graduate student involved in research on bird nesting noticed that when she would make repeat visits to peoples’ yards the birds would alarm and attack her, while they would ignore people gardening or doing other things nearby…. Indeed, it seemed they could even recognize her car, and she had to start parking around the corner [AP]. So the researchers designed an experiment to investigate whether the birds really could identify an individual person.

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It may be the first example of a serious scientific study being launched by a viral video. Neuroscientist Aniruddh Patel was astonished when someone e-mailed him a link to a YouTube video of a sulfur-crested cockatoo named Snowball dancing to the Backstreet Boys.”I said, you know, this is much more than just a cute pet trick. This is potentially scientifically very important,” recalls Patel [NPR].

Researchers had previously assumed that only humans move in time to a beat, but Snowball appeared to bob and rock to the rhythm just like any dancer. But Patel still wondered if the tail-shaking cockatoo had simply learned one dance routine that happened to synchronize to the Backstreet Boys song. For his study, published in Current Biology, Patel made slowed down and sped up versions of the song, and played them back to the bird while Snowball’s owner videotaped the reaction.  They found that Snowball did adjust his moves to match the tempo. At slower speeds the bird swayed rhythmically from side to side, and when the beats came fast and furious, the bird erupted into rapid head-bobbing.

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Egyptian health officials have just reported two deaths from bird flu within days of each other. The dangerous virus variant H5N1 struck down a six-year-old boy and a young woman, bringing the total death toll in Egypt to 25. While bird flu experts note that Egypt has seen a surge in human cases in recent months, with 16 confirmed since the start of the year, compared to seven cases between January 1 and April 17 last year [Reuters], they also say that the Egyptian people’s level of alarm is out of proportion to the threat.

Rumors have appeared in the Egyptian media that the virus is circulating widely, and that some people get “silent infections” which show no symptoms, but still allow them to pass on the virus. The rumors have been fueled by the pattern of recent infections: Many of the infected patients have been toddlers, leading to the belief that stronger adults are also infected but simply show no symptoms. Although thousands of Egyptians have rushed their children to hospitals this flu season, there is no evidence yet of asymptomatic avian flu cases or any significant mutation in the H5N1 virus. “Right now, it’s all hot air,” said Dr. Robert G. Webster, a flu expert…. “I hope to hell it’s not happening, because it would mean the virus is adapting to humans. But there’s not a shred of data” [The New York Times].

While the H5N1 virus rarely infects people, the looming fear is that the virus may mutate into a form that can be transmitted easily from person to person, which could spark a deadly pandemic. However, an outbreak of swine flu across the world from Egypt, in Southern California, has reminded people of the hazards of overreacting before all the information is in.

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Researchers have learned the universal secret behind the graceful, aerial turns executed by everything from insects to cockatoos. And it’s a surprisingly simple process: To turn left, all a bird has to do is flap its right wing a little bit harder than the left wing. To end the turn, the bird simply returns to flapping its wings in unison [Discovery News]. Researchers hope to duplicate the simple set of motions to create more nimble and acrobatic flying robots.

Though the dynamics probably can’t work at large scales — building-sized robotic birds won’t ever be as agile as a swallow — they could be harnessed in small drones used by explorers or the military. Compared to the average hummingbird or fruit fly, such craft are now clumsy and unstable. “The results will inform all future research into maneuvering flight in animals and biomimetic flying robots” [Wired], wrote biomechanicist Bret Tobalske in a commentary.

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Young chickens just a few days old can count and perform basic arithmetic, according to a fluffy new study. Researchers manipulated objects that the chicks had formed an attachment to, moving the objects behind little screens, and found that the observant young birds kept track of where the objects were. In effect, the chicks were solving simple math problems like “4 – 2 = 2.”

While some adult animals, including primates and dogs, have been found to have an understanding of basic math, researchers had not previously demonstrated numerical abilities in any young animals (except for humans). Karen Wynn, who has reported evidence of numerical skills in human babies, points out that the chicks haven’t had a chance to learn or develop much. “This work, then, is a compelling existence proof that numerical understanding comprises a built-in system of unlearned knowledge,” Wynn says [Science News].

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A migrating bird has found a quick and effective way to boost its endurance for a grueling task, according to a new study, and it’s a tactic that would make human marathon runners jealous–provided they like seafood.

Like all migrating birds, the tiny sandpiper instinctively heads to warmer climates for the winter. The [1,900-mile] trek from the birds’ summer home in the Canadian Arctic to the South American coast includes 3 days of nonstop flight over open water. The journey is so arduous it can kill younger or weaker members of the flock [ScienceNOW Daily News]. Sandpipers prepare for the flight in a number of ways: Autumn’s shorter days and cooler weather trigger hormonal changes in the birds, causing their stomachs to stretch to hold more food. The birds also start flying more, as if exercising for their upcoming ordeal.

But the final, and arguably most important step seems to be a stop at the Bay of Fundy, where sandpipers spend two weeks gorging on mud shrimp, which have some of the highest levels of omega-3 fatty acids of any marine animal. Researchers say the feast drastically increases the birds’ endurance by making their muscles use oxygen more efficiently. These omega-3 fatty acids are the same fats shown to reduce the risk of cardiovascular disease and lower blood pressure in humans [CBC]. 

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The Gouldian finch female has a neat trick for maximizing her offspring’s chance of survival: If she mates with a male who is a poor match for her genetically, she increases the proportion of male chicks in the resulting brood. In a new study, researchers say they’ve found unprecedented evidence that these birds can exert control over the gender of their offspring.

The endangered finch, native to the northern savannahs of Australia, can have either a black or red head, and the two different “morphs” have significant genetic differences, lead researcher Sarah Pryke says. “Gouldian finches wear their genes on their head so it is easy for a female to assess the genetic suitability of the male,” she says [Australian Broadcasting Corporation]. The birds prefer to mate with males that have the same head coloring, as chicks from a mismatched mating – particularly the females – are weaker and more likely to die very early [BBC News].

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The birds of America are in trouble, and those living in Hawaiian paradise are the worst off, according to a dire report issued by the U.S. Interior Department. The State of the Birds report spreads the alarming news that one-third of bird species across the nation are endangered, threatened, or in serious decline due to habitat loss, polluted water, invasive species, and disease, says the study. Climate change will make things worse, and work is urgently needed to prevent “a global tragedy” of bird loss, the report added [The New York Times].

Bird species native to Hawaii, an isolated ecosystem, are particularly at risk, with 31 species currently listed as endangered. “That is the epicenter of extinctions and near-extinctions,” said John Fitzpatrick, director of the Cornell Lab of Ornithology, which helped produce the study. “Hawaii is (a) borderline ecological disaster.” Hawaii’s native birds are threatened by the destruction of their habitats by invasive plant species and feral animals like pigs, goats and sheep. Diseases, especially those borne by mosquitoes, are another killer [AP]. Researchers say that 71 bird species that were found only on Hawaii have gone extinct since humans first settled the islands.

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Two handprints pressed into the mud of an ancient lakeshore 198 million years ago has given paleontologists new insights into the anatomy and evolution of early carnivorous dinosaurs. The theropod who crouched down had a bird-like forelimb structure with palms that always faced inwards, says lead researcher Andrew Milner, which indicates that they stopped using their forelimbs for walking early in their evolutionary history.

The handprints discovered in Utah are part of a larger track that clearly show the hind feet and, occasionally, the dragging tail. But at one point, Milner said, the theropod apparently stopped and crouched to rest. At that point, between the footprints, is the clear circular impression of the ischium or pelvis, “basically a butt print,” Milner said. And to each side of the tracks are the handprints, which are mirror images of each other. They clearly show the third digit pressed into the ground and traces of the second digit, with the claw curling inward. The hands were positioned as they would be for “holding on to a basketball rather than dribbling it,” [Los Angeles Times], comments paleontologist Tom Holtz, who wasn’t involved in the research.

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The songbirds that live in the backyards and parks of the northeast United States have just earned a little more respect. Researchers strapped cutting-edge geolocator devises to the backs of purple martins and wood thrushes to track their migrations, and found that the diminutive warblers can fly more than 300 miles each day, tripling previous estimates. But researchers say the biggest achievement was proving that the new technology works, which lays the groundwork for future studies of small birds.

“Never before has anyone been able to track songbirds for their entire migratory trip,” explained co-author Bridget Stutchbury…. She said that most songbirds were too small to be fitted with conventional satellite tracking devices, so the team mounted miniature “geolocators” on the birds [BBC News]. Each tiny bird backpack weighs less than a dime, and contains light detectors that record each day’s sunrise and sunset times, and also record where the bird is in relation to the sun. When the researchers retrieved the monitors, they used that data to calculate where the birds had been, and when they were there.

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A flock of unfortunate Canada geese are thought to have crossed paths with a U.S. Airways Airbus A320 yesterday afternoon, causing the plane to make an emergency splash landing in the Hudson River. All 155 passengers survived with no serious injuries, but the incident is highlighting the problem of birds striking aircraft, which experts say is common but rarely dangerous. Since 2000, at least 486 commercial aircraft have collided with birds, according to the Federal Aviation Administration. Of those incidents, 166 led to emergency landings and 66 resulted in aborted takeoffs [The New York Times].

Just seconds after take-off from LaGuardia airport, the pilot of the U.S. Airways plane reported a “double bird strike” that damaged both engines. Such collisions are most common at low altitudes and the birds most likely to be sucked into aircraft engines are waterfowl, gulls, and raptors. Canada geese, a frequent visitor to golf courses and open spaces in the metropolitan New York area during the winter, pose a particular danger to planes because of their size. The impact of a 12 pound bird hitting a plane traveling at 150 miles per hour is equal to that of a 1,000 pound weight dropped from a height of 10 feet, according to experts on bird strikes [The New York Times]. But smaller birds can pose dangers too. Bird Strike Committee USA even refers to starlings as “feathered bullets,” since they say these birds possess “a body density 27 percent higher than herring gulls” [Discovery News]. Sometimes the impact can cause the engine blades to break off, becoming dangerous pieces of shrapnel that further destroy the engine. 

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For feathered dinosaurs, it appears that fashion came before function. A new study of a dinosaur fossil found in northeast China has revealed that the dinosaur, Beipiaosaurus, not only had the soft downy feathers that have been spotted in other fossils, it also had a more primitive type of feather that appears to have been used only for peacock-like displays. These primitive feathers don’t cover the dinosaur’s entire body, they’re found only on the creature’s head, neck and tail. The filaments couldn’t have generated lift, so they’re not flight worthy, and they’re too sparse to have retained the creature’s body heat. [Lead researcher Xing] Xu and his colleagues therefore speculate that the filaments served as display structures, just as many similarly placed feathers do on modern birds [Science News].

The feathers detected on the Beipiaosaurus, which lived in the Cretaceous Period, have a very basic structure. The modern-day feathers sported by birds are elaborate constructions with numerous fibers that branch out from a central filament and hook together. This arrangement is so complicated that many scientists theorize it could have evolved only once…. But paleontologists have proposed that a variety of simpler structures — including peculiar, branched structures colloquially called “dinofuzz” — evolved before feathers [Science News]. The new discovery reveals an even earlier piece of the evolutionary puzzle: the proto-feathers that Beipiaosaurus sported on its head, neck and tail are long filaments without any branches.

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Disoriented and emaciated brown pelicans are turning up in California’s suburban backyards and parking lots, far from their coastal habitats, and biologists are struggling to figure out what’s wrong with the ailing birds. The pelicans are exhibiting very strange behavior, they say. A social animal, it is rarely found alone. So it was startling to find one bewildered bird in a Kmart parking lot in Lompoc, another outside a Costco in Goleta and a third on the runway at Los Angeles International Airport. One pelican was found at an elevation of 7,200 feet in the New Mexico snow…. “Normally, they’re on piers and places where they can find fish,” said Rebecca Ryan of the Peninsula Humane Society in San Mateo, which has stabilized several sick birds. “Now they are appearing in really unusual places” [San Jose Mercury News].

Researchers first wondered in the culprit might be neurotoxin domoic acid, which is produced by microscopic algae in the coastal waters; the birds ingest the acid by eating fish that consumed the algae. But researchers say that the pelicans’ symptoms don’t match the usual pattern seen in a domoic acid outbreak. Domoic acid poisoning usually causes seizures, researchers say, and these birds have had none. The toxin also typically affects marine mammals as well as birds, and no such problems have been reported in sea lions or other mammals. Finally, most of the hundreds of ailing pelicans are thin, but birds poisoned by domoic acid are typically of good body weight [AP].

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Paleontologists believe that majestic pterosaurs ruled the skies during the Jurassic and Cretaceous periods, soaring overhead on their leathery wings while dinosaurs stomped over the ground below. But researchers recently began wondering how exactly those “winged lizards” lifted off, as some of them weighed more than 500 pounds and were as tall as a giraffe. Last year, researchers tried to figure out how they got off the ground by looking at the largest bird now flying, the albatross. They concluded that anything much bigger couldn’t get off the ground the same way [AP], because the wing muscles wouldn’t be able to generate enough lift. But researcher Mike Habib now says pterosaurs shouldn’t be compared to birds. “The catch is that they are not built like birds,” Habib said [AP].

Habib thinks he has the answer to the pterosaurs’ launching maneuver. When the pterosaurs’ strong wings were folded they created “knuckles” that the animals rested on in four-legged stance, he says, which allowed them to take off in a motion akin to leap-frogging. The back legs kicked off first, Habib says, and then the front legs gave a mighty push to propel them into the air. This procedure would negate the need for launching aids that other paleontologists have suggested, like strong winds, a downslope, or a cliff to jump from. “Using all four legs, it takes less than a second to get off of flat ground, no wind, no cliffs,” Habib said. “This was a good thing to be able to do if you lived in the late Cretaceous period and there were hungry tyrannosaurs wandering around” [LiveScience].

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Fiddler crabs take carefully calibrated steps to find their way home, according to a new study in Current Biology [subscription required]. Scientists testing the tiny crustaceans’ homing skills found that both the length and number of their strides were guided by some sort of internal mileage counter. This allows them to plot a direct path back to their sandy burrows even if the burrows are out of sight. “We were able to measure every step by every leg of every animal in this experiment, and since these are eight-legged animals, that’s a lot,” [Scientific American] says co-author John E. Layne.

Many animals appear to have built-in GPS systems, although exactly how they function is not well-understood. Birds and sea turtles may use the position of the stars and the earth’s magnetic field to navigate. The honeybee has been shown to use the flow of the passing landscape across its field of vision. Some other animals may be able to gauge linear acceleration and use that to determine distance [The New York Times]. The way animals keep track of their movements and the distance they’ve traveled is known as path integration.

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