Before they can talk, babies use gestures to communicate: sentiments such as “take this away,” “look over there,” and “put me down” can be made abundantly clear without words. Chimps gesture to each other, as well, pointing out particular spots where they’d like to be scratched or groomed. These symbolic gestures are believed to be an important precursor to language. Now, researchers have observed ravens using gestures in the wild—the only non-primates seen doing so.

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California birds are getting slightly bigger, according to a study published in Global Change Biology in which researchers measured and weighed 33,000 birds over the past 40 years. The increases were small, but significant: in the last 25 years robins have grown 0.2 ounces in mass and 1/8th of an inch in wing length, for example. But the finding runs counter to the only other long-term study measuring avian size in North America, which found that birds in Pennsylvania have shrunk slightly over recent decades. And it seems to disagree with other recent suggestions that animals may shrink in a warming world: Bergmann’s rule holds that animals generally get bigger as they get farther away from the equator, because larger animals are better able to retain heat.

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Researchers at Wake Forest University in North Carolina have now learned that Nazca boobies perpetuate a “cycle of violence”: bullied chicks tend to become bullies and pass on the pain. When parent birds leave their nests to eat, baby boobies are often visited by sexually and physically abusive non-breeding adults; the chicks, when grown, are more likely to abuse unrelated chicks. “The link we found indicates that nestling experience, and not genetics, influences adult behaviour,” lead researcher David Anderson told BBC.

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The marsh-loving song sparrow uses its beak to stay cool.

What’s the News: Scientists have long known that the size and shape of a bird’s beak is largely dependent on its diet. A hummingbird’s long, thin beak, for example, allows it to reach deep down into a tubular flower to get nectar. But in a new study in the journal Ecography, scientists have found that birds in warm climates have evolved beaks larger than their cooler-climate counterparts as a means of staying cool (birds, like most animals, don’t sweat). The new study adds weight to past research suggesting the same thing.

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What’s the News: The more we study other species, the more we learn just how well we fit into the animal kingdom. Recently, scientists described how some parrots share our ability to use logical reasoning, and now a new study is showing that our syntactical language may not be all that unique either. The research, published recently in the journal Nature Neuroscience, explains that the society finches (Lonchura striata domestica) sing according to an acquired set of grammatical rules. Scientists previously thought that language syntax only existed in humans and some whales.

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Flapping while running up a ramp takes far
less energy than flight at the same angle.

What’s the News: How did birds get their wings? And how did they start using them to fly? These questions have bedeviled evolutionary biologists for more than a century, and with flight’s origins long buried, a lot of careful measurements of how modern birds work combined with clever guesswork has resulted in several fiercely differing theories. The two major camps have proto-birds either dropping from trees or running along the ground before finally taking to the air.

A new study lends credence to the idea that flapping wings while running could have been involved by showing that it requires much less energy than flying while still helping birds get over obstacles. This suggests that it could have been an easy way for proto-birds to start going through the motions.

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What’s the News: Parrots are even less bird-brained than previously thought, suggests a new study in the journal Biology Letters. In a series of tests, researchers have learned that some African grey parrots can use logical reasoning to uncover hidden food.

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What’s the News: The reproductive life of a cuckoo is both easy—it lays its eggs in others birds’ nests, and lets them feed the young—and difficult: cuckoos are involved in an “evolutionary arms race” with other birds, finds a new study. Even as cuckoos improve their counterfeiting skills—producing eggs that look more like others birds’—the host birds get better and better at identifying the forged eggs.

How the Heck:

• Knowing that birds have four types of color-sensitive cone cells in their eyes, allowing them to see ultraviolet wavelengths, researchers used a spectroscope to measure the amount of light reflected from hundreds of cuckoo and host-bird eggs. They then fed this data into models to produce images showing how birds see the different types of eggs.
• They discovered that while cuckoo and redstart eggs have a high degree of color overlap, cuckoo eggs targeted for dunnock nests did not.
• Here’s the kicker: Redstarts and dunnocks don’t spot forgeries equally. Redstarts are more discerning of foreign eggs and readily kick out cuckoo forgeries, while the dumb dunnocks accept even the most mismatched eggs. So these findings suggest that cuckoos targeting redstarts evolved the ability to create better forgeries because the redstart has such a good eye. With dunnocks, that evolutionary force wasn’t at play because the birds are so accepting of forgeries; why bother?

What’s the Context:

• What sets this research apart from previous work is how the researchers used UV-sensing equipment to mimic bird vision. (Past research relied merely on human inspection.)
• Not Exactly Rocket Science covers a lot of cuckoo news, from how some host birds have an evolutionary advantage to take care of cuckoo eggs to how grown cuckoos actually mimic hawks to fool small birds.
• Carl Zimmer in The Loom touches on how humans are like cuckoos.

The Future Holds: Scientists still aren’t sure why some hosts, like the dunnock, are so accepting of cuckoo eggs. Some scientists argue that this is because the risk in mistakenly rejecting a real egg outweighs the cost of raising a cuckoo egg. The jury’s still out.

Reference: “AVIAN VISION AND THE EVOLUTION OF EGG COLOR MIMICRY IN THE COMMON CUCKOO” Mary Caswell Stoddard and Martin Stevens. DOI: 10.1111/j.1558-5646.2011.01262.x

Image: NHM

What’s the News: After tracking baby gray catbirds with miniature radio transmitters, biologists found that cats were by far the #1 bird killer: 47 percent of the birds died at the paws of pet and feral felines (out of 80 percent that were killed by predators in general). This echoes some biologists’ view that cats are a destructive, human-assisted invasive species: “Cats are way up there in terms of threats to birds — they are a formidable force in driving out native species,” said one of the authors of the study.

What’s the Context:

• Previous research suggested that cats kill around 1,000 times more birds than windmills do.
• With an estimated 500 million birds killed every year by cats, felines also cause far more deaths than more spectacular (and media-friendly) events, like the 2,000 bird carcasses that recently rained down on Arkansas.
• 80beats has covered the dangers of wind turbines to both bat and bird populations.
• And this link between cats and death shouldn’t be confused with Oscar the cat, who earned fame for his abilities to sniff out death before it happened.

Not So Fast: While cats were the biggest threat to birds in this study, the lead author notes that the biggest culprit for bird deaths over all is still building collisions.

Reference: Balogh, Anne L., Ryder, Thomas B., and Marra, Peter P. 2011. Population demography of Gray Catbirds in the suburban matrix: sources, sinks and domestic cats. Journal of Ornithology. DOI 10.1007/s10336-011-0648-7 (pdf)

Image: flickr /  emilydickinsonridesabmx

In the realm of meteorology, bats, birds, and insects are usually considered “animalas non grata,” since they create unwanted noise in the Doppler radar readouts used to study storms. But now, thanks to better radar station networking and the sharing of unfiltered data, ecologists have realized that these radar systems can be used as powerful animal tracking tools.

At last week’s American Association for the Advancement of Science meeting, researchers Thomas Kunz, Winifred Frick, and Phillip Chilson explained how Dopplar data can be used by ecologists. They call their new discipline aeroecology.

This melding of meteorology and ecology started with an “Aha!” moment:

“Dr Kunz and I were meeting Dr Chilson about a year ago over breakfast and they kept talking about the ‘QPE’, and finally I asked what it is,” Dr Frick told the meeting. It stands for quantitative precipitation estimator — a numerical method to measure how much rain there is in a storm front. “I paused and said, ‘you can estimate the number of raindrops in a raincloud? Do you think we could estimate the number of bats in a bat cloud?’” To calibrate their experiment, the team took a bat into a chamber where the degree to which it reflects radio waves could be measured. “From those measurements and using radar, we’ve been able to adapt those QPE measurements to a ‘QBE’ – a quantitative bat estimator,” Dr Frick said. [BBC News]

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The next time you enjoy the sight of a hummingbird in a garden, you might want to look twice–because it could be the government’s new avian-inspired drone. Dubbed “Nano Hummingbird,” this camera-toting, remote-controlled surveillance tool is the latest gadget to fly out the doors of DARPA (Defense Advanced Research Project Agency).

Commissioned by the Pentagon in 2006 and designed by AeroVironment, this bird-drone’s abilities match its $4 million price tag: It flies forward, backward, and sideways, and it can even hover in mid-air. That’s not bad for a battery-powered, 6.5-inch long bundle of communication systems and motors that weighs in at two-thirds of an ounce. “We’ve achieved what our customer asked us to,” AeroVironment Vice President Steve Gitlin told TIME Magazine. But with the robot’s maximum speed clocking in at 11 miles per hour, natural hummingbirds can fly circles around this bot.

DARPA hopes Nano Hummingbird could eventually be used as an extra eye on the battlefield.

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Raptors don’t lie. At least, not with plastic.

Black kites are a raptor variety that lives on multiple continents, and like several other varieties of bird (including the crafty bowerbirds), they’re avid decorators. For whatever reason, these black kites are terribly fond of white plastic, and the birds use these bits of our refuse to decorate their nests. Scientists who studied these birds in Spain report in Science this week that there is a meaning—and a strict honesty—to the decoration scheme.

They found that, several weeks before females laid eggs, birds festooned their nests with pieces of white plastic. Fitter birds, in possession of the best territory, tended to use more plastic. Weaker birds, with less-desirable territory, used less. Elderly and very young birds used none. Territorial confrontations are common among kites, and proved closely linked to displays of plastic. Kites with much plastic in their nest were rarely challenged, while those with little were challenged daily, even hourly. [Wired]

With so much at stake, you might think these raptors have the ideal motivation to cheat—decorating more liberally than their status would allow, perhaps, as a “don’t mess with me” message to their rivals. But not so, Fabrizio Sergio and his team found. Kites tell the truth with their status symbols because it’s not worth the risk of being caught in a lie.

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This fossil of an ancient winged reptile, bought from a farmer in China’s Liaoning province, tells a dramatic tale. About 160 million years ago, a female pterosaur fractured its wing and sank to the bottom of a muddy lake. Somehow, in the process of either dying or decomposing, she expelled a single egg, which has been preserved through the ages.

That’s the story that researchers told in a study published in the journal Science, anyway. And if the remarkably preserved fossil of the reptile Darwinopterus is female, they say, it sheds light on the sex differences and mating rituals of the extinct species. The preserved egg also seems to reveal new details of pterosaur reproduction.

Pterosaurs were the first vertebrates to take to the air, first appearing in the fossil record some 220 million years ago in the late Triassic period. Before their demise 65 million years ago the group evolved to include the largest flying animals ever to live – some had a wingspan of 10 metres. [New Scientist]

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Though the swine flu scare of 2009 may have bumped the avian variety of flu from of the popular imagination, biomedical researchers certainly haven’t forgotten the potential danger it poses. But researchers are constantly forced to play catch-up by following bird flu’s path through the avian population and trying to track its shifting genetics.

The way to finally get the jump on bird flu would be to create a weapon that works against the whole family of avian flu viruses, whatever their slight genetic quirks. And researchers led by Laurence Tiley say in Science this week that they might have found that kind of comprehensive trick: a genetic modification that seems to prevent flu from spreading in chickens.

It’s a decoy.

The birds carry a genetic tweak that diverts an enzyme crucial for transmitting the H5N1 strain. Although they die of the disease within days, the molecular decoy somehow impedes the virus from infecting others. [Nature]

Specifically, this genetic tweak allows the birds to create an RNA impostor. It matches up to the polymerase enzyme the flu virus would use to replicate its genetic material, so that enzyme is attracted to the decoy, which throws off viral replication. Though the modified chickens that were infected with avian flu died, the fact that they didn’t spread the virus is a potentially huge find—once avian flu enters a chicken population it typically spreads like wildfire.

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No, the large ibis that lived in Jamaica millions of years ago couldn’t fly. But it could probably bash you to death.

Researchers studying Xenicibis xympithecus now believe the bird’s peculiar wing structure, which confused them for decades, was ideally formed to be used as a club.

From Ed Yong:

Xenicibis is a large, extinct, flightless ibis. It was discovered by Storrs Olson from the Smithsonian Institution, who found some partial remains in a Jamaican cave in 1977. When Olson eventually saw the bird’s wing bones, he was baffled. They were so “utterly strange” that he thought the animal must have been suffering from some inexplicable disease.

Since then, Olson has found more remains including an almost complete skeleton. Now, he and his partner Nicholas Longrich from Yale University, have a very different view of the wing. They think it was a club. Weapons like clubs and bats have large weighted ends to deliver heavy impacts, and long handles to increase the speed of the swing. That’s exactly what you see in Xenicibis’s wing.

For more about the these birds and their weapons of mass pummeling (and why they may have evolved this way), check out the rest of the post at Not Exactly Rocket Science.

Related Content:
Discoblog: I Can’t Fly! Birds Lost Their Aerial Abilities Multiple Times
Not Exactly Rocket Science: First birds were poor fliers – flaps would have buckled Archaeopteryx feathers
DISCOVER: Tuxedo Junction—speaking of weird flightless birds, read Mary Roach’s feature on the migration of Patagonian penguins

Image: Proceedings of the Royal Society B