If you want to enhance your memory, consider moving up a mountain. The spatial recall of mountain chickadees – tiny songbirds that inhabit high regions of the western US – is better the higher up they live.

of the University of Nevada, in Reno, and his colleagues collected 48 juvenile birds (Poecile gambeli) from three different elevations in the Sierra Nevada mountains. Chickadees that lived just 600 metres higher than others had larger hippocampi – a part of the brain strongly linked to memory. Not only that, they were also better at remembering where food was hidden in lab tests.

It makes sense that birds living higher up would have a better memory, says Pravosudov. Mountain chickadees are “scatter hoarders”, storing their favourite winter food of pine seeds in thousands of different spots among the trees. At higher altitudes, where it stays cold for longer, birds must store more seeds, and remember where they cached them.

The effect could apply to other scatter-hoarding species, says Pravosudov, though he rules out most squirrels and rodents, which are either not active during the winter or put everything in one place and so do not need a better memory.

Could global warming change things? Very possibly. “The selection pressure that the winter provides will be less, so the birds are going to get dumber,” says Pravosudov. Time to consider a simpler pantry?

Journal reference: Animal Behaviour, DOI: 10.1016/j.anbehav.2012.04.018

Madagascar is a country of paradoxes. It lies just 400 kilometres off the coast of Africa yet appears to have been colonised only within the last 1500 years. Stranger still, it now looks as if most of the women in that first population came from Indonesia rather than Africa.

We know from language and culture that modern Malagasy have African and Indonesian ties. To identify Madagascar’s “founding mothers”, of Massey University in Palmerston North, New Zealand, and colleagues analysed mitochondrial DNA from 266 Malagasy and 2745 Indonesians. This mtDNA is inherited from mothers.

Their results suggest Madagascar’s initial population contained around 30 women of reproductive age, with roughly 93 per cent of their genes indicating ties to Indonesia. Such a small population suggests they may have colonised Madagascar after crossing the ocean by accident.

Cox says that accidental crossings of the Indian Ocean are not without precedent. “In the second world war there was bombing around Java and a lot of that wreckage – including in one case a survivor in a life raft – actually washed up on Madagascar,” he says. “So you could imagine a boat being blown off course in Indonesia and making it to the island.”

Earlier theories had suggested that initial colonisation of Madagascar was planned, because the island made a convenient port of call on the silk road – an ancient trading route that ran across African and Eurasia. “We need to rethink a lot of our ideas about how Madagascar was settled,” says Cox.

at the University of Cambridge points out that the initial population was not pure Indonesian, suggesting the first people arrived in Madagascar via a generation of interbreeding with Africans. His earlier work suggests the DNA of the first population was just 60 per cent Indonesian. However, he studied fewer living Malagasy and analysed shorter sections of DNA – although his analysis included members of four Malagasy ethnic groups, while Cox studied just three.

Cox now wants to repeat his simulations with Y chromosome data to work out how many men were in the first population. “This isn’t just a story of the women.”

Journal reference: , DOI: 10.1098/rspb.2012.0012

A tarsier could be screaming its head off and you would never know it. Uniquely among primates, some of the diminutive mammal’s calls are made up of pure ultrasound.

Marissa Ramsier of Humboldt State University in California and her colleagues were puzzled to sometimes hear no sound when Philippine tarsiers () opened their mouths as if to call. Placing 35 wild animals in front of an ultrasound detector revealed that what they assumed to be yawns were high-pitched screams beyond the range of human hearing.

While some primates can emit and respond to calls with ultrasonic components, none are known to use only ultrasonic frequencies in a call. The dominant frequency of the Philippine tarsier’s ultrasonic call was 70 kilohertz, amongst the highest recorded for any terrestrial mammal. They can hear up to 91 kHz, well beyond the 20 kHz limit of human hearing. Whales, dolphins, domestic cats and some bats and rodents are the only other mammals known to communicate in this way.

Having the equivalent of a private communication channel could help tarsiers warn others of predators such as lizards, snakes and birds which can’t detect such frequencies, says Ramsier. Eavesdropping on insects could also help them locate their prey.

Although the tarsier’s hidden talent may be unique, future studies could reveal that more primates use pure ultrasound calls. “Many primatologists have observed ‘silent’ mouth-opening behaviours in other primates,” says Ramsier. “It is certainly possible that some of these behaviours are accompanied by ultrasonic vocalisations.”

Journal reference: , DOI: 10.1098/rsbl.2011.1149

Scorpions don’t need to use their eyes to get a full picture of their surroundings: their body seems to function as a basic eye under ultraviolet light.

To test the idea that the waxy cuticle covering a scorpion’s body can detect light, of the University of Oklahoma in Norman exposed 40 of the arachnids to visible or UV light. He studied their behaviour both with and without “eye-blocks” – pieces of foil placed over their eyes to act like opaque glasses.

Wearing their shades, the scorpions did not move around much when illuminated by green light. But under UV light they scuttled around freely with or without the glasses, suggesting they did not rely on their eyes to see. The larva of the fruit fly is thought to be the only other creature whose body can detect light.

at California State University in Bakersfield says the idea complements his own work. He found that the ability of scorpions’ cuticles to fluoresce in UV light affects their behaviour at night, since moonlight contains a modest amount of UV.

Journal reference:

A FEATHER as large as my arm drifts from the azure sky. It doesn’t distract me – atop the dusky pink Vermilion cliffs, I continue to train my binoculars on the huge cage that sits some 80 metres away. This corner of Arizona, where the 450-kilometre-long Grand Canyon first begins to carve its way into the Colorado plateau, is one of the reintroduction sites for the California condor () – a bird with a 2.9-metre wingspan. And condor trapping season has just begun.

North America’s largest flying land bird is also one of the most endangered species on Earth. The scavengers ingest bullet fragments when they feed on remains left by hunters, leaving them at risk of lead poisoning. Chris Parish of the , a non-profit organisation headquartered in Boise, Idaho, leads a project here which includes both trapping the birds to test lead levels in their blood and detoxifying any with high levels.

Trapping is easy, he says, because the birds can’t resist the stillborn calf carcass lying at the back of the cage. As the birds soar above us, field biologist Andria Kroner confers on a radio with her counterpart, Derek Buchner, who is observing the action from the base of the cliffs. There are no takers yet for the meat inside.

There are nearly 400 California condors in the world, with over 200 living wild at a handful of reintroduction sites in Arizona, California and the Baja California peninsula in Mexico. Back in 1987 the wild population dropped to just 22. All of the birds were caught for captive breeding, and 16 of them helped to bring the species back from the brink.

The genetic bottleneck has given biologists a first-of-a-kind opportunity to map the genetic diversity of an entire species. Genomes of the 16 birds that gave rise to the recovered population are now being sequenced by Pennsylvania State University and San Diego Zoo. Once complete, conservationists will know about every gene circulating in the population.

“The California condor will become the first species to have its entire genetic diversity mapped”

The information could help the condor escape the problems of inbreeding caused by its brush with extinction. About 10 per cent of the population carry a recessive gene for a lethal form of dwarfism. When two of these birds breed, their chicks may develop the condition.

With the genetics of the entire species known, it should be possible for the biologists working on captive breeding programmes to act as matchmaker and reduce the risk.

That genomic work will be useless, though, unless the poisonous lead problem is fixed. A recent review concluded that the wild population would disappear without the detox programme (). Even with it, lead poisoning is a leading cause of death, and action to prevent it is slow to make an impact. California banned lead bullets inside condor ranges in 2008 but has seen good and bad years for poisoning since. Arizona has taken a voluntary approach to the problem.

Condors finally enter the cage in the mid-afternoon, after we have moved down the cliffs to join Buchner. I hear over the radio that, up on top, Kroner is stealing towards the cage.

“Don’t let them see you,” says Buchner, holding his breath. Kroner doesn’t and closes the cage. She enters it herself, corralling the three birds she wants into an isolation pen at the back. Mission complete, she opens the doors again and soon more birds begin to trickle in. “Short-term memory I guess,” jokes Buchner.

Later, I hear the results of the tests: all negative except for one bird. He faces a long bumpy ride to the treatment facility. But lead removed via a series of injections, he will soon soar over the Grand Canyon again.

Tracing disease outbreaks down to individual cities via social networking could help track dengue’s spread

“MY MOTHER is suspected of having dengue,” tweets a woman in Rio de Janeiro, Brazil. “I think I have dengue. Hopefully I’m wrong!” tweets a man in São Paulo, 350 kilometres away.

These short messages posted on Twitter might not seem much, but when the dengue season begins again in Brazil this November, tweets like this could help the country better control outbreaks of a virus that kills hundreds of people each year.

That’s thanks to software created by a collaboration between two Brazilian National Institutes of Science and Technology, led by , a computer scientist at the Federal University of Minas Gerais. The team has used it to identify a high correlation between the time and place where people tweet they have dengue and the official statistics for where the disease appears each season.

Social media has been used in real-time surveillance of diseases ; Twitter was used to follow the 2009 swine flu pandemic, for example. But this is the first time it has been used to track dengue fever, and the first time data on the scale of individual cities has been collected in this way. It is also the first attempt to pick up on people tweeting about their personal experience of a disease.

Dengue outbreaks occur every year in Brazil, but exactly where varies every season. It can take weeks for medical notifications to be centrally analysed, creating a headache for health authorities planning where to concentrate resources. Using Twitter messages could mean a much faster response, says Meira. “It isn’t predicting the future but the present,” he says. “This means we aren’t weeks behind like we used to be.”

“Using Twitter to track the incidence of dengue fever means the health response is no longer weeks behind”

The approach – helped by increased access to the internet in Brazil – uses software to filter tweets for those that contain the word “dengue” and information on the user’s location. Tweets that express personal experience of the disease are identified using criteria such as sentence structure and wording. Those mentioning public campaigns, or telling jokes are all filtered out.

Testing the software on 2447 tweets containing the word “dengue” and a location sent between January and May 2009 shows “personal experience tweets” tightly correlated with the outbreaks identified by the Brazilian Ministry of ��ҹ����1000����. The work was presented at the in Koblenz, Germany, last month.

The team now plan to analyse 181,845 tweets sent between December 2010 and April 2011, but are waiting for the ministry’s 2011 data before they do so. However, Meira says that the tweets mirror the trend seen in cities where changes in the dengue outbreak are known to have occurred.

Philip Polgreen, an infectious disease expert at the University of Iowa in Iowa City, and his colleague Alberto Segre, a computer scientist, recently on the use of Twitter to track swine flu in different regions of the US. They say Meira’s work is significant. “They have included sentiment analysis and they have a fine degree of geography,” says Segre.

Miera says terms such as “bone pain” and “eye pain”, which are typical symptoms of dengue fever, are now being included in his team’s software. He adds that the tool will also get better as more Brazilians come online: “Every year we get more data.”

Last month, Google unveiled a tool that records spikes in web searches for dengue fever, which taps into the fact that people who have dengue fever are likely to look for information about it.

Epidemiologist John Brownstein, at the Children’s Hospital Boston, who worked with Google on the project, setting out the underlying science last month (PLoS Neglected Tropical Diseases, ). He says the Google and Twitter methods are complementary; while Google searches are more common, Twitter provides more context.

When this article was first posted, “Minas Gerais” was spelled incorrectly.

Could teaching kids how robots are used in the real world create a new generation of designers to build revolutionary machines? That’s the idea behind a new study of children’s perceptions of robots.

In a study echoing the 1983 test – in which researcher , now of the Institute of American Indian Arts in Santa Fe, New Mexico, used drawings to highlight the differences between children’s view of scientists and the reality – psychologist and engineer of Illinois State University in Normal asked 143 schoolchildren aged between 6 and 10 to “draw a picture of a robot doing something robots often do”.

The results showed a clear stereotype of robots, says Zimmerman, who presented the study at the in Berkeley, California, earlier this month. The children saw them as boxy humanoids with legs and a square head, typically operating free of direct human control to engage in human-like work and play, from washing dishes and doing kids’ homework to golfing, skipping and dancing – About 30 per cent of the children drew them boogieing.

No more dancing

A group of 29 children who had previously submitted robot drawings were then given lessons about what robots currently do in the real world, including a field trip to see an industrial robot. They were then asked to redraw a robot.

Subsequently, only one child drew a humanoid robot – most instead drew industrial robots doing things like food processing or building cars. “The drawings were just as creative and complex, but they lacked the fictional elements of robots,” says Zimmerman.

What’s more, the change in perceptions stuck. After a three-month gap, repeat robot drawings were much the same. Zimmerman believes this demonstrates the teaching “narrowed the gap” between science fiction and reality. It is more realistic to conceive of an automaton under human control than a robot with free will, she says, adding that a better grasp of real robots may help students move into related careers.

But , a robotics researcher at the University of Sheffield, UK, doubts that “damping the children’s ideas” will breed a new generation of robot designers. Existing humanoid robots can perform many tasks, from caring for the elderly to folding towels, he adds.

Sharkey isn’t surprised that the children’s robots danced: a search on YouTube will show many real dancing humanoid robots have been built over the past 10 years, he says. “We should encourage a realistic view of robots among children, but we should not limit this so as to stifle their creativity.”