In the mountainous forests of Ecuador, you might hear this fast, lilting song:

The melody sounds like it comes from a single bird, but it is actually sung by two: one male and one female. The couple alternates their syllables with almost unbelievable precision, each one placing its notes in the gaps left by its partner. The result is one of nature’s finest duets. And the singers are a pair of (rather drably named) plain-tailed wrens.

By studying the singing wrens, Eric Fortune from Johns Hopkins University has found that each bird has brain circuits that encode the entire song. Rather than focusing on just their own contribution, they process the whole melody. Their duet is conceived as a whole in both their brains, but emerges as two distinct parts, one from each beak.

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Many birds sing to woo females, but some hummingbirds go to great lengths to do so. They climb to between 5 and 40 metres before plummeting past perched females in death-defying dives. They pull up at the last minute, spread their tail feathers and produce a loud chirpy song. The song comes not from the birds’ mouths, but from their tails. The splayed tail feathers vibrate as air rushes past them, causing them to flutter.

Flutter sounds colloquial and innocuous, but it can be deadly. It’s what happens when air, moving at just the right speed, zooms past objects with just the right stiffness, setting up large and potentially disastrous vibrations. Flutter brought down the passenger plane Braniff Airways Flight 542, killing everyone on board. Flutter wrecked the Tahoma Narrows Bridge, causing it to warp and twist like a piece of rope. But flutter also ensures that male hummingbirds get some action.

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One by one, three bee-eater chicks hatch in their underground nest, and they are all about to die. There is a fourth chick in with them, but it is no bee-eater. It is a greater honeyguide, a different species that was laid in the nest and mistakenly incubated by the bee-eater parents. Having hatched a few days ago, it has been lying in wait for its foster siblings. As each emerges in turn, the honeyguide attacks it with vicious spikes on its bill. Completely blind, it is literally stabbing in the dark but it makes up for its imprecision with brutality. Within minutes of entering the world, the other chicks are dead.

Warning: this video is not pleasant. Watch at your own risk.

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How does an ostrich sleep? Almost imperceptibly, it seems. Even though an ostrich might be sound asleep, it can look wide awake or, at most, a little drowsy. John Lesku from the Max Planck Institute of Ornithology discovered this by fitting six ostrichers with “Neurologgers”, electrode-laden helmets that measures their temperature, brain activity, eye movements and neck muscle contractions.

The video above shows three of the birds cycling through two different types of sleep. The first is called ‘slow wave sleep’ or SWS, where the ostriches’ brain waves are slow and strong. Even though this is typically known as deep sleep, the birds look alert. They stay still, but their eyes are open and their necks upright. Nonetheless, the readings from the Neurologgers clearly showed that they were asleep.

In the second phase, known as ‘rapid eye movement’ or REM sleep, the ostriches’ brain waves are fast and weaker. Now, the birds shut their eyes, which move rapidly behind closed eyelids. They necks also start to droop and sway, righting themselves with awkward jerks like people falling asleep at a talk. Biologists have previously interpreted this as a sign of a tired ostrich. That’s partly right, although the animal is already asleep rather than on its way.

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A stressful early life can have long-lasting consequences, not just for you but for your partner. Pat Monaghan from the University of Glasgow found that zebra finches are more sensitive to stress as adults if they had unusually high levels of stress hormones as chicks. To no one’s surprise, they also died at a younger age. But it came as more of a shock that these tightly wound finches passed the consequences of their early hardships to their partners. They too died earlier even if their early days had been stress-free.

A wide variety of animals react to stressful conditions by become physiologically more jumpy. Their bodies flood with stress hormones at slight provocations, and they take longer to return to normal. In the short term, these changes help animals to survive through difficult times. But they can also be harmful in the long term. Not only can they shorten an individual’s life, but they can turn it into an undesirable partner.

Many studies have found that individuals across many different species are less likely to secure mates when they grow up if they have stressful upbringings. This might be because they are less physically attractive but, based on his study, Monaghan thinks that it could also be that such individuals pose a health hazard to their mates.

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The eleven specimens of Archaeopteryx are some of the most iconic and captivating fossils in existence. The fingers end in claws, the tail is long and bony, and the head – arched back in the throes of death – contains toothed jaws. But the splayed arms are lined with the faint but unmistakeable outlines of feathers. This was an animal halfway between a small flesh-eating dinosaur and a modern bird. In fact, Archaeopteryx is widely heralded as the first bird, occupying a pivotal position in the origins of this group.

But Xing Xu from Linyi University thinks that this first bird was nothing of the sort. The Chinese palaeontologist, who has found one fascinating dinosaur after another, has identified a new species called Xiaotingia that threatens to oust Archaeopteryx from its position.

By comparing Xiaotingia’s features with those of Archaeopteryx and other related birds and dinosaurs, Xu has drawn up a new family tree (see slideshow below). In it, Archaeopteryx sits with Xiaotingia among the deinonychosaurs, a celebrity-filled group of small, predatory dinosaurs that includes Deinonychus and Velociraptor. The lineage that led to modern birds perches on a different branch of the tree.

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It seemed like such a simple story. Some birds lay their eggs in the nests of other birds of their own species. This practice, known as brood parasitism, foists the burden of parenthood onto other birds, who unwittingly devote their energies to raising someone else’s chicks. The exploiter wins; the victim loses.

This story is wrong, at least for eider ducks. Ralph Tiedemann from the University of Potsdam has shown that among these birds, brood parasites are most likely to target their own relatives, especially older ones who lay smaller clutches of eggs themselves. They aren’t putting their babies on the doorsteps of random strangers; they’re offering them to Grandma. The ‘victim’ isn’t really a victim; she’s the family babysitter.

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Uek has a problem. She can see a piece of food through a hole in a plastic box, but she cannot reach it. Fortunately, Uek is a New Caledonian crow, a bird that is both intelligent and adept with tools. She grabs a stick with her bill, pushes it forward through the hole and knocks the morsel onto a slope,. It rolls within her reach, and she tucks in.

Kermit has an even bigger problem. He’s faced with the same out-of-reach snack. He has the same stick and the same smarts. But Kermit is a kea, a green parrot with a sharp, curved beak. He can’t wield a stick with the same precision as Uek with her short, straight beak. So Kermit improvises. He picks the stick sideways in his beak and pushes one end through the hole. He holds it there with his foot, grabs the other end in his beak, and finally (and awkwardly) pushes it at the food. Eventually, he too gets a meal.

Uek and Kermit are members of arguably the most intelligent groups of birds – the parrots and the corvids (the family that includes crows, ravens, jays and magpies). For their size, their brains are roughly as big as those of great apes, and their behaviour can be just as sophisticated. They’ve shown many advanced skills including planning for the future, using tools and solving problems.

Now, Alice Auersperg from the University of Vienna has challenged them to the same task. The obvious question is: which one did better? Who is the brainiest of the bird brains? But that would miss the point.

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In Israel’s Khai Bar Reserve, a pair of brown-necked ravens has a problem. They’re after the tasty contents of ostrich eggs and there are plenty to go around. The eggs – the largest of any bird – would provide a nutritious meal but they’re so thick that even a pair of ravens can’t puncture them. But they don’t need to. The ravens know that the desert is also home to a master egg-cracker – the Egyptian vulture. All they have to do is wait, and they can rob the robber.

Shai Kabesa from Ben Gurion University first noticed the ravens at work in 2008. Together with Reuven Yosef, she pieced together their strategy in the following years.

The Khai Bar Reserve has no native ostriches – they were hunted to extinction in the area during the 1940s. There is, however, a thriving conservation project that’s breeding the birds in the hope of reintroducing them. Ostriches lay their eggs in a single nest. The dominant female goes first, laying around 15 to 20. Her subordinates follow with 3 to 4 of their own. However, the top pair of ostriches can only incubate around a dozen eggs effectively, and they roll the rest away from the nest. This creates a ring of nutritious treats for any bird skilful enough to break into the eggs.

The Egyptian vulture does so with a special technique – it uses a tool, and is one of the few birds to do so. It picks up rounded stones in its beak and uses them to hammer the egg shells until they crack. Even ostrich eggs eventually give way. But the vultures don’t always get to enjoy the fruits of their labours. Yosef found that on at least three occasions, a pair of ravens, watching nearby but hidden behind a bush, quickly flew in and drove the vultures away.

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Meet the Transylvanian naked neck chicken – you can understand how it got its name, and why it used to be called a “turken”. This unusual bird isn’t part-turkey; it’s a genuine chicken, albeit one with an unusual lack of feathers on its neck and sparser plumes on its body. Now, Chunyan Mou from the University of Edinburgh has discovered the single genetic tweak behind the chicken’s unusual appearance. In doing so, she revealed a hidden pattern that lurks in the skin of all birds.

The pattern of feathers on a bird’s body is set early on in its life, when it’s still inside the egg. When bird embryos are seven days old, they develop stripes of cells down their body where feathers will eventually grow. Over the next week, the stripes broaden out. As they expand, they lay down rows of cells called placodes, which will eventually produce feathers.

Two sets of chemicals – activators and inhibitors – set the pattern of the placodes. The activators promote the growth of feathers (as well as patterns in other animals), while the inhibitors are feather-blockers. These opposing chemicals can produce many different patterns depending on how they react with one another, the balance between the two, and the speed with which they spread through the skin (see footnote). By tweaking these variables, birds can evolve countless different patterns of feathers. The naked neck chicken provides a great example of how this works.

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