When Snowball, a male cockatoo (凤头鹦鹉), was shown last year in a YouTube video apparently moving in time to pop music, he immediately became an Internet star. But only now scientists have begun to study his dancing.

“Real dancing should require that Snowball adjust his movements to match different music speeds,” said Aniruddh Patel, one of the researchers from Tufts University,

To examine this, Patel and his colleagues created some new music and played it for Snowball to dance in his favorite spots. They changed the speed of the music in small steps and videoed his dancing.

“To our surprise, when the music speed was slow, his dancing slowed down. When the music was faster, his dancing sped up, too.” says Patel. “Above all, we were really shocked to see that Snowball even taught himself different dance moves.”

Based on their research, the researchers further identified some amazing abilities in the animal: the abilities to understand complex sounds and learn movements, communicative gestures and the tendency to build long-term social bonds, which parrots can form with humans and other parrots.

“The ability to dance was believed to be uniquely human until this research,” said Tecumseh Fitch, a biologist at the University of St. Andrews in Scotland who is interested in the origin of music. “Their study has opened ways for all kinds of new experiments. For example, what genes are turned on while a bird is dancing? And what would happen if a bird never heard any music for the first few years of its life? Could it still dance later on? That would be an interesting study and one that could never be done on children.”

Kielder Forest in Northumberland, England, is home to birds of prey (捕食) and red squirrels. Around 90 years ago, it was also home to the pine marten (松貂). The 0.5 meters animal was driven to extinction in England by 1926 because gamekeepers wanted to secure the safety of their game birds, according to The Guardian.

The martens grew well in Scotland, however, and the animals appear to be crossing back into England.A pine marten was spotted in Kielder Forest by John Hartshorne, a volunteer who monitors the red squirrel population in the forest, part of an effort to stop grey squirrels from further invading the red squirrels’ territory. “I heard loads of cries of red squirrels, wondering what it was. I zoomed in (拉近镜头) and saw a pine marten, which is superb, ” he told The Guardian. “We know that there are pine martens around in Northumberland from anecdote, but we’ve been waiting for a clear picture of evidence that they are here.”

The pine marten is one of the animals receiving a helping hand from Back from the Brink, one of the conservation groups working together to help save 20 species from extinction in England. Their efforts are aimed at helping the pine marten and other at-risk species.

Red squirrels are threatened by grey squirrels, which outcompete the native squirrels for food and pass on a deadly virus. Martens keep grey squirrel numbers in check, especially since the invasive animals aren’t used to having a predator like the pine marten around. A 2018 study found that the presence of pine martens can be enough to push the grey squirrel population out of an area.

So the pine marten returning to Kielder Forest is a win-win: The pine marten returns to part of its historic range and in doing so, helps red squirrels continue to survive.

When a tiny glass frog sleeps, its body becomes so transparent that it almost cannot be seen. The frog’s glass-clear skin makes no shadows. Even the red blood disappears. It’s an unusual trick—most see-through animals live in water all the time, which don’t produce red blood cells.

But when the frogs are active, blood begins to flow again, forming a pattern of bright red that can be seen. So, scientists set out to discover what happens to all that blood.

In a new study, researchers found out how, while sleeping, a glass frog sends most of the red blood cells to its liver(肝脏). In the process, the liver grows in size by about 40% to accommodate the extra cells. Like its heart and some other organs, the frog’s liver is covered in a mirrored part, which reflects lights, that helps the frog hide itself from enemies.

“If these frogs are awake, stressed or under anesthesia(麻醉), their blood systems are full of red blood cells, and they are not transparent,” explains an expert. “The only way to study transparency is when these animals are happily asleep, which is difficult to achieve in a research lab.”

Luckily, there is an imaging technology which can check red blood cells without breaking the skin of frogs. The team used this technique on frogs while they were sleeping. They found the animals moved a shocking 89% of their red blood cells to their livers while sleeping.

How exactly these frogs can pack their red blood cells together without getting blood clots (血栓) remains a mystery. Most other animals’ blood becomes very thick if the cells bump into each other, which can help cure a wound or—in a worse situation—stop blood from flowing to important areas. Understanding more about how the frogs stay healthy while jam-packing their livers with red blood cells could help advance blood clot research in humans.