The flying salamanders that live on top of the tallest tree in the world

Looming behind the mist-covered coastline of Redwood National Park in Northern California, USA, one can see the silhouette of a redwood tree (Sequoia sempervirens).

According to the Guinness Book of World Records, this giant redwood tree called Hyperion is the tallest tree in the world. In 2019, its measured height from base to tip was 116.07 meters. With this number, the height of the Hyperion tree in California should be equivalent to a 35-story building.

This giant redwood tree called Hyperion is the tallest tree in the world.

The tree is 800 years old. You can see its shadow, but the path to Hyperion is always hidden. That's because people want to protect this tree against the human chainsaw. For a long time, coastal redwood has always been the target of loggers.

And when a redwood is brought down. Not only is it dead. The creatures that rely on these giant trees have also lost their homes. On it is a special species of salamander that scientists are studying.

They called them Aneides vagrans, or wandering salamanders.

The flying salamanders

They are the subject of research by Christian Brown, a doctoral candidate at the University of South Florida (USF). For the past few years, he has been involved in a project to study the wandering salamanders that live in the redwoods of California.

The project, founded 20 years ago by James Campbell-Spickler, now director of the Sequoia Park Zoo in Eureka, brings together researchers, conservationists and non-profit organizations interested in salamanders. wandering Aneides vagrans.

In it, they often have to climb to the top of the redwood trees, hundreds of meters above the ground to mark and tag the iguanas.

The salamander Aneides vagrans usually lives in stilts overgrown with moss and ferns of redwoods.

Climbing to their habitat height is already hard, the job of marking them is even harder.

The salamander Aneides vagrans usually lives in stilts overgrown with moss and ferns of redwoods. There was a rotten vegetation, but the salamander's favorite home. Climbing to their habitat height is already hard, the job of marking them is even harder.

Whenever Brown lightly touched a branch, or almost caught a salamander, they usually didn't mind jumping out of his hand to fall to the ground.

And at 116 meters above the ground, these salamanders somehow survived. Curious about the vagrant salamander's ability to parachute, Brown and his colleagues took some of them back to the laboratory to study.

They put them in a wind tunnel to simulate a free fall. A camera with a speed of 400 frames per second was placed there to record the salamander handling its fall. Research has finally revealed the mysteries of this parachute salamander.

Unlike flying squirrels, gliding frogs, and a species of gecko that have flaps of skin on their legs to help them glide through the air, the salamander Aneides vagrans was not created with any tools to aid in the jump.

Instead, they rely solely on their masterful body control skills. "During the skydiving, these salamanders have very good maneuverability control," Brown said. "They can flip. They can flip themselves over if upside down. They can maintain that skydiving posture and swing their tails up and down to perform horizontal maneuvers. Level of control is very impressive".

The salamander Aneides vagrans shows off its parachute skills in the wind tunnel

Professor Robert Dudley, an expert in flight animals at the University of California, Berkeley added: "What struck me when I first saw the video was that they (these salamanders) move so smoothly — There were no interruptions or disturbances in their movement, they were merely gliding through the air.

That, to me, implies that the behavior must be something ingrained in their motor reflexes. How often the salamanders had to fall for this behavior to become a natural selection for them.

And it's not just a passive parachute, they don't just jump to the ground. The salamanders are also making obvious horizontal movements, which is what we call gliding."

The flying and landing skills of the salamander Aneides vagrans

Back to the wind tunnel, to highlight the flight ability of the salamander Aneides vagrans, scientists brought three other salamander species with similar bodies, A. lugubris and Ensatina eschscholtzii, to compare. compare.

They found that Ensatina eschscholtzii (forest-dwelling), A. lugubris (lower-altitude tree-dwelling) and A. flavipunctatus (mixed-dwelling) did not possess such skilled skydiving skills. Aneides vagrans.

"We call it inefficient motion, because they're not really gliding, they're not moving horizontally, they're just hovering in the wind tunnel," Brown said.

How the salamander Aneides vagrans navigates horizontally through the air

In contrast, the Aneides vagrans salamanders have spent their entire lives living in the tops of tall trees, so they know how to effectively parachute. Scientists analyzed thousands of frames of Aneides vagrans' 10-second falls to understand its skill.

Accordingly, this salamander often flexibly uses both legs, body and tail to navigate in the air. They usually fall at a steep angle of only about 5 degrees from vertical, but when they need to shift their torso to parallel to the ground, they just need to adjust the position of their toes and feet.

By adopting this parachute pose, the salamander Aneides vagrans can reduce its vertical drop speed by up to 10%. "Wandering salamanders have large feet, long legs, and a flexible tail. All of these things benefit their airborne navigational behavior," Brown said.

So while they don't really have a dedicated aerodynamic control unit (like the flaps of skin found in flying squirrels, for example), this salamander is adept at flying. The scientists explain that Aneides vagrans salamanders learned skydiving skills from their high-altitude living conditions.

For an iguana only about 10 centimeters long, crawling between a redwood tree up to 116 meters tall is a survival risk for them. They can be spotted by predators, suffer from dry skin and even run out of energy.

So Aneides vagrans opted for a one-way migration. They only crawl from low branches to rake branches, and when they need to crawl from high branches to low branches, they will choose to parachute.

The salamander Aneides vagrans can reduce its vertical drop speed by up to 10%.

"Let's say you're just a five-gram salamander, and then you've managed to climb the tallest tree on Earth. You must be exhausted. You've used up all your energy. So So if you want to go down, why walk? You won't want to walk down, you'll want to use that gravity elevator," Brown said.

Since the salamanders Aneides vagrans can navigate through the air, they can choose any low branch below to land. Because they are very light and often choose to land on rotten wood, the Aneides vagrans salamander is almost never hurt after its landing.

"This salamander's ability to fly is something very novel, something unexpected in a group of animals that we thought we'd studied so closely," said Associate Professor Dudley. "It shows what evolution required for an arboreal animal, which had to develop the ability to fly in the air, even without wings."

Studying this salamander not only helps us understand the evolutionary mechanism of animal diversity, but also helps to lift a curtain on the ecology of the redwood tree, the tallest plant on the planet.