High speed video of a tree salamander in a vertical wind tunnel.
The salamanders, which live all their lives in the crowns of the world’s tallest trees, the California redwoods, have developed behaviors well adapted to the dangers of falling from great heights: the ability to parachute, glide and maneuver in the air.
Flying squirrels, as well as numerous species of sliding frogs, geckos, ants and other insects, are known to use such aerial acrobatics when jumping from tree to tree or when falling so as to stay in the trees and avoid landing on The Earth .
Similarly, researchers believe that this salamander’s parachuting skills are a way to retreat to a tree from which it fell or jumped to avoid terrestrial predators.
“While parachuting, they have a tremendous amount of maneuver control,” said Christian Brown, a doctoral student at the University of South Florida (USF) in Tampa and the first author of an article on the behavior. “They are able to turn around. They can turn over if they are turned upside down. They are able to maintain this position when parachuting and pump their tail up and down to make horizontal maneuvers. The level of control is simply impressive. “
The aerial dexterity of the so-called wandering salamander (Aneides vagrans) was revealed by high-speed video taken in a wind tunnel at the University of California, Berkeley, where salamanders were pushed from a perch into an upward column of air that simulated free fall.
The wandering salamander, Aneides vagrans, is about 4 inches (10 centimeters) long and lives all its life in the crowns of redwood trees more than 150 feet above the ground. Researchers have found that it has adapted to its lifestyle in tall buildings by developing the ability to parachute and glide when falling. Credit: Christian Brown
“What struck me when I first saw the videos was that they (the salamanders) are so smooth – there is no interruption or noise in their movements, they just surf the air,” said Robert Dudley, a professor at Integrative University in Berkeley. . biology and animal flying expert. “For me, this means that this behavior is something deeply embedded in their motor response, that (falling) must occur at reasonably high frequencies in order to influence the selection of this behavior. And it’s not just passive parachuting, they’re not just parachuting down. They also obviously make a lateral movement, which we would call sliding.
The behavior is even more surprising because salamanders, in addition to having slightly larger footrests, do not look different from other salamanders that are not maneuverable from the air. They do not have leather flaps, for example, that would tell you about their ability to parachute.
The high-speed video reveals a big difference in the reaction of salamanders when falling. While terrestrial (non-arboreal) salamanders seem helpless during a free fall in a vertical wind tunnel, tree salamanders maneuver confidently. This suggests that tree dwellers have adapted to routine falls and may be using falls as a way to move quickly in the shadows of the world’s tallest trees. White spots are paper discs attached with water to track the movement of the head, body and tail. Credit: Video produced by Roxana Makasjian with footage courtesy of Christian Brown
“Wandering salamanders have big legs, they have long legs, they have active tails. All of these things lend themselves to air behavior. But everyone just guessed it was climbing, because that’s what they use these features when we look at them, “Brown said. “So it’s not really a special aerodynamic control surface, but it works like both. It helps them climb and it also seems to help them parachute and glide. “
Among the questions researchers hope to answer in future research are how salamanders manage to parachute and maneuver without obvious anatomical adaptations to gliding, and whether many other animals with similar aerial skills have never been seen before.
“Salamanders are slow, you don’t think of them as having particularly fast reflexes. This is life in the slow lane. And flight control involves fast response to dynamic visual signals and the ability to focus, orient and change the position of your body, “said Dudley. “So it’s just a little weird. How often can this happen and how do we know? “
A document describing the behavior was published on May 23, 2022 in the journal Current Biology.
Life in a canopy
Using the wind tunnel, Brown and University of California, Berkeley student Eric Sate compared A. vagrans’ sliding and parachuting behavior – about 4 inches (10 centimeters) from the snout to the tip of the tail – with the abilities of three other salamander species. originating in Northern California, each with a different degree of woodiness – that is, a tendency to climb or live in trees. The wandering salamander, who probably spent his entire life in a single tree, moving up and down but never touching the ground, was the most experienced parachutist. A related species, the so-called tree salamander, A. lugubris, which lives in lower trees such as oaks, was almost as effective at parachuting and gliding.
Two of the smallest tree salamanders – Ensatina eschscholtzii, a salamander inhabiting forest floors, and A. flavipunctatus, the spotted black salamander that occasionally climbs trees – essentially fluttered inefficiently for a few seconds while in the air. in the wind tunnel. All four species are plethodontids or salamanders without lungs, the largest family of salamanders and are found mainly in the western hemisphere.
Aneides vagrans parachute into a vertical wind tunnel at an air speed approximately equal to the final speed of the animal. Credit: Christian Brown
“The two smallest tree species rotate a lot. We call it inefficient, wavy motion, because they don’t slide, they don’t move horizontally, they just float in the wind tunnel, crazy, “Brown said. “The two most woody species have never really swung.”
Brown encounters these salamanders while working in Humboldt and Del Norte counties in California with nonprofit and university conservation groups that mark and track animals that live in redwood canopies, mostly in an old growing forest about 150 feet off the ground. Using ropes and boats, biologists regularly climb redwoods – the tallest of which rise to a height of 380 feet – to catch and mark stray salamanders. For the past 20 years, as part of a project led by James Campbell-Speaker, now director of the Sequoia Park Zoo in Eureka, researchers have found that most of their marked salamanders can be found on the same tree year after year, though at different heights. They live mainly in fern mats growing in the pouf, the decomposing plant matter that collects at the junction of large branches. Brown said a few marked wandering redwood salamanders were found on the ground and most of them were found dead.
Brown noticed as he picked them up to mark that the salamanders were quickly jumping out of his hands. Even a light tap on a branch or a shadow passing by was enough to make them jump out of the redwood shed. Given their location high above the forest floor, their carefree jumps in the air were surprising.
A. tramps jumping. Credit: Christian Brown
“They jump even before they’re done, have their forelegs outstretched and ready to go,” he said. “So the jump and the parachute are very closely connected. They shall take up their position immediately. “
As he approached Dudley, who is studying similar behavior in other animals, he invited Brown to bring some of the salamanders into his wind tunnel to record their behavior. Using a high-speed video camera shooting at 400 frames per second, Brown and Sate captured the salamanders as long as they hovered over the air, sometimes up to 10 seconds.
They then analyzed the frames to determine the posture of the animals in the air and to determine how they used their legs, bodies and tails to maneuver. They usually fall at a steep angle, only 5 degrees from the vertical, but based on the distances between the branches in the crowns of redwoods, this is usually enough to reach a branch or trunk before hitting the ground. Parachuting reduced their speed of free fall by about 10%.
Brown suspects that their aerial skills have evolved to cope with falls, but have become part of their behavioral repertoire and perhaps their default descent method. He and USF student Jesaline Aretz found, for example, that walking down was much harder for a salamander than walking on a horizontal branch or up a trunk.
“This suggests that when they wander, they probably walk on flat surfaces or walk uphill. And when they run out of habitat, because the top canopy is getting drier and drier and there’s nothing else for them upstairs, they can just go back to those better habitats, “he said. “Why go back down?” You are probably already exhausted. You have burned all your energy, you are a small 5 gram salamander and you have just climbed the tallest tree on Earth. You will not turn around and go down – you will take the gravity elevator.
Brown sees A. vagrans as another poster child for old forests, which is similar to the spotted owl, as it is found mainly in the crowns of the tallest and oldest redwoods, although in Douglas fir and Sitka spruce.
“This salamander is a child on the poster for the part of the redwoods that was almost completely lost from logging – the world of canopies. It is not in these new forests created by logging companies, “he said. “Maybe…
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