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In one of the tallest trees on Earth, a tan, mottled salamander ventures out on a fern growing high up on the trunk. Reaching the edge, the amphibian leaps, like a skydiver exiting a plane.

The salamander’s confidence, it seems, is well-earned. The bold amphibians can expertly control their descent, gliding while maintaining a skydiver’s spread-out posture, researchers report May 23 in Current Biology.

Wandering salamanders (Aneides vagrans) are native to a strip of forest in far northwestern California. They routinely climb into the canopies of coast redwoods (Sequoia sempervirens). There — as high as 88 meters up — the amphibians inhabit mats of ferns that grow in a suspended, miniature ecosystem. Unlike many salamanders that typically spend their days in streams or bogs, some of these wanderers may spend their whole lives in the trees.
Integrative biologist Christian Brown was studying these canopy crawlers as a graduate student at California State Polytechnic University, Humboldt in Arcata, when he noticed they would jump from a hand or branch when perturbed.

Now at the University of South Florida in Tampa, Brown and his colleagues wondered if the salamanders’ arboreal ways and proclivity to leap were related, and if the small creatures could orient themselves during a fall.

Brown and his team captured five each of A. vagrans, a slightly less arboreal species (A. lugubris), and two ground-dwelling salamanders (A. flavipunctatus and Ensatina eschscholtzii). The researchers then put each salamander in a vertical wind tunnel to simulate falling from a tree, filming the animals’ movements with a high-speed camera.

In all of 45 trials, the wandering salamanders showed tight control, using their outstretched limbs and tail to maintain a stable position in the air and continually adjusting as they sailed. All these salamanders slowed their descents’ speed, what the researchers call parachuting, using their appendages at some point, and many would change course and move horizontally, or glide.

“We expected that maybe [the salamanders] could keep themselves upright. However, we never expected to observe parachuting or gliding,” Brown says. “They were able to slow themselves down and change directions.”
A. lugubris had similar aerial dexterity to A. vagrans but glided less (36 percent of the trials versus 58 percent). The two ground huggers mostly flailed ineffectively in the wind.

The wandering salamanders’ maneuverable gliding is probably invaluable in the tops of the tall redwoods, Brown says. Rerouting midair to a fern mat or branch during an accidental fall would save the effort spent crawling back up a tree. Gliding might also make jumping to escape a hungry owl or carnivorous mammal a feasible option.

Brown suspects that the salamanders may also use gliding to access better patches to live. “Maybe your fern mat’s drying out, maybe there’s no bugs. Maybe there are no mates in your fern mat, you look down — there’s another fern mat,” Brown says. “Why would you take the time to walk down the tree and waste energy, be exposed and [risk] being preyed upon, when you could take the gravity elevator?”

There are other arboreal salamanders in the tropics, but those don’t live nearly as high as A. vagrans, says Erica Baken, a macroevolutionary biologist at Chatham University in Pittsburgh who was not involved with the research.

“It would be interesting to find out if there is a height at which [gliding] evolves,” she says.

A. vagrans’ relatively flat body, long legs and big feet may allow more control in the air. Brown and his colleagues are now using computer simulations to test how body proportions could impact gliding.

Such body tweaks, if they do turn out to be meaningful, wouldn’t be as conspicuous as the sprawling, membraned forms seen in other animals like flying snakes and colugos that are known for their gliding (SN: 6/29/20; SN: 11/20/20). There may be many tree-dwelling animals with conventional body plans that have been overlooked as gliders, Brown says. “The canopy world is just starting to unfold.”

Six years ago, tour guide Brenden Miles was traveling down the Kinabatangan River in the Malaysian part of Borneo, when he spotted an odd-looking primate he had never seen before. He snapped a few pictures of the strange monkey and, on reaching home, checked his images.

“At first, I thought it could be a morph of the silvered leaf monkey,” meaning a member of the species with rare color variation, Miles says. But then he noticed other little details. “Its nose was long like that of a proboscis monkey, and its tail was thicker than that of a silvered leaf [monkey],” he says. He posted a picture of the animal on Facebook and forgot all about it.

Now, an analysis of that photo and others suggests that the “mystery monkey” is a hybrid of two distantly related primate species that share the same fragmented habitat.
The putative offspring was produced when a male proboscis monkey (Nasalis larvatus) mated with a female silvered leaf monkey (Trachypithecus cristatus), researchers suggest April 26 in the International Journal of Primatology. And that conclusion has the scientists worried about the creature’s parent species.

Hybridization between closely related organisms has been observed in captivity and occasionally in the wild (SN: 7/23/21). “But hybridization across genera, that’s very rare,” says conservation practitioner Ramesh Boonratana, the regional vice-chair for Southeast Asia for the International Union for Conservation of Nature’s primate specialist group.

Severe habitat loss, fragmentation and degradation caused by expanding palm oil plantations along the Kinabatangan River could explain how the possible hybrid came to be, says primatologist Nadine Ruppert.

“Different species — even from the same genus — when they share a habitat, they may interact with each other, but they may usually not mate. This kind of cross-genera hybridization happens only when there is some ecological pressure,” says Ruppert, of the Universiti Sains Malaysia in Penang Island.

The state of Sabah, where Kinabatangan River is located, lost about 40 percent of its forest cover from 1973 to 2010, with logging and palm oil plantations being the main drivers of deforestation, a study in 2014 found.
“In certain areas, both [monkey] species are confined to small forest fragments along the river,” Ruppert says. This leads to competition for food, mates and other resources. “The animals cannot disperse and, in this case, the male of the larger species — the proboscis monkey — can easily displace the male silvered leaf monkey.”

Since 2016, there have been some more documented sightings of the mystery monkey, though these have been sporadic. The infrequent sightings and the COVID-19 pandemic has, for now, prevented researchers from gathering fecal samples for genetic analysis to reveal the monkey’s identity. Instead, Ruppert and colleagues compared images of the possible hybrid with those of the parent species, both visually as well as by using limb ratios. “If the individual was from one of the two parent species, all its measurements would be similar to that of one species,” Ruppert says. “But that is not the case with this animal.”

A photograph of a male proboscis monkey mating with a female silvered leaf monkey, along with anecdotes from boat operators and tour guides about a single male proboscis monkey hanging around a troop of female silvered leaf monkeys, has added further weight to the researchers’ conclusion.

The mystery monkey is generating a lot of excitement in the area, but Ruppert is concerned for the welfare of both proposed parent species. The International Union for Conservation of Nature classifies proboscis monkeys as endangered and silvered leaf monkeys as vulnerable. “The hybrid is gorgeous, but we don’t want to see more of them,” Ruppert says. “Both species should have a large enough habitat, dispersal opportunities and enough food to conduct their natural behaviors in the long term.”

Increasing habitat loss or fragmentation in Borneo and elsewhere as a result of changing land uses or climate change could lead to more instances of mating — or at least, attempts at mating — between species or even genera, Boonratana says.

The mystery monkey was last photographed in September of 2020 with swollen breasts and holding a baby, suggesting that the animal is a fertile female. That’s another surprising development, the researchers say, because most hybrids tend to be sterile.

When a star gets too close to a black hole, sparks fly. And, potentially, so do subatomic particles called neutrinos.

A dramatic light show results when a supermassive black hole rips apart a wayward star. Now, for the second time, a high-energy neutrino has been spotted that may have come from one of these “tidal disruption events,” researchers report in a study accepted in Physical Review Letters.

These lightweight particles, which have no electric charge, careen across the cosmos and can be detected upon their arrival at Earth. The origins of such zippy neutrinos are a big mystery in physics. To create them, conditions must be just right to drastically accelerate charged particles, which would then produce neutrinos. Scientists have begun lining up likely candidates for cosmic particle accelerators. In 2020, researchers reported the first neutrino linked to a tidal disruption event (SN: 5/26/20). Other neutrinos have been tied to active galactic nuclei, bright regions at the centers of some galaxies (SN: 7/12/18).
Discovered in 2019, the tidal disruption event reported in the new study stood out. “It was extraordinarily bright; it’s really one of the brightest transients ever seen,” says astroparticle physicist Marek Kowalski of Deutsches Elektronen-Synchrotron, or DESY, in Zeuthen, Germany.

Transients are short-lived flares in the sky, such as tidal disruption events and exploding stars called supernovas. Further observations of the brilliant outburst revealed that it shone in infrared, X-rays and other wavelengths of light.

Roughly a year after the flare’s discovery, the Antarctic neutrino observatory IceCube spotted a high-energy neutrino. By tracing the particle’s path backward, researchers determined that the neutrino came from the flare’s vicinity.

The matchup between the two events could be a coincidence. But when combined with the previous neutrino that was tied to a tidal disruption event, the case gets stronger. The probability of finding two such associations by chance is only about 0.034 percent, the researchers say.

It’s still not clear how tidal disruption events would produce high-energy neutrinos. In one proposed scenario, a jet of particles flung away from the black hole could accelerate protons, which could interact with surrounding radiation to produce the speedy neutrinos.

‘We need more data … in order to say that these are real neutrino sources or not,” says astrophysicist Kohta Murase of Penn State University, a coauthor of the new study. If the link between the neutrinos and tidal disruption events is real, he’s optimistic that researchers won’t have to wait too long. “If this is the case, we will see more.”

But scientists don’t all agree that the flare was a tidal disruption event. Instead, it could have been an especially bright type of supernova, astrophysicist Irene Tamborra and colleagues suggest in the April 20 Astrophysical Journal.

In such a supernova, it’s clear how energetic neutrinos could be produced, says Tamborra, of the Niels Bohr Institute at the University of Copenhagen. Protons accelerated by the supernova’s shock wave could collide with protons in the medium that surrounds the star, producing other particles that could decay to make neutrinos.

It’s only recently that observations of high-energy neutrinos and transients have improved enough to enable scientists to find potential links between the two. “It’s exciting,” Tamborra says. But as the debate over the newly detected neutrino’s origin shows, “at the same time, it’s uncovering many things that we don’t know.

A speck of gold dancing to a pipe organ’s tune has helped solve a long-standing mystery: why certain wind instruments violate a mathematical formula that should describe their sound.

In 1860, physicist Hermann von Helmholtz — famous for his law of the conservation of energy — devised an equation relating the wavelength of a pipe’s fundamental tone (the lowest frequency at which it resonates) to pipe length (SN: 3/31/28). Generally, the longer a pipe is, the lower its fundamental tone will be.

But the equation doesn’t work in practice. A pipe’s fundamental tone always sounds lower than the pipe’s length suggests it should according to Helmholtz’s formula. Fixing this problem requires adding an “end correction” to the equation. In the case of open-ended pipes such as flutes and those of organs, the end correction is 0.6 times the radius of the pipe. Why this was, nobody could figure out.

A break in the case came in 2010. Instrument builder and restorer Bernhardt Edskes of Wohlen, Switzerland was tuning an organ when he spotted a piece of gold that had come loose from a pipe’s gilded lip. Air pumping through the pipe should have carried away the gold. Instead, it seemed to be trapped in a vortex just above the pipe’s upper rim.

Edskes told his friend, physicist Leo van Hemmen of the Technical University of Munich, about the observation. Together with colleagues from Munich and Wageningen University in the Netherlands, they studied how air moves through playing organ pipes using cigarette smoke.

When an organ pipe sounds, a vortex indeed forms over the pipe’s rim, the team reported March 14 in Chicago at a meeting of the American Physical Society. What’s more, this vortex is capped by a hemisphere of resonating air.
This vibrating air cap, van Hemmen says, is the long-sought explanation for the “end correction.” The cap effectively lengthens the organ pipe by the exact amount that must be tacked on to Helmholtz’s formula to explain the pipe’s fundamental tone.