There’s more subtlety than humans have realized in dropping out of the sky so fast your tail feathers sing.
Male Costa’s hummingbirds in western North America are masters of the tail-screaming courtship plunge. Acoustic cameras recorded these repeated stunts and revealed that, as the male whooshes down, he twists half of his tail sideways, says ornithologist Christopher J. Clark of the University of California, Riverside. That twist aims the prolonged feather whistle toward the female he’s swooping by, Clark and his colleague Emily Mistick of the University of British Colombia in Vancouver report April 12 in Current Biology. The recordings, which use microphone arrays to localize a sound on video, shed light on another quirk of Calypte costae’s performance. While male hummingbirds of other species swoop over the female during courtship dives, the shimmery purple-faced Costa’s zoom by on the side.
Extra distance in the side flyby minimizes the Doppler effect on the feather sound. That effect may be familiar from the EEEEEEooooo of an ambulance’s siren that sounds high-pitched as the vehicle approaches and then seems to lower after it passes. Masking the Doppler effect could make it harder for a female to pick out the fastest divers, although researchers haven’t shown how these females perceive speed or whether it matters much to them.
The diving sounds, made from the flutter of the outermost tail feather, also seem similar to the males’ vocalizations, Clark says. So he wonders if females find something in both especially seductive.
No fantasy world is complete without a fire-breathing dragon. SpaceX founder Elon Musk even wants to make a cyborg version a reality, or so he tweeted April 25. But if someone was going to make a dragon happen, how would it get its flame? Nature, it seems, has all the parts a dragon needs to set the world on fire, no flamethrower required. The creature just needs a few chemicals, some microbes — and maybe tips from a tiny desert fish.
Fire has three basic needs: something to ignite the blaze, fuel to keep it burning and oxygen, which interacts with the fuel as it burns. That last ingredient is the easiest to find. Oxygen makes up 21 percent of Earth’s atmosphere. The bigger challenges are sparking and fueling the flame. All it takes to strike a spark is flint and steel, notes Frank van Breukelen, a biologist at the University of Nevada, Las Vegas. If a dragon had an organ like a bird’s gizzard, it could store swallowed rocks. In birds, those rocks help get around a lack of teeth, allowing them to break down tough foods. Inside a dragon, swallowed flint might rub against some steel, sparking a flame. “Maybe what you have is sort of scales that are flintlike and click together,” van Breukelen says. If the spark was close enough to a very sensitive fuel, that might be enough to ignite it. But some chemicals don’t need that initial spark. Pyrophoric molecules burst into flame the instant they contact air. Consider the element iridium, says Raychelle Burks, a chemist at St. Edwards University in Austin, Texas. It burns different colors when it becomes part of various molecules. One of them burns a warm orange or red. Another burns a violet-blue. (That’s one way to get the blue flame of the zombie ice dragon in George R.R. Martin’s Game of Thrones series.) Unfortunately, iridium isn’t common, especially in biology. “There are a lot of cool elements on the periodic table, but [living things] only use a few,” Burks explains.
There are other pyrophoric chemicals that a dragon might find a little closer to home, notes Matthew Hartings, a chemist at American University in Washington, D.C. Assume that dragons like caves, he begins. “If you’re living amongst a bunch of rocks, you’ll have access to a high amount of iron.”
Iron can react with another chemical, hydrogen sulfide. This is a flammable gas that smells like rotten eggs, and gives Uranus its new signature scent. It is found in crude oil. When hydrogen sulfide and iron get together — in a rusty oil pipe, for example — the result is iron sulfide. Combine it with air and you’ve got an explosive mix. Iron sulfide is sometimes the culprit when gas pipelines or tanks blow up.
Another explosive option comes from Anne McCaffrey’s series The Dragonriders of Pern. McCaffrey describes her dragons chewing on rocks containing phosphine, a chemical made of one phosphorus atom and three hydrogen atoms. In gas form, phosphine is extremely flammable and explodes on contact with oxygen. It’s also very toxic: Just seven drops of its liquid form can kill someone.
Burning burps Fictional dragons often spout flaming gas. But a gas would present problems, Hartings says. Gas, he notes, expands to fill available space. To keep it contained, a dragon would have to keep that gas under pressure.
Chemicals like phosphine, therefore, aren’t the perfect dragon-fire solution, Hartings says. The boiling point for phosphine is -84° Celsius (-120° Fahrenheit). At room (or dragon breath) temperature, it’s a gas. “You’d have to really compress it,” he says, to make it a liquid that a dragon could store and use.
Also, Hartings notes, gases are difficult to control. If a dragon blew some fiery gas into the wind, the flames might wash back on the creature and singe its face. “You have a much better chance of controlling your flame spray if you’re pushing liquid rather than a gas,” he explains.
A liquid also would help avoid self-burning, Hartings notes. The liquid with its flammable gas would ignite as soon as it hit air. Speed is key. “As long as you are shooting it out fast enough, [the] particles don’t hit the air until they are far enough away from your face,” he notes.
A combination of liquid and gas might work even better, Burks suggests. In an aerosol spray, tiny liquid droplets are suspended in a pressurized gas, which spurts out when it is released. If a dragon were to shoot an aerosol spray, it could look like a gas, with some of the properties of a liquid. “In a fine aerosol spray it would look like the dragon is spraying fire,” Burks notes. The aerosol would spread out, she says, “and the minute it hits air — kaboom!”
Something fiery, something fishy Plenty of liquids in nature will burn. Living things already produce two of these that might work for a dragon: ethanol and methanol. Both are alcohols often burned as fuels.
“Certainly, we know that yeast makes ethanol,” Hartings says. These single-celled fungi transform sugars into alcohol. That’s why they’re used to brew beer and make other alcoholic beverages. A dragon with a bellyful of yeast is not as silly as it might appear. Yeast are part of the microbial community that lives on and in people and other animals.
Methanol first requires methane. Ruminants — including cows, goats, giraffes and deer — make methane during digestion. Certain bacteria can turn methane into methanol, Hartings notes. A dragon that got enough fiber in its diet to make methane could pass that gas on to its bacterial buddies, who would convert it into methanol. But those bacterial coworkers might not even be needed. The Devil’s Hole pupfish doesn’t bother with them. The fish are a tiny, incredibly rare species found in Devil’s Hole — a single, naturally heated pool in Nevada. This fish can whip up its own whiskey in a pinch, van Breukelen and his colleagues have shown. Temperatures in Devil’s Hole reach 33 °C (91 °F). There is very little oxygen in the water to start with. When it gets hot, the oxygen levels drop even lower — too low for the fish to breathe. So pupfish stop using oxygen. Instead, they produce energy anaerobically, no oxygen required. In the process, their bodies make ethanol.
The fish produce 7.3 times more ethanol than fish living in cooler water, van Bruekelen and his colleagues reported in 2015 in the Journal of Experimental Biology.
A dragon might be able to produce ethanol under similar circumstances. However, van Breukelen says, it’s not quite so simple. “I don’t think there’s a way to keep ethanol. I don’t think you could store it,” he says. The reason: It seeps through everything. Ethanol, he explains “goes right through membranes.” Those include the membranes that surround cells and organs. When pupfish produce ethanol, the chemical ends up throughout the fish. It would not pool as a concentrate in some pouch or organ. So any dragon that made ethanol would have trouble storing enough to get a decent flame going.
The pupfish won’t be setting the world on fire — nor will dragons. One is a tiny fish, and the other isn’t real. But if Musk wants to figure out how to make his cyborg dragon light up the world, he doesn’t need to look to fossil fuels. Nature has him covered.
There’s new hope for making modern roses smell sweeter than the florist paper they’re wrapped in.
By decoding the genetics of an heirloom variety, a fragrant pink China rose called “Old Blush,” an international team of researchers has uncovered some new targets to tweak. That roster of genes plus an analysis of scent revealed at least 22 previously uncharacterized biochemical steps the plants can use to make terpene compounds, which help give roses their perfume, researchers report April 30 in Nature Genetics. Modern roses have had a crazy history of blending genes from eight to 20 species, so decoding the DNA hodgepodge has been difficult. Rose breeders have opted for “showy plants,” says molecular geneticist Mohammed Bendahmane of École Normale Supérieure in Lyon, France. In the process, fragrances dwindled, and efforts to build them back in have not been fabulous.
The new paper focused on Rosa chinensis, one of the major contributors to modern hybrids, now mixed with European and Middle Eastern lineages of roses. The study’s new details clarify that some of the rose’s genes work in opposition to one other, with some turning on to brew a scent component while others shut down manufacture of anthocyanin pigments needed for rosy petals. Knowing this could help modern rose breeders resolve a trade-off that has sacrificed scent for color.
Examining one of the early hybrids, called La France, also suggests the China rose contributed the genes for the prized trait of prolonged blooming. And the genetic survey turned up genes that might inspire ways to make the plants more water efficient and last longer in a vase.
It was the eclipse felt ‘round the world. The August 21, 2017, total solar eclipse that crossed the United States launched a wave in the upper atmosphere that was detected nearly an hour later from Brazil (SN Online: 8/11/17).
“The eclipse itself is a local phenomenon, but our study shows that it had effects around the world,” says space scientist Brian Harding of the University of Illinois at Urbana-Champaign.
Harding watched the eclipse from St. Louis. But he and his colleagues activated a probe near São João do Cariri, Brazil, to observe uncharged particles 250 kilometers high in a part of the atmosphere called the thermosphere. The probe recorded a fast-moving wave in the thermosphere go by half an hour after sunset in São João do Cariri and 55 minutes after the end of the total eclipse, the team reported April 24 in Geophysical Research Letters. The wave is produced by the motion of the moon’s shadow, which cooled the atmosphere below it. That cold spot then acted like a sink, sucking in the warmer air ahead of it and causing a ripple in the atmosphere as the cold spot moved across the globe.
Previous eclipses also have launched waves at similar altitudes in the ionosphere, the charged plasma of the atmosphere, which overlaps with the electrically neutral thermosphere (SN Online: 8/13/17). This is the first time that scientists have observed a wave in the uncharged part of the atmosphere. Neutral particles are 100 to 1,000 times denser than plasma in the atmosphere, and it’s important to know how they behave too, Harding says.
As Richard Feynman once said, “a man cannot live beyond the grave,” and so surely Feynman could not speak from the grave, either. Except that actually, he did.
For years after his death in 1988, books appeared with collections of Feynman’s articles, talks and other miscellaneous writings. Together with his two autobiographical books and his famous lectures on physics, those works offer an enormous corpus of wisdom, advice, opinion and insight into nature, science, life and society. His words are widely quoted, and in fact his most noteworthy quotations fill up a fat book edited by his daughter Michelle, The Quotable Feynman (Princeton University Press, 2015). You could read that whole book if you like, of course. But if you’re short on time, you could just peruse the Top 10 Feynman Quotes below, selected from his works to commemorate the 100th anniversary of Feynman’s birth on May 11. (At least they’re my favorite 10. He might have ranked them differently.)
“If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis … that all things are made of atoms — little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.” From the famous Feynman Lectures on Physics, this statement exemplifies Feynman’s gift for distilling the essence from complicated science and expressing it colloquially. His words really ought to be inscribed somewhere in a permanent form, just in case.
“There is nothing that living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics.” A further expression of the importance of atoms from the opening pages of Feynman’s lectures. If anyone still disagrees with this sentiment, they should watch Westworld.
“For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.” This statement was Feynman’s succinct way of telling NASA to clean up its act after the explosion of the space shuttle Challenger in 1986.
“From my knowledge of the world that I see around me, I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence.” In a set of lectures compiled in book form as The Character of Physical Law, Feynman discussed scientific exploration as not seeking certainty, or proving some things impossible, but identifying what is probable. Flying saucers are possible, but are not therefore likely to exist; they are much more probably figments of overactive human imaginations (or deliberate attempts at deception).
“Most likely anything that you think of that is possible isn’t true. In fact that’s a general principle in physics theories: no matter what a guy thinks of, it’s almost always false.” From another series of lectures, compiled as The Meaning of It All, in which Feynman expanded on the probabilistic nature of scientific knowledge. Many more things are possible than reality can accommodate; statistically, therefore, most possibilities are actually not true. That explains why so much that so many people say is so wrong.
“What is necessary ‘for the very existence of science,’ and what the characteristics of nature are, are not to be determined by pompous preconditions, they are determined always by the material with which we work, by nature herself.” Also from The Character of Physical Law, this Feynman sentiment should remind scientists blinded by philosophical predispositions that defining “science” is not up to people, whether lexicographers or philosophers. Nature writes the rules. Science is the process of finding out what its own rules need to be to decipher the rules for the universe that nature has written.
“There’s plenty of room at the bottom.” This simple statement was the title of a talk Feynman delivered in 1959, widely regarded today as the original inspiration for the origin of nanoscience and nanotechnology. Feynman recognized that miniaturization in recording information was limited only by the size of atoms, and he even imagined that atoms could someday be manipulated individually. And they have been.
“Nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical.” Feynman wasn’t the first to consider the idea of a quantum computer, but his words (from a 1981 talk, published in 1982) inspired some physicists to take the idea seriously. Feynman had no idea how to actually build a quantum computer, and serious work on real designs didn’t begin until the late 1990s. Today’s primitive versions of quantum computers can solve some simple problems and may soon be able to outperform standard computers on some types of problems, many experts believe. And perhaps such computers will, in fact, be able to simulate how nature works. (By the way, this statement is misquoted in The Quotable Feynman. As Feynman would have advised, always check things out for yourself.)
“I think I can safely say that nobody understands quantum mechanics.” As Feynman said in The Character of Physical Law, many people understand other sophisticated physical theories, including Einstein’s relativity. But quantum mechanics resists an equivalent depth of understanding. Some disagree, proclaiming that they understand quantum mechanics perfectly well. But their understanding disagrees with the supposed understanding of others, equally knowledgeable. Perhaps Feynman’s sentiment might better be expressed by saying that anyone who claims to understand quantum mechanics, doesn’t.
“The first principle is that you must not fool yourself — and you are the easiest person to fool.” The best Feynman quote of all (from a 1974 address), and the best advice to scientists and anybody else who seeks the truth about the world. The truth may not be what you’d like it to be, or what would be best for you, or what your preconceived philosophy tells you that it is. Unless you recognize how easily you can be fooled, you will be.
Of course the guy’s wearing a full-body protective suit with face mask and goggles good and snug. He’s about to confront a nest of little fluffy caterpillars.
Insect control can get surreal in the London area’s springtime battle against the young of oak processionary moths (Thaumetopoea processionea). The species, native to southern Europe, probably hitchhiked into England as eggs on live oak trees in 2005, the U.K. forestry commission says.
Adults are just harmless mate-seeking machines in city-soot tones. But when a new generation’s caterpillars finish their second molt into a sort of preteen stage, their short barbed hairs (called setae) can prick an irritating, rash-causing protein into any overconfident fool who pokes them. Even people who’d never torment, or even touch, a caterpillar can suffer as stray hairs waft on spring breezes. (More on that below.) The caterpillars aren’t much for house cleaning. The baggy silk nest a group spins itself high in several kinds of oak trees accumulates cast-off skins still hairy with the toxic protein.
The name processionary comes from the caterpillars lining up head-to-rump. “A column of caterpillars moving together like a train,” is how evolutionary biologist Jim Costa of Western Carolina University in Cullowhee, N.C., describes it. A little rearrangement can get processions trudging round and round in a circle. England’s ongoing battle against these oak leaf–stripping caterpillars has gripped the news, but other nations have irritating processions of their own, says entomologist Terrence Fitzgerald of State University of New York at Cortland. One of the London invader’s cousin, called a pine processionary moth (T. pityocampa), may be edging northward in Europe as the climate warms. In the United States, dark and spiky caterpillars of the buck moth Hemileuca maia show up largely unremarked in pockets in the East but are a traditional vexation of spring in New Orleans. Annoyances aside, these creatures represent part of the glorious but underappreciated social side of insects, Fitzgerald says. Ants, bees, wasps and termites have long been the social insects, but building joint nests and traveling in caravans are just some of caterpillars’ coordinated projects. If fish or birds did that, he grumbles, they’d be acclaimed as “fabulous animals.”
Inspired by this rethink, Costa published The Other Insect Societies. Admittedly caterpillars, too young for sex anyway, don’t have the extreme reproductive specialty of a honeybee queen with a whole caste of sterile workers. But then people don’t either, and we certainly think we’re pretty social. — Susan Milius
Self-driving taxis that use an algorithm to work together like a well-oiled machine could someday cut down on city traffic.
Researchers have created a computer program that can continually analyze incoming ride-hailing requests sent from a smartphone app and plot the most efficient course for each car in a self-driving fleet to take (SN Online: 11/21/17). Unlike standard taxis, which pick up customers spotted on the side of the road, this algorithm assigns cars to customers based on traffic conditions as well as the pickup and drop-off locations of all ride requests.
Moe Vazifeh, a physicist at MIT, and colleagues tested this algorithm by feeding it information on more than 150 million cab rides taken in New York City in 2011. The program, described online May 23 in Nature, was able to choreograph routes to pick up more than 90 percent of customers within five minutes of their ride requests.
That’s not as immediate as flagging down a taxi. But the algorithm’s method required only about 5,400 cabs on the street at once, on average, compared with the average 7,700 cabs cruising the city at any given time in 2011. By serving customers using far fewer cars, such precision-guided fleets of self-driving vehicles could help curb traffic pollution and congestion (SN: 9/30/17, p. 18).
By the end of this century, rice may not deliver the same B vitamin levels that it does today. Protein and certain minerals will dwindle, too, new data suggest.
Testing higher carbon dioxide concentrations in experimental rice paddies in China predicts losses in four vitamins — B1, B2, B5 and B9 — an international team reports May 23 in Science Advances. Adding results from similar experiments in Japan, the researchers also note an average 10.3 percent decline in protein, an 8 percent fall in iron and a 5.1 percent fall in zinc, supporting previous studies of rice and other crops (SN: 4/1/17, p. 14). Two bright spots: Vitamin B6 levels remained unchanged and vitamin E increased. In experimental setups nicknamed FACE (free-air CO₂ enrichment) in China’s Yangtze River delta and near the Japanese city of Tsukuba, researchers grew a total of 18 varieties of rice. Piping exposed the rice to CO2 concentrations elevated to 568 to 590 parts per million — higher than the current level of 410 ppm, but in line with the current trend toward 570 ppm in this century.
The nine rice varieties from China, from three years’ crops and analyzed in their unrefined brown form, differed in degree of vitamin loss. On average, B1 levels (thiamine) declined 17.1 percent; B2 levels (riboflavin), 16.6 percent; B5 (pantothenic acid), 12.7 percent; and B9 (folate), 30.3 percent.
Such declines in rice nutrients could hit economically strapped populations in Asia the hardest. Nine of the world’s 10 most rice-dependent countries are in Asia. (The other is Madagascar.) The researchers predict that about 600 million people currently without good options for switching diets could risk nutrient deficiencies from rice declines. B vitamins help with a range of bodily tasks, from maintaining a healthy brain to enabling normal fetal development.
Antarctica is losing ice at an increasingly rapid pace. In just the last five years, the frozen continent has shed ice nearly three times faster on average than it did over the previous 20 years.
An international team of scientists has combined data from two dozen satellite surveys in the most comprehensive assessment of Antarctica’s ice sheet mass yet. The conclusion: The frozen continent lost an estimated 2,720 billion metric tons of ice from 1992 to 2017, and much of that loss occurred in recent years, particularly in West Antarctica. Before 2012, the continent shed ice at a rate of 76 billion tons each year on average, but from 2012 to 2017, the rate increased to 219 billion tons annually. Combined, all that water raised the global sea level by an average of 7.6 millimeters, the researchers report in the June 14 Nature. About two-fifths of that rise occurred in the last five years, an increase in severity that is helping scientists understand how the ice sheet is responding to climate change.
“When we place that against the [Intergovernmental Panel on Climate Change’s] sea level projections, prior to this Antarctica was tracking the low end of sea-level-rise projections,” says study coauthor Andrew Shepherd, an earth scientist at the University of Leeds in England. “Now it’s tracking the upper end.”
Antarctica currently contains enough frozen water to raise the oceans by 58 meters. Melting ice from the continent is a major driver of the sea level rise that’s threatening coastal communities and ecosystems around the world with flooding as the climate changes (SN: 12/27/14, p. 29). A good estimate of Antarctica’s ice loss will help climate scientists better predict future sea level rise, Shepherd says, as the planet continues to warm. But in a place as big as Antarctica, it’s not easy to gauge the amount of ice and how it fluctuates. Satellites can collect different kinds of data to inform estimates, measuring the mass of the ice sheet or the depth of the ice or the speed at which glaciers flow into the ocean. But sorting out seasonal changes (such as the ice added annually from winter snowfall) from more meaningful long-term ones is hard. This group of researchers made their last big estimate of Antarctica’s shrinking ice sheet in 2012 and found that it had lost 1,320 billion tons of ice from 1992 to 2011 (SN: 12/29/12, p. 10). The new analysis paints a more dire picture. “In 2012, we concluded that over the 20-year period before that, Antarctica had been losing ice at a steady rate,” Shepherd says. But the new findings indicate that the rate of ice loss has now tripled, compared with the average rate from 1992 to 2011.
The new study combines data from three different ways of measuring ice via satellite to pinpoint a composite number. Researchers first computed the average mass change in ice suggested by each technique. Then they integrated those data, accounting for specific kinds of errors introduced by the different measurements.
West Antarctica dominates the melting, Shepherd and colleagues found. It was losing about 53 billion tons of ice each year, on average, in 1992. Now the rate has risen to about 159 billion tons per year.
That region probably loses ice more than other parts of the continent because the ice in West Antarctica is more sensitive to small temperature fluctuations. It sits on the seabed submerged in water, while other parts of the continent’s ice sheet, such as East Antarctica, sit higher, exposed to air. Even a small increase in ocean temperature (say, 0.5 degrees Celsius) transfers a lot more heat to that ice than a comparable increase in air temperature, Shepherd says. And when warm water starts to eat away at an ice shelf from underneath, it thins the shelf and hastens melting even further.
East Antarctica seems to be more stable. It appears to have even slightly gained mass in recent years, but those measurements are more uncertain. “I think it’s fair to say that the more work that gets done, the picture we get of Antarctica is that it’s more dynamic and more capable of rapid change than we used to think,” says Steve Rintoul, an oceanographer at CSIRO based in Hobart, Australia. Scientists had thought that such a large mass of ice was relatively resilient. Now its vulnerabilities are showing. Rintoul was not involved in the new analysis, but coauthored a perspective and a review on the future of Antarctica and the Southern Ocean in the same issue of Nature.
While ice cores can provide clues to Antarctica’s climate going back millennia, researchers have reliable satellite data on Antarctic ice going back only about 25 years. Getting a better handle on long-term trends for Antarctica — and for melting ice in Greenland and in glaciers around the world — requires more data. And that means keeping Earth-observing satellites, funded by governmental agencies such as NASA and the European Space Agency, in the air (SN Online: 2/9/18).
Narwhals are among the most elusive of whales. But for the first time, researchers have been able to eavesdrop on the creatures for days at a time as these unicorns of the sea dove, fed and socialized.
Biologist Susanna Blackwell and colleagues listened in on the clicks, buzzes and calls of the East Greenland narwhal (Monodon monoceros). The team’s findings, published June 13 in PLOS ONE, provide a peek into the daily behavior of the long-toothed whale. The research could help scientists determine how human-made noises may affect narwhals as the Arctic warms due to climate change and shipping lanes become more open.
Many whale sounds are recorded using hydrophones, underwater microphones that dangle in the water. But these acoustic devices have several drawbacks: They can’t sense the depth or direction from which noise comes, and they can’t detect which animal is making a sound.
Blackwell and colleagues skirted these issues by attaching an acoustic recording device to the narwhals themselves. “It is really like sitting on the back of a narwhal for a few days and experiencing the world,” Blackwell says. With the help of native Greenland hunters, the researchers tagged six of the skittish creatures from 2013 to 2016. The devices were attached with suction cups, and held in place for several days by a nylon string threaded through a ridge of cartilage on the narwhals’ backs. After three to eight days in the water, magnesium links to the string degraded and released the device, which the researchers retrieved using GPS. Tagging was stressful for the narwhals, says Blackwell, who works for Greeneridge Sciences, Inc., the Santa Barbara, Calif., company that manufactures the acoustic devices (SN Online: 12/7/17). But after a day of silence, the narwhals resumed their normal behavior. Like other species of toothed whales, narwhals use echolocation to hunt in the dark arctic waters. “They’re like wet bats,” says Kate Stafford, an oceanographer at the University of Washington in Seattle who did not participate in the study. The researchers found that the narwhals clicked while diving to locate their prey, often arctic and polar cod or squid. When closing in on a meal, the clicking sounds turned into a rapid buzzing noise. At the surface, the narwhals used whistle and trumpetlike calls to communicate with one another.
“We were very surprised that they actually have a very specialized way of using sound,” says study coauthor Mads Peter Heide-Jørgensen, a biologist at the Greenland Institute of Natural Resources based in Copenhagen. The narwhals’ sounds varied not only with each activity the animals did, but also with their depth. “Having some of this baseline data from an area that is relatively pristine is going to be really valuable going forward,” Stafford says.
Though the Scoresby Sound where the narwhal research took place is very remote, it won’t be for long. Human presence in the Arctic is increasing thanks to climate change, says Jens Koblitz, a bioacoustician at the University of Konstanz in Germany. Fishing boats, ships of oil prospectors and others are expected to spend more time in the Arctic as global warming reduces the extent of sea ice in the region (SN: 12/10/16, p. 15).
“This study is a great stepping-stone,” Koblitz says. If scientists discover that human sounds negatively affect the ways that the whales communicate, researchers might be able to protect some areas from human activity.
