1-29-21 Naked mole rats mimic the dialect of their colony’s queen
Colonies of naked mole rats develop dialects in their vocalisations that may help them distinguish between friends and foes. These dialects are influenced by each colony’s queen, and become more varied if the queen dies. Naked mole rats (Heterocephalus glaber) are extremely vocal creatures that live in colonies in which only one queen reproduces. To see whether their vocalisations help maintain their social structure, Alison Barker at the Max Delbrück Center for Molecular Medicine in Germany and her colleagues recorded more than 36,000 greeting calls, from 166 naked mole rats in seven colonies raised in labs in Germany and South Africa. After identifying the acoustic features of these soft chirps, such as pitch, peak frequency and duration, the researchers used the calls to train a machine-learning algorithm. Not only could the algorithm reliably recognise individuals within a colony, but the chirps’ features were also highly predictive of which colony an animal belonged to, akin to human accents or dialects. This suggests that individuals from each colony have unique voices while all sharing the same dialect. In another experiment, naked mole rats responded far more frequently to recordings of their own dialect than to other dialects, suggesting they use call and response when identifying colony members. The animals also responded to artificial chirps that shared the features of their dialect but were distinct from other colony members’ calls. “That shows that they respond to the general dialect,” says team member Gary Lewin. Barker and her team placed three abandoned pups in foster colonies and found that they all developed their adoptive homes’ dialect. The two younger pups replicated the new dialect entirely, but the slightly older one didn’t learn it as well, says Lewin.
1-29-21 Naked mole-rat colonies speak with unique dialects
The different vocalizations may help colony members tell friend from foe. When one naked mole-rat encounters another, the accent of their chirps might reveal whether they’re friends or foes. These social rodents are famous for their wrinkly, hairless appearance. But hang around one of their colonies for a while, and you’ll notice something else — they’re a chatty bunch. Their underground burrows resound with near-constant chirps, grunts, squeaks and squeals. Now, computer algorithms have uncovered a hidden order within this cacophony, researchers report in the Jan. 29 Science. These distinctive chirps, which pups learn when they’re young, help the mostly blind, xenophobic rodents discern who belongs, strengthening the bonds that maintain cohesion in these highly cooperative groups. “Language is really important for extreme social behavior, in humans, dolphins, elephants or birds,” says Thomas Park, a biologist at the University of Illinois Chicago who wasn’t involved in the study. This work shows naked mole-rats (Heterocephalus glaber) belong in those ranks as well, Park says. Naked mole-rat groups seem more like ant or termite colonies than mammalian societies. Every colony has a single breeding queen who suppresses the reproduction of tens to hundreds of nonbreeding worker rats that dig elaborate subterranean tunnels in search of tubers in eastern Africa (SN: 10/18/04). Food is scarce, and the rodents vigorously attack intruders from other colonies. While researchers have long noted the rat’s raucous chatter, few actually studied it. “Naked mole-rats are incredibly cooperative and incredibly vocal, and no one has really looked into how these two features influence one another,” says Alison Barker, a neuroscientist at the Max Delbrück Center for Molecular Medicine in Berlin.
1-28-21 Legal threat over bee-harming pesticide use
The Wildlife Trusts is to take legal action against the UK government over its decision to allow a pesticide that is almost entirely banned in the EU. In 2018, the EU banned the outdoor use of neonicotinoid pesticides, which harm pollinating insects such as bees. But following Brexit, the government approved the emergency use of one neonicotinoid to combat a crop disease. The charity has told Environment Secretary George Eustice of their intention to challenge the decision. In a letter to Mr Eustice, the Trusts says it will push for a judicial review unless the government can "prove it has acted lawfully". Multiple studies, including large-scale field trials, have found that neonicotinoids harm pollinators and aquatic life. Research has also shown that they can be linked to the wider collapse in biodiversity. The government says it allowed the use of the neonicotinoid thiamethoxam because of the "potential danger" to the sugar beet crop from beet yellows virus, which is spread by aphids. The virus can have a severe impact on sugar beet. It stressed that use of the chemical would be strictly limited, and the risk to bees was "acceptable" because sugar beet doesn't flower. Alternative chemicals should be used to kill any wild flowering plants in and around the crops, the government said. Neonicotinoids are the most widely-used class of insecticides in the world and they work by disrupting the insect central nervous system. Two years ago, the EU's ban was supported by then-Environment Secretary Michael Gove, who said the weight of evidence was "greater than previously understood". Unless the evidence changed, he said, the restrictions would be maintained post-Brexit. The government says the change in policy is based on "new evidence". But, so far, they haven't made this science public. However, Craig Bennett, chief executive of the Wildlife Trusts, said there was no new evidence to justify the change in policy. He said: "The government refused a request for emergency authorisation in 2018 and we want to know what's changed. Where's the new evidence that it's okay to use this extremely harmful pesticide? "Using neonicotinoids not only threatens bees but is also extremely harmful to aquatic wildlife because the majority of the pesticide leaches into soil and then into waterways. Worse still, farmers are being recommended to use weedkiller to kill wildflowers in and around sugar beet crops in a misguided attempt to prevent harm to bees in the surrounding area. This is a double blow for nature."
1-28-21 A new species of baleen whale has been found in the Gulf of Mexico
A small group of whales living in the Gulf of Mexico belong to a new species that has remained undetected for millennia. There are fewer than 100 of them, so they are immediately an endangered species. The new species belongs to a group called baleen whales, which filter food out of the water and include the largest whale of all, the blue whale. Despite their size, we still haven’t been able to track down how many species of baleen whale there are. Scientists recognise a species called Bryde’s whale (Balaenoptera edeni), which are medium-sized whales that live in and around the tropics. It isn’t clear if they are all one species, or several, so they are often called Bryde’s-like whales. There are already thought to be two subspecies, called B. edeni brydei and B. edeni edeni, says Patricia Rosel at the National Oceanic and Atmospheric Administration’s Southeast Fisheries Science Center in Louisiana. However, since 2003 some Bryde’s-like whales from the Indian Ocean have been recognised as a separate species called Omura’s whale. Rosel and her colleagues have long studied Bryde’s-like whales in the Gulf of Mexico. “We kind of knew, starting in the 1990s, that there was this resident small population,” she says. In 2014, they published a genetic analysis of tissue samples from the whales, which showed they were genetically distinct from other Bryde’s-like whales. “But we didn’t have a skull,” which is crucial for identifying a new whale species, she says. Then in January 2019, an adult male stranded in the Florida Everglades, and the researchers obtained the skull and skeleton. They have now found that the skull is distinct from those of other Bryde’s-like whales. Combined with further genetic evidence, they say this is enough to establish the Gulf of Mexico whales as a new species.
1-28-21 Bog beetles finally reveal their remarkable age
It's amazing what treasures are tucked away in the collections of London's Natural History Museum - some not fully recognised yet even by the curators. Consider two beetles wedged in the grooves of a piece of oak that was dug from a Cambridgeshire bog in the 1970s. The insects were donated to the London institution by a farmer concerned they might be an invasive species. They weren't, and so were put in a drawer. Only now have they been examined and shown to be nearly 4,000 years old. The beetles are Oak Capricorns (Cerambyx), a species not previously known to have ever existed in Britain. About the size of your thumb, they have wonderful long antennae. And if alive today and resident in the UK, they would certainly be among the country's largest beetles. "They're as big as a stag beetle," said the NHM's senior curator of insects, Max Barclay. "As far as I know, the story is this: A farmer in eastern England was cutting up wood he'd found while doing some deep ploughing and discovered these insects inside; dead, of course. This was a huge piece of waterlogged oak, and he sent us a sample. I think, primarily, he was concerned the beetles were pests. My colleagues at the time said, 'well, they're not British', and so they were left. "Today, you find this species halfway down France. You get it in Poland, Hungary and into Slovakia. And there are also old records from southern Germany. "We recently had the opportunity with some American collaborators to actually date the wood and the beetles. This was really interesting. Because the beetles are inside the wood, you know they're the same age; and it's therefore a test of the dating techniques to show they get the same results whether it's plant material or animal material. It's a kind of Rosetta Stone moment." The radiocarbon dating found the beetles and the oak to be 3,785 years old. The farmer's land near Ramsey in Cambridgeshire would have looked very different back then. It was the Bronze Age, and we think these islands were experiencing relatively dry and warm conditions. We don't have thermometer records but many other similar "proxies" suggest this. The presence of the wood-chomping beetles probably speaks also to more forested times. East Anglia has since been cleared of nearly all its ancient woodlands.
1-27-21 No, native plants aren't always the best choice for gardens
There's a tendency among horticulturists to prefer native plant species, but we shouldn't assume they are better, writes James Wong. IT ISN’T an exaggeration to say that in the world of horticulture “native” is frequently used as a byword for “better”. Native plants are often considered easier to grow and better for wildlife, while also being less invasive and more resistant to pests. This belief is so institutionalised that many local planning rules in the UK specify that a certain percentage of landscaping schemes must include native species. Indeed, this conviction runs so deep that some see sharing evidence to the contrary as being hugely controversial, even deeply irresponsible. But accuracy is what matters, so let’s explore how well this entrenched dogma stands up to analysis. First, it is important to clarify that, in many cases, native plants are great choices for a garden. What I am examining here is whether they are automatically a superior option for both garden performance and ecological value, in the context of Britain. The problem with considering a group of plants to be inherently superior is that many measures of “better” are contradictory. For example, one of the key features that makes a plant invasive is it being so easy to grow that it overwhelms efforts to manage its spread, resulting in its escape into natural ecosystems where it can cause havoc. So the idea that native plants are both less invasive and easier to grow can only be maintained if you are very selective with your evidence. You also have to ignore, for instance, that many native plants, such as bracken, are so invasive that they can swamp huge areas of land, with catastrophic effects on local biodiversity. So if we are concerned about biodiversity, we should also be concerned about invasive native species. Unless, in reality, we are worried only about the “alien” part of “alien invasives”, not the invasive potential or impact on ecosystems of all plants.
1-27-21 Sparrows are healthier living in groups with diverse personalities
House sparrows are healthier when they live in groups in which different individuals have different personality types, rather than if all individuals share the same personality type. The “surprising” findings suggest that personality diversity promotes not only a healthier society, but also better physical and mental health for each individual within that society, says Zoltan Barta at the University of Debrecen in Hungary. While his team’s study focused on birds, its results may be applicable to other social species as well. “You can’t ignore the analogy with humans,” he says. Barta and his fellow researchers trapped 240 wild house sparrows (Passer domesticus) and ran a “personality” test on each bird by placing it alone in a cage for up to 10 minutes and observing its behaviour. “We don’t know bird emotions well enough to classify them as ‘funny’ or ‘shy’ or ‘extroverted’ like we would for describing human personalities,” says Barta. “But we can get standardised, measurable information about their personality differences by seeing what they do when they’re isolated.” The birds’ responses are akin to what humans might do if placed alone in a prison cell, he says. “Some are going to try frantically to get out; others are going to just sit in a corner and try to understand what’s going on; others might go wandering about exploring to see where they can get a glass of water. And this, in many ways, represents personality.” The fact that such personality testing in animals yields consistent results – the same animal gets the same personality score every time it is tested – indicates that it is a “robust” measurement of personality, says Attila Fülöp, also at the University of Debrecen, who collaborated on the study.After giving a personality score to each bird, the researchers placed the birds in aviaries in groups of 10 birds according to personality. In some groups, they placed only birds of similar personality scores. In other groups, they placed birds with a variety of personality scores. They weighed and took blood samples from each bird before and during the experiment.
1-27-21 Sharks at unprecedented risk of extinction after 71 per cent decline
Numbers of oceanic sharks and rays have declined at what researchers describe as an “alarming” 71 per cent over almost half a century, leading to what researchers say is an unprecedented increase in risk of extinction. Conservationists have been warning for years about the unsustainable killing of the apex predators, based on regional reports and data on individual species, but a paper published today is the first to offer an authoritative global overview. It focuses on oceanic sharks and rays – those that live in open seas rather than in shallow coastal waters – and reveals that shark finning and fishing worldwide have driven a decline in numbers of at least 71 per cent between 1970 and 2018. Prior research has shown that coastal shark populations are declining too. “Policy-makers can no longer ignore the plight of sharks and rays,” says Nathan Pacoureau at Simon Fraser University, Canada, who worked on the study. The estimate drew from new data on all 31 oceanic shark and ray species from the IUCN Red List of Threatened Species and 18 on the Living Planet Index, including information on fish catches and markets. Pacoureau and his colleagues found the declines first hit the largest species, before being inflicted on progressively smaller ones over time. The global average masks even worse declines for some regions and species. “The Indian Ocean is the worst ocean. There is almost no [fisheries] management at all,” says Pacoureau. The oceanic white-tip (Carcharhinus longimanus), once the most common shark in tropical waters, is now critically endangered, the last step before extinction in the wild. The smooth hammerhead (Sphyrna zygaena) is the only species with growing numbers. “Such steep declines are shocking even to experts, especially when compared to land animal statistics,” says Sonja Fordham at the Shark Trust, a UK-based non-profit. She notes that while the shark and ray data in the analysis is the best available, there are gaps for some species over time.
1-27-21 Extinction: 'Time is running out' to save sharks and rays
Scientists say sharks and rays are disappearing from the world's oceans at an "alarming" rate. The number of sharks found in the open oceans has plunged by 71% over half a century, mainly due to over-fishing, according to a new study. Three-quarters of the species studied are now threated with extinction. And the researchers say immediate action is needed to secure a brighter future for these "extraordinary, irreplaceable animals". They are calling on governments to implement science-based fishing limits. Study researcher, Dr Richard Sherley of the University of Exeter, said the declines appear to be driven very much by fishing pressures. He told BBC News: "That's the driver for the 70% reduction in the last 50 years. For every 10 sharks you had in the open ocean in the 1970s, you would have three today, across these species, on average." Sharks and rays are caught for their meat, fins and liver oil. They are also captured for recreational fishing and turn up by accident in the catch of fishing boats that are targeting other stocks. Of the 31 species studied, 24 are now threatened with extinction, and three shark species (the oceanic whitetip shark, and the scalloped and great hammerhead sharks) have declined so sharply they are now classified as critically endangered - the highest threat category, according to the International Union for Conservation of Nature (IUCN). Prof Nicholas Dulvy of Simon Fraser University in British Columbia, Canada, said oceanic sharks and rays are at exceptionally high risk of extinction, much more so than the average bird, mammal or frog, despite ranging far from land. "Overfishing of oceanic sharks and rays jeopardises the health of entire ocean ecosystems as well as food security for some of the world's poorest countries," he said.
1-27-21 Sharks’ tooth-like scales help to boost their acceleration rates
Tooth-like scales on shark skin reduce drag as they manoeuvre through the ocean, and they are at their most effective when the sharks accelerate. Josephine Galipon at Keio University Institute for Advanced Biosciences in Japan and her colleagues created synthetic shark skin from 3-D printed moulds based on scanning electron microscope images of Pacific spiny dogfish (Squalus suckleyi) shark skin samples. They then covered an aeroplane wing-shaped model with the skin and studied the fluid dynamics – specifically, the vortices, or water swirls, left in the model’s wake – as they moved the model through water. They moved the sample at a constant “cruising” speed in some experiments, while in others they accelerated the object at the shark’s natural range of acceleration. They found that the wake was thinnest – meaning drag was reduced the most– when the object was accelerating. “Shark skin helps avoid ‘flow separation,’ meaning it prevents these water vortices from crashing into each other in the wake of the swimming body specifically during acceleration,” says Galipon. “That makes the shark’s take-off and turns extremely effective.” This would help improve shark manoeuvrability and speed – important when chasing down prey or evading larger predators. The findings might lay to rest a decades-old debate about how exactly shark denticles reduce drag. “Many researchers have tried to resolve this mystery, but they may not have considered that a shark is always oscillating and turning through acceleration,” says Galipon, whose team worked in collaboration with scientists at Queen’s University in Kingston, Ontario, Canada.The study could also change the way people view, manufacture, and use synthetic sharkskin in aquatic sports equipment, and especially better understand its benefits. “It’s possible that for the moment they are not used with the right purpose in mind,” says Galipon. “The benefit may be minimal at constant, cruising speeds.”
1-26-21 Swarm of Pacific eels is largest group of fish seen in the abyss
Deep-sea explorers have found the largest collection of fish ever seen in the abyssal zone of the ocean, which stretches from 3000 to 6000 metres deep. Footage of more than 100 cutthroat eels on top of an underwater mountain in the Pacific suggests that these areas may be less empty than previously believed. “This was totally unprecedented for the deep ocean,” says Astrid Leitner from the Monterey Bay Aquarium Research Institute in California. Various countries have plans to mine minerals from the underwater plains in the Clarion-Clipperton zone of the Pacific, an area roughly the size of the continental US. This could lead to marine life seeking refuge on nearby underwater mountains. To learn more about these areas, Leitner and her colleagues dropped autonomous underwater vehicles equipped with baited cameras on several seamounts just south-east of Hawaii. They started with a seamount 3100 metres below the surface. When they retrieved the lander, the first images they saw were initially disappointing as they seemed to show a black screen. But a closer look revealed the frame was so full of eels that it just appeared black. “We basically landed on top of eels, then they just swarmed at us,” says Leitner. The video contained at least 115 individual eels. This is the biggest known aggregation of eels, or indeed any fish, ever seen deeper than 1000 metres, including around sunken whale carcasses, which often attract scavengers. The largest previous example the researchers could find record of in the deep sea was a group of 68 eelpouts, an eel-like fish, on the abyssal plains of the Arabian Sea, gathered around a large shark carcass that was submerged as part of an experiment. A few specimens captured by the underwater vehicles confirmed them to be cutthroat eels (Ilyophis arx), which are up to a metre long. Only a handful of these had ever been captured before.
1-26-21 Dozens of smuggled chameleons found in suitcase in Austria
Dozens of protected chameleons are being nursed back to health at an Austrian zoo after they were discovered in a suitcase at Vienna airport. The animals were spotted by security after an X-Ray of the suitcase appeared suspicious. Some 74 chameleons were found hidden in socks and boxes. They would sell for about 37,000 euros (£32,850; $44,970) on the black market, officials said. A 56-year-old man who had travelled from Tanzania was later arrested. The man, who has not been identified by police, could face a fine of up to 6,000 euros, the finance ministry said. "[Chameleons] can camouflage themselves well... but they ultimately did not outsmart the X-Ray machine," the ministry said in a statement. The animals were immediately transported to Vienna's Schoenbrunn Zoo where they were examined by specialists. Three of the chameleons did not survive the journey. They range in age from one week old, to adult specimens. "According to the zoo's experts, they come from the Usambara Mountains, a currently very rainy and cool region in Tanzania," the finance ministry said. The surviving chameleons are now being cared for at Schoenbrunn Zoo.
1-25-21 A new orange and black bat species is always ready for Halloween
Old-style science fieldwork finds an unknown bat in the sky islands of Africa’s Nimba Mountains. Bats, better known for their mousy looks, can have a colorful side. A new species, discovered when two bats were caught at an abandoned miners’ tunnel in western Africa, sports showy swathes of orange fur. The new finds “are just gorgeous,” says mammalogist Nancy Simmons of the National Museum of Natural History in New York City. Orange fur on the bats’ backs contrasts with black sections of wing membranes. But that’s not what sets this bat apart: Three other Myotis species from the continent are similarly flashy. Rather less visible traits, from details of hidden striping in its fur to its echolocation calls, peg Myotis nimbaensis as something unusual, Simmons and colleagues report online January 13 in American Museum Novitates. The new species was discovered the old-fashioned way — out in a remote forest at night with keen eyes studying real animals. That’s not so common nowadays in the age of sensitive genetic tools, Simmons says. Many of the 20 or so new bat species typically named every year are detected through genetic analyses of museum specimen lookalikes. M. nimbaensis differs genetically from near kin — about as much as humans differ from gorillas. Differences also show up in teeth as well as other anatomy. But when researchers collected the first bat, near the mouth of an abandoned tunnel for mineral exploration up in Guinea’s section of the Nimba Mountains, the flashy beast wasn’t obviously anything new. While most of the more than 1,400 known kinds of bats are various shades of brown, bats here and there around the world can be yellow, fluffball white or coppery red. And there was the matter of the three other orange Myotis species. (How, or whether, the colors matter in animals active at night, Simmons says, is “one of the mysteries.”)
1-24-21 Protecting great apes from the unknown effects of COVID-19
Humans can transmit many diseases to chimps, orangutans and their kin. People who study and care for the creatures are taking lockdown-style measures to limit the risk. Wildlife veterinarian Stephen Ngulu starts his typical working day watching from a distance as the chimpanzees under his care eat their breakfast. He keeps an eye out for runny noses, coughing, or other hints of illness. These days, Ngulu and others at the Ol Pejeta Conservancy's Sweetwaters Chimpanzee Sanctuary in Kenya have doubled down on their vigilance. Chimpanzees and other great apes — orangutans, gorillas, and bonobos — are prone to many human viruses and other infections that plague people. So when SARS-CoV-2 began circulating, the community that studies and cares for great apes grew worried. "We don't know what will happen if the virus is transmitted to the great apes. It might get severe," says Fabian Leendertz, an infectious-disease ecologist at the Robert Koch Institute in Berlin. These endangered apes have the same receptor that SARS-CoV-2 uses to enter human cells — angiotensin-converting enzyme 2 (ACE2) — making infection a distinct possibility. What's less predictable is how sick the apes might get were the virus to take hold. Genetic similarities — we share at least 96 percent of our DNA with each great ape species — mean that apes are susceptible to many viruses and bacteria that infect human beings. And though some human pathogens (such as a coronavirus called HCoV-OC43 that causes some cases of the common cold) cause only minor illness in the animals, others can be disastrous. "There have been incidents of common human respiratory pathogens spilling into chimpanzees, and it's fatal to them," says Fransiska Sulistyo, an orangutan veterinary consultant in Indonesia. Between 1999 and 2006, for example, several outbreaks of respiratory disease occurred among chimpanzees in the Ivory Coast's Taï National Park, including a 2004 episode that infected a group of 44 and killed eight. Analyses suggest that the underlying pathogens were human respiratory syncytial virus or human metapneumovirus, which both cause respiratory illnesses in people, along with secondary bacterial infections. And in 2013, rhinovirus C, a cause of the human common cold, caused an outbreak among 56 wild chimpanzees in Uganda's Kibale National Park, killing five. Even in normal times, those who work at ape sanctuaries or study apes in the wild are perpetually trying to stave off disease. Guidelines from the International Union for Conservation of Nature (IUCN) recommend that field researchers and sanctuary staff coming from other countries quarantine for at least a week before entering ape habitat, in the wild or otherwise. They should wear face masks and stay at least seven meters away from apes. The IUCN also recommends that people working with apes stay up to date on immunizations, get screened for infectious diseases of regional concern (tuberculosis and hepatitis, for example), and watch for signs of illness in research staff. Sanctuaries should routinely disinfect surfaces within their facilities.
1-22-21 A quarter of all known bee species haven't been seen since the 1990s
The number of bee species recorded worldwide has been sharply decreasing since the 1990s. Eduardo Zattara and Marcelo Aizen at the National University of Comahue in Argentina analysed how many wild bee species are observed each year as recorded in the Global Biodiversity Information Facility – a publicly available platform where researchers and citizens can record sightings of bee species. They found that there were a quarter fewer species reported between 2006 and 2015, as compared with the records we have from before 1990. The decline is especially alarming considering the number of bee records in this database has increased by around 55 per cent since 2000, so it isn’t down to a lack of observations. “Our work is the first long-term assessment of global bee decline,” says Zattara. Previous bee research has been confined to a specific species or a particular location. The researchers found that the decline isn’t consistent across all bee families. Records of the rare Melittidae family of around 200 bee species have fallen by as much as 41 per cent since the 1990s, versus 17 per cent for the more common Halictidae family. It may not necessarily mean unrecorded bee species are extinct, but they are now rare enough that people who tend to report bee sightings aren’t encountering them. The destruction of natural habitats, heavy use of pesticides and climate change could explain this decline in species richness, says Zattara. “We are producing more food to feed our growing population,” says Zattara. “[We are] using highly economically convenient ways to grow single-culture crops, which is removing a lot of the bees’ natural habitat.” The global decline in species mirrors what has previously been reported in Britain. But the researchers note that studies in more remote areas are needed to gain a full picture, as most existing data comes from North America and Europe, where it may be easier to record bee species.
1-21-21 Physicists find best way for insects to avoid collisions when jumping
A mathematical solution to a biological puzzle that may not really exist might prove useful for designing hopping rovers for space exploration. Alberto Vailati at the University of Milan, Italy, normally researches the physics of fluid dynamics. However, about 10 years ago, after noticing jumping insects on a holiday, he was intrigued to read some lab studies in which insects, including fruit fly larvae, gall midge larvae and froghoppers, had all been seen leaping with an average take-off angle of about 60 degrees. The idea that many different types of insects should have independently evolved to leap at this take-off angle seemed odd to Vailati: for insects wanting to escape predators, or simply move efficiently from A to B, a 45-degree take-off angle is the natural choice, as this maximises the range of a jump. For several years, Vailati mentioned the insects to his first-year students, in the hope that it would pique their curiosity too. After a recent lecture, one student, Samuele Spini, came back with two pages of hand calculations and the idea that a 60-degree take-off angle may help the insects avoid obstacles mid-jump. Vailati, Spini and their colleagues then built a mathematical model to investigate the idea. They considered the trajectory an insect would take depending on the take-off angle and explored which aerial path would give the insect the best chance of avoiding step-like or fence-like obstacles of random size and position lying ahead. The researchers also factored in wind and air resistance to make their calculations more applicable to the real world. Defining a successful jump as one in which the insect leaps over or lands on top of an obstacle, they found that a take-off angle of 60 degrees minimised the probability of striking the side of an obstacle, while maintaining a long jump range.
1-21-21 Elephants counted from space for conservation
At first, the satellite images appear to be of grey blobs in a forest of green splotches - but, on closer inspection, those blobs are revealed as elephants wandering through the trees. And scientists are using these images to count African elephants from space. The pictures come from an Earth-observation satellite orbiting 600km (372 miles) above the planet's surface. The breakthrough could allow up to 5,000 sq km of elephant habitat to be surveyed on a single cloud-free day. And all the laborious elephant counting is done via machine learning - a computer algorithm trained to identify elephants in a variety of backdrops. "We just present examples to the algorithm and tell it, 'This is an elephant, this is not an elephant,'"Dr Olga Isupova, from the University of Bath, said. "By doing this, we can train the machine to recognise small details that we wouldn't be able to pick up with the naked eye." The scientists looked first at South Africa's Addo Elephant National Park. "It has a high density of elephants," University of Oxford conservation scientist Dr Isla Duporge said. "And it has areas of thickets and of open savannah. "So it's a great place to test our approach. "While this is a proof of concept, it's ready to go. "And conservation organisations are already interested in using this to replace surveys using aircraft." Conservationists will have to pay for access to commercial satellites and the images they capture. But this approach could vastly improve the monitoring of threatened elephant populations in habitats that span international borders, where it can be difficult to obtain permission for aircraft surveys. The scientists say it could also be used in anti-poaching work. "And of course, [because you can capture these images from space,] you don't need anyone on the ground, which is particularly helpful during these times of coronavirus," Dr Duporge said. "In zoology, technology can move quite slowly. "So being able to use the cutting-edge techniques for animal conservation is just really nice."
1-20-21 Natural wonder: Wing 'clap' solves mystery of butterfly flight
The fluttering flight patterns of butterflies have long inspired poets but baffled scientists. Researchers have struggled to understand how these delicate creatures can fly with their large but inefficient wings. Now, a new study shows that butterflies evolved an effective way of cupping and clapping their wings to generate thrust. The scientists say that this ability helps them avoid dangerous predators. Flying species have evolved various methods of evading death. Some have developed powerful and efficient wings to speed them to safety. Others survive by tasting awful when eaten. But what about the slow-moving, meandering butterfly? The problem for these creatures is that they have unusually large wings relative to their body size, which are aerodynamically inefficient for flight. Back in the 1970s, researchers developed a theory that their big wings allowed the butterfly to clap them together on the upstroke to power their take off. But no one has shown how this works in natural flying conditions. Now, Swedish scientists, using a wind tunnel and high-speed cameras, have captured the butterfly's unique flying skill. "The wings are behaving in quite an interesting way," co-author Dr Per Henningsson, from Lund University, in Sweden, told BBC News. "The leading and the trailing edge are meeting before the central part, forming this pocket shape. "We think that sort of behaviour is going to improve the clap because it forms an air pocket between the wings which, when the wings collapse, that makes the jet even stronger and more efficient." As well as recording slow-motion video of the butterflies in flight, the researchers constructed two simple pairs of mechanical clappers to test their ideas. One was rigid, the other flexible and more akin to the butterfly wings observed in the wind tunnel tests. The team found that the flexible wings dramatically increased the force created by the clap. It also improved the efficiency by 28%, which the authors describe as a huge amount for a flying animal.
1-20-21 Male mantises fight females to mate - but they get eaten if they lose
Female praying mantises are famous for attacking and cannibalising their mates during or after a sexual encounter, but evidence is emerging that some males attack too, and that winning a fight is crucial for successful mating. Sexual cannibalism is common amongst praying mantises. Typically, the female is the aggressor, which encourages males to approach the female carefully and cautiously when mating. But Nathan Burke and Gregory Holwell at the University of Auckland, New Zealand, say some male praying mantises go on the attack instead. They wrestle and sometimes seriously injure the females in an attempt to mate and avoid being eaten. The two researchers studied 52 pairs of Miomantis caffra, commonly known as the springbok mantis, in the lab for 24 hours. During the first 12 hours, they watched the insects carefully to see which pairs fought, and which member of each pair “won” the fight. Over half of the praying mantis pairs had a fight within the first 12 hours. “These struggles were always initiated by the males and involved bouts of violent wrestling where each sex tried to be the first to pin down the other,” says Burke. He and Holwell think that the males were trying to use force to encourage the females to mate. At the end of the 24 hours, Burke and Holwell recorded if the insect pairs had mated or whether the male had met its demise. It turns out the outcome was dependent on who won the fights recorded within the first 12 hours. If the female won the fight, she always cannibalised the male. But if the males won, mating was the most common outcome. “It seems that many females would rather eat a male than mate with one,” says Burke. It’s no surprise that the females are in no hurry to mate, as M. caffra females are able to reproduce asexually without sperm. In four of the fights that Burke and Holwell observed, the male praying mantis used its dagger-like claws to strike the female, inflicting a wound that leaked plenty of bodily fluid. “Sex is rarely a bed of roses, even at the best of times. But for praying mantises, it’s a deadly game,” says Burke.
1-20-21 Some bacteria are suffocating sea stars, turning the animals to goo
Microbes that thrive in high nutrient settings deplete oxygen in water around the animals. The mysterious culprit behind a deadly sea star disease is not an infection, as scientists once thought. Instead, multiple types of bacteria living within millimeters of sea stars’ skin deplete oxygen from the water and effectively suffocate the animals, researchers report January 6 in Frontiers in Microbiology. Such microbes thrive when there are high levels of organic matter in warm water and create a low oxygen environment that can make sea stars melt in a puddle of slime. Sea star wasting disease — which causes lethal symptoms like decaying tissue and loss of limbs — first gained notoriety in 2013 when sea stars living off the U.S. Pacific Coast died in massive numbers. Outbreaks of the disease had also occurred before 2013, but never at such a large scale. Scientists suspected that a virus or bacterium might be making sea stars sick. That hypothesis was supported in a 2014 study that found unhealthy animals may have been infected by a virus (SN: 11/19/14). But the link vanished when subsequent studies found no relationship between the virus and dying sea stars, leaving researchers perplexed (SN: 5/5/16). The new finding that a boom of nutrient-loving bacteria can drain oxygen from the water and cause wasting disease “challenges us to think that there might not always be a single pathogen or a smoking gun,” says Melissa Pespeni, a biologist at the University of Vermont in Burlington who was not involved in the work. Such a complex environmental scenario for killing sea stars “is a new kind of idea for [disease] transmission.” There were certainly many red herrings during the hunt for why sea stars along North America’s Pacific Coast were melting into goo, says Ian Hewson, a marine biologist at Cornell University. In addition to the original hypothesis of a viral cause for sea star wasting disease — which Hewson’s team reported in 2014 in Proceedings of the National Academy of Sciences but later disproved — he and colleagues analyzed a range of other explanations, from differences in water temperature to exposing the animals to bacteria. But nothing reliably triggered wasting.
1-20-21 New owners of Tiger King zoo ordered to surrender cubs
The new owners of an Oklahoma zoo featured in the hit Netflix documentary Tiger King have been ordered to surrender all tiger cubs and their mothers to the federal government. The case was filed against Jeff and Lauren Lowe, owners of the Greater Wynnewood Exotic Animal Park. They are accused of violating the Endangered Species Act and the Animal Welfare Act. Mr Lowe is the former business partner of Joe Exotic, star of the hit show. Exotic, real name Joseph Maldonado-Passage, is currently serving a 22-year sentence for his involvement in a contract killing plot and animal abuse. "The Lowes have showed a shocking disregard for both the health and welfare of their animals, as well as the law," said the acting assistant attorney general Jonathan D Brightbill of the Justice Department's environment and natural resources division. Both Jeff and Lauren Lowe appeared in Tiger King. The court found that the pair's "failure to provide safe conditions, proper nutrition, and timely veterinary care resulted in harm to a number of animals, including the death of two tiger cubs less than a week apart". The court rejected claims by the Lowes that they were not "exhibitors" under the Animal Welfare Act as the zoo was still under construction. Joe Exotic has formally requested a pardon from US President Donald Trump, who is expected to pardon dozens of people in his final hours in office.
1-20-21 People in Scotland to be asked about reintroducing lynx to the country
Conservationists are taking the first step towards a potential reintroduction of the Eurasian lynx (Lynx lynx) to Scotland, with the launch of a year-long study into public attitudes. Believed to have been wiped out in Scotland between 500 and 1000 years ago, the carnivore has already been returned to several European countries since the 1970s, including France, Germany and Switzerland. However, previous efforts to reintroduce the species to the UK have failed, with the UK government rejecting a 2018 bid to release six in Northumberland. Now three charities are embarking on research to better understand Scottish public attitudes to the lynx. “This project is not a reintroduction project, it’s a social feasibility project. This is the first step in what could be a very long journey,” says Peter Cairns at Scotland: The Big Picture, one of the three groups conducting the research, along with Trees for Life and the Vincent Wildlife Trust. The study will use face-to-face interviews, initially held via video calls due to the pandemic, to find out if people even know what lynx are, and whether a lack of knowledge is an obstacle or a benefit to their return. “There’s a tendency to tribalise these things: farmers against, bunny huggers for it. In reality that’s not true, there’s a massive spectrum of perspectives even under those tribal umbrellas,” says Cairns. Bringing the species back to Scotland would be one piece in a wider jigsaw of efforts to rewild landscapes. The predator could help bring deer numbers in Scotland under control, and boost tree-planting efforts that are hampered by deer damage to saplings. The return of the lynx could also serve as a precursor to hopes to return wolves to Scotland. Past research has found broadly strong public support for a reintroduction of lynx either to the Scottish Highlands or the Forest of Dean in England, with a 2014 paper finding 65 per cent in favour.
1-19-21 Monitor lizards’ huge burrow systems can shelter hundreds of small animals
The giant reptiles are “ecosystem engineers, providing a service similar to beavers and seabirds. Meters below the copper, sun-broiled dirt of northwestern Australia, an entire community hides in the dark. Geckos lay their eggs as centipedes and scorpions scuttle by. A snake glides deeper underground, away from the light. This subterranean menagerie is capitalizing on an old burrow, gouged into the earth by a massive lizard. Now, a new study shows that two different species of Australian monitor lizard dig arrays of these burrows into the earth and that the openings have a great impact on local biodiversity, providing shelter to a surprisingly wide assortment of animal life. The findings, published December 18 in Ecology, indicate that the lizards are “ecosystem engineers,” akin to beavers that flood streams with dams or seabirds that fertilize reefs with their guano, the researchers say (SN: 7/11/18). Sean Doody, an ecologist at the University of South Florida in St. Petersburg, started monitoring the cat-sized lizards in northern Australia with colleagues from Australia’s University of Canberra in Bruce and the University of Newcastle. The team was tracking how invasive, poisonous cane toads were adversely impacting the reptiles. Until recently, it wasn’t clear where monitor lizards lay their eggs. Reaching into burrows thought to contain their eggs yielded nothing. Then Doody and his team started excavating burrows of the yellow-spotted monitor (Varanus panoptes) and found that the holes were a tight helical shape, plunging into the soil roughly four meters — deeper than any other known vertebrate nest — with eggs at the very bottom. What’s more, the nests was part of a warren consisting of dozens of twisting burrows, each made by a single monitor and arranged in the soil like dozens of fusilli noodles set vertically.
1-18-21 Australian lungfish has largest genome of any animal sequenced so far
The Australian lungfish has the largest genome of any animal so far sequenced. Siegfried Schloissnig at the Research Institute of Molecular Pathology in Austria and his colleagues have found that the lungfish’s genome is 43 billion base pairs long, which is around 14 times larger than the human genome. Its genome is 30 per cent larger than that of the previous record holder: the axolotl, a Mexican amphibian that the team sequenced in 2018. The researchers used high-powered computer sequencers to piece together the lungfish genome. To account for inherent errors that the sequencers introduce, they used multiple copies of the genome, each fragmented into small pieces of DNA. After all the fragments were sequenced, the team used algorithms to reassemble the pieces into a complete genome. The result took roughly 100,000 hours of computer processing power, Schloissnig estimates. The Australian lungfish (Neoceratodus forsteri), native to south-east Queensland, has changed little in appearance since the time when animals began transitioning from a water-based to a terrestrial-based lifestyle, says Schloissnig. The animal’s fins are fleshy and flipper-like, and it has a single dorsal lung, which it can use to breathe air at the water’s surface. Previously, it was unclear whether lungfish or coelacanths – a group of archaic fish found in the Indian Ocean and around Indonesia – were more closely related to land-based vertebrates such as mammals and birds. The new genomic analysis shows unequivocally that lungfish are more closely linked to the evolutionary line that gave rise to four-legged animals. Coelacanths diverged earlier, while lungfish branched off 420 million years ago. “In order to get out of the water, you need to adapt towards a terrestrial lifestyle,” says Schloissnig. “You have to be able to breathe air, you have to be able to smell.”
1-15-21 Some electric eels coordinate attacks to zap their prey
The knifefishes were thought to dine alone, but in the Amazon, hundreds hunt together. One Volta’s electric eel — able to subdue small fish with an 860-volt jolt — is scary enough. Now imagine over 100 eels swirling about, unleashing coordinated electric attacks. Such a sight was assumed to be only the stuff of nightmares, at least for prey. Researchers have long thought that these eels, a type of knifefish, are solitary, nocturnal hunters that use their electric sense to find smaller fish as they sleep (SN: 12/4/14). But in a remote region of the Amazon, groups of over 100 electric eels (Electrophorus voltai) hunt together, corralling thousands of smaller fish together to concentrate, shock and devour the prey, researchers report January 14 in Ecology and Evolution. “This is hugely unexpected,” says Raimundo Nonato Mendes-Júnior, a biologist at the Chico Mendes Institute for Biodiversity Conservation in Brasilia, Brazil who wasn’t involved in the study. “It goes to show how very, very little we know about how electric eels behave in the wild.” Group hunting is quite rare in fishes, says Carlos David de Santana, an evolutionary biologist at the Smithsonian’s National Museum of Natural History in Washington, D.C. “I’d never even seen more than 12 electric eels together in the field,” he says. That’s why he was stunned in 2012 when his colleague Douglas Bastos, now a biologist at the National Institute of Amazonian Research in Manaus, Brazil, reported seeing more than 100 eels congregating and seemingly hunting together in a small lake in northern Brazil. Two years later, de Santana’s team returned to the lake to make more detailed observations. The nearly 2-meter-long eels lethargically lay in deeper waters during much of the day, the researchers found. But at dusk and dawn, these long streaks of black come together, swirling in unison to form a writhing circle over 100 strong that herds thousands of smaller fish into shallower waters.
1-15-21 Electric eels work together to zap prey
More than 200 years after the electric eel inspired the design of the first battery, it has been discovered that they can co-ordinate their "zaps". Researchers working in the Amazon filmed eels gathering in packs to herd prey, then stunning them with a synchronised electric shock. "It was really amazing - we thought these were solitary animals," said researcher Carlos David de Santana. The discovery is published in the journal Ecology and Evolution. Douglas Bastos, from the National Centre for Amazonian research in Manaus, Brazil, filmed the behaviour - capturing the moment of the collective electric strike. Small fish, called tetras, are the target of the attack; they fly into the air and land stunned and motionless on the water. Dr de Santana, who works at the Smithsonian Museum of Natural History in Washington DC, was amazed when he saw this behaviour. "In my childhood, I visited my grandparents in the Amazon and I collected fishes in the streams. " he told BBC News. "I've spent 20 years studying electric fishes in the region, but I have never in my life seen so many adult electric eels together." As a scientist, Dr de Santana's expeditions into the murky, remote waters of the Amazon have revealed 85 new species of electric fishes. In one recent study, he and his colleagues discovered that there are actually three individual species of electric eel - for 250 years it had been believed that there was just one. It is the most powerful of these species that was the subject of this discovery - Volta's electric eel. The animal is capable of producing an 860-volt electric shock - the strongest electric discharge of any animal on Earth, and almost four times the voltage from a UK plug socket. These animals can grow 2m (6ft) in length and are more closely related to carp and catfish than eels.
1-14-21 Seabirds raise fewer chicks as the pandemic keeps tourists away
The birds were behaving strangely. Normally, the summer months would be a productive breeding season for the seabirds known as guillemots or murres living on the island of Stora Karlsö in the Baltic Sea. But, of course, 2020 wasn’t a normal year. Lockdowns in response to the coronavirus pandemic dramatically reduced human activity around the world. And, in many cases, this “anthropause” has benefited animal species. The guillemots don’t seem to be one of them. Jonas Hentati-Sundberg at the Swedish University of Agricultural Sciences and his colleagues say that the tourists who travel to the iconic seabird colony every summer may have been acting as unwitting “guardians” for the guillemots that live and breed there. Without tourists around, another bird flocked in: the white-tailed eagle – numbers of them jumped sevenfold. Although the eagles didn’t prey on the guillemots, analysis of CCTV footage shows that their presence caused the guillemots to “panic” and frequently flee their cliffside perches in droves. This disrupted mating and allowed other birds, like gulls and crows, to swoop in and eat unattended eggs. Other eggs fell from the steep ledges. “As a conservationist, it’s kind of heartbreaking to see these birds suffer for the first time actually in all the years I’ve been there,” says Sundberg. Compared with previous years, the guillemots successfully hatched 26 per cent fewer young than usual and had the worst breeding season ever recorded, particularly in areas the researchers visited less frequently. In one subcolony, not even one chick hatched. For Sundberg, the story of the guillemots complicates the “general notion that people are just messing up things”. “I think this illustrates that we are so deeply embedded in ecological relationships and in ecosystems, and in many, many different ways,” he says. “A much more fruitful [conservation] strategy for the future is to try and to understand what is actually our role… Because stepping back will not solve all our problems.”
1-14-21 Embryos set to be implanted in the last two northern white rhinos
The northern white rhino may be able to avoid extinction for a while longer. Fertilised eggs are set to be implanted in the two remaining rhinos this year in the hope of producing offspring. “There is still some hope left that we can save the white rhino species,” says Thomas Hildebrandt at the Leibniz Institute for Zoo and Wildlife Research, who is part of an international team working to do just that. However, time is not our side, he says. The last male northern white rhino, named Sudan, died in March 2018. The only remaining northern white rhinos are two females – Najin and her daughter Fatu, both of which live in the Ol Pejeta Conservancy, a non-profit organisation and protected wildlife area in Kenya. In 2019, Hildebrandt and his colleagues at Ol Pejeta retrieved 10 eggs from Najin and Fatu. These were then fertilised using a technique called intracytoplasm sperm injection with sperm from Sudan. The process resulted in two viable embryos. The team now plans to implant the embryos in Najin and Fatu. This could happen in the next few months, but it may take longer, partly because of impacts from the covid-19 pandemic. The gestation period of a northern white rhino is between 16 and 18 months. “We hope to implant very soon as we are now more sure than ever that it will work,” says Hildebrandt. “In the next few months, we hope to have a major announcement.” “Insemination will take place as soon as possible in the near future, but before 2022,” says Elodie Sempere at Ol Pejeta Conservancy. White rhinos are split into two subspecies. There are northern white rhinos (Ceratotherium simum cottoni), the last of which live in Ol Pejeta Conservancy, and southern white rhinos (Ceratotherium simum simum), which live in southern Africa. Southern white rhinos are faring much better than their northern counterparts and currently number about 20,000. However, both are at risk from poaching. The northern white rhinos are under 24-hour armed guard.
1-14-21 Honey detective work raises fears for bees
DNA detective work on honey has given a rare insight into the foraging habits of honeybees. Scientists used genetic tools to discover which plants the pollinators visited in the countryside. They compared this with a study from 1952, finding big shifts in the wildflowers available to bees. In the 1950s, honeybees mainly gathered pollen and nectar from white clover. Today, there is not so much of this plant about, so they seek alternatives. These include oilseed rape and Himalayan balsam. And there are fears that honeybees and other vital pollinators are running out of food supplies as wildflowers disappear in hedgerows and fields. "We've seen these major changes in the UK landscape and the honeybees have shown us that from their honey samples," Dr Natasha de Vere, head of conservation and research at the National Botanic Garden of Wales, told BBC News. She said the agricultural systems of today didn't have enough nectar for pollinators, with much of the habitat for bees being grasslands, which are a "kind of green desert". "There's nothing that really flowers within those pastures anymore, whereas in the 1950s, those pastures would have been full of white clover and other wildflowers as well." To come up with their findings, the researchers analysed hundreds of honey samples sent in by beekeepers up and down the country, following an appeal on the BBC TV programme Gardeners' World. These were analysed by DNA barcoding, where fragments of plant DNA are identified in pollen trapped in honey. The historic study also looked at pollen grains in honey, but different plants were identified by examining the structure of pollen under the microscope. They found that white clover - the favourite source of nectar for honeybees in 1952 - is still important now but used a lot less as the plant is becoming more scarce. Instead, honeybees have switched to bramble; oilseed rape, which started to be grown from the 1960s onwards; and Himalayan balsam, an invasive plant that has been spreading rapidly across the countryside.
1-14-21 Wind farm construction creates noise that may harm squid fisheries
The noisy construction of offshore wind turbines can discourage squid from hunting, which could lead to decreased squid populations and potentially decrease profits at fisheries. Securing offshore wind turbines to the seabed involves a drilling technique called pile-driving that causes intense, continuous noise for up to three years during construction. Previous research has shown that pile-driving may damage the hearing of seals and dolphins. People in the fishing industry wanted to know how this noise might affect squid populations because planned wind farms in the north-east US are set to be built near important squid fisheries, so the US Bureau of Ocean Energy Management commissioned a study. Aran Mooney at Woods Hole Oceanographic Institution in Massachusetts and his colleagues tested how longfin inshore squid (Doryteuthis pealeii) respond to the noise while hunting their killifish prey (Fundulus heteroclitus). The team put individual squid in a circular tank that was 1 metre in diameter. They released a killifish in the tank then observed the unfolding action. In some cases, the researchers played recorded sounds of pile-driving for 5 minutes before releasing the fish. In other cases, they turned the noise on as soon as the squid began to show hunting behaviour. In others, they didn’t play any sounds at all. Mooney’s team found that squid didn’t catch significantly fewer fish under noise conditions. But it took them more tries to catch their prey, and they were discouraged from hunting in the first place more often. “The squid were actually less affected than we thought they were going to be,” says Mooney. Even so, he thinks the effects might be more severe in the real world. For instance, in a confined tank, it is easy for a squid to try again if it fails to catch a fish at the first attempt, but in the wild, it is less likely to get a second chance with a particular fish.
1-13-21 Rats with poisonous hairdos live surprisingly sociable private lives
It’s snuggling and togetherness when the deadly, swaggering rodents have families. Crested rats don’t just chew tree bark that’s poisonous enough to kill an elephant. The rabbit-sized rodents dribble and lick the toxic drool into their long rat fluff for a weaponized hairdo. Yet these dangerous rats, which scientists assumed were loners, turn out to have a close and cuddly family life. They even purr. Chewing on bark or other parts of East Africa’s arrow poison trees gives the rats toxic saliva to apply to specialized zones of fur. The toxins sink in to porous, easily detached hairs on the rat’s flanks. Any predator foolish enough to bite a Lophiomys imhausi gets a hairy mouthful of bitter toxins that human poachers use on arrows for hunting big game. The rats “have the personality of something poisonous,” says ecologist Sara Weinstein, who studied them during a Smithsonian fellowship at the Mpala Research Center in Kenya. “They can run quickly if they feel like it, but they don’t typically.” The rats are more likely to jog away from trouble or stand their ground, hissing, growling and grunting. Trapping crested rats took some experimenting, says ecologist Katrina Nyawira, who worked on the project with Weinstein before moving to Oxford Brookes University in England. “Sometimes we’d set traps for about two weeks and just get one individual and, trust me, that would be a win.” Researchers set traps in a weird variety of locations, from remote spots in the Kenyan savanna to behind somebody’s bedroom door, Nyawira and Weinstein realized that the common success factor was access to arrow poison trees (Acokanthera schimperi). With glossy, green leaves shaped like fat teardrops, this widespread shade tree is a cousin of the North American milkweeds that give monarch butterfly caterpillars their defensive toxins. From roots to shoots, the arrow poison tree carries potent cardenolides that can give would-be predators a heart attack.
1-13-21 Houseflies have specialised wings that make them harder to swat
Some flies have specialised hindwings to help them take off faster, making them harder to swat. They primarily use sight to escape danger, but Alexandra Yarger at Case Western Reserve University, Ohio, and her team have found a new mechanism that might be helping them get away. All fly species have shortened hindwings called halteres. These don’t generate useful lift, but are used as sensory organs for balance to help stabilise the insect while in flight. A group of flies known as Calyptratae, which includes houseflies and blowflies, rhythmically move these wings when standing. “We know that they’re the only group that does this,” says Yarger. “It’s still a bit of a mystery why they do it.” Yarger and her team tested to see if this behaviour affected their take-offs. Using high-speed cameras to film the flights of over 20 fly species, they found that, overall, Calpytrate flies were roughly five times faster at taking off than other flies. The team then removed the halteres and found that both speed and stability of take-offs reduced in Calyptratae species. Yarger suggests this haltere movement increases the amount of sensory information these flies receive, but what they can sense and how it is processed remains unclear. “We think there might be a pathway from halteres to the legs that’s causing them to take off faster,” says Yarger. “It doesn’t go through any central nervous system, it’s almost like a reflex,” she says. Being able to have a speedy take-off allows this group of flies to better avoid harm. “It’s part of the reason they’re so successful, they can escape very quickly,” says team member Jessica Fox. “Transitioning from taking off to flight is a challenging thing and using halteres to help both is clearly very advantageous,” she says.
1-12-21 Mice may ‘catch’ each other’s pain — and pain relief
After an hour of mingling, healthy mice mirror a companion’s pain or morphine-induced relief. In pain and pain relief, mice may feel for each other. Research has shown that mice can “catch” the emotions of an injured or fearful fellow. When some mice are injured, other healthy mice living alongside them behave as though in pain. Now, a study suggests that not only can pain be passed along, but also pain relief is contagious too. In the last decade, researchers have done a lot of work showing that animals can pick up and share each other’s emotions, particularly fear (SN: 5/20/19), says Monique Smith, a neuroscientist at Stanford University. She and colleagues published their new findings on pain and relief in the Jan. 8 Science. Investigating these building blocks of empathy in animals can help researchers understand human empathy, Smith says, and may someday lead to treatments for disorders that affect the ability to be sensitive to the feelings and experiences of other people. “Pain isn’t just a physical experience,” Smith says. “It’s an emotional experience” as well. In experiments on pairs of mice, one mouse received an injection that caused arthritis-like inflammation in one hind paw while the other mouse was unharmed. After hanging out together for an hour, “the bystander has it worse than the mouse that got the injection,” says Jeffrey Mogil, a neuroscientist at McGill University in Montreal who was not part of the work. Injected mice acted as though one paw is in pain, as expected, showing extra sensitivity to being prodded there with a plastic wire. Their uninjured companions also showed heightened sensitivity, and in both hind paws. Those mice act as though they’re in the same amount of pain and in more places, Mogil says. “The behavior is astounding.”
1-12-21 Brown tree snakes use their tails as lassos to climb wide trees
A never-before-seen climbing technique could inspire the creation of new serpentine robots. Snakes do a lot more than slither. Some swim, while others sidewind across sand (SN: 10/9/14). Some snakes even fly (SN: 6/29/20). But no one has ever seen a snake move the way that brown tree snakes do when they climb certain trees. By wrapping its tail around a tree or pole in a lasso-like grip and wriggling to propel itself, a brown tree snake can shimmy up structures that would otherwise be too wide to climb. Better understanding how brown tree snakes (Boiga irregularis) get around could inform strategies to control their population in Guam, where the snakes are an invasive species. The reptiles are infamous for having wiped out almost all of the native forest birds on Guam and frequently cause power outages by clambering up utility poles. The discovery of brown tree snakes’ lasso climbing method, reported online January 11 in Current Biology, was somewhat serendipitous. Julie Savidge, an ecologist at Colorado State University in Ft. Collins, and colleagues were investigating ways to keep these tree-climbing snakes away from Guam’s Micronesian starlings — one of only two native forest birds left on the island. One of these ways involved tests to see whether a wide pipe, or baffle, around a pole could prevent predators from reaching a starling nest box at the top. In reviewing hours of footage of the baffle to monitor how well it deterred brown tree snakes, the team saw one snake do something wholly unexpected: The snake lassoed itself around the baffle and began scooting upward. “We were in total shock,” says study coauthor Thomas Seibert, also an ecologist at Colorado State. “This isn’t something that a snake is supposed to do.” Brown tree snakes and other snakes typically climb trees that are too smooth to slither up by coiling around a trunk multiple times. A snake wraps the front of its body around the trunk and then coils its back end around the tree in another loop to get a second grip. The snake then stretches its neck up and repeats the process to inch upward. But wrapping around a tree multiple times limits the width of a tree that a snake can scale. Using a single, large, lasso-like grip allows the brown tree snake to climb wider trees — or baffles, explains study coauthor Bruce Jayne, a biologist at the University of Cincinnati in Ohio.
1-11-21 Snakes make their bodies lassos in a strange new climbing technique
Brown tree snakes in Guam have been seen climbing poles by making their bodies into lasso shapes, a type of snake locomotion that hasn’t been documented before. Five invasive brown tree snakes (Boiga irregularis) were spotted climbing vertical metal cylinders about 15 to 20 centimetres in diameter that were holding up bird boxes. To do so, they wrapped their bodies around the pole and hooked their tail around their midsection, allowing them to wiggle upwards to reach prey. “The loop of that lasso shape is effectively where all of the action is, because that loop squeezes on the cylinder to prevent the snake from slipping down,” says Bruce Jayne at the University of Cincinnati in Ohio. Only four other types of locomotion have been observed in snakes until now. Compared with the other forms, this new type is “painfully slow”, says Jayne. The movement was first spotted when Julie Savidge and Thomas Seibert at Colorado State University were developing safe nesting sites for native birds in Guam. They used a bird box that was perched atop a vertical pole and surrounded by a smooth metal baffle – a protective shield – to defend birds against predators. “[The research team was] watching video from during the night and, lo and behold, most of the snakes couldn’t defeat the baffle,” says Savidge. “All of a sudden, [one snake] latched on and started wiggling up,” says Seibert. “The upper part of the snake that’s not in the lasso is constantly searching for the next nubbin or something it can grip onto.” Lasso locomotion allows these snakes to reach otherwise unobtainable prey, but seems to be energetically demanding for them, as they take several pauses when climbing. “I broadly estimated that it might take around 2 hours to go 10 feet with this sort of movement,” says Savidge.
1-11-21 UK allows emergency use of bee-harming pesticide
A pesticide believed to harm bees has been authorised for emergency use in England, despite an earlier ban. In 2018, an almost total ban was put in by the EU and UK because of the serious damage it could cause to bees. The Department for Environment, Food and Rural Affairs (Defra) says its use will be limited to this year only. A spokeswoman told Newsbeat the measures "will be tightly controlled to minimise any potential risk to pollinators". Emergency use of a product containing the chemical thiamethoxam has been allowed because a virus is threatening sugar beet seeds. Scientific studies have long linked the use of these chemicals to the decline of honeybees, wild bees and other animals which pollinate plants. At the time of the ban, Michael Gove, then environment secretary, said the UK was in favour as it couldn't "afford to put our pollinator populations at risk". But according to Defra, the amount of sugar beet grown in 2020 was reduced due to the yellow virus - and similar conditions in 2021 would cause the same problems, unless it took action. Along with the UK, 10 EU countries including Belgium, Denmark and Spain - countries with significant sugar production - have granted emergency authorisations. Milan Wiercx van Rhijn, from the charity Bees for Development feels "disappointed" by the government's decision. The 32-year-old says the insects play a vital role in the food chain - with around a third of the food we eat relying on pollination mainly by bees. "If we kill the insects which are the starting blocks in the chain, we'll kill the animals higher up," he tells Radio 1 Newsbeat. "It's hard to grasp how much of an impact it'll have on us." Milan agrees it's important to protect sugar beet - but says the government has to find another way. "If we keep thinking about these short-term solutions and rolling back, we'll never get to the point where we don't use these products." (Webmaster's comment: When push comes to shove it's always us over every other creature!)
1-10-21 How South African police are tackling pangolin smugglers
Quiet, solitary and nocturnal, the pangolin has few natural enemies, but researchers believe it is the most trafficked mammal in the world. The tough scales covering its body are sought after for use in Chinese medicine, in the erroneous belief that they have healing properties. The animal has also been of interest to researchers during the coronavirus pandemic. Related viruses have been found in trafficked pangolins, though there is continued uncertainty around early theories that pangolins were involved in the transmission of the virus from animals to humans. After South African police seized a pangolin from suspected smugglers, BBC Africa correspondent Andrew Harding witnessed how vets tried to save the animal's life.
1-8-21 UK may allow gene editing of crops and livestock following Brexit
The UK government is exploring the possibility of using gene editing to modify livestock and food crops, for instance to make crop plants resistant to drought and disease. Gene editing is strictly regulated in the European Union, in what virtually amounts to a ban, but now the UK has left the EU it has some freedom to set its own rules. The consultation was announced by Environment Secretary George Eustice at the Oxford Farming Conference on Thursday. “Gene editing is a mechanism to precisely edit the genome of an organism,” says Lesley Torrance of the James Hutton Institute in Dundee, UK. Instead of inserting entire genes, or changing the DNA at random, gene editing allows for highly specific changes – even changing a single “letter” of an organism’s DNA sequence. For instance, in 2018 British researchers grew a trial crop of a genetically edited oilseed, Camelina sativa, a relative of oilseed rape. The gene editing altered three genes, causing the plants to produce lots of oleic acid, a relatively healthy fatty acid. Like many gene editing projects, the modified oilseed was created using a technology called CRISPR-Cas9, which in 2020 won two of its pioneers the Nobel Prize in Chemistry. One possible use of gene editing is to improve the iron content of white flour, says Janneke Balk, at the John Innes Centre in Norwich, UK. In the UK, the law requires that white flour contains a minimum amount of iron, so the iron is added artificially. Her lab is exploring ways to create high-iron wheat by gene editing. However, prior to Brexit these crops had little chance of reaching supermarkets, because the European Union has a fraught history with genetic modification. It has strictly regulated “transgenic” crops, which carry genes transplanted from other species. Genetically modified crops like these prompted the 1990s scare around “Frankenfoods” and were opposed by environmental groups like Greenpeace. This opposition was primarily cultural, as the health and environmental risks from these crops were minimal.
1-8-21 Ice Age hunters’ leftovers may have fueled dog domestication
Ancient people tamed wolves by feeding them surplus game, researchers suggest. Sometime between around 29,000 and 14,000 years ago, hunter-gatherers navigating northern Eurasia’s frigid landscapes turned wolves into dogs by feeding them lean-meat leftovers. That, at least, is a likely scenario that would have benefited both wolves and people, say archaeologist Maria Lahtinen of the Finnish Food Authority in Helsinki and colleagues. In harsh Ice Age winters, when game hunted by both species was lean and fat-free, prey animals would have provided more protein than humans could safely consume, the researchers conclude January 7 in Scientific Reports. People could have fed surplus lean meat to captured wolf pups being raised as pets because the animals wouldn’t have had the same dietary limitations, the team proposes. That idea is largely based on inferences from previous research on how ancient hunter-gatherers survived in arctic environments and new calculations suggesting that, for dietary reasons, Ice Age groups could not have eaten all of the lean meat that was hunted. Though far from the final word on the controversial origins of dogs (SN: 5/21/15), Lahtinen’s group offers a novel take on how that process may have unfolded. The researchers’ calculations assume that, like some arctic hunter-gatherers today, ancient humans acquired 45 percent of their calories from animal protein. Humans can’t eat a completely carnivorous diet because of the liver’s ability to generate only part of our energy needs from protein. Edible plants could have been stored for the winter as a source of carbohydrates, but supplies would have waned as the annual big freeze wore on, the scientists suspect. So Ice Age hunter-gatherers probably reached a point where they focused on hunting in order to extract fatty marrow and grease from the bones of prey to meet energy needs, the researchers argue, leaving plenty of lean meat untouched and available as wolf food.
1-7-21 Humans may have domesticated dogs by accident by sharing excess meat
Dogs may have become domesticated because our ancestors had more meat than they could eat. During the ice age, hunter-gatherers may have shared any surplus with wolves, which became their pets. The timing and causes of the domestication of dogs are both uncertain. Genetic evidence suggests that dogs split from their wolf ancestors between 27,000 and 40,000 years ago. The oldest known dog burial is from 14,200 years ago, suggesting dogs were firmly installed as pets by then. But it isn’t clear whether domestication happened in Europe or Asia – or in multiple locations – or why it happened. Dogs are the only animals domesticated by hunter-gatherers: all the others were domesticated after farming became widespread. One suggestion is that people domesticated dogs to help them with hunting, while another scenario has wolves scavenging human waste dumps and becoming accustomed to people. Maria Lahtinen of the Finnish Food Authority in Helsinki and her colleagues suggest that the key may have been a surfeit of meat. Dogs were domesticated when ice sheets covered much of northern Eurasia and the climate was colder than today. During this time, humans and wolves would have competed for food, as both are top predators. However, wolves can survive on nothing but lean meat – which contains protein and little else – for months. In contrast, humans cannot. There are limits to how much protein our bodies can handle, so we have to eat other food groups such as fat as well. “We are not fully adapted to eat meat,” says Lahtinen. Her team calculated how much food was available during the Arctic winters, based on the prey species living there. They found there was an excess of lean meat, suggesting human hunters would have ended up with more of this than they could consume. Wolves could have eaten this surplus, implying the two species weren’t in competition during the harsh winters. Instead, humans could have shared lean meat with wolves without losing out themselves.
1-6-21 Plants that suck metals from the soil can be farmed to make our tech
Farms that grow metal-rich plants are cropping up around the world and promise a greener, less destructive alternative to mining for rare minerals. WHEN you cut into a branch of Phyllanthus rufuschaneyi, the sap runs an intensely bright blue-green. That’s the sort of thing that makes plant hunter Anthony van der Ent sit up and take notice. So when he came across this unusual woody shrub at a national park ranger’s station in Malaysian Borneo, he knew he had to investigate further. It turned out that the sap was chock-full of nickel. Van der Ent, based at the University of Queensland, Australia, is one of several scientists who think plants like this might be a solution to one of the most pressing problems of our age. Demand for many metals has been creeping upwards for years because they are essential ingredients in everyday tech like phones and computers. Our appetite for these metals will soon become even more voracious because they are also needed for green technologies such as wind turbines and the rechargeable batteries in electric cars. Yet mining them is difficult, environmentally damaging and sometimes extremely dangerous. Could those problems be addressed by growing metals instead? That is what van der Ent believes. We will soon see if he is right as the first metal farms are now springing up in China, Europe and Malaysia. On the face of it, these farms are all-round winners: the profits are tidy, the environmental credentials excellent. So steel yourself for the latest disruptive mining technology: the plant. The nickel colouring the blue-green sap of the shrub van der Ent discovered is just one of the metals we depend on. Nickel has long been a crucial ingredient in stainless steel. It is also used in many lithium-ion batteries in electric vehicles, phones and other consumer electronics.
1-6-21 Huntsman spiders stitch leaves together to trap tree frogs
Your home is your sanctuary – except when you are a tree frog and a nice-looking retreat contains a huntsman spider looking to make a meal of you. These spiders have now been seen making traps out of leaves the frogs tend to hide in. Researchers ran across this behaviour for the first time while doing wildlife surveys in vanilla plantations in north-east Madagascar in 2017. While surveying birds, Dominic Martin at the University of Goettingen in Germany noticed a huntsman spider (Damastes sp.) feasting on a tree frog (Heterixalus andrakata). “The spider had grabbed the frog and was starting to suck out the body of the frog,” he says. The researchers haven’t confirmed the spider species yet, but are working on identifying a specimen. His colleague Thio Fulgence at the University of Antananarivo in Madagascar, who was surveying reptiles and amphibians in the plantations, noticed that the spider was sitting between two leaves it had stitched together with its silk to form a type of envelope. Martin took photos of the spider eating the frog (pictured), as they had never seen anything like this before. In the following weeks, Fulgence found three other instances of leaves sewn together with silk, with huntsman spiders waiting at the back, although the team only observed one case of a spider eating a frog. The researchers believe these spiders, which may even be an undescribed species, build what looks like the perfect daytime retreat for Heterixalus tricolor and similar frogs of the same genus. Martin says the spiders may build these traps specifically to catch the nocturnal tree frogs, which typically like to hide from predators such as birds between overlapping leaves during the hot daylight hours. “We think that there is a systematic trapping,” says Fulgence, adding that it is also possible the spiders trap small geckos, which also hide between leaves. The shelter serves a dual purpose, giving the spiders cover from birds that may try to eat them as well.
1-6-21 Jellyfish push off a pocket of water under their bell to swim faster
Even though they lack fins and their bodies are gelatinous, jellyfish are some of the most energy-efficient swimmers. They achieve this by making use of their bells to create a wall of water to push off so they can propel themselves more quickly. When flying or swimming, an animal can get a boost from the ground effect, in which drag is reduced and lift increased as it approaches a surface. The effect also comes into play in aeroplanes. But moon jellies (Aurelia aurita) spend most of their time in open water, so they don’t have surfaces to push against. Instead, they create a high-pressure pocket of water beneath their bells that gives them a boost. Brad Gemmell at the University of South Florida in Tampa and his colleagues recorded the movements of eight moon jellyfish swimming freely in a tank. To track the eddies of water created as the jellyfish swam, they shone a laser into the tank to illuminate microscopic glass beads that moved with the flowing water. They found that as the jellyfish squeezed their bodies to swim, they generated two pairs of vortices. As a jellyfish extends and contracts its bell, it creates two vortices at the edge of the bell that move water away from the animal’s body. Another two vortices flowing in the opposite direction are then made underneath the bell, pushing water towards the jelly’s tentacles. There, the water collides, creating a pocket of high pressure that makes a kind of wall of water, which serves a similar purpose to a real surface in allowing the ground effect to take place. Previous work has shown that this “stopping vortex” beneath the jellyfish lets the animal recapture energy and move 30 per cent further than it would have done otherwise. Gemmell thinks that this finding could be useful for creating more efficient vehicles by inspiring new designs that employ this vortex effect ? to allow submarines to move more quickly through open water, for example.
1-6-21 Palm cockatoo: Why a unique ‘drumming’ bird is in peril
The palm cockatoo is thought to be the only bird species to use tools musically – drumming wood to attract a mate. Found only in Australia and neighbouring New Guinea, the species is facing a dramatic population decline, scientists say.
1-4-21 These spiders may sew leaves into fake shelters to lure frogs to their doom
Madagascar’s huntsman spiders use silk to attach two leaves, forming a temptingly cool hollow. On a sweltering afternoon in northeastern Madagascar, the coolness of a leaf’s shade is an attractive respite for a frog. But some of these oases may hide hungry architects: huntsman spiders. New observations show that the gangly spiders partially attach two leaves together using silk, creating a leafy hollow. One of the arachnids was spotted eating a frog inside one of the pockets, suggesting that the spiders create the structures to lure and trap frogs, researchers report December 11 in Ecology and Evolution. In 2017 and 2018, biologist Thio Rosin Fulgence and colleagues were conducting an ecological survey in Madagascar when Dominic Martin, an ecologist at the University of Göttingen in Germany, spotted a large huntsman spider (Damastes sp.) eating a small Madagascar reed frog (Heterixalus andrakata). The spider was on a small tree, near a pair of overlapping leaves that had been attached together with spider silk to create a pocket. Upon approach, the spider backed into its leafy lair, amphibian prize in tow. “The first time that we found this phenomenon, we were very excited,” says Fulgence, of the University of Antananarivo in Madagascar. The next year, while conducting reptile and amphibian surveys in roughly the same region, Fulgence found three more of the spiders hiding in similar leaf retreats. These spiders weren’t spotted with prey, he says. Some spiders are known to prey on larger and stronger vertebrates such as a mouse opossum and even frogs, if given the opportunity. (SN: 2/28/19). When that happens, the arachnids are commonly seen as winning the vertebrate jackpot. But huntsman spiders, in contrast, may be specifically targeting frogs as prey, the researchers say. By attaching the leaves together, the spiders are creating cool and dark microhabitats that would be desirable in a dry, searing environment with plenty of predatory birds, Fulgence says.
1-3-21 Fears rise over Indonesia's Jurassic Park
Indonesia is charging foreigners for an encounter with giant lizards — what could go wrong? The Komodo dragon lives up to its name: nearly 200 pounds of lizard, 8 feet from tail to tongue, with teeth like a shark. Its bite implants venom that can stop your heart within hours. That's if you don't bleed out first. The creature tends to grip and rip, sinking jaws into prey and tearing off limbs. But its fearsome reputation is exactly what makes the beast so attractive to a certain type of tourist — one willing to pay good money for a selfie with a so-called "dragon" in the background. Charging foreigners for an encounter with these giant lizards is a niche industry in Indonesia's Flores Island and its environs. This is the natural habitat of the Komodo dragon. Fewer than 6,000 are left. Yet, in recent years, hundreds of thousands of tourists have surged into the area annually — and many crave an encounter with a Komodo dragon. That's way too much contact for an animal classified as "vulnerable," a diagnosis preceding "endangered" status. So, officials have a plan. While the tourism boom is on pause — thanks to the COVID-19 pandemic — it will proceed with a plan to build a sleek new facility in Komodo National Park. In lieu of herding in backpackers, the project will target a smaller class of "premium" tourists, charging them roughly $1,000 per head. A park charging wealthy travelers to behold massive, ancient lizards? Comparisons to Jurassic Park are inevitable. But the architects seem to be leaning into the allusion — scoring a video mock-up of the park with the orchestral Jurassic Park theme song. This has handed ammunition to activists who note the movie is, in fact, about the calamity that follows when humans meddle with nature. "Jurassic Park, really?" said Aloysius Suhartim Karya, a local tour operator, activist, and former park ranger at Komodo National Park. "This is a mistake. I really don't understand what the government is thinking." Fears surrounding this project have nothing to do with dragons running amok. What environmentalists fear, Aloysius says, is that the park will be a harbinger of "ecocide" for the lizards. "This island is a diamond of Indonesia," he said. "It's beautiful as it is — real and pure — not because of super-premium amenities. Now, they want to turn it into a zoo." Mowing down trees to build the park, Aloysius says, will wipe out the habitat for lizards and their prey. Opening a cafeteria on-site will suffuse the air with odd smells — scrambling the senses of Komodo dragons, which can detect scents from miles away. "It's safe for people," Aloysius said. "But it's not safe for the animals."
1-1-21 Was I wrong to fall for a cheating cat?
There's a well-known saying that goes, "You don't choose a cat, a cat chooses you." So what should you do, asks Anisa Subedar, when a persistent pussycat in the neighbourhood decides to adopt you? For me, it began about 18 months ago, one long, hot summer evening when two huge wanting eyes, accompanied by serenading mews appeared at the kitchen door. It didn't recoil when I approached it. In fact it appeared quite pleased when I began speaking in ridiculously high-pitched baby speak (imagine the word "choochy-face" being used). Nor did it flinch when I softly stroked behind its grey, fluffy ears. Instead it lay on its back and allowed me to feel the softness of its white belly fur and loudly purred in gratitude. In appreciation that my affections were returned, I opened a can of tuna which it hastily scoffed and left. I didn't think anything of it at the time other than that it was a cosy exchange. A summer memory made and I had performed a good deed. A few days later The Cat returned and we behaved like two long lost friends. There was mutual loving, petting and nuzzles. I gave it some more food, it noisily ate and we parted ways again. The meetings soon became a daily occurrence and something I found myself looking forward to. The Cat had taken to coming into the house, napping on the sofa and didn't mind being put out for the night when I went to bed. My evenings were now gloriously cosy. The stresses of the day instantly dissolved when The Cat and I would curl up together to watch television in the evenings. In retrospect, I should have stopped to think whether The Cat - though apparently in need of food and affection - lived with someone else. But I didn't. That only came later. After a couple of months I bought a pet bed for The Cat to relax in and dedicated bowls for food and water. I would go to work, discover cat hair on my clothes and smile in anticipation of being together in the evenings. Photos of The Cat would appear on my social media. Colleagues at work would notice my online activity and ask, "How's your cat?" I would answer as if The Cat was mine, in denial about my new status as a catnapper.
1-1-21 Koalas are being given birth control to fight overpopulation
Koalas in parts of Australia have been sterilised and given long-term contraceptives to control overpopulation – and it seems to have worked. David Ramsey at the Arthur Rylah Institute for Environmental Research in Melbourne, Australia, and his colleagues have analysed the effect of two fertility control programmes on koala populations in areas where the animals have bred too successfully, risking starvation. The researchers studied a programme implemented between 2004 and 2013 in Budj Bim National Park, Victoria, in which female koalas were captured and treated with an implant of levonorgestrel hormone, a contraceptive that usually lasts for 10 to 12 years. They also looked at the effectiveness of a sterilisation programme on Kangaroo Island, South Australia, between 1997 and 2013. In certain Australian states such as Queensland and New South Wales, koalas are listed as a vulnerable species. But in parts of Victoria and South Australia, their populations have increased to such high densities that the trees they feed on are at risk. Koalas prefer to eat the foliage of only a few species of eucalyptus trees – the manna gum (Eucalyptus viminalis) in particular, which is only found in south-east Australia. The overbrowsing of manna gums – consumption of all leaves on a specimen – kills the trees. Overpopulation has previously led to koala starvation and drastic drops in the animal’s numbers in certain areas – with more than 70 per cent of koalas dying in one case. Moving koalas to other less populated areas is also used as a solution, but is expensive and not always possible. The team found that the koala fertility programmes led to the recovery of manna gum trees with light or moderate defoliation, and significantly reduced tree deaths in Budj Bim National Park. The researchers suggest that koalas should live at a density of less than one per hectare to avoid overbrowsing.