That’s how it works for humans, but when it comes to the question of yodeling animals, it depends on how you define yodeling, according to bioacoustician Tecumseh Fitch of the University of Vienna in Austria, who co-authored this latest paper. Plenty of animal vocalizations use repeated sudden changes in pitch (including birds), and a 2023 study found that toothed whales can produce vocal registers through their noses for echolocation and communication.
There haven’t been as many studies of vocal registers in non-human primates, but researchers have found, for example, that the “coo” call of the Japanese macaque is similar to a human falsetto; the squeal of a Syke monkey is similar to the human “modal” register; and the Diana monkey produces alarm calls that are similar to “vocal fry” in humans.
It’s known that non-human primates have something humans have lost over the course of evolution: very thin, light vocal membranes just above the vocal folds. Scientists have pondered the purpose of those membranes, and a 2022 study concluded that this membrane was crucial for producing sounds. The co-authors of this latest paper wanted to test their hypothesis that the membranes serve as an additional oscillator to enable such non-human primates to achieve the equivalent of human voice registers. That, in turn, would render them capable in principle of producing a wider range of calls—perhaps even a yodel.
The team studied many species, including black and gold howler monkeys, tufted capuchins, black-capped squirrel monkeys, and Peruvian spider monkeys. They took CT scans of excised monkey larynxes housed at the Japan Monkey Center, as well as two excised larynxes from tufted capuchin monkeys at Kyoto University. They also made live recordings of monkey calls at the La Senda Verde animal refuge in the Bolivian Andes, using non-invasive EGG to monitor vocal fold vibrations.
Crafty cuttlefish employ several different camouflaging displays while hunting their prey, according to a new paper published in the journal Ecology, including mimicking benign ocean objects like a leaf or coral, or flashing dark stripes down their bodies. And individual cuttlefish seem to choose different preferred hunting displays for different environments.
It’s well-known that cuttlefish and several other cephalopods can rapidly shift the colors in their skin thanks to that skin’s unique structure. As previously reported, squid skin is translucent and features an outer layer of pigment cells called chromatophores that control light absorption. Each chromatophore is attached to muscle fibers that line the skin’s surface, and those fibers, in turn, are connected to a nerve fiber. It’s a simple matter to stimulate those nerves with electrical pulses, causing the muscles to contract. And because the muscles are pulling in different directions, the cell expands, along with the pigmented areas, changing the color. When the cell shrinks, so do the pigmented areas.
Underneath the chromatophores, there is a separate layer of iridophores. Unlike the chromatophores, the iridophores aren’t pigment-based but are an example of structural color, similar to the crystals in the wings of a butterfly, except a squid’s iridophores are dynamic rather than static. They can be tuned to reflect different wavelengths of light. A 2012 paper suggested that this dynamically tunable structural color of the iridophores is linked to a neurotransmitter called acetylcholine. The two layers work together to generate the unique optical properties of squid skin.
And then there are leucophores, which are similar to the iridophores, except they scatter the full spectrum of light, so they appear white. They contain reflectin proteins that typically clump together into nanoparticles so that light scatters instead of being absorbed or directly transmitted. Leucophores are mostly found in cuttlefish and octopuses, but there are some female squid of the genus Sepioteuthis that have leucophores that they can “tune” to only scatter certain wavelengths of light. If the cells allow light through with little scattering, they’ll seem more transparent, while the cells become opaque and more apparent by scattering a lot more light.
Scientists learned in 2023 that the process by which cuttlefish generate their camouflage patterns is significantly more complex than scientists previously thought. Specifically, cuttlefish readily adapted their skin patterns to match different backgrounds, whether natural or artificial. And the creatures didn’t follow the same transitional pathway every time, often pausing in between. That means that contrary to prior assumptions, feedback seems to be critical to the process, and the cuttlefish were correcting their patterns to match the backgrounds better.
There have been many studies on the capability of non-human animals to mimic transitive actions—actions that have a purpose. Hardly any studies have shown that animals are also capable of intransitive actions. Even though intransitive actions have no particular purpose, imitating these non-conscious movements is still thought to help with socialization and strengthen bonds for both animals and humans.
Zoologist Esha Haldar and colleagues from the Comparative Cognition Research group worked with blue-throated macaws, which are critically endangered, at the Loro Parque FundaciĂłn in Tenerife. They trained the macaws to perform two intransitive actions, then set up a conflict: Two neighboring macaws were asked to do different actions.
What Haldar and her team found was that individual birds were more likely to perform the same intransitive action as a bird next to them, no matter what they’d been asked to do. This could mean that macaws possess mirror neurons, the same neurons that, in humans, fire when we are watching intransitive movements and cause us to imitate them (at least if these neurons function the way some think they do).
But it wasn’t on purpose
Parrots are already known for their mimicry of transitive actions, such as grabbing an object. Because they are highly social creatures with brains that are large relative to the size of their bodies, they made excellent subjects for a study that gauged how susceptible they were to copying intransitive actions.
Mirroring of intransitive actions, also called automatic imitation, can be measured with what’s called a stimulus-response-compatibility (SRC) test. These tests measure the response time between seeing an intransitive movement (the visual stimulus) and mimicking it (the action). A faster response time indicates a stronger reaction to the stimulus. They also measure the accuracy with which they reproduce the stimulus.
Until now, there have only been three studies that showed non-human animals are capable of copying intransitive actions, but the intransitive actions in these studies were all by-products of transitive actions. Only one of these focused on a parrot species. Haldar and her team would be the first to test directly for animal mimicry of intransitive actions.
According to Amazonian folklore, the area’s male river dolphins are shapeshifters (encantade), transforming at night into handsome young men who seduce and impregnate human women. The legend’s origins may lie in the fact that dolphins have rather human-like genitalia. A group of Canadian biologists didn’t spot any suspicious shapeshifting behavior over the four years they spent monitoring a dolphin population in central Brazil, but they did document 36 cases of another human-like behavior: what appears to be some sort of cetacean pissing contest.
Specifically, the male dolphins rolled over onto their backs, displayed their male members, and launched a stream of urine as high as 3 feet into the air. This usually occurred when other males were around, who seemed fascinated in turn by the arching streams of pee, even chasing after them with their snouts. It’s possibly a form of chemical sensory communication and not merely a need to relieve themselves, according to the biologists, who described their findings in a paper published in the journal Behavioral Processes. As co-author Claryana AraĂşjo-Wang of CetAsia Research Group in Ontario, Canada, told New Scientist, “We were really shocked, as it was something we had never seen before.”
Spraying urine is a common behavior in many animal species, used to mark territory, defend against predators, communicate with other members of one’s species, or as a means of mate selection since it has been suggested that the chemicals in the urine carry useful information about physical health or social dominance.
Those results supported the initial hypothesis that chimps tended to urinate in sync rather than randomly. Further analysis showed that the closer a chimp was to another peeing chimp, the more likely the probability of that chimp peeing as well—evidence of social contagion. Finally, Onishi et al. wanted to explore whether social relationships (like socially close pairs, evidenced by mutual grooming and similar behaviors) influenced contagious urination. The only social factor that proved relevant was dominance, with less-dominant chimps being more prone to contagious urination.
There may still be other factors influencing the behavior, and more experimental research is needed on potential sensory cues and social triggers in order to identify possible underlying mechanisms for the phenomenon. Furthermore, this study was conducted with a captive chimp population; to better understand potential evolutionary roots, there should be research on wild chimp populations, looking at possible links between contagious urination and factors like ranging patterns, territory use, and so forth.
“This was an unexpected and fascinating result, as it opens up multiple possibilities for interpretation,” said coauthor Shinya Yamamoto, also of Kyoto University. “For instance, it could reflect hidden leadership in synchronizing group activities, the reinforcement of social bonds, or attention bias among lower-ranking individuals. These findings raise intriguing questions about the social functions of this behavior.”
Elaborate courtship, devoted parenthood, gregarious nature (and occasional cannibalism)—earwigs have a lot going for them.
Few people are fond of earwigs, with their menacing abdominal pincers—whether they’re skittering across your floor, getting comfy in the folds of your camping tent, or minding their own business.
Scientists, too, have given them short shrift compared with the seemingly endless attention they have lavished on social insects like ants and bees.
Yet, there are a handful of exceptions. Some researchers have made conscious career decisions to dig into the hidden, underground world where earwigs reside, and have found the creatures to be surprisingly interesting and social, if still not exactly endearing.
Work in the 1990s and early 2000s focused on earwig courtship. These often intricate performances of attraction and repulsion—in which pincers and antennae play prominent roles—can last hours, and the mating itself as long as 20 hours, at least in one Papua New Guinea species, Tagalina papua. The females usually decide when they’ve had enough, though males of some species use their pincers to restrain the object of their desire.
Males of the bone-house earwig Marava arachidis (often found in bone meal plants and slaughterhouses) are particularly coercive, says entomologist Yoshitaka Kamimura of Keio University in Japan, who has studied earwig mating for 25 years. “They bite the female’s antennae and use a little hook on their genitalia to lock them inside her reproductive tract.”
Size matters
Female earwigs collect sperm in one or more internal pouches and can use it to fertilize multiple broods, so they don’t need to mate again. The only thing most males can do is add their own sperm, but Kamimura has seen males of the pale-legged earwig Euborellia pallipesremove the sperm of other males using an elongated part of their peculiar penis.
It’s better if females can prevent this from happening, because they can be particular about the males they mate with. This may explain why, in some species, male and  female genitalia have increased in size as part of a kind of evolutionary arms race in which males benefit from access to the pouch and females benefit from keeping them out. In the bristly earwig Echinosoma horridum, the male’s genitalia are nearly as long as the rest of his body, and the female’s genitalia almost four times as long as the rest of hers.
Fascinating though they are, the amorous adventures of earwigs weren’t what first caught Kamimura’s attention. Rather, he was intrigued by the female’s dedication to her offspring. “When I was a student, I accidentally disturbed an earwig caring for her eggs in our backyard,” he recalls. “She ran away but returned the next day. I was very interested, and I started to rear them.”
Grow your own earwigs
The care that female earwigs provide to their eggs has also become the focus of study in Europe, where a surge of lab research on European earwigs—Forficula auricularia—was kick-started almost 20 years ago by entomologist Mathias Kölliker at the University of Basel, Switzerland. “Getting them to breed continuously over multiple generations was a big challenge,” he recalls. “The females did lay eggs, but they didn’t develop, and never hatched.”
It turned out that the eggs, which are laid in late fall and hatch in January, need the winter cold to start their development. So the scientists figured out a lab regimen that would chill but not kill the eggs. “That took us about two years,” says Kölliker.
In 2009, Kölliker hired entomologist Joël Meunier, who continues to study earwigs at the University of Tours in France and wrote an overview of the biology and social life of earwigs for the Annual Review of Entomology. Earwigs are high maintenance, he says. “If you work with fruit flies, you can breed 10 generations in a few months, but earwigs take much longer.… And they’re all kept in separate petri dishes—thousands of them—that we have to open twice a week to replace the food.
“I think this is one of the reasons few people work on them. But they’re very fascinating.”
Fending off males
The female’s careful egg grooming has at least two important functions. First, she uses a small brush on her mouthparts to remove the spores of fungi that can kill the eggs. Secondly, as Kölliker, Meunier, and colleagues found, she applies water-repellent hydrocarbons to keep them from drying out.
Males that attempt to approach the nest are aggressively chased away, and with good reason, says Meunier. “Once, when we were in the field in Italy to collect earwigs, we found a male and a female together with a clutch of eggs. We were quite excited: ‘Wow, biparental care, cool!’ So we brought them to the lab. But what we actually observed was that the female was very stressed out, showing a lot of aggression towards the male, while the clutch size was continuously decreasing.”
Males, it turns out, love to snack on eggs, even ones that they fathered. To chase them off, females raise their abdomens to show off their pincers. If that’s not enough, they can use the pincers to hurt the male—even to cut him in half. (Scary as they look, the pincers can’t harm people at all, Meunier says.)
Earwigs can also spray each other with defensive secretions that may have antimicrobial properties, too. “They often use those secretions when meeting others,” says Meunier. “Maybe it also prevents the spread of disease.”
As far as scientists know, these secretions are harmless to humans. But because they contain quinone derivatives, which are also found in substances like henna, they have some quirky side effects. “When you get a lot of it on your hands,” Meunier says, “they’ll turn blue, like a bruise, and these marks can last all week.”
The secretions smell quite pleasant, says Kölliker. “When I had a visitor in the lab, I would sometimes pick up an earwig and hold it under their nose. It’s a very nice odor, actually, kind of an earthy smell.” Kölliker’s cat was less appreciative when he tried it on her: “She immediately backed off,” he says.
“In the best case, the mother’s presence doesn’t change a thing,” says Meunier. “At worst, nymphs that grow up with their mother are less likely to reach adulthood and will become smaller adults.” It’s unclear why. But things may be different in the wild, where male earwigs or predators like spiders pose threats, making it safer to stay with mom.
The mother herself seems to benefit. Meunier has observed that as soon as the nymphs emerge, they eat the parasitic mites that often bother breeding females. And once they start foraging on their own, the feces they leave all over the nest may be food for their mother and help her to produce a second brood. The nymphs also feast on each other’s feces, sometimes straight from the source.
The voracious nymphs don’t stop there: They regularly eat each other, and nymphs of the hump earwig Anechura harmandi will almost always eat their mother. “It occurs in every family,” Meunier says, “and it helps the nymphs grow.”
Let’s get together
With all this aggression and cannibalism, you’d expect adult earwigs not actively seeking mates to avoid each other, and in many species, they do. Yet European earwigs regularly group together by the hundreds, sometimes mixing things up with other earwig species.
And the hose-showering behavior was “lateralized,” that is, Mary preferred targeting her left body side more than her right. (Yes, Mary is a “left-trunker.”) Mary even adapted her showering behavior depending on the diameter of the hose: she preferred showering with a 24-mm hose over a 13-mm hose and preferred to use her trunk to shower rather than a 32-mm hose.
It’s not known where Mary learned to use a hose, but the authors suggest that elephants might have an intuitive understanding of how hoses work because of the similarity to their trunks. “Bathing and spraying themselves with water, mud, or dust are very common behaviors in elephants and important for body temperature regulation as well as skin care,” they wrote. “Mary’s behavior fits with other instances of tool use in elephants related to body care.”
Perhaps even more intriguing was Anchali’s behavior. While Anchali did not use the hose to shower, she nonetheless exhibited complex behavior in manipulating the hose: lifting it, kinking the hose, regrasping the kink, and compressing the kink. The latter, in particular, often resulted in reduced water flow while Mary was showering. Anchali eventually figured out how to further disrupt the water flow by placing her trunk on the hose and lowering her body onto it. Control experiments were inconclusive about whether Anchali was deliberately sabotaging Mary’s shower; the two elephants had been at odds and behaved aggressively toward each other at shower times. But similar cognitively complex behavior has been observed in elephants.
“When Anchali came up with a second behavior that disrupted water flow to Mary, I became pretty convinced that she is trying to sabotage Mary,” Brecht said. “Do elephants play tricks on each other in the wild? When I saw Anchali’s kink and clamp for the first time, I broke out in laughter. So, I wonder, does Anchali also think this is funny, or is she just being mean?
For several months in 1898, a pair of male lions turned the Tsavo region of Kenya into their own human hunting grounds, killing many construction workers who were building the Kenya-Uganda railway. Â A team of scientists has now identified exactly what kinds of prey the so-called “Tsavo Man-Eaters” fed upon, based on DNA analysis of hairs collected from the lions’ teeth, according to a recent paper published in the journal Current Biology. They found evidence of various species the lions had consumed, including humans.
The British began construction of a railway bridge over the Tsavo River in March 1898, with Lieutenant-Colonel John Henry Patterson leading the project. But mere days after Patterson arrived on site, workers started disappearing or being killed. The culprits: two maneless male lions, so emboldened that they often dragged workers from their tents at night to eat them. At their peak, they were killing workers almost daily—including an attack on the district officer, who narrowly escaped with claw lacerations on his back. (His assistant, however, was killed.)
Patterson finally managed to shoot and kill one of the lions on December 9 and the second 20 days later. The lion pelts decorated Patterson’s home as rugs for 25 years before being sold to Chicago’s Field Museum of Natural History in 1924. The skins were restored and used to reconstruct the lions, which are now on permanent display at the museum, along with their skulls.
Tale of the teeth
The Tsavo Man-Eaters naturally fascinated scientists, although the exact number of people they killed and/or consumed remains a matter of debate. Estimates run anywhere from 28–31 victims to 100 or more, with a 2009 study that analyzed isotopic signatures of the lions’ bone collagen and hair keratin favoring the lower range.
In 2014, researchers monitoring acoustic recordings from the Mariana Archipelago picked up an unusual whale vocalization with both low- and high-frequency components. It seemed to be a whale call, but it sounded more mechanical than biological and has since been dubbed a “biotwang.”
Now a separate team of scientists has developed a machine-learning model to scan a dataset of recordings of whale vocalizations from various species to help identify the source of such calls. Combining that analysis with visual observations allowed the team to identify the source of the biotwang: a species of baleen whales called Bryde’s (pronounced “broodus”) whales. This should help researchers track populations of these whales as they migrate to different parts of the world, according to a recent paper published in the journal Frontiers in Marine Science.
Marine biologists often rely on a powerful tool called passive acoustic monitoring for long-term data collection of the ocean’s acoustic environment, including whale vocalizations. Bryde’s whale calls tend to be regionally specific, per the authors. For instance, calls in the eastern North Pacific are pretty well documented, with frequencies typically falling below 100 Hz, augmented by harmonic frequencies as high as 400 Hz. Far less is known about the sounds made by Bryde’s whales in the western and central North Pacific, since for many years there were only three known recordings of those vocalizations—including a call dubbed “Be8” (starting at 45 Hz with multiple harmonics) and mother-calf calls.
That changed with the detection of the biotwang in 2014. It’s quite a distinctive, complex call that typically lasts about 3.5 seconds, with five stages, starting at around 30 Hz and ending with a metallic sound that can reach as high as 8,000 Hz. “It’s a real weird call,” co-author Ann Allen, a scientist at NOAA Fisheries, told Ars. “Anybody who wasn’t familiar with whales would think it was some sort of artificial sound, made by a naval ship.” The 2014 team was familiar with whale vocalizations and originally attributed the strange sound to baleen whales. But that particular survey was autonomous, and without accompanying visual observations, the scientists could not definitively confirm their hypothesis.
Enlarge/ “The only species of fish confirmed to be able to escape from the digestive tract of the predatory fish after being captured.”
Hasegawa et al./Current Biology
Imagine you’re a Japanese eel, swimming around just minding your own business when—bam! A predatory fish swallows you whole and you only have a few minutes to make your escape before certain death. What’s an eel to do? According to a new paper published in the journal Current Biology, Japanese eels opt to back their way out of the digestive tract, tail first, through the esophagus, emerging from the predatory fish’s gills.
Per the authors, this is the first such study to observe the behavioral patterns and escape processes of prey within the digestive tract of predators. “At this point, the Japanese eel is the only species of fish confirmed to be able to escape from the digestive tract of the predatory fish after being captured,” co-author Yuha Hasegawa at Nagasaki University in Japan told New Scientist.
There are various strategies in nature for escaping predators after being swallowed. For instance, a parasitic worm called Paragordius tricuspidatus can force its way out of a predator’s system when its host organism is eaten. There was also a fascinating study in 2020 by Japanese scientists on the unusual survival strategy of the aquatic beetle Regimbartia attenuata. They fed a bunch of the beetles to a pond frog (Pelophylax nigromaculatus) under laboratory conditions, expecting the frog to spit the beetle out. That’s what happened with prior experiments on bombardier beetles (Pheropsophus jessoensis), which spray toxic chemicals (described as an audible “chemical explosion”) when they find themselves inside a toad’s gut, inducing the toad to invert its own stomach and vomit them back out.
But R. attenuata basically walks through the digestive tract and escapes out of the frog’s anus after being swallowed alive. It proved to be a successful escape route. In the case of the bombardier beetles, between 35 and 57 percent of the toads threw up within 50 minutes on average, ensuring the survival of the regurgitated beetles. R. attenuata‘s survival rate was a whopping 93 percent. In fact, 19 out of 20 walked out of the frog, unharmed, within an hour, although one industrious beetle bolted out in just five minutes. Granted, the beetles often emerged covered in fecal pellets, which can’t have been pleasant. But that didn’t stop them from resuming their little beetle lives; all survived at least two weeks after being swallowed.
Hasegawa co-authored an earlier study in which they observed Japanese eels emerging from a predator’s gills after being swallowed, so they knew this unique strategy was possible. They just didn’t know the details of what was going on inside the digestive tract that enabled the eels to pull off this feat. So the team decided to use X-ray videography to peer inside predatory fish (Odontobutis obscura) after eels had been eaten. They injected barium sulfate into the abdominal cavity and tail of the Japanese eels as a contrast agent, then introduced each eel to a tank containing one O. obscura. The X-ray video system captured the interactions after an eel had been swallowed.
Out through the gills
The escaping behavior of a Japanese eel. Credit: Hasegawa et al./Current Biology
O. obscura swallow their prey whole along with surrounding water, and a swallowed eel quickly ends up in the digestive tract, a highly acidic and oxygen-deprived environment that kills the eels within 211.9 seconds (a little over three minutes). Thirty-two of the eels were eaten, and of those, 13 (or 40.6 percent) managed to poke at least their tails through the gills of their predator. Of those 13, nine (69.2 percent) escaped completely within 56 seconds on average, suggesting “that the period until the tails emerge from the predator’s gill is particularly crucial for successful escape,” the authors wrote. The final push for freedom involved coiling their bodies to extract their head from the gill.
It helps to be swallowed head-first. The researchers discovered that most captured eels tried to escape by swimming back up the digestive tract toward the esophagus and gills, tail-first in the cases where escape was successful. However, eleven eels ended up completely inside the stomach and resorted to swimming around in circles—most likely looking for a possible escape route. Five of those managed to insert their tails correctly toward the esophagus, while two perished because they oriented their tails in the wrong direction.
“The most surprising moment in this study was when we observed the first footage of eels escaping by going back up the digestive tract toward the gill of the predatory fish,” said co-author Yuuki Kawabata, also of Nagasaki University. “At the beginning of the experiment, we speculated that eels would escape directly from the predator’s mouth to the gill. However, contrary to our expectations, witnessing the eels’ desperate escape from the predator’s stomach to the gills was truly astonishing for us.”
Enlarge/ As female macaques age, the size of their social network shrinks.
Walnut was born on June 3, 1995, at the start of what would become an unusually hot summer, on an island called Rum (pronounced room), the largest of the Small Isles off the west coast of Scotland. We know this because since 1974, researchers have diligently recorded the births of red deer like her, and caught, weighed and marked every calf they could get their hands on—about 9 out of every 10.
Near the cottage in Kilmory on the northern side of the island where the researchers are based, there has been no hunting since the project began, which allowed the deer to relax and get used to human observers. Walnut was a regular there, grazing the invariably short-clipped grass in this popular spot. “She would always just be there in the group, with her sisters and their families,” says biologist Alison Morris, who has lived on Rum for more than 23 years and studies the deer year-round.
Walnut raised 14 offspring, the last one in 2013, when she was 18 years old. In her later years, Morris recalls, Walnut would spend most of her time away from the herd, usually with Vanity, another female (called a hind) of the same age who had never calved. “They were often seen affectionately grooming each other, and after Walnut died of old age in October 2016, at the age of 21—quite extraordinary for a hind—Vanity spent most of her time alone. She died two years later, at the grand age of 23.”
Are old hinds left behind?
Such a shift in social life is common in aging red deer females, says ecologist Gregory Albery, now at Georgetown University in Washington, DC, who spent months on the island studying the deer during his PhD training. (Males roam around more and associate less consistently with others, so they are harder to study.) “Older females tend to be observed in the company of fewer others. That was easy to establish,” he says. “The more difficult question to answer has been why we are seeing this pattern, and what it means.”
The first question one should ask, Albery says, is whether individual deer alter their behavior to associate with fewer others as they age, or whether individuals that associate with fewer others tend to live to an older age. This is the kind of question that many researchers are unable to answer when simply comparing individuals of different ages. But long-term studies like the one at Rum can do so through long-term tracking of populations. Forty times a year, the deer are censused by fieldworkers like Morris who recognize the deer on sight and meticulously note where they are and with whom.
When they accounted for the age and survival of the deer in their analysis, Albery and colleagues found that the link between age and number of associates remained solid: Social connections do, indeed, decrease as individuals age. Might this be because many of the older deer’s friends have died? On the contrary, Albery and colleagues found that older deer who had recently lost friends tended to hang out with others more often.
So why do old hinds have fewer contacts? Part of the explanation may be that they don’t range as widely as they grow older. Studying the deer for a couple of months would not have exposed this trend, says Albery: It was only revealed by tracking the same individuals through time. “Deer with a larger home range generally live longer,” he explains, so an analysis at any single point in time would show larger ranges for older deer and suggest that home ranges expand with age. Tracking individuals through time reveals the opposite is true. “Their home ranges decrease in size as they age,” Albery says.
It is unlikely that older deer move around less because they are concentrating on the core of their favorite habitat, says Albery. The center of their range shifts with age, and they are observed more often in taller and probably less nutritious vegetation, away from the most popular spots. This indicates there might be some kind of competitive exclusion going on: Perhaps more energetic, younger deer with offspring to feed are colonizing the best grazing patches.
On the other hand, older deer may also have different preferences. “Perhaps the longer grasses are easier to eat when your incisors are too worn to clip the short grass everyone else is after,” Albery says. Plus the deer don’t have to bend over as far to reach the longer grass.
A recent study by Albery and colleagues in Nature Ecology & Evolution  found that older deer reduce their contacts more than you’d expect if their shrinking range was the only cause. That suggests the behavior may have evolved for a reason—one that Albery prosaically summarizes as, “Deer shit where they eat.”
Gastrointestinal worms are rampant on the island. And though the deer do not get infected through direct contact with others, being at the same place at the same time probably does increase their risk of ingesting eggs or larvae in the still-warm droppings of one of their associates.
“Younger animals need to put themselves out there to make friends, but perhaps when you’re older and you already have some, the risk of disease just isn’t worth it,” says study coauthor Josh Firth, a behavioral ecologist at the University of Oxford.
In addition, says ecologist Daniel Nussey of the University of Edinburgh, another coauthor, “there are indications that the immune system of aging deer is less effective in suppressing worm infections, so they might be more likely to die from them.”
Enlarge/ Ariel and Caliban learned as kittens that scratching posts were fair game for their natural claw-sharpening instincts.
Sean Carroll
Ah, cats. We love our furry feline overlords despite the occasional hairball and their propensity to scratch the furniture to sharpen their claws. The latter is perfectly natural kitty behavior, but overly aggressive scratching is usually perceived as a behavioral problem. Veterinarians frown on taking extreme measures like declawing or even euthanizing such “problematic” cats. But there are alternative science-backed strategies for reducing or redirecting the scratching behavior, according to the authors of a new paper published in the journal Frontiers in Veterinary Science.
This latest study builds on the group’s prior research investigating the effects of synthetic feline facial pheromones on undesirable scratching in cats, according to co-author Yasemin Salgirli Demirbas, a veterinary researcher at Ankara University in Turkey. “From the beginning, our research team agreed that it was essential to explore broader factors that might exacerbate this issue, such as those influencing stress and, consequently, scratching behavior in cats,” she told Ars. “What’s new in this study is our focus on the individual, environmental, and social dynamics affecting the level of scratching behavior. This perspective aims to enhance our understanding of how human and animal welfare are interconnected in different scenarios.”
The study investigated the behavior of 1,211 cats, with data collected via an online questionnaire completed by the cats’ caregivers. The first section collected information about the caregivers, while the second asked about the cats’ daily routines, social interactions, environments, behaviors, and temperaments. The third and final section gathered information about the frequency and intensity of undesirable scratching behavior in the cats based on a helpful “scratching index.”
The team concluded that there are several factors that influence the scratching behavior of cats, including environmental factors, high levels of certain kinds of play, and increased nocturnal activity. But stress seems to be the leading driver. “Cats might scratch more as a way to relieve stress or mark their territory, especially if they feel threatened or insecure,” said Demirbas. And the top source of such stress, the study found, is the presence of small children in the home.
Enlarge/ A corrugated fiberboard scratching pad can redirect your cat’s unwanted scratching away from the furniture.
