New Caledonian crows are some of the world’s most famous non-human tool users. The crows employ sticks, leaves, and even bits of wire in the lab to probe holes in branches or logs, fishing out tasty bugs. But scientists are usually stuck studying these behaviors in artificial environments. To get a better perspective on how these birds make and use tools in nature, researchers in the United Kingdom tried something new: they turned wild crows into documentary filmmakers.
Jolyon Troscianko, of the University of Birmingham, and Christian Rutz, of the University of Oxford, developed tiny video cameras for spying on crows. Then they went to New Caledonia, the archipelago east of Australia where the birds (Corvus moneduloides) live.
In their forest study area, the researchers trapped 19 wild crows. Each time they trapped a bird, they held it overnight while custom-building and programming a video logger that wouldn’t weigh the bird down too much. They attached the camera to the underside of the bird’s tail, so that the lens pointed forward and up along the belly. Then they released the birds back into the forest. Read More
If your favorite activity is lying motionless on the ground, you’d better make sure hungry animals can’t find you. Snakes and other creatures that hunt by ambush, waiting for their prey to wander past, often have impressive visual camouflage. But at least one type of viper seems to disguise itself in another way, too: its smell is undetectable to predators.
Puff adders (Bitis arietans) are big, fat vipers that move around very little while they wait for prey. They’re widespread in Africa. Despite carrying powerful venom, these sluggish snakes often become meals for other animals.
Ashadee Kay Miller, a graduate student at the University of the Witwatersrand in Johannesburg, South Africa, decided to investigate the smelliness of puff adders because of some strange observations her coauthor Graham Alexander had made in the wild. Alexander spent a lot of time tracking these snakes in South Africa, and noticed that other animals were often oblivious to puff adders. He saw dogs and mongooses, with their noses to the ground and actively sniffing, walk right over the snakes. These animals would have been happy to eat a puff adder if they’d found it. Read More
Cynde McInnis arrived in San Francisco for this week’s Society for Marine Mammalogy conference after traveling cross-country with an unusual companion: a 43-foot-long inflatable humpback whale.
McInnis coordinates education for Cape Ann Whale Watch in Massachusetts, which focuses on traditional flesh-and-blood whales. But on the side, she runs a company called The Whalemobile. She drives her blowup cetacean to schools and other sites and uses it to teach people about whales and the environment. The whale is modeled after a real animal she knows well—a female humpback named Nile.
Right now McInnis is halfway through a seven-week tour of the country with her family. The inflatable whale has made stops in Maryland, Pennsylvania, Indiana, Illinois, and Tennessee. After the conference, McInnis will start back across the country with her family and whale, though their plans are still open. I met up with her in San Francisco to talk about the surprises and smells of traveling with a whale. (I’ve edited our conversation.) Read More
The rubber hand illusion is a classic experiment that reveals how our brains build a sense of our bodies. For the latest twist on the illusion, researchers simulated OCD-like feelings of disgust in subjects by starting with rubber hands and adding fake blood, vomit and feces.
The basic rubber hand experiment is simple to set up. It requires a fake hand, two paintbrushes, a table, and something to use as a little wall. A subject sits with both hands flat on the table, one of them farther out to the side. The barrier blocks her view of that hand. The rubber hand lies just inside the wall, so that when the subject looks down she sees two hands in front of her—but only one is her own. Across the table, an experimenter uses the two brushes to stroke the backs of the hidden hand and the rubber hand at the same time. Gradually, as the subject feels the paintbrush on her skin and watches the brush stroking the rubber hand, she experiences a powerful illusion that the fake hand is part of her body. Read More
Swedish scientists have built a camera that makes methane gas visible. The tool could help researchers study greenhouses gases and answer tricky questions about climate change. It’s also good for visualizing cow farts.
Magnus Gålfalk of Linköping University explains that the camera works using infrared spectroscopy. Called “hyperspectral imaging,” the method simultaneously captures a spectrum of infrared light for every pixel in a photo. Many gases absorb infrared light, Gålfalk says, not just methane (CH4). But the camera is fine-tuned to see the signature of methane gas.
In the picture above, the purple plume is methane the researchers released from their lab to test the camera. They also tried taking pictures of a waste incineration plant, a heap of sewage sludge, and a barn with 18 cows inside (the red area is methane): Read More
If the view outside your home is picture-perfect, you’re more likely to be the picture of health. A study in Great Britain found that even taking into account poverty and a host of other factors, people in prettier locations report being healthier.
Chanuki Seresinhe, a graduate student at the University of Warwick in the United Kingdom, explains that the question of whether living in picturesque surroundings is good for your health “seems to come up again and again.” A study in Toronto, for example, found a link between residents’ self-reported health and the number of trees in their neighborhoods.
But it’s hard to answer the question conclusively. To start with, how do you measure a neighborhood’s beauty? Rather than counting trees, Seresinhe used data from an online game called Scenic-or-Not. Read More
You know when you’re out walking with a big horde of your friends and you come to a chasm you can’t step across, so a bunch of you clasp each other’s limbs and make yourselves into a bridge for the rest to walk on?
Eciton army ants do this. And they’re not the only ants that build incredible structures out of their strong, near-weightless bodies. Weaver ants make chains between leaves by holding onto each other’s waists. Fire ants cling together to form rafts and survive flooding.
Ants build these structures democratically, without any leaders. (Or language, or tools.) To learn more about how they do it, scientists went into the forests of Panama.
Led by Chris Reid of the New Jersey Institute of Technology and Matthew Lutz of Princeton University, researchers designed an apparatus to test ants’ bridge-making skills. Eciton hamatum army ants need to build bridges because they’re constantly on the move. They swarm an area of the forest, devour any bugs they find there, and then move on. When they come to a gap in the leaves covering the forest floor, they bridge it to keep the troops moving quickly. Bridges can be just a few ants, or hundreds of them.
The researchers built a device like a miniature, raised roadway with a sharp kink in it. Then they found an army ant trail and put their device right in the middle. They used leaves and sticks that were already covered with the ants’ pheromones to guide the insects onto their device.
If ants walked all the way along this artificial road, they would have to make a wide detour from their original path. But if they built a bridge across the angle, they could continue marching in more of a straight line. A hinge let the scientists widen or narrow the angle the ants would have to navigate.
The army ants successfully shortened their detour by building bridges across the gap. But they didn’t start at the widest part. Instead, they built their bridge at the skinny end of the angle, where it took only a few ant bodies. Then they gradually scooted the bridge toward the wider end, adding ants as they went.
Although the ants bridged the gap handily, they didn’t manage to stretch across the very widest part. Reid and Lutz think this is because of tradeoffs that come with building a footbridge made of soldiers. The more ants are part of a bridge, the fewer are left to carry stuff across it, for example. And the ants maintained a steady ratio of length to width in their bridges, so as bridges got longer, they also needed to get wider.
Once all the troops are across, an ant bridge breaks apart and marches away too. Being part of a living bridge is, presumably, a thankless job for the army ants. But it won’t be long before they get to walk on someone else’s back.
Image and videos: Courtesy of Matthew Lutz, Princeton University, and Chris Reid, University of Sydney.
Reid CR, Lutz MJ, Powell S, Kao AB, Couzin ID, & Garnier S (2015). Army ants dynamically adjust living bridges in response to a cost-benefit trade-off. Proceedings of the National Academy of Sciences of the United States of America PMID: 26598673
They say you can catch more flies with honey than with vinegar. But what about with lazy spiders versus lively ones? When it comes to keeping pests at bay, the personalities of the spiders hunting them are important.
That’s what two behavioral ecologists reported after watching bug dramas play out in a sunny hilltop alfalfa patch. Raphaël Royauté of North Dakota State University and Jonathan Pruitt of the University of Pittsburgh were studying the personalities of wolf spiders (Pardosa milvina). The spiders are common in many types of crop fields, and prey on all kinds of bugs. But individual spiders, like other animals, can have different habits or tendencies. So, the scientists asked, shouldn’t those differences affect which prey the spiders catch?
Yes, it’s important not to anthropomorphize other species or impose our values on them—but sometimes animals are just horrible. For example, kelp gulls. A few decades ago the birds in one part of Argentina realized that for a tasty snack, they could tear flesh from the backs of whales when they came up for air. Eventually the whales learned to protect themselves somewhat from the gulls. But now the gulls have shifted their attention to the whales’ babies, and might be killing them.
Kelp gulls (Larus dominicanus) first got a taste for whale flesh in the 1970s. They began pulling pieces of dried-out skin from the backs of southern right whales (Eubalaena australis) while the whales were relaxing at the water’s surface at Península Valdés, Argentina. This is a calving ground, where mother whales travel to have their young. The pairs stay here for a few months, nursing and swimming together, before they migrate to their feeding grounds.
The gull attacks have escalated over time. Birds now gash the whales over and over with their beaks, opening holes and then gouging deeper into their skin and blubber. They sometimes chase the whales while they swim, waiting for them to come up for air so they can attack again. Read More
Names like “giraffe” and “jerboa” are nice and snappy, but what are you supposed to do when you’re a naturalist trying to name yet another smallish rodent or brownish beetle?
Sometimes all the good options are already taken. At other times, humans have named animals based only on their usefulness to us. Whatever the reason, here are a few species that got a bum deal.