When a banana is at stake, a low-status capuchin monkey may deceive the other monkeys in his troupe in order to get his hands on that tasty fruit. A new study of monkeys in an Argentinian national park found evidence that lowly monkeys give spurious alarm calls in order to scare off more dominant monkeys competing for food.
Tufted capuchin monkeys give a two-syllable “hiccup” call when they detect danger, like an approaching ocelot. Lead researcher Brandon Wheeler was studying a group of capuchins eating food left on platforms constructed in trees, when he noticed some of the monkeys made the calls when predators weren’t around. “They were giving the same calls that they give for cats extremely frequently,” he says. “When they do, other individuals often run out off the platform, which potentially leaves [the platform] available for whoever called to jump in to get some food” [ScienceNOW Daily News].
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Four rooks by the names of Cook, Connelly, Fry, and Monroe have upped estimates of birds’ intelligence by mastering a series of challenges in which they had to use tools to get tasty worms. Researchers say that the birds’ skills rivalled those of well-known tool users such as chimpanzees and New Caledonian crows…. “The study shows the creativity and insight that rooks have when they solve problems,” [BBC News], says study coauthor Nathan Emery. Their abilities are all the more remarkable, researchers say, because rooks are not known to use tools in the wild.
In the laboratory tests, researchers devised a series of challenges in which the rooks had to figure out how to release food from glass tubes. The first featured a worm on a platform that would collapse, allowing it to be eaten if a stone were nudged into the tube. All four birds completed the task. They also chose stones of appropriate shape for tubes of differing sizes.The rooks were also quick to realise that long, thin stones would fit in every tube, regardless of its diameter, as long as it went in lengthways [The Times]. But picking up stones was a modest accomplishment compared to what came next.
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If you get on a mockingbird’s enemy list, expect to be dive-bombed every time you come within the bird’s sight. That’s one lesson that can be taken from a new study which proved that mockingbirds can recognize individual people, and attack those who have bothered their nests in the past. While ornithologists knew that certain highly intelligent birds like parrots and crows can recognize humans in a lab setting, they were surprised to find similar behavior in a songbird living in the wild. This paper is “a beauty,” says John Fitzpatrick, an ornithologist at Cornell University. “It’s amazing what a bird brain can do” [ScienceNOW Daily News].
The study was prompted by a series of bird attacks. A graduate student involved in research on bird nesting noticed that when she would make repeat visits to peoples’ yards the birds would alarm and attack her, while they would ignore people gardening or doing other things nearby…. Indeed, it seemed they could even recognize her car, and she had to start parking around the corner [AP]. So the researchers designed an experiment to investigate whether the birds really could identify an individual person.
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Human females may get offended at dates who expect a little something extra after they buy a steak dinner, but for chimpanzees, the exchange may be a fair one [Reuters]. A new study of a chimp community living in the western African nation Côte d’Ivoire has found that males regularly share meat from their hunting expeditions with females, and get sex in return.
The researchers observed males sharing meat with females in estrus, who have sexual swellings that indicate their current fertility. More surprising was that males shared meat with females that didn’t have sexual swellings, perhaps in hopes of future success, the researchers say. The sex “may not necessarily occur immediately—it could occur sometime in the future,” said study co-author Cristina M. Gomes [National Geographic News]. The findings, she says, support the theory that chimps can engage in long-term planning, anticipating future events and remembering past interactions.
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Young chickens just a few days old can count and perform basic arithmetic, according to a fluffy new study. Researchers manipulated objects that the chicks had formed an attachment to, moving the objects behind little screens, and found that the observant young birds kept track of where the objects were. In effect, the chicks were solving simple math problems like “4 – 2 = 2.”
While some adult animals, including primates and dogs, have been found to have an understanding of basic math, researchers had not previously demonstrated numerical abilities in any young animals (except for humans). Karen Wynn, who has reported evidence of numerical skills in human babies, points out that the chicks haven’t had a chance to learn or develop much. “This work, then, is a compelling existence proof that numerical understanding comprises a built-in system of unlearned knowledge,” Wynn says [Science News].
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Human toddlers aren’t the only ones who throw tantrums to get their way, and human parents aren’t the only ones who give in, guiltily, to avoid causing a scene. Researchers have found that rhesus macaque monkeys engage in very similar behavior, in which baby monkeys pitch screaming fits until their mothers give in and feed them in order to prevent attacks from irritated onlookers. Explains lead researcher Stuart Semple: “The baby monkeys’ cries are high-pitched, grating and nasty to listen to – not just to their mother but to animals nearby. And we found that the way mothers respond to their crying infants is affected by who is around them at the time” [BBC News].
Researchers observed the behavior of wild monkeys on the island of Cayo Santiago, Puerto Rico. When a baby wanted to nurse but the mom wasn’t willing the shrieks started up, and researchers then monitored the actions of baby, mom, and any other monkeys within six feet. The researchers noted that during a temper tantrum the onlookers seemed bothered and on occasion made threatening gestures, or even chased, grabbed or bit the mother or the infant. Most of the aggression came from monkeys that weren’t close relatives and outranked mom in the social hierarchy. Her relatives proved more tolerant [Science News].
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A close examination of over 400 Triceratops skulls suggests that the iconic dinosaurs used their powerful horns to clash with rivals over mates, territory, and dominance. In a new study, researchers looked carefully for traces of scrapes and healed fractures on the fossilized skulls, and say the pattern they found fits the theory that the three-horned herbivores were going head-to-head. “The most likely culprit for all of the wounds on Triceratops frills was the horns of other Triceratops,” [lead researcher Andrew] Farke said. “Our findings provide some of the best evidence to date that Triceratops might have locked horns with each other, wrestling like modern antelope and deer” [Times Online].
The researchers compared the Triceratops skulls to those of another dinosaur called Centrosaurus, which also boasted three horns and a bony protective frill around its face. The two species were related, but Centrosaurus died out about 75 million years ago and had its largest horn on its snout, while Triceratops lasted until 65 million years ago and had more prominent horns over its eyes. With such different horn patterns, the researchers assumed that if the dinosaurs were horn-butting with members of their own species the injuries of Triceratops and Centrosaurus should also be different from each other. But if they weren’t poking and butting one another with those horns, the injuries should be relatively similar, perhaps due to random nicks from clumsily running into a tree or head butts from predators, Farke said [LiveScience].
As the researchers report in the journal PLoS ONE, the Triceratops skulls showed a pattern of old injuries in one specific part of the bony frill that would likely have been impacted if two individuals were banging their heads together, but the Centrosaurus showed no such pattern.
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