Mar. 21st, 2017

Corvids are the star of the show.
  • In fact, as far as we know, only four groups of animals on the planet craft their own complex tools: humans, chimps, orangutans, and New Caledonian crows. And even fewer make tools they keep and reuse.
  • Especially when you look at the catalog of, say, orangutan tools, which range from toothpicks and teeth cleaners to autoerotic tools and missiles aimed at predators, from leaf napkins and moss sponges to leafy branch fans and scoops, chisels, hooks, nail cleaners, and bee covers—branches or leaves used as a hat to protect against stinging bees.Green-backed herons are expert bait fishers, known to entice their prey with bread, popcorn, seeds, flowers, live insects, spiders, feathers, even pellets of fish food. Dung is the decoy of choice for the burrowing owl.
  • It takes many complex moves conducted in a very precise manner to complete the tool—snipping at one spot and tearing along that edge, then snipping at another spot and tearing from there, several times in a row. The final version looks a lot like a miniature saw but is used as a probe to wheedle out grasshoppers, crickets, cockroaches, slugs, spiders, and other invertebrates from otherwise inaccessible nooks and crannies.
  • On the island of Mare, just adjacent to New Caledonia, says Hunt, the crows make only wide tools. In other words, it seems there may be local styles or traditions of toolmaking that are passed down over generations. Faithful transmission of local tool designs: If it’s true, that fairly well defines the term culture.
  • Islands are castles of experiment surrounded by moats. Competition is less fierce and predators less abundant than on continents, so evolutionary experimentation is not so quickly or ruthlessly punished. That includes behavioral experimentation, like tooling around with tools.
  • suggests that the two traits may be causally related. It’s called the early learning hypothesis. Perhaps possessing learning-intensive tool skills plays a role in lengthening the juvenile period. In this way, New Caledonian crows may provide a good model for investigating the evolutionary effect of tool use on life history, not just for birds but for people.
  • This suggests that the crows understand water displacement, a fairly sophisticated physical concept, on par with the comprehension of a child five to seven years old. It also suggests that they’re able to grasp the basic physical properties of objects and make inferences about them.
  • In fact, we owe the expression “pecking order” to studies of the social relations among chickens by the Norwegian zoologist Thorleif Schjelderup-Ebbe, who found that pecking orders are ladderlike
  • The idea that a demanding social life might drive the evolution of brainpower was developed by Nicholas Humphrey, a psychologist at the London School of Economics received. “Leaving gifts suggests that crows understand the benefit of reciprocating past acts that have benefited them and also that they anticipate future reward,”
  • Corvids and cockatoos can delay gratification if they think a reward is worth waiting for—a form of emotional intelligence involving self-control, persistence, and the ability to motivate oneself.
  • A colorful member of the intelligent crow family, the male Eurasian jay appears to intuit his mate’s state of mind—or at least her appetite—and responds by giving her what she most desires.
  • The team also found that different species of tits—great, blue, and marsh—share news of food with one another. “The marsh tits are the best information providers,”

  • Nine years later, the masked scientists returned to the scene of the crime. The crows in these neighborhoods—including those that weren’t even hatched at the time of the capture—reacted to the people with the dangerous masks as if they were a threat, dive-bombing, scolding, and mobbing them.
  • Scientists have observed experienced tandem-running ants modifying their journeys when trailed by a naïve follower, pausing en route to let a follower-pupil explore landmarks and resuming the journey only when the follower taps them with an antenna.
  • Highly intelligent, accomplished mimics, they sound false alarm calls of babblers and other species, which make the babblers drop their mealworms and run for cover. Drongos then steal in to seize the dropped food even if it’s abandoned only for an instant, right beside the unwitting victim. Ridley and her team recently found that drongos fool the babblers by varying the type of alarm calls they produce, making it harder for the babblers to detect the deception.
  • the young birds use at least two clever social strategies to boost the amount of food they get. First, they’re picky about whom they follow, choosing to tag along with adults who are especially proficient at capturing prey. Second, when they’re hungry, they “blackmail” adults into feeding them at higher rates by venturing into riskier open locations.
  • Nancy Burley of the University of California, Irvine, and her colleagues who study the budgerigar suspect that this may be the evolutionary reason for the ability of parrots to parrot—to quickly learn and mimic new sounds: “It could also explain why parrot enthusiasts suggest that the ‘best talkers’ among pet budgerigars are typically males that were obtained when very young and kept in isolation from other budgerigars,”
  • New research shows that food sharing in chimps raises oxytocin levels more than grooming does. This is evidence, perhaps, for the truth of the maxim “The way to your lover’s heart is through her stomach”
  • Birds have their own versions of these neurohormones, called mesotocin and vasotocin.
  • The highly social, flocking zebra finches and spice finches had far more mesotocin receptors in the dorsal lateral septum—a key part of the brain involved in social behavior—than did their more solitary relatives.
  • West proposes that it’s not just the challenges of maintaining pair-bonds in birds that have boosted their brainpower. Rather, she says, it’s “the complexity of achieving a successful pair bond and extra-pair copulations that is simultaneously driving the increase.” It’s what she calls an “intersexual arms race.”
  • DNA analysis has revealed that extra-pair copulations occur in about 90 percent of bird species. In any given nest, up to 70 percent of chicks are not sired by the male caring for them.
  • In essence, by not putting all their eggs in one basket, so to speak, females are pumping up the public good, encouraging safer and more productive neighborhoods. “Where maternity certainty makes females care for offspring at home, paternity uncertainty and a potential for offspring in several broods make males invest in communal benefits and public goods,” say the Norwegian scientists.
  • A scrub jay will think to do this—to resort to these clever cache-protection tactics—only if he’s had his own piratical experience. Birds that have never pilfered themselves hardly ever recache. In other words, say the researchers, “it takes a thief to know a thief.”
  • Asian elephants were lately added to the list with a study showing that they may console a distraught individual with their trunks, gently touching its face or putting their trunk in its mouth—akin to an elephant hug.

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