Mar. 22nd, 2017

The last chapters come as a downer.
  • how songbirds have “speech defects” just as we do (they stutter, for instance) and the way song learning in a bird literally crystallizes brain structure, teaching us about the neurological nature of our own learning.
  • But songbirds go through the same process of vocal learning that people do—they listen to adult exemplars, they experiment, and they practice, honing their skills like children learning a musical instrument.
  • Close to half the birds on the planet are songbirds, some four thousand species, with songs ranging from the mumbled melancholy chortle of the bluebird to the forty-note aria of the cowbird, the long, byzantine song of the sedge warbler, the flutelike tune of the hermit thrush, and the amazing seamless duets of male and female plain-tailed wren.
  • In the open, sound travels best a few feet or so above the vegetation, so birds sing from perches to reduce interference. Those singing on the forest floor use tonal sounds and lower frequencies than those singing in the canopy. Some use frequencies that avoid the noise from insects and traffic. Birds living near airports sing their dawn chorus earlier than normal to reduce overlap with the roar of airplanes.
  • Certain songbirds, such as European starlings and zebra finches, can contract and relax these tiny vocal muscles with submillisecond precision—more than a hundred times faster than the blink of a human eye.
  • You can tell where a mockingbird lives by the songs he sings. So particular is a song to its bird that individual birds within a population may share only 10 percent of their song patterns.
  • The ideal model organism for studying any kind of learning is a rare beast, says biologist Chip Quinn: It “should have no more than three genes, be able to play the cello or at least recite classical Greek, and learn these tasks with a nervous system containing only ten large, differently colored, and therefore easily recognizable neurons.”
  • This discovery—that some young birds are capable of learning almost any song they hear yet possess a genetic template that predisposes them to their species’ song—has a human parallel.
  • This, says Jarvis, may be one reason vocal learning is rare. “All the varied vocalizations an animal learns make it an easy target.”
  • Extravagance in nature is so often found in proximity to sex.
  • “It’s like a superstimulus,” he says. “Like the allure of a big egg to a chicken.” (As ethologist Niko Tinbergen learned, hens like big eggs: Give a hen a giant egg to sit on, even an artificial one, and she will prefer it to a small egg. In her mind, bigger is better, even if it’s not natural.)
  • It’s what’s known as vocal consistency, the ability to perfectly replicate the acoustic features of a song—the notes, the rhythms, the pauses—from one rendition to the next. To a bird, these subtleties make all the difference.
  • To make the walls symmetrical, he uses a mental tool called templating. “In templating, a male picks up a stick and positions himself along the midline of the bower avenue,” explains Borgia. He puts the stick in or against one wall and, still holding on to it, pulls it away from the wall—then, using a precise reversal of his movements, he places the stick in an identical position in the opposite wall.
  • Great bowerbirds apparently do just the opposite: They put smaller objects closer to the bower entrance and bigger stones and bones farther away. To the female looking out from her cozy enclosure, the researchers speculate, this creates the illusion that the court is smaller than it is. The foreshortened stage may make the parading male himself and his colored objects look bigger and more vibrant.
  • The painter and colorist Raoul Dufy reportedly said that “blue is the only color which maintains its own character in all its tones . . . it will always stay blue.”
  • In nature blue is unusual in part because vertebrates never evolved the ability to make or use blue pigments. The deep electric blue an eastern bluebird carries on its back is an example of what scientists call a structural color: It’s generated by light interacting with the three-dimensional arrangement of keratin in the bird’s feathers.
  • In other words, says Patricelli, sexual selection seems to favor both the evolution of elaborate display traits and also the ability to use them appropriately. And this may be where our hero fell short. He lacked social grace.
  • When a young male visits the bower of a mature male, he often plays the female’s part while he closely observes the older male. He may be a bit more fidgety than his feminine counterpart, but the older bird tolerates his presence because the mentor, too, benefits from practicing with a live audience. “It’s a win-win situation,” says Borgia; “otherwise you can bet it wouldn’t happen.”
  • In the case of the bowerbird, the beauty of the bower is shaped by the perception of the female. In other words, her mind shapes male display; she is the architect of the male bird’s artistic creation and the brains required to achieve it, just as the female songbird is the architect of the male’s elaborate song and the fancy neural networks that produce it.
  • I think I could distinguish a bad ballet dancer from a good one. But could I tell a 3.7-second grand jeté from a 3.8-second one? Somehow, the female golden-collared manakin registers these whiskers of temporal difference.
  • The Arctic tern, a bird who lives by his love of long daylight and bent for high mileage, circles the world in orbit with the seasons, flying from its nesting grounds in Greenland and Iceland to its wintering grounds off the coast of Antarctica—a round-trip of almost forty-four thousand miles. In an average thirty-year lifetime, then, a tern may fly the equivalent of three trips to the moon and back.
  • In fact, pigeons are better than most people—and even better than some mathematicians—at solving certain statistical problems: the Monty Hall Dilemma
  • In 2014, Mouritsen and his team reported in Nature that even extremely weak electromagnetic “noise” generated by human electronic devices in urban environments may disrupt the magnetic compasses of migrating European robins. We’re not talking cell towers or high-voltage transmission lines here; more like the background buzz of everything run by electrical currents.
  • To fuel their air derbies, they have to harvest hundreds of flowers per day; they don’t want to waste a dime visiting blossoms they’ve already sucked dry. So they keep track. And they do it, apparently, not on the basis of color or shape or other visual tips offered by the flowers themselves, but rather through spatial cues,
  • “A honeyguide has to find a suitable nest to drop her eggs into at just the right time. If she puts them in a nest where chicks will be hatching the next day, her babies will be bumped off as runts; if she drops it in too early, the host bird may not be ready to lay or incubate. So she has to monitor the position of nests and the stages they’re in.”
  • After Sandy passed, the whole eastern edge of the continent was swarming with vagrants. It’s an interesting term, commonly used for someone who travels idly with no means of support.
  • the polarized light cues available at sunset. (Twilight is a rich source of information for navigating animals of all types. It’s the only period in the day when birds and other animals can combine light-polarization patterns, stars, and magnetic cues.)
  • Zebra finches, whose bulbs are tiny indeed, use their sense of smell to spot their relatives, just as mammals do, to avoid inbreeding and facilitate cooperation with their kin.
  • Shanahan sees in the similarity what he calls a common blueprint for high-level cognition. In simplified terms: The human brain is thought to be a so-called small-world network, not unlike Facebook. Different modules—or regions—of the brain are connected by a relatively small number of neurons known as hub nodes.
  • In 1889, just a few decades after the house sparrow’s introduction, sparrow clubs were formed with the sole objective of destroying the birds, and county and state officials were offering two cents a head for each sparrow killed.
  • Big brains are costly in terms of development and maintenance. But they’re thought to enhance a bird’s survival by allowing it to rapidly adjust to unusual, novel, or complex ecological challenges such as finding new food or avoiding unfamiliar predators. It’s called the cognitive buffer hypothesis. A big brain “buffers” an animal from environmental change by allowing it to adapt to novel resources—
  • two ecologists watched house sparrows working their way along a line of parked cars in a parking lot, gleaning insects trapped in the radiators.
  • In some cities, you can find smoked cigarette butts in sparrow nests, which effectively function as a parasite repellent.
  • On Mount Karimui, an extinct volcano on the main island, the range of the magnificent bird-of-paradise had ascended more than three hundred feet as a result of warming of just 0.7 degree Fahrenheit. “Because a mountain is like a pyramid,” says Freeman, “there’s less area for habitat available as they move up the mountain. They’re being squeezed both by temperatures and for space.”
  • “A long reproductive life can increase the productivity of these slow-living species—but they will never achieve the high productivity of fast-living species that prioritize reproduction over survival.”

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