Birds do indeed have brains very different from our own—and no wonder. Humans and birds have been evolving independently for a very long time, since our last common ancestor more than 300 million years ago. But some birds, in fact, have relatively large brains for their body size, just as we do. Moreover, when it comes to brainpower, size seems to matter less than the number of neurons, where they're located, and how they're connected.
And some bird brains, it turns out, pack very high numbers of neurons where it counts, with densities akin to those found in primates, and links and connections much like ours.
This may go a long way toward explaining why certain birds have such sophisticated cognitive abilities.#4639•
Magpies can recognize their own image in a mirror, a grasp of "self" once thought limited to humans, great apes, elephants, and dolphins and linked to highly developed social understanding#4638•
Western scrub jays use Machiavellian tactics to hide their food caches from other jays—but only if they've stolen food themselves. These birds seem to have a rudimentary ability to know what other birds are "thinking" and, perhaps, to grasp their perspective. They can also remember what kind of food they buried in a particular place—and when—so they can retrieve the morsel before it spoils.
This ability to remember the what, where, and when of an event, called episodic memory, suggests to some scientists the possibility that these jays may be able to travel back into the past in their own minds—a key component of the kind of mental time travel once vaunted as uniquely human.#4627•
Some birds are born Euclideans, capable of using geometric clues and landmarks to orient themselves in three-dimensional space, navigate through unknown territory, and locate hidden treasures. Others are born accountants. In 2015 researchers found that newborn chicks spatially "map" numbers from left to right, as most humans do (left means less; right means more).
This suggests that birds share with us a left-to-right orientation system—a cognitive strategy that underlies our human capacity for higher mathematics.
Baby birds can also understand proportion and can learn to choose a target from an array of objects on the basis of its ordinal position (third, eighth, ninth).
They can do simple arithmetic, as well, such as addition and subtraction.#4636•
INTELLIGENCE IS a slippery concept, even in our own species, tricky to define and tricky to measure. One psychologist describes it as "the capacity to learn or to profit by experience." And another, as "the capacity to acquire capacity"—the same sort of circular definition offered up by Harvard psychologist Edwin Boring: "Intelligence is what is measured by intelligence tests." As Robert Sternberg, a former dean at Tufts University, once quipped, "There seem to be almost as many definitions of intelligence as . . .
experts asked to define it."#4634•
As a class, birds have been around for more than 100 million years. They are one of nature's great success stories, inventing new strategies for survival, their own distinctive brands of ingenuity that, in some respects at least, seem to far outpace our own.#4629•
After all, evolution isn't about advancement; it's about survival. It's about learning to solve the problems of your environment, something birds have done surpassingly well for a long, long time.#4630•
Perhaps it's because they're so unlike people that it's difficult for us to fully appreciate their mental capabilities. Birds are dinosaurs, descended from the lucky, flexible few that survived whatever cataclysm did in their cousins. We are mammals, related to the timid, diminutive shrewlike creatures that emerged from the dinosaurs' shadows only after most of those beasts died off.
While our mammal relatives were busy growing, birds, by the same process of natural selection, were busy shrinking.
While we were learning to stand up and walk on two feet, they were perfecting lightness and flight.
While our neurons were sorting themselves into cortical layers to generate complex behavior, birds were devising another neural architecture altogether, different from a mammal's but—in some ways, at least—equally sophisticated.
They, like us, were figuring out how the world works, and all the while, evolution was fine-tuning and sculpting their brains, giving their minds the magnificent powers they have today.#4626•
BIRDS LEARN. They solve new problems and invent novel solutions to old ones. They make and use tools. They count. They copy behaviors from one another. They remember where they put things.#4640•
Maybe genius is a better word. The term comes from the same root as gene, derived from the Latin word for "attendant spirit present from one's birth, innate ability or inclination." Later, genius came to mean natural ability, and finally (thanks to the essay "Genius" by Joseph Addison in 1711) to denote exceptional talent, natural or learned.
More recently, genius has been defined as "nothing more nor less than doing well what anyone can do badly." It's a mental skill that's exceptional compared with others, either of your kind or another kind. Pigeons have a genius for navigation that far, far exceeds our own. Mockingbirds and thrashers can learn and remember hundreds more songs than most of their fellow songbird species.
Scrub jays and nutcrackers have memories for where they put things that make our capacity look meager.#4637•
IN THIS BOOK, genius is defined as the knack for knowing what you're doing—for "catching on" to your surroundings, making sense of things, and figuring out how to solve your problems. In other words, it's a flair for meeting environmental and social challenges with acumen and flexibility, which many birds seem to possess in abundance.#4641•
Nature is a master of bricolage, hanging on to biological bits that are useful and modifying them for new purposes. Many of the changes that separate us from other creatures have arisen not through the evolution of new genes or cells but through subtle shifts in how existing ones are used.#4632•
5
Clearly all birds are not equally bright or able in all ways—at least by current accounting. Pigeons, for instance, don't do well on tasks that require them to abstract a general rule to solve a suite of similar problems, a skill easily learned by crows. But the lowly pigeon is a wizard in other ways: It can remember hundreds of different objects for long periods of time, discriminate between different painting styles, and figure out where it's going, even when displaced from familiar territory by hundreds of miles.
Shorebirds such as plovers, sanderlings, and sandpipers show no evidence of "insight learning," that grasp of relationships that permits birds like the New Caledonian crow to use tools or to operate man-made devices that reward their ingenuity with food.
But one shorebird, the piping plover, is a master of theatrics, capable of diverting predators from their shallow, exposed nests with a feigned "injured wing" display.#4688•
Like Lefebvre, most scientists who study birds prefer the term cognition to intelligence. Animal cognition is generally defined as any mechanism by which an animal acquires, processes, stores, and uses information. It usually refers to the mechanisms involved in learning, memory, perception, and decision making.
There are so-called higher and lower forms of cognition.
For instance, insight, reasoning, and planning are considered high-level cognitive abilities.
Lower-level cognitive skills include attention and motivation.#4715•
Harvard psychologist Howard Gardner identifies eight different types of intelligence and suggests that they're independent. They are bodily, linguistic, musical, mathematical or logical, naturalistic (sensitivity to the natural world), spatial (knowing where you are relative to a fixed location), interpersonal (sensing and being in tune with others), and intrapersonal (understanding and controlling one's own emotions and thoughts)#4675•
It was here in the land of the bullfinch that Lefebvre devised a scale of intelligence based on the idea that smart birds innovate. Like the bullfinch and those cream-skimming tits, they do new things. Birds with lesser brains are set in their ways and rarely invent, explore, or dip into the novel.#4680•
"These two birds are virtual genetic twins with the same ancestor, having diverged probably only a couple of million years ago," Lefebvre explains. "Both live in the same environment. Both are territorial and share the same social system." The only difference is that the bullfinch is clever, fearless, and opportunistic; and the grassquit, skittish, deeply conservative, and afraid of nearly everything.#4709•
In a small expanse of woods and fields at Folkestone Marine Park, he offers an informal experiment to demonstrate his point. Several grassquits are visible, poking about in the grass thirty yards away, foraging on seed. A few other birds are off in the trees at some distance. Lefebvre throws out a handful of birdseed, then squats in the grass.
The grackles are the first to notice.
Within half a minute, they're gathering around in a noisy flock.
Their squawks draw doves, more grackles, and squadrons of bullfinches.
The grassquits have not budged.
They just keep their heads down, closely attending only to their little plots of grass.
Lefebvre lowers his voice to a whisper and says in a British accent: "A perfect result, as if staged, with David Attenborough hiding in the wings." And in an uncanny imitation of the famous naturalist: "This bird does amazing things . . ."#4703•
He stands up abruptly and points at the grassquits. "Zero opportunism there," he says. "They're attracted neither by the seed nor by the birds feeding on it. They're just not on the lookout for alternative food sources."#4694•
"Why is the grassquit the way it is?" wonders Lefebvre. "It has the same ancestral genotype as the bullfinch, lives in the same environment. What makes it take such a totally different approach to food?" Why is one bird so much bolder, smarter, and more opportunistic than the other?#4689•
"Studies show that species that differ in feeding ecology also differ in learning ability—and in the brain structure underlying learning," says Lefebvre. So first up is an experiment presenting both birds with tasks to measure their basic cognitive abilities. It's a step toward linking the natural behavior the scientists see in the field with differences they can measure in the laboratory.#4707•
It's not an easy task. Just catching the grassquits is challenging. Lefebvre uses walk-in traps for bullfinches, but in twenty-five years of work here, he has never caught a grassquit in such a trap; the birds are far too wary. So the team uses mist nets to capture their subjects.#4711•
"Then the trick is to find something the grassquits will do," says Lefebvre. "They're so skittish that if an experimental apparatus is a little too weird, they just don't participate." In the field, one of Lefebvre's graduate students, Lima Kayello, has measured the speed at which the two species will feed from an open cup of seed.
The bullfinches find the novel food source in about five seconds, she says.
It takes the grassquits five days.
"A yogurt top filled with seeds is just too odd for them," says Kayello.#4690•
The great naturalist Edmund Selous, who loved birds passionately and observed them with scientific fervor, attributed this flocking phenomenon to telepathic thought transference from one bird to the next. "They circle; now dense like a polished roof, now disseminated like the meshes of some vast all-heaven-sweeping net, now darkening, now flashing out a million rays of light . . .
a madness in the sky," he wrote.
"They must think collectively, all at the same time, or at least in streaks or patches—a square yard or so of an idea, a flash out of so many brains."#4710•
There's no question—the bullfinches are quick studies. Most get the hang of the switching after only a few trials. The grassquits, on the other hand, take their time. They're slow, wary. But eventually they master the trick and end up making fewer wrong color choices than the bullfinches.#4712•
"Surprising," says Lefebvre, "but reassuring in a way: At least we found one test that grassquits do well. If one of the species you're using in your experiment fails every test you give it, the problem may be you, the researcher, not the animal. You may have failed to understand what is relevant to the way a bird sees the world."#4702•
It's tricky, however. In these kinds of lab tests, all sorts of variables may affect a bird's failure or success. The boldness or fear of an individual bird may affect its problem-solving performance. Birds that are faster at solving tasks may not be smarter; they may just be less hesitant to engage in a new task.
So a test designed to measure cognitive ability may really be measuring fearlessness.
Is the grassquit just a shier bird?#4697•
What's needed is an ecological rather than a laboratory measure of intelligence, they suggested. This can be found in an animal's ability to innovate in its own environment, "to find a solution to a novel problem, or a novel solution to an old one."#4691•
Other examples involved ingenious new ways of getting at food. There was the cowbird in South Africa using a twig to pick through cow dung. Several observers noted instances of green herons using insects as bait, placing them delicately on the surface of the water to lure fish. A herring gull adapted its normal shell-dropping technique to nail a rabbit.
Among the more inventive examples: bald eagles ice fishing in northern Arizona#4693•
One of Lefebvre's favorites was the report of vultures in Zimbabwe that perched on barbed-wire fences near minefields during the war of liberation, waiting for gazelles and other grazers to wander in and detonate the explosives. It gave the birds a ready-made meal already pulverized. However, says Lefebvre, "occasionally a vulture got caught at its own game and was exploded by a mine."#4686•
What are the smartest birds according to Lefebvre's scale?
Corvids, no surprise—with ravens and crows as the clear outliers—along with parrots. Then came grackles, raptors (especially falcons and hawks), woodpeckers, hornbills, gulls, kingfishers, roadrunners, and herons. (Owls were excluded from the search because they are nocturnal and their innovations are rarely observed directly, but rather inferred from fecal evidence.) Also high on the totem pole were birds in the sparrow and tit families.
Among those at the low end were quails, ostriches, bustards, turkeys, and nightjars.#4704•
simpletons?
"We're trying to come at these questions from different angles," says Lefebvre. "You have to begin in the field, with your boots on the ground, and really look closely at the species in question. If you want to understand birds, you have to know how they behave in the wild," he says. "Then you try to get inside their heads.
So we're doing field observations of behaviors, comparing innovations per species, conducting experiments with captive birds, and now, looking for a way to connect what we see in the field with what we're learning about genes and cells in the lab."#4674•
6
But the chickadee is more than just the bird of verve and agility. It's also acrobatic in its aptitudes, curious, intelligent, and opportunistic, with a remarkable memory: "a bird masterpiece beyond all praise," in the words of Forbush.#4706•
The signature chickadee-dee-dee flags a stationary predator, a raptor perched in the treetops or an eastern screech owl looming on a limb above. The number of those skipping-stone dees indicates the predator's size and hence the degree of threat. More dees means a smaller, more dangerous predator. This may seem counterintuitive, but small, agile predators that can maneuver easily are a greater menace than larger, more cumbersome ones.
So a pygmy owl may elicit four dees, while a great horned owl may garner only two#4681•
When gallflies were introduced to the American West in the 1970s to help control the spread of invasive spotted knapweed, chickadees seized the new opportunity. Templeton discovered that the birds quickly learned to spot the knapweed seedheads that harbored the highest densities of gallfly larvae—an unusually rich food.
Whatever cues they used were subtle, captured on the wing, with little to no time spent hovering over the plants deciding.
And yet almost invariably they found the seedheads with the major lode.
They would snatch their prizes in flight and carry them back to a tree to pluck out the larvae.#4696•
When you look at it this way, many bird species have surprisingly large brains for their body size. They're what scientists call hyperinflated, like our brains#4682•
Evolution has found other ways to streamline or totally eliminate a bird's unnecessary body parts. Bladders have been done away with. The liver has dwindled to a mere half gram. A bird's wild knot of a heart is four-chambered and double-barreled like our own, but tiny, with a beat far more rapid (between 500 and 1,000 times a minute for black-capped chickadees; 78 for humans).
Its respiratory system is quite extraordinary, proportionately larger than in mammals (one fifth of its body volume, compared with one twentieth in mammals), but much more efficient.
Its "flow-through" lung, encased in a rigid trunk, maintains a constant volume (in contrast with mammalian lungs, which expand and contract in a flexible body) and is connected to an intricate web of balloonlike sacs that store air outside the lungs.
Unlike most of its reptilian relatives, birds have only one functional ovary, on the left side; the right one was lost over evolutionary time.
Only in the breeding season is a bird burdened with heavy sex organs; for most of the year, testes, ovaries, and oviducts are vanishingly small.#4698•
Huxley was right, of course. Birds evolved from dinosaurs during the Jurassic period, 150 million to 160 million years ago. In fact, says paleontologist Stephen Brusatte of the University of Edinburgh, "we find that there is no clear distinction between 'dinosaur' and 'bird'. A dinosaur didn't just change into a bird one day; instead, the bird body plan began early and was assembled gradually, piece by piece, over 100 million years of steady evolution."#4700•
It's easy to catch the reptilian in birds. You can see it in their beady eyes and quick darting movements; in the pterodactyl-like wings of a rhinoceros hornbill; in a robin holding up his head in frozen alertness to catch a sound, his expressionless face remindful of a lizard's; or in a great blue heron—the slow heavy wing beat, the snaky finesse of its neck, the hoarse squawks, are all a throwback to dinosaur lagoons.
But it baffles the imagination to think that the tiny flashlike chickadee could have arisen from the big beasts of vanished ages.#4692•
Dinosaurs gave rise to chickadees and herons in part through a process of relentless shrinking, a kind of Alice in Wonderland phenomenon known as sustained miniaturization#4684•
How does a creature hold on to a big brain while the rest of its body shrinks? Birds managed the trick the same way we did: by keeping a babyish head and face. It's an evolutionary process called paedomorphosis (literally, "child formation"), whereby a creature evolves in such a way as to retain juvenile traits even after it matures.#4687•
Reproductive strategy plays a role in brain size. The 20 percent of bird species that are precocial—born with their eyes open and able to leave the nest within a day or two—have larger brains at birth than altricial birds. The latter are born naked, blind, and helpless and remain in the nest until they're as big as their parents, and only then fully fledge.
Precocial birds, such as shorebirds, typically take to life straightaway.
Though their brains are relatively large at hatching—allowing them to catch and eat an insect or run short distances when only days old—they don't grow much after birth, so they end up smaller than the brains of altricial birds#4685•
The same is true of brood parasites such as cuckoos, black-headed ducks, and honeyguides, birds that lay their eggs in the nests of others, sparing themselves the costs of rearing their own young. Their chicks, after chucking out their host's offspring (cuckoos) or killing them (honeyguides), also leave the nest early with a brain that's big enough to allow them to fend for themselves but without much later growth#4695•
Why do brood parasites have such small brains? Louis Lefebvre, who has studied brain size in honeyguides, suggests two possibilities. Maybe these birds need to outpace the developmental schedule of their host species, and as a result, they have evolved smaller brains. Or perhaps being a brood parasite relieves the brain of responsibility for all those things associated with raising your own young.
"We humans know how much energy it takes to raise a child," says Lefebvre.
"If we just dropped our babies into the nests of chimps, we would save ourselves a lot of information processing."#4699•
The 80 percent of bird species that are altricial, such as chickadees, tits, crows, ravens, and jays, among others, may be born small brained and helpless, but their brains—like ours—grow a great deal after birth, in part thanks to the nurturing of their parents.
In other words, nest sitters end up with bigger brains than nest quitters.#4677•
BRAIN SIZE is also correlated with how long a bird stays in its nest to apprentice with its parents after fledging; the longer the juvenile period, the bigger the brain, perhaps so that a bird can store all it learns. Most intelligent animal species have long childhoods.#4716•