Bird Brains
by Gareth Huw Davies
The scene: a traffic light crossing
on a university campus in
Japan. Carrion crows and
humans line up patiently,
waiting for the traffic to
halt.
When the lights change,
the birds hop in front of
the cars and place
walnuts, which they
picked from the adjoining
trees, on the road. After
the lights turn green again, the birds fly away and vehicles drive
over the nuts, cracking them open. Finally, when it’s time to
cross again, the crows join the pedestrians and pick up their
meal.
If the cars miss the nuts, the birds sometimes hop back and put
them somewhere else on the road. Or they sit on electricity
wires and drop them in front of vehicles.
Biologists already knew the corvid family–it includes crows,
ravens, rooks, magpies and jackdaws–to be among the smartest
of all birds. But this remarkable piece of behavior–it features in
the final program of “Life of Birds”–would seem to be a
particularly acute demonstration of bird intelligence.
The crows in Japan have only been cracking nuts this way since
about 1990. They have since been seen doing it in California.
Researchers believe they probably noticed cars driving over nuts
fallen from a walnut tree overhanging a road. The crows already
knew about dropping clams from a height on the seashore to
break them open, but found this did not work for walnuts
because of their soft green outer shell.
Other birds do this, although not with quite the same precision.
In the Dardia Mountains of Greece, eagles can be seen carrying
tortoises up to a great height and dropping them on to rocks
below. The hapless Aeschylus (525-456 BC), a father of Greek
tragic drama, is said to have met his end by this means.
A seer predicted he would die when a house fell on him, so the
wary scribe departed for the hillsides, well away from any
dwellings, where he believed he was safe. He wasn’t. An eagle is
said to have mistaken Aeschylus’ bald pate for a stone, and
dropped the creature in its “house” onto it.
A Japanese
carrion crow
examines the
fruit of its
labors
Scientists have argued for decades over whether wild creatures,
including birds, show genuine intelligence.
Some still consider the human mind to be unique, with animals
capable of only the simplest mental processes. But a new
generation of scientists believe that creatures, including birds,
can solve problems by insight and even learn by example, as
human children do. Birds can even talk in a meaningful way.
Some birds show quite astonishing powers of recall. The Clarke’s
nutcracker, a type of North American crow, may have the animal
world's keenest memory. It collects up to 30,000 pine seeds
over three weeks in November, then carefully buries them for
safe keeping across over an area of 200 square miles. Over the
next eight months, it succeeds in retrieving over 90 percent of
them, even when they are covered in feet of snow.
On the Pacific island of
New Caledonia, the crows
demonstrate a toolmaking, and tool using,
capability comparable to
Palaeolithic man’s. Dr
Gavin Hunt, a New
Zealand biologist, spent
three years observing the
birds. He found that they
used two different forms
of hooked “tool” to pull
grubs from deep within tree trunks.
Other birds and some primates have been seen to use objects to
forage. But what is unusual here is that the crows also make
their own tools. Using their beaks as scissors and snippers, they
fashion hooks from twigs, and make barbed, serrated rakes or
combs from stiff leathery leaves. And they don’t throw the tools
away after one use–they carry them from one foraging place to
another.
Scientists are still debating what this behavior–shown in program
three–means. Man’s use of tools is considered a prime indication
of his intelligence. Is this a skill acquired by chance? Did the
crows acquire tool making skills by trial and error rather than
planning? Or, in its ability to adapt and exploit an enormous
range of resources and habitats, is the crow closer to humans
than any other creature?
Dr Hunt, then of Massey University in New Zealand, said this of
his research: “There are many intriguing questions that remain
to be answered about crows’ tool behavior. Most important
would be whether or not they mostly learn or genetically inherit
the know-how to make and use tools. Without knowing that it is
The
Caledonian
Crow uses a
twig as a tool
to extract
grubs
difficult to say anything about their intelligence, although one
could guess that these crows have the capability to be as clever
as crows in general.”
The woodpecker finch, a
bird of the Galapagos, is
another consummate
toolmaker. It will snap off
a twig, trim it to size and
use it to pry insects out
of bark. In captivity, a
cactus finch learnt how to
do this by watching the
woodpecker finch from its
cage. The teacher helped
the pupil by passing a
ready-made spine across for the cactus finch to use.
Sometimes a bird species’ very survival depends on its ability to
learn fast. Birds need to recognize a cuckoo egg dumped in their
own nest and either throw out the strange egg or desert the nest
to start afresh. In Japan, the common cuckoo recently switched
to a new, unsuspecting host on which to dump its eggs, the
azure-winged magpie. The emerging cuckoo chicks ejected their
foster siblings, and the magpie population dropped dramatically.
Ten years on, the magpies started to fight back. They learnt to
detect the “foreign” eggs. Within a few years, there was a fourfold increase in its rejection of cuckoo eggs. The speed with
which the magpie changed its behavior has astounded
biologists.
Another sign of
intelligence, thought to
be absent in most nonhuman animals, is the
ability to engage in
complex, meaningful
communication. The work
of Professor Irene
Pepperberg of the
University of Arizona,
Tucson, has now shown
the general perception of
parrots as mindless mimics to be incorrect.
The captive African grey parrot Alex is one of a number of
parrots and macaws now believed to have the intelligence and
emotional make-up of a 3 to 4 year old child. Under the tutelage
of Professor Pepperberg, he acquired a vocabulary of over 100
words. He could say the words for colors and shapes and,
apparently, use them meaningfully. He has learned the labels for
The Galapogos
Finch also uses
a twig to
extract a meal
more than 35 different objects; he knows when to use “no,” and
phrases such as “come here”, “I want X,” and “Wanna go Y.”
A bird’s ability to understand, or speak, another bird’s language
can be very valuable. New Zealand saddlebacks, starling-like
birds, occupy the same territory for years. They have distinct
song “dialects” passed on through the generations.
New territory vacancies are hard to find, so young males are
always on the look-out for new widows into whose territory they
can move. While they wander around the forest, they learn the
different dialect songs, just as we might learn a language or
develop a regional dialect.
As soon as a territory-owning male dies, a new young male may
move in to take over within 10 minutes. He will immediately
start singing the dialect of the territory he is in.
Intelligence–if this is what scientists agree these birds possess–
is not limited to the birds we always thought of as “bright.” In
recent experiments at Cardiff University in Britain, a pigeon
identified subtle differences between abstract designs that even
art students did not notice. It could even tell that a Picasso was
not the same as a Monet. The experiment seems to show that
pigeons can hold concepts, or ideas, in their heads. The visual
concept for the pigeon is Picasso’s painting style.
Some birds seem to indulge in “intelligent” play. The kea, a New
Zealand parrot, has been filmed ripping (inedible) windscreen
wipers off cars. Young keas, in a neat variation of ringing the
doorbell and running away, are known to drop rocks on roofs to
make people run outside.
Jack the jackdaw was raised by wildlife film producer John
Downer. As soon as Jack was mature, he was released into the
wild. However, he couldn’t stay away. “One thing he is totally
fascinated by is telephones,” said Downer. “He knows how to hit
the loudspeaker button and preset dial button. Once we came
into the office to find him squawking down the telephone to the
local travel agent.”
Jack also likes to fly down onto the mirror of the production car
when he sees somebody going out. “He turns into the wind, gets
his head down and surfs on the air current until we reach about
30 mph when he gives up.
“Like all jackdaws, Jack shows great versatility and intelligence.
Because he has to exploit a wide range of foods, he is
investigating things all the time.”
However, scientists believe it is not physical need that drives
creatures to become smarter, but social necessity. The
complexities of living together require a higher level of
intelligence. Corvids and parrots, along with dolphins, chimps,
and humans are all highly social–and smart–animals.
Some ravens certainly apply their intelligence for the good of the
flock. In North America, they contact other ravens to tell them
the location of a carcass. Ravens are specialized feeders on the
carcasses of large mammals such as moose during the harsh
winter months of North America. The birds roost together at
night on a tree, arriving noisily from all directions shortly before
sunset. The next morning, all the birds leave the roost as highly
synchronized groups at dawn, giving a few noisy caws, followed
by honking.
They may all be flying off in the direction taken by a bird, which
had discovered a carcass the previous day. This bird leads the
others to his food store, apparently sharing his prize finding with
the rest of the flock.
Ravens share information about their findings of food carcasses
because dead animals are patchily distributed and hard to find.
Many eyes have a better chance of finding a carcass, and once
one has been located, the information is pooled.
Although the carcass now has to be shared between more
individuals, the heavy snowfall and risk of mammal scavengers
taking the kill mean that a single bird or a small group could not
eat it all alone anyway. Some are even believed to solicit help
with the carving, by tipping off other predators, such as wolves,
about the meat so they will rip it open and make it more
accessible to the ravens.
The African honeyguide lures badgers to bees nests, and feeds
on the leftovers. To humans they offer their services as paid
employees. They call and fly backwards and forward to draw
local tribespeoples’ attention to the location of honeycombs, and
are then rewarded with a share of the takings for their trouble.
Of course, the bird world has its share of “bird brains.” There are
the birds that build three nests behind three holes under a flower
pot, because they can't remember which is which, and birds that
attack their own reflections. The Hawaiian goose is as innocent
of danger as a baby crawling along the girder in an unfinished
skyscraper. It would walk up to an introduced mongoose on
Hawaii, and be attacked.
The level of intelligence among birds may vary. But no living bird
is truly stupid. Each generation of birds that leaves the
protection of its parents to become independent has the inborn
genetic information that will help it to survive in the outside
world and the skills that it has learned from its parents.
They would never have met the challenge of evolution without
some degree of native cunning. It’s just that some have much
more than others.