Minds of Their Own: Birds Gain Respect
By SANDRA BLAKESLEE

Published: February 1, 2005

Birdbrain has long been a colloquial term of ridicule. The common notion is that birds' brains are simple, or so scientists thought and taught for many years. But that notion has increasingly been called into question as crows and parrots, among other birds, have shown what appears to be behavior as intelligent as that of chimpanzees.

The clash of simple brain and complex behavior has led some neuroscientists to create a new map of the avian brain.

Today, in the journal Nature Neuroscience Reviews, an international group of avian experts is issuing what amounts to a manifesto. Nearly everything written in anatomy textbooks
about the brains of birds is wrong, they say. The avian brain is as complex, flexible and inventive as any mammalian brain, they argue, and it is time to adopt a more accurate
nomenclature that reflects a new understanding of the anatomies of bird and mammal brains.

"Names have a powerful influence on the experiments we do and the way we think," said Dr. Erich D. Jarvis, a neuroscientist at Duke University and a leader of the Avian Brain
Nomenclature Consortium. "Old terminology has hindered scientific progress."

The consortium of 29 scientists from six countries met for seven years to develop new, more accurate names for structures in both avian and mammalian brains. For example, the bird's
seat of intelligence or its higher brain is now termed the pallium.

"The correction of terms is a great advance," said Dr. Jon Kaas, a leading expert in neuroanatomy at Vanderbilt University in Nashville who did not participate in the
consortium. "It's hard to get scientists to agree about anything."

Scientists have come to agree that birds are indeed smart, but those who study avian intelligence differ on how birds got that way. Experts, including those in the consortium, are
split into two warring camps. One holds that birds' brains make the same kinds of internal connections as do mammalian brains and that intelligence in both groups arises from these
connections. The other holds that bird intelligence evolved through expanding an old part of the mammal brain and using it in new ways, and it questions how developed that intelligence is.

"There are still puzzles to be solved," said Dr. Peter Marler, a leading authority on bird behavior at the University of California, Davis, who is not part of the consortium. But the
realization that one can study mammal brains by using bird brains, he said, "is a revolution."

"I think that birds are going to replace the white rat as the favored subject for studying functional neuroanatomy," he added.

The reanalysis of avian brains gives new credibility to many behaviors that seem odd coming from presumably dumb birds. Crows not only make hooks and spears of small sticks to carry
on foraging expeditions, some have learned to put walnuts on roads for cars to crack. African gray parrots not only talk, they have a sense of humor and make up new words. Baby
songbirds babble like human infants, using the left sides of their brains.

Avian brains got their bad reputation a century ago from the German neurobiologist Ludwig Edinger, known as the father of comparative anatomy. Edinger believed that evolution was
linear, Dr. Jarvis said. Brains evolved like geologic strata. Layer upon layer, the brains evolved from old to new, from fish to amphibians to reptiles to birds to mammals. By
Edinger's standards, fish were the least intelligent. Humans, created in God's image, were the most intelligent. Edinger cut up all kinds of vertebrate brains, noting similarities and
differences, Dr. Jarvis said.

In mammals, the bottom third of the brain contained neurons organized in clusters. The top two-thirds of the brain, called the neocortex, consisted of a flat sheet of cells with six
layers. This new brain, the seat of higher intelligence, lay over the old brain, the seat of instinctual behaviors.

In humans, the neocortex grew so immense that it was forced to assume folds and fissures, so as to fit inside the skull.

Birds' brains, in contrast, were composed entirely of clusters. Edinger concluded that without a six-layered cortex, birds could not possibly be intelligent. Rather, their brains were fully dedicated to instinctual behaviors.

This view persisted through the 20th century and is still found in most biology textbooks, said Dr. Harvey Karten, a neuroscientist at the University of California, San Diego, and
a member of the consortium, whose research has long challenged the classic view.

There is a bird way and a mammal way to create intelligence, Dr. Karten said. One uses clusters. One uses flat sheet cell in six layers. Each exploits the basic design of having a
lower brain and a higher brain with mutual connections.

In the 1960's, Dr. Karten carried out experiments using new techniques to trace brain wiring and identify the paths taken by various brain chemicals. In humans, a chemical called
dopamine is found mostly in lower brain areas, called basal ganglia, which consist of clusters.

Using the same tracing techniques in birds, Dr. Karten found that dopamine also projected primarily to lower clusters and no higher. Later studies show numerous similarities between
clusters in the mammalian brain and lower clusters in the avian brain. Experts now agree that the two regions are evolutionarily older structures that lie underneath a newer mantle.

Where the experts divide is on the question of the upper clusters in a bird's brain. Agreed, they are not primitive basal ganglia. But where did they come from? How did they
evolve? What is their function?

Dr. Karten and others in the consortium think these clusters are directly analogous to layers in the mammalian brain. They migrate from similar embryonic precursors and perform the
same functions.

For example, in mammals, sensory information - sights, sounds, touch - flows through a lower brain region called the thalamus and enters the cortex at the fourth layer in the
six-layered cortex.

In birds, sensory information flows through the thalamus and enters specific clusters that are functionally equivalent to the fourth layer. In this view, other clusters perform functions done by different layers in the mammal brain.

A second group, including Dr. Georg Striedter of the University of California, Irvine, a consortium member, believes that upper clusters in the avian brain are an elaboration of two mammalian structures - the claustrum and the amygdala. In this view, these structures look alike in bird and mammal embryos. But in birds they grow to enormous proportions and have evolved entirely new ways to support intelligence.

In mammals, the amygdala is involved in emotional systems, Dr. Striedter said. "But birds use it for integrating information," he said. "It's not emotional anymore."

Meanwhile, examples of brilliance in birds continue to flow from fields and laboratories worldwide.

Dr. Nathan Emery and Dr. Nicola Clayton at the University of Cambridge in England study comparisons between apes and corvids - crows, jays, ravens and jackdaws. Relative to its
body size, the crow brain is the same size as the chimpanzee brain.

Everyone knows apes use simple tools like twigs, Dr. Emery said, selecting different ones for different purposes. But New Caledonian crows create more complex tools with their beaks
and feet. They trim and sculpture twigs to fashion hooks for fetching food. They make spears out of barbed leaves, probing under leaf detritus for prey.

In a laboratory, when a crow named Betty was given metal wires of various lengths and a four-inch vertical pipe with food at the bottom, she chose a four-inch wire, made a hook and
retrieved the food.

Apes and corvids are highly social. One explanation for intelligence is that it evolved to process and use social information - who is allied with whom, who is related to whom
and how to use this information for deception. They also remember.

Clark nutcrackers can hide up to 30,000 seeds and recover them up to six months later.

Nutcrackers also hide and steal. If they see another bird watching them as they cache food, they return later, alone, to hide the food again. Some scientists believe this shows a
rudimentary theory of mind - understanding that another bird has intentions and beliefs.

Magpies, at an earlier age than any other creature tested, develop an understanding of the fact that when an object disappears behind a curtain, it has not vanished.

At a university campus in Japan, carrion crows line up patiently at the curb waiting for a traffic light to turn red. When cars stop, they hop into the crosswalk, place walnuts
from nearby trees onto the road and hop back to the curb. After the light changes and cars run over the nuts, the crows wait until it is safe and hop back out for the food.

Pigeons can memorize up to 725 different visual patterns, and are capable of what looks like deception. Pigeons will pretend to have found a food source, lead other birds to it and then
sneak back to the true source.

Parrots, some researchers report, can converse with humans, invent syntax and teach other parrots what they know. Researchers have claimed that Alex, an African gray, can grasp
important aspects of number, color concepts, the difference between presence and absence, and physical properties of objects like their shapes and materials. He can sound out letters the same way a child does.

Like mammals, some birds are naturally smarter than others, Dr. Jarvis said. But given their range of behaviors, birds are extraordinarily flexible in their intelligence quotients.
"They're right up there with hominids," he said.

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Tracking reveals albatross habits By Richard Black BBC environment correspondent

The albatross is one of the most endangered bird groups in the world

Research by UK scientists may prove vital in protecting the albatross.

British Antarctic Survey researchers followed more than 40 grey-headed albatrosses as they flew around the world, identifying where they fed.

All the birds which made a circumnavigation stopped for food in the same places.

Banning harmful fishing methods from those areas of the ocean could help halt the decline of what is one of the world's most endangered group of birds.

They are being killed in large numbers by becoming snared on the hooks of long-line fishing boats.

Light tags

Five years ago scientists from the British Antarctic Survey attached tiny tags to grey-headed albatrosses as they reared chicks on the Atlantic island of South Georgia.

They were able to follow the birds for 18 months until they returned to South Georgia to breed again.

The tags are simple devices weighing just a few grams.

We hope it's the beginning of a process of dialogue with the fishing industry   Dr John Croxall

They record the timing of sunrise and sunset, enabling scientists to work out their position on each day; researchers retrieved the tags when the birds returned to South Georgia.

Many of the tagged albatrosses flew around the world, some more than once, and some completing a circumnavigation in just six weeks.

Others stayed close to home, and a third group went to winter habitats in the Indian Ocean.

"It's the first time we've managed to achieve coverage for an entire breeding interval," the British Antarctic Survey's director of conservation biology Dr John Croxall told BBC News.

"We were absolutely staggered to find how stable these three patterns are. "Birds that went round the world twice went back to the same locations, which is pretty amazing, because these are just about the most spectacular migrations of any albatross."

More species

The reason why birds should stop off at the same places is not clear, but the implication for conservation is.

Scientists have been tracking the birds using satellites

In principle, it should be possible to protect albatrosses simply by making sure that boats in the crucial areas use safe fishing gear.

"We hope it's the beginning of a process of dialogue with the fishing industry," said Dr Croxall.

"We and other groups are now carrying out the same kind of research with other species of albatross; and as one year follows the next we can have more of these species on line."

Currently boats fishing south of a latitude of 60 degrees are obliged to use techniques which are "albatross-safe", which can reduce the number of birds snared by about 90%.

These techniques include using heavier weights on the fishing lines, which make them sink faster, giving the birds less time to eat the bait, and hanging streamers from the back of the boat which move in the wind, scaring the birds away.

Dr Croxall believes that this sort of measure should be extended to latitudes between 30 and 60 degrees south.

Shedding feathers early may enhance sex appeal, new songbird study shows

 Birds that migrate early in the season may have a distinct advantage when it comes to attracting the opposite sex, say researchers from Queen's University and the Smithsonian Institution.

And it's all about the feathers.

Researchers were surprised to discover that the timing of a male songbird's reproduction cycle affects the colour of his feathers and may have important implications for his success in attracting mates. When migratory songbirds raise their young extremely late in the summer, many don't have time to molt (shed their feathers and replace with new growth) before heading south, the new study shows.

"This means they must molt at stopover sites on their journey to tropical winter habitats," explains Ryan Norris, who conducted the research as part of his PhD in biology at Queen's, supervised by Professors Laurene Ratcliffe (Queen's Biology) and Peter Marra (Smithsonian Environmental Research Center).

"Their replacement feathers, grown en route, are less colourful than those of birds that had time to molt before migration, which may put them at a disadvantage in attracting females the following breeding season," says Dr. Norris. "Both findings - that molting in some songbirds occurs after migration has begun, and that their new feathers are duller in colour - were surprising."

The study will be published Dec. 24 in the journal Science.

Until now scientists have assumed that most species of migratory birds molt before they migrate. The team discovered that in fact some begin their migration, molt at a "stopover" site, then continue to their winter habitat. Forty per cent of the male American Redstarts in the study molted in their tail feathers at areas up to 2000 kilometers south of their breeding grounds.

By measuring stable hydrogen isotopes in the newly grown feathers when birds returned the following spring to breed at the Queen's University Biology Station north of Kingston, the researchers were able to determine the approximate region where molting had occurred. And when the feathers were analyzed with a spectrometer measuring how much light of different wavelengths is reflected, significant differences in colour were also detected.

A key indicator of the songbirds' health and quality is the concentration of carotenoid in the feathers, which causes orange-red light to be reflected in their feathers. Physiological stress during molting can reduce carotenoid deposits in the feathers.

"Studies of other bird species have shown that females prefer males with higher concentrations of carotenoids, and thus brighter, more intense colours," says Queen's biologist Bob Montgomerie, who did the colour analysis of feathers for this project. "What we didn't know until now is that birds' colours in any given year may be affected by what happened to them in the previous breeding season.

"That's exciting because 'cost of reproduction' is a general, organism-wide problem of many species, not just birds."

The other member of the research team from Queen's is geology professor Kurt Kyser, director of the university's Facility for Isotope Research, where the stable isotope measurements were conducted.

The study was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Foundation for Innovation (CFI), Ontario Innovation Trust (OIT), National Science Foundation (NSF), the Smithsonian Institution, and the American Museum of Natural History.
 

 

 

Environmental Enrichment for Captive Animals
by Rob J. Young

For the first time, science and practice have been integrated in a text that will appeal to academics and practitioners. In this comprehensive book, Young covers scientific principles on environmental enrichment as it relates to animal welfare. The text presents scientific evidence that environmental enrichment improves animal welfare and describes practical ways to implement environmental enrichment. By bringing theory and practice together, Young aims to advance the understanding of environmental enrichment and improve animal welfare. This text will appeal to animal welfare experts, laboratory animal technicians, veterinarians, farmers, and animal behavior specialists, as well as students of these disciplines.