Crows’ memories are made of this

An important prerequisite for intelligence is a good short-term memory which can store and process the information needed for ongoing processes. This “working memory” is a kind of mental notepad – without it, we could not follow a conversation, do mental arithmetic, or play any simple game.

In the animal kingdom, the group of birds including crows and ravens – the corvids – are known for their intelligence because they have just such a working memory. However, their endbrain – which is highly-developed but has a fundamentally different structure from that of mammals – has no cerebral cortex; and that is the part of the brain which in mammals produces the working memory. How do corvids manage to store important information from moment to moment?

To answer that question, three researchers from the Institute for Neurobiology at Tübingen University taught crows to play a version of the children’s game of “pairs.” Using a computer monitor, Lena Veit, Konstantin Hartmann and Professor Andreas Nieder briefly showed the crows a random image. The crows had to remember it for one second before choosing the same image from a selection of four by tapping the remembered picture with their beaks. In order to choose the correct image, they must have stored it in a working memory – which they appeared to do quite easily.

Simultaneous measurements of electric potentials in the crows’ brains showed that nerve cells in one particular area of the endbrain were responsible for this capacity to remember. Although the image had disappeared from the screen, those cells remained active during the short period of remembering – retaining the information about the image until the crow retrieved it in order to make the right choice. If a crow couldn’t remember and selected a wrong image, those particular endbrain cells were barely activated. Prolonged activation of such cells ensured that important information could be stored and later accessed.

Professor Nieder and his team conclude that cognitive abilities are possible in a range of differently-structured brains. “Clearly, a good working memory – an important characteristic of human beings – can also exist without a layered cerebral cortex. The corvids’ fundamentally differently-structured endbrain shows that evolution has found a number of independent solutions,” says Lena Veit.

There are great benefits in the ability to temporarily store information. “An organism with a good working memory is intelligent; it is released from the compulsion to respond immediately to stimuli,” says Professor Nieder. “The big question is now – how do neural networks in the brain have to be composed in order to actively store and process information?”

Physics-minded crows bring Aesop’s fable to life

Eureka! Like Archimedes in his bath, crows know how to displace water, showing that Aesop’s fable The Crow and the Pitcher isn’t purely fictional.

To see if New Caledonian crows could handle some of the basic principles of volume displacement, Sarah Jelbert at the University of Auckland in New Zealand and her colleagues placed scraps of meat just out of a crow’s reach, floating in a series of tubes that were part-filled with water. Objects potentially useful for bringing up the water level, like stones or heavy rubber erasers, were left nearby.

The crows successfully figured out that heavy and solid objects would help them get a treat faster. They also preferred to drop objects in tubes where they could access a reward more easily, picking out tubes with higher water levels and choosing tubes of water over sand-filled ones.

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Eat crow if you think I’m a bird-brain

Scientists have long suspected that corvids – the family of birds including ravens, crows and magpies – are highly intelligent. Now, Tübingen neurobiologists Lena Veit und Professor Andreas Nieder have demonstrated how the brains of crows produce intelligent behavior when the birds have to make strategic decisions. Their results are published in the latest edition of Nature Communications.

Crows are no bird-brains. Behavioral biologists have even called them “feathered primates” because the birds make and use tools, are able to remember large numbers of feeding sites, and plan their social behavior according to what other members of their group do. This high level of intelligence might seem surprising because birds’ brains are constructed in a fundamentally different way from those of mammals, including primates – which are usually used to investigate these behaviors.

The Tübingen researchers are the first to investigate the brain physiology of crows’ intelligent behavior. They trained crows to carry out memory tests on a computer. The crows were shown an image and had to remember it. Shortly afterwards, they had to select one of two test images on a touchscreen with their beaks based on a switching behavioral rules. One of the test images was identical to the first image, the other different. Sometimes the rule of the game was to select the same image, and sometimes it was to select the different one. The crows were able to carry out both tasks and to switch between them as appropriate. That demonstrates a high level of concentration and mental flexibility which few animal species can manage – and which is an effort even for humans.

The crows were quickly able to carry out these tasks even when given new sets of images. The researchers observed neuronal activity in the nidopallium caudolaterale, a brain region associated with the highest levels of cognition in birds. One group of nerve cells responded exclusively when the crows had to choose the same image – while another group of cells always responded when they were operating on the “different image” rule. By observing this cell activity, the researchers were often able to predict which rule the crow was following even before it made its choice.

The study published in Nature Communications provides valuable insights into the parallel evolution of intelligent behavior. “Many functions are realized differently in birds because a long evolutionary history separates us from these direct descendants of the dinosaurs,” says Lena Veit. “This means that bird brains can show us an alternative solution out of how intelligent behavior is produced with a different anatomy.” Crows and primates have different brains, but the cells regulating decision-making are very similar. They represent a general principle which has re-emerged throughout the history of evolution. “Just as we can draw valid conclusions on aerodynamics from a comparison of the very differently constructed wings of birds and bats, here we are able to draw conclusions about how the brain works by investigating the functional similarities and differences of the relevant brain areas in avian and mammalian brains,” says Professor Andreas Nieder.

Are Crows Mind Readers … Or Just Stressed Out?

Are crows mind readers? Recent studies have suggested that the birds hide food because they think others will steal it — a complex intuition that has been seen in only a select few creatures. Some critics have suggested that the birds might simply be stressed out, but new research reveals that crows may be gifted after all.

Cracks first began forming in the crow mind-reading hypothesis last year. One member of a research team from the University of Groningen in the Netherlands spent 7 months in bird cognition expert Nicola Clayton’s University of Cambridge lab in the United Kingdom studying Western scrub jays, a member of the crow family that is often used for these studies. The Groningen team then developed a computer model in which "virtual jays" cached food under various conditions. In PLOS ONE, they argued that the model showed the jays’ might be moving their food—or recaching it—not because they were reading the minds of their competitors, but simply because of the stress of having another bird present (especially a more dominant one) and of losing food to thieves. The result contradicted previous work by Clayton’s group suggesting that crows might have a humanlike awareness of other creatures’ mental states—a cognitive ability known as theory of mind that has been claimed in dogs, chimps, and even rats.

In the new study, Clayton and her Cambridge graduate student James Thom decided to test the stress hypothesis. First, they replicated earlier work on scrub jays by letting the birds hide peanuts in trays of ground corn cobs—either unobserved or with another bird watching—and later giving them a chance to rebury them. As in previous studies, the jays recached a much higher proportion of the peanuts if another bird could see them: nearly twice as much as in private, the team reports online today in PLOS ONE.

If two birds meet deep in the forest, does anybody hear? Until now, nobody did, unless an intrepid biologist was hiding underneath a bush and watching their behavior, or the birds happened to meet near a research monitoring station. But an electronic tag designed at the University of Washington can for the first time see when birds meet in the wild.

A new study led by a biologist at Scotland’s University of St. Andrews used the UW tags to see whether crows might learn to use tools from one another. The findings, published in Current Biology, supported the theory by showing an unexpected amount of social mobility, with the crows often spending time near birds outside their immediate family.

The study looked at crows in New Caledonia, an archipelago of islands in the South Pacific. The crows are famous for using different tools to extract prey from deadwood and vegetation. Biologists wondered whether the birds might learn by watching each other.

The results, as reported by St. Andrews, revealed “a surprising number of contacts” between non-related crows. During one week, the technology recorded more than 28,000 interactions among 34 crows. While core family units of New Caledonian crows contain only three members, the study found all the birds were connected to the larger social network.

The new paper is the first published study using the UW tags to record animal social interactions.

Why clever crow is no bird brain

Corvus moneduloides, a native of France’s South Pacific territory of New Caledonia, is one of the stars of the avian world.

It uses its beak to craft complex tools from sticks, leaves and other material and then inserts them into deadwood or vegetation to fish out insects and other food.

Researchers led by Jolyon Troscianko of the University of Birmingham in central England used an ophthalmoscope video camera to record field of view and eye movement as three wild-caught birds examined a baited tube.

The bird’s eyes are more forward-positioned, rather than sideways-positioned, which gives it exceptional “binocular overlap,” they found.

This is the area that is viewed by both eyeballs, and is important because it helps the brain judge the distance of nearby objects.

In New Caledonian crows, the binocular overlap is 61.5 degrees, which is at least 23.9 degrees greater than in non-tool-using species of crow that the researchers also examined.

Added to this is the crow’s unusually straight bill, the investigators found.

With it, the bird can get a firm grip on a tool and bring its tip into its field of binocular vision.

"These features enable a degree of tool control that would be impossible in other corvids [crows], despite their comparative cognitive abilities," says the study, published by the journal Nature Communications.

Dolphins, elephants and other birds are among non-primates that have been found to use tools. But the New Caledonian crow occupies a privileged place because its features are so specifically adapted for tools, says the study.

New Caledonian crows reason about hidden causal agents

We have generally believed that animals are not capable of very complex thought, even though many species use tools and engage in other complex behaviors.

Even a bird brain appears to be capable of understanding things that are not visible may be affecting their environment.

This study looks at whether New Caledonian crows, that were caught just for this experiment, are capable of attributing actions to a hidden cause, when they see that possible cause come and go.

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Cross a crow and it’ll remember you for years. Crows and humans share the ability to recognize faces and associate them with negative, as well as positive, feelings. The way the brain activates during that process is something the two species also appear to share, according to new research being published this week.

"The regions of the crow brain that work together are not unlike those that work together in mammals, including humans," said John Marzluff, University of Washington professor of environmental and forest sciences. "These regions were suspected to work in birds but not documented until now.

"For example it appears that birds have a region of their brain that is analogous to the amygdala of mammals," he said. "The amygdala is the region of the vertebrate brain where negative associations are stored as memories. Previous work primarily concerned its function in mammals while our work shows that a similar system is at work in birds. Our approach could be used in other animals – such as lizards and frogs – to see if the process is similar in those vertebrates as well."

Marzluff is the lead author of a paper being published the week of Sept. 10 in the online edition of the Proceedings of the National Academy of Sciences.