this weekAnimals with Jobs

February 1, 2005

Crows that Make Tools

The brains behind the beaks

Betty, a New Caledonian crow

I’ve seen numerous books about the differences between men and women. My own theory is that the main difference has to do with tools. When I walk into the tool section of a hardware store—guys, you know what I’m talking about—I get wide-eyed and giddy. Every tool suggests a new project or task. I want to come up with things to make or repair simply to justify owning another obscure tool. Although, to be perfectly honest, I don’t even care that much about using the tools, I just want to own them. One day when I was helping a friend of mine install some kitchen cabinets, he pointed out a particular piece of decorative trim that had cost US$100, then mentioned that he didn’t have the right kind of saw to cut it with. “Oh well,” he said with mock resignation, “I may have to break down and buy one. Too bad it costs $200.” I said, “It seems a pity to pay more for the tool than the material you’ll use it on.” My friend replied, “Not really—I have two pieces of trim to cut!” We laughed about this because to guys, tool ownership is its own reward.

Women, on the whole, don’t seem to appreciate the stereotypical male trait of wanting equipment for its own sake. This is equally true for things like computers and stereo components. Women don’t understand why we would spend our money on seemingly useless or frivolous tools instead of, say, shoes. But there are also, of course, counterexamples. I know women who are carpenters, computer geeks, and hi-fi buffs, as well as guys who like shoes better than tools. For every theory about the important differences between men and women, there seems to be a reason to doubt it.

Tools Are for the Birds
Likewise, humans, on the whole, tend to think of the ability to make and use tools as a defining characteristic of our species, something that sets us apart from other animals, that proves we’re more intelligent and more highly evolved. But here again, there are counterexamples. A few species of animals use tools, the canonical example being a stick pressed into service to fish insects out of a log or burrow for food. But there are even a few—very few—nonhuman species that make their own tools. It’s not too much of a stretch to think of other primates making tools—especially if you’ve read Congo by Michael Crichton. And in fact, some chimpanzees and orangutans have been known to make simple tools (though not, as far as anyone knows, stone paddles). But even some birds have been observed to make their own tools. The latest species to make waves among scientists and achieve worldwide acclaim is the New Caledonian crow (Corvus moneduloides), a bird with surprising and impressive abilities.

At the University of Oxford, researchers in the Behavioural Ecology Research Group are studying tool use among New Caledonian crows. It’s one thing to observe animals using tools in the wild, but in the relatively controlled environment of a university laboratory, scientists are able to watch (and film) the crows much more extensively and determine in greater detail how they behave. Their findings over the last several years have given the crows (and the people studying them) minor celebrity status. Time after time, the crows have unhesitatingly used a variety of wooden tools to retrieve food by pushing or pulling it out of a tube.

But these crows also make new tools to accomplish specific tasks. It had long been known that New Caledonian crows in the wild made simple tools from leaves and twigs, but they have even figured out how to make tools out of materials they could never have encountered before. In one experiment, researchers provided a pair of crows, Betty and Abel, with two pieces of wire—one straight, one hooked. They put some food in a small bucket with a handle and dropped the bucket into a tube, so that the only way to retrieve it would be to pull it out with the hooked wire. After Abel tried and failed, he flew off with the hooked wire, leaving Betty with the straight wire. No problem—she immediately bent it into a hook, pulled out the bucket, and had lunch. The first time I saw a video of this, I was absolutely stunned. It sounds like such a simple task, but it is just not the kind of ability I’ve ever thought of animals as having—certainly not birds.

Crows Just Want to Have Fun
New Caledonian crows—at least those being observed in the lab—seem to use tools constantly, not just when they’re trying to get food. This poses some unexpected challenges for the scientists who work with them. The crows are so adept at using tools that researchers have come into the lab to find the fire alarms disassembled. And crows are just as likely to try prodding around in an electrical socket as a test tube. If you thought it was difficult to child-proof your living room, imagine crow-proofing a university research facility.

But lest you think these crows are all work and no play, they also seem to use tools just to have fun. Dr. Jackie Chappell, a researcher who spent years working with the crows, had this to say about the way they like to play:

One aviary in particular has an obsession with stones. They pick stones up from the aviary floor and bring them into the housing room. We then find stones everywhere. They carefully place them inside the tubes that we use to test their tool use, and they have hammered perfectly sized stones into holes we’ve drilled in logs to give them natural probing sites. They are such a tight fit that we can’t get them out. They also play at rolling pebbles inside a tube. We have some film of them carefully inserting a pebble into a plastic tube, then slowly lifting one end of the tube so that the pebble rolls to the other end (and makes a nice noise—we don’t know if this is the objective), then they repeat the procedure from the other end. This can go on for minutes on end.

Is “Bird Brain” a Compliment?
While it’s very interesting that New Caledonian crows make and use tools, what exactly does this prove? By itself, nothing. But what scientists studying the New Caledonian crow hope to demonstrate is evidence of complex cognitive abilities—including things like abstract reasoning. It may be that the crows’ cognitive abilities are limited to tool-related tasks, or it could be that they’re more general. A series of experiments is underway to find out.

One type of experiment involves selectivity. Observation in the wild suggests that crows select their tools according to the task at hand (or beak). Given a range of tasks and materials the crows have never encountered before, will they consistently select (or make) the best tool for the job? Likewise, are they flexible in their use of tools? Having used a certain type of tool for a given task, will they also use less-suitable tools for the same task if necessary? And does their use of tools suggest an implicit understanding of the basic rules of physics?

You’ve Got Questions? We’ve Got Birds
Tool use by New Caledonian crows also raises a host of other questions. For instance, how do they learn to do this? Are there secret tool-making classes in the trees, or do young birds just watch their parents attentively? Once acquired, how does the knowledge spread? Is there something unique in their social interactions that facilitates learning about tools? And why don’t other birds make tools? The New Caledonian crow doesn’t have the largest brain among birds or the most complex social system, so what makes it unique in this regard? Could other birds learn how to use tools too, given the right environment? For that matter, could a New Caledonian crow teach another species of bird to use tools? These are just a few of the many questions scientists are hoping to answer.

How soon these answers arrive will depend on whether the researchers can keep ahead of the birds. The crows are so clever at solving problems that they often come up with entirely novel ways of accomplishing tasks, thus derailing carefully designed experiments. As I read about the research, I’m reminded of the white mice in Douglas Adams’s Life, the Universe, and Everything. The furry little creatures were really “hyperintelligent pan-dimensional beings”; while scientists thought they were running experiments on the mice, the mice were actually experimenting on humans. But I don’t worry about a conspiracy of crows. Any creature that likes tools is OK with me. —Joe Kissell

More Information about Crows that Make Tools…

This article was featured in I and the Birds of Idaho, the 25th edition of the “I and the Bird” Blog Carnival.

Everything you ever wanted to know about New Caledonian crows and their use of tools can be found on Oxford University’s Behavioural Ecology Research Group Web site, specifically the Tool Use in Corvids section. This includes photos and movies, the most impressive one of which shows Betty making a hook to lift a bucket out of a tube.

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Michael Crichton (Congo) and Douglas Adams (Life, the Universe, and Everything) are two of my favorite authors.

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I can’t take credit for the “task at beak” bit—that goes to Jackie Chappell, a researcher who spent years working with the crows. Dr. Chappell doesn’t usually go by “Jack,” but I can’t resist mentioning the song “Jack’s Crows” by folk singer John Gorka (on the album of the same name). It’s not an especially cheery song, but the title is apropos. Jack’s Crows is one of my favorite John Gorka albums, by the way—I especially like the songs “Good” and “I’m From New Jersey.”