Nicky Clayton: Are crows as smart as children?

In this edition of Titans of Science, Chris Smith speaks with expert in animal comparative cognition, Nicky Clayton...

Chris - Today I am at Clare College to meet Nicky Clayton, professor of comparative cognition at the University of Cambridge and also a fellow of the Royal Society. Nicky's dedicated much of her life to the study of the cognitive performance, behaviour and problem solving abilities of corvids, they're members of the crow family. She graduated with a degree in Zoology from the University of Oxford in 1984 before she embarked on a PhD at the University of St. Andrews. It's Nicky's work on animal cognition as well as cognitive development in human children here in Cambridge. That's made her a leader in the field. Nicky, you've pioneered this field of how birds think. Why did that attract you in the first place? Why did you go into that?

Nicky - I always wanted to be a bird. I've got invisible wings. That's why you can't see them. And it's my passion and fascination for birds that drew me to both science and the arts. I wanted to move like a bird and that's what drew me to ballet. And then later in life, other forms of dance and my long standing collaboration with Mark Baldwin, OBE. But it also drew me to science because I wondered what lies behind that beady eye. What do birds think about and how do they do it without the linguistic narrative structure that we take for granted?

Chris - They do have a language of sorts though, because they seem to one another.

Nicky - Yes, they certainly communicate and they're very vocal. We can hear some blackbirds singing in the background and a couple of great tits actually. But whether it's language in the way humans use language is another issue because we have words that have very specific meanings with a very tight grammatical structure. So for example, if I say 'A loves B', it doesn't necessarily follow that 'B loves A'. Although it's interesting because recent work not done by me, but colleagues in Germany have shown that crows are able to verbalise numbers and count. So yes, there is some evidence that they do have some kind of rudimentary linguistic skills. And in our lab, one of my PhD students, Francesca Cornero, has been working with our superstar rook. His name is Leonidas, Leo for short. And he responds to human commands in the way that dogs do. But unlike dogs, he's not domesticated. So he can do come here, he can do speak, and he goes 'rah rah rah' in rook style. He can do stay and wait and fly up. So he responds to human commands and from different humans. So it is interesting that there are some linguistic skills and it's certainly true that vocal learners in general, so songbirds, hummingbirds and parrots seem to be particularly intelligent.

Chris - If birds could sit an IQ test like we do for humans, what IQ would we give them?

Nicky - Well, that's a good question. Obviously, if we are talking about language one thing's for sure. They can't read and write. So there's no point asking them to sit at a desk. They could perch that wouldn't be a problem. Holding a pencil and a beak is probably all right as well. But the reading and writing bit, I fear is a non-starter. So I suppose really you start with problem solving tasks. And I've always thought that the important thing was to pick behaviours that they naturally do for a living so that you tap into their natural talents. And that I suppose has been the approach throughout my career. I've studied many different species of birds, many of them but not exclusively corvid. But I've always thought to look at natural behaviours that they do for a living and use those to see if you can tap into their cognitive abilities.

Chris - How old would a child have to be, though, in order to do some of the things that you found these birds are capable of working out how to do and doing?

Nicky - Well, it depends on the task. One example comes from one of Aesop's fables. And I do wonder whether Aesop's fable had some fact to it originally, but the fable is called the crow and the picture and the story is that as this crow is thirsty and it encounters a jug of water and it wants a drink from the jug because that's the only water source currently available. But it can't reach the water because the water level's too low. And so it gathers up some stones, plops them into the picture, raising the water level in the jug, therefore enabling it to drink. Well, we've done similar tasks with our corvids. We've looked at rooks and we've looked at Eurasian jays and New Caledonian crows and they all do it. We don't make them thirsty. That seems a bit cruel. It's fine if a bird happens to be thirsty. But in the lab we bribe them using wax worms. And for children actually we bribe them using stickers, <laugh> and the stickers say 'University of Cambridge, I'm as clever as a crow'. And the children love them because they can't get these fancy stickers anywhere else. So it's bribery, but it's not a cruel kind of bribery.

Chris - The birds can do this if you give them a challenge like the Aesop fable trying to get to the water, they naturally seem to know, in inverted commas, how to raise the water level by dropping something in. And that will displace water upwards.

Nicky - So we give them stones and what we find is that once a stone has accidentally been knocked into the tube, they then start adding stones to the tube to raise the water level. We know that they don't put stones in the tube if the tube is full of sand instead of water. And they don't put stones into the tube if it's full of air rather than water. So they seem to understand that it only works with water. First trial, so they instantly know it. And then you can give them a choice of objects to put in the tube with water. And they deliberately choose the heavy ones that raise the water level, not the ones that sink. And I've got wonderful videos of this and the audience can probably see some of these on YouTube or on BBC cleverest animal footage where Romero, one of my rather handsome gentleman Eurasian jays, he's rather gorgeous darlings, and he loves to put the stones in. But if he puts an item that floats in, he immediately removes the offending article and then focuses on the stones to raise the water level to get his delicious wax worm.

Chris - Is it just weight or do they also know that displacement is proportional to the volume? So if they put something that will sink but has a big volume, it's going to displace more water and push the level up so it takes them less time. Do they get that?

Nicky - Well, I don't think they've been trained on Archimedes' principle to be fair. However, yes, they do get it. So they only add in the number of stones they need to raise the water level and they don't need to have felt the stones beforehand. So in one experiment, which we called the fan experiment, they could simply see or infer which ones were heavy and which ones were light based on the way they moved in the wind. So obviously the light ones blew all over the place and the heavy ones didn't. And they instantly then went for the heavy ones to raise the water level. And we did the same thing with kids, with children, except obviously we didn't put wax worms on the top. I don't think the children would've been very interested in those. We had little stickers that float and the little stickers that float could then be exchanged at the end if they got a sticker for this really fancy posh sticker that said, I'm as clever as a crow. And children didn't pass the task until they were eight years of age.

Chris - Wow. So that would put the bird reasoning at the level of maybe an 8-year-old? In some respects,

Nicky - Yes, in some respects. Because I always think we have to be a bit careful. There are many ways in which they're not like 8-year-old children. They don't have hands, for example. They do have wings. Most children do not. Although as I told you I have invisible wings. But that's another story. But it does give you an indication that some of the cognitive capacities that they seem to have are really quite sophisticated ones that develop relatively late in childhood, at least in our species.

Chris - Not to mix metaphors, but are there one trick pony on this? Is that all they can do or do they also display uncanny cognitive powers in other domains as well?

Nicky - They can do all kinds of other things. So there are observations in the wild, for example, of rooks on the Membury service station on the M4 being able to work in cooperative teams to pull up the bin liner under their feet. And then they have two working in tandem at opposite ends of the bin. And then they start chucking the food out of the bin. And then once one of them has a good grip of most of the food, the other hops down to the floor to guard the food so that the blackbirds and wagtails and starlings and other birds around can't steal their stash of delicious treats. And then they just keep chucking them out. But it takes about 20 or 25 pulls before you even get to the right level of the bin where the food is. So it shows a sense of time, of persistence, of self-control. It's not just 'I pull it, I get food, I'll keep pulling'. It's not simply trial and error learning or one trial learning as it's sometimes called. They've really got to plan ahead to do this. So it takes time, it takes teamwork because you need at least two to stand at either end of the bin to do it. And of course it's an understanding of tools. They're using the bin liner as a tool with which to get the food. And although they don't use tools habitually in the wild New Caledonian, crows and Hawaiian crows do. But most of the corvids don't use tools in the wild. And yet all the ones I've worked with readily use and manufacture tools in the lab. We think they don't use them in the wild because they don't need to. If I lived on a diet of soup apples and potato crisps, I wouldn't use tools either. I could drink my soup, I could bite into my apple and using a knife and fork or some chopsticks for crisps would be a really rather stupid idea methinks. Not that that's my diet, it probably wouldn't be too healthy. But you know, I

Chris - Don't think you're doing your dancing much good if you lived on that.

Nicky - Well that's true. Yeah. You know, you don't see many obese ballerinas now do you <laugh>