Something to crow about

Aesop’s Fable, “The Crow and the Pitcher,” tells the story of a thirsty crow that comes across a pitcher of water. There is a problem, though: The mouth of the pitcher can fit the crow’s beak, but not its head, and the pitcher is only half full. The crow thinks for a moment and looks around. It spots some small stones on the ground, and it thinks a little more. It picks up the stones with its beak and plops them into the pitcher. The water in the pitcher rises a little bit higher with each stone dropped in, and after putting in a few stones, the crow dips its beak back in. The water is now high enough to reach its beak! Success!

The moral of Aesop’s fable here is that ingenuity can be used to overcome whatever barriers we face – in sum, “where there’s a will, there’s a way.”

The cool thing about Aesop’s fable here is that it describes a thing that actually happens.

I invite you to take a few minutes and watch the video below. In the video, you will see several crows (and you can tell they are different by the color-coded identifiers attached to their legs) engaging in six different puzzle-solving tasks. These clips reflect the work of Jelbert, Taylor, Cheke, Clayton, and Gray (2014) who investigated the extent to which crows understand the concept of water displacement and their ability to use that knowledge using the aptly named “Aesop’s Fable” paradigm:

https://www.youtube.com/watch?v=ZerUbHmuY04

Before the experiment, the crows (captured from the wild and released after the study was completed) were given some initial training to teach them to drop stones into a tube. This task is not too difficult for them to learn: In the wild, crows will drop nuts from a large height to break them on the ground – and what’s more, crows that live in environments with particularly hard nuts will drop the nuts on roads and wait for cars to run over them and crack them open (Cristol & Switzer, 1999). One video of this phenomenon in occurring in Japan shows that they have even learned to do this practice at traffic lights.

https://www.youtube.com/watch?v=_5_DuZ8WuMM

Diagram of the apparatus used in Jelbert, Taylor, Cheke, Clayton, and Gray (2014).

Following some trials to get them acclimated to the tube and objects, the birds were put through a series of successively harder tasks that tested their understanding of water displacement. In the first experiment, the crows were faced with two tubes, one with water and one with sand, and each with a piece of food that was too far down to be reached just with their beak. The crows also had access to small objects. To get the food reward, the crows had to put several small objects in the tube with the water to make the water rise (see Figure 1, a).

When the experiments are broken down, the complexity of the tasks becomes evident. The crows demonstrate a functional understanding of the difference between things that sink and things that float – and understand that this is something that occurs in water, not sand. They know that putting an object into a container of water will cause the water and any floatable objects to go higher and they understand the object characteristics of hollowness and solidness. They know the difference between a high water level and a low water level, even when neither can reach their beak.

While these puzzles would hardly constitute challenges from the average adult human, the concept of water displacement is too difficult for very young children to grasp. Research in developmental psychology has found that children under the age of five put to the challenge of the “Aesop’s Fable” paradigm assessing their understanding of displacement will drop stones in water – but they make mistakes and act inconsistently, with the proportion of correct actions being no greater than chance. Children above the age of eight can complete all six tasks with a high degree of accuracy. Interestingly, children who are 5-7 perform about as well as the crows do. Like the crows, they are unable to do the most complex task (the U-Tube) which requires the capacity for associative learning (Cheke, Loissel, & Clayton, 2012).

Crows may not have the ability to organize en masse and attack us à la Hitchcock’s The Birds, but their intelligence continues to surprise the scientific community.

Maybe we should make “bird-brain” a compliment.

References

Cristol, D. D., & Switzer, P. P. (1999). Avian prey-dropping behavior. II. American crows and walnuts. Behavioral Ecology, 10(3), 220-226.

Cheke, L. G., Loissel, E., & Clayton, N. S. (2012). How Do Children Solve Aesop’s Fable?. Plos ONE, 7(7), 1-12. doi:10.1371/journal.pone.0040574

Jelbert, S. A., Taylor, A. H., Cheke, L. G., Clayton, N. S., & Gray, R. D. (2014). Using the Aesop’s Fable Paradigm to Investigate Causal Understanding of Water Displacement by New Caledonian Crows. Plos ONE, 9(3), 1-9. doi:10.1371/journal.pone.0092895