Crows have become rather famous for their cleverness. They have been observed using and making a variety of tools,1 and also seem to be able to understand the basic concept of cause and effect.2 Dr. Alex Taylor specializes in corvid cognition, and is researching the problem solving abilities of New Caledonian crows.
In one of his experiments, Dr. Taylor set up a complex puzzle consisting of 8 separate stages. Each stage posed its own problem, which when solved, provided a tool that could be used to solve the next stage. This act of using one tool on another is called metatool use, a significant indicator of intelligence.3 Every stage had to be solved in successive order for the entire puzzle to be completed. For a crow to solve the puzzle, it would need to employ both its metatool use skills and understanding of cause and effect. Impressively, crows were able to solve the puzzle with relative ease.
Dr. Taylor recently published an extensive paper4 on corvid cognition, in which he states that “while the work to date establishes corvids as one of the most intelligent groups of animals on the planet, the real scientific potential of the Corvidae has yet to be realized.” The following excerpt from the paper details some of the many examples and intricacies of corvid tool use.
Excerpt from the paper:
A third line of work on corvid cognition has examined what this group of birds think about tools and the causality underpinning events in the world. Much of this work has focused on New Caledonian crows, because of their tool-making abilities in the wild and rooks, which produce impressive tool behaviors in captivity.
New Caledonian crows can choose tools of the right length for the task in hand, can make tools of the right diameter for a problem, and will risk their tools, rather than their beaks when faced with hazardous objects such as a model snake (context-dependent tool use). Rooks have been shown to choose between functional and nonfunctional tools, to spontaneously use sticks as tools and to spontaneously modify sticks so they can be used as tools. Both species have also produced meta-tool behaviors where they use tools to gain access to other tools which can be used to get food.
One of the most impressive behaviors produced by both these corvid species is the bending of man-made material into hooks. After using a wooden hook to pull a bucket by its handle from a tube, Betty, a New Caledonian crow, subsequently bent a straight piece of wire into a hook shape in order to do the same. Rooks, given similar experience using a wooden hook to pull a bucket from a tube, also then bent wire to make a functional hook.
More recent work has shown that New Caledonian crows will use stones as tools after limited experience pushing a platform with their beaks and that rooks, crows, and Eurasian jays can, like children over the age of learn the functional properties of stones and stone-like tools when dropping these objects into a water-filled tube.
Finally, both rooks and New Caledonian crows have been able to solve the trap-tube problem, where an animal has to pull food from within a horizontal tube while avoiding a trap. One rook, Guillem, was able to solve various transfer tasks that required him to switch between treating the same cues as negative or positive. Three New Caledonian crows solved several transfer tasks, including the trap-table problem, a problem with an identical causal structure to the trap-tube task, in that an animal must avoid pulling food into a hole, but with very different perceptual elements. In contrast, chimpanzees fail to transfer from the trap-tube to the trap-table problem when required to use tools to do so.
You can watch a crow completing the 8 stage puzzle in the video below:
This article was written by Amanda Pachniewska, founder & editor of AnimalCognition.org
1 – Amanda Seed, Richard Byrne
2 – Corina J. Logan, et al.
Modifications to the Aesop’s Fable Paradigm Change New Caledonian Crow Performances.
3 – Alex H. Taylor, et al.
Spontaneous Metatool Use by New Caledonian Crows
4 – Alex H. Taylor
WIREs Cognitive Science