Experiments showed New Caledonian crows can solve puzzles by building and using compound tools. Photo by University of Oxford

Oct. 24 (UPI) -- New Caledonia crows are capable of building compound tools. New research showed the species, , Corvus moneduloides, can successfully combine smaller tools to form a larger, farther-reaching tool.

The ability to convert variable components into a new type of tool has previously only been observed in apes. Anthropologists regard compound tool innovation as a breakthrough in the early evolution of the human brain.


Scientists revealed the birds' propensity for problem solving using a puzzle box containing several openings and a food treat in the center. To retrieve the food, birds must use a long thin tool to push the treat to an opening the birds can fit their beak through.

When researchers initially exposed the crows the box, they left long, thin sticks lying around. All eight birds quickly utilized the sticks to solve the puzzle box.

In a followup experiment, researchers only left the pieces of hypodermic syringes, separated barrels and plungers, lying around. The pieces were too short to be utilized on their own, but because some pieces fit inside others, they could be assembled to form a longer tool.

Four of the eight birds, unprompted and untrained, successfully inserted the thinner pieces into the hollow pieces and formed a tool long enough to solve the puzzle.

"The finding is remarkable because the crows received no assistance or training in making these combinations, they figured it out by themselves," Auguste von Bayern, a researcher at the Max-Planck-Institute for Ornithology and University of Oxford, said in a news release.

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In subsequent tests, researchers used smaller and smaller pieces, requiring additional assembly. One of the birds, named Mango, was able to make tools out of four separate parts.

Scientists described the problem solving prowess of New Caledonia crows this week in the journal Scientific Reports.

Researchers have yet to study the brain activities that underpin the compound tool-building abilities of New Caledonia crows, but the findings suggest the birds boast impressive cognitive abilities. Though infants use tools in their second year of life, toddlers don't invent, build or deploy compound tools with novel functions until they're at least five.

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"The results corroborate that these crows possess highly flexible abilities that allow them to solve novel problems rapidly, but do not show how they do it," said Alex Kacelnik, a researcher at the University of Oxford. "It is possible that they use some form of virtual simulation of the problem, as if different potential actions were played in their brains until they figure out a viable solution, and then do it."