The rook, a member of the crow family, is the most recent bird to prove the ability to use tools, a capacity once thought to belong only to humans. Although rooks have never been observed using tools in the wild, researchers were astounded at how quickly—sometimes during the first try—rooks were able to employ tools to attain food.
“This finding is remarkable because rooks do not appear to use tools in the wild, yet they rival habitual tools users such as chimpanzees and New Caledonian crows when tested in captivity,” said Chris Bird, the lead author of the study, published in the Proceeding of the National Academy of Sciences.
During experiments, rooks quickly learned to drop a stone to collapse a platform, which, when released, provided them with a piece of food. The rooks chose the right size and shape of the stone without any training. The birds were also able to use and fashion sticks to accomplish the same task.
Further tests showed that the rooks could deftly use a hook tool to obtain food, and when the tool provided was straight instead of hooked the rooks would bend it correctly to reach the food. The brainy birds were also able to use tools sequentially by employing one tool to obtain the correct tool for a task.
“We suggest that this is the first unambiguous evidence of animal insight because the rooks made a hook tool on their first trial and we know that they had no previous experience of making hook tools from wire because the birds were all hand-raised,” said Dr Nathan Emery, Queen Mary University of London, in whose lab these experiments were performed.
Since it was known that the subject rooks had not employed tools in the past, the researchers theorize that their capacity for tool use may be due to sophisticated physical intelligence, rather than having evolved as an adaptive specialization, i.e. specific traits evolved to fit their environment, which is the explanation scientists have given to the tool use shown by New Caledonian crows.
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