Ken Bohn/San Diego Zoo Global

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Hawaiian crows show their tool-using smarts

The clever crows of New Caledonia, long known for their unique ability to make tools, may want to step aside for a distant U.S. cousin. The endangered Hawaiian ‘alalā, a crow that is extinct in the wild and lives only in captivity, has been shown to use sticks to forage for food, much like New Caledonian crows. The discovery, adds the ‘alalās to a short list of fewer than a dozen bird species known to use tools. To earn that title, 104 captive ‘alalās were tested for their tool-using smarts with a food reward. Without any training, 78% spontaneously picked up sticks placed in their enclosures and used them to extract food from crevices in pieces of wood, much as New Caledonian crows use twigs to pry grubs and insects from rotted logs. Many also shortened the sticks to make more suitable tools. Finally, just like the New Caledonian crows, some also manufactured their own instruments by cutting sticks from bushes and dead ferns. But because the two species separated from a last common ancestor about 11 million years ago, scientists think the two species evolved their skills independently, they report today in Nature. The scientists also say that the ‘alalās likely use tools as part of their natural behavior—that’s because all the adults adeptly wielded their sticks, and young chicks did so without observing the adults or being trained. Tool use is rare in the animal kingdom. So why did two crow species evolve this ability? The scientists aren’t certain, but they say it may have something to do with living on remote tropical islands without woodpeckers and fierce bird predators.