Something to crow about

To: Birding Aus <>
Subject: Something to crow about
From: knightl <>
Date: Fri, 28 Mar 2003 19:56:27 +1000

Something to crow about: birds with tools of trade
Date: March 28 2003

By Roger Highfield

A remarkable colony of inventors has emerged on an isolated Pacific island. They can fashion tools out of materials scavenged from the rainforest. They can even customise a tool for a given job.

Early studies showed crows to be almost human-like in their use of tools, with technological features that match the stone and bone-tool cultures that emerged among primitive humans between 2.5 million and 70,000 BC.

But the anthropocentric still took solace from the fact that only humans were thought to have the brain power required for cumulative technological evolution. This is the skill for innovation that two million years ago took our ancestors from creating flakes of flint, for use in cutting, to honing knives, blades, arrowheads and axeheads.

Now this "unique" attribute of humans has also turned out to be a flattering delusion. A new study shows that the crows of New Caledonia are inventive. With their evolving leaf tools, the birds have levered man off his pedestal.

The creative skills of the birds are described this month in the Proceedings of the Royal Society by Dr Gavin Hunt and Dr Russell Gray, of the University of Auckland. They have spent the past decade studying feathered technology in the islands of Grande Terre and Mare in the South Pacific archipelago of New Caledonia.

After an intensive field survey of local crow industry - sampling 21 sites and 5550 leaf tools - the scientists found that the birds rip the barbed leaves of the pandanus (screw pine) tree to fashion three distinct types of tools for grub and insect extraction: wide, narrow and stepped.

Because the strap-like leaves are reinforced by tough parallel fibres, the latter tapered design is best made in steps. With precision beak work, the crow nips the leaf, then rips along the fibres. Next it makes another cut and tears again, repeating until it has a tool with usually two, three or four steps.

The scars on the remains of leaves used by the crows revealed similarities in the cutting and ripping used for each of the three basic tool designs, and their different but overlapping geographic distributions.

All the designs are found around Riviere Bleue, at the end of Grand Terre, suggesting that the first prototype leaf tool was invented there to winkle bugs out of crannies.

The ability of the birds to innovate is further shown by their making of other tools, such as hooks, and how they do not rely on one raw material: as well as pandanus, the birds make hooks out of twigs and similar materials. They often strip a twig of leaves, and sometimes of bark, and cut it off just below a shortened offshoot to create a hook to weedle out bugs.

Professor Alex Kacelnik, a fellow of Pembroke College, Oxford, praised the study as "extremely important". It complements his own research which has turned Betty the New Caledonian crow into a star by revealing her to be the first animal, other than man, to show a basic understanding of cause and effect.

Betty began making tools after her partner, an old male called Abel (now deceased), snatched away a hook made for her by the researchers, forcing her to make her own from garden wire to fish out morsels from a tube.

She wedged the end of the wire into the base of the food tube and turned her head to form the hook.

What amazed the researchers was that she could even adapt her hooks if they were not up to the job, something that even chimpanzees were unable to do.

- Telegraph

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