AUGUST 10, 2016
by John Hopton
Understanding of crows' crafting
and use of tools has been slow to progress, but just took a major step
forward through observing wild New Caledonian crows.
It was back in 2002 that a
captive crow, Betty, blew scientists' minds as they watched the bird bend twigs
into hooks in order to extract buried food.
The University of Oxford, UK,
researchers wondered if the trait may have emerged in captivity, but a new
study of the wild crows from New Caledonia in the South Pacific suggests the
trait may in fact be part of the birds' natural behavior.
Along with crows, captive rooks
have previously been seen to fashion tools in such a way. Wild crows have also
long been known to use twigs to get at food. But seeing wild birds
fashion tools represents a new development.
Dr. Christian Rutz, from the
University of St Andrews in Scotland, who is lead author of the new study
published in the journal Open Science, explained how short-term capture of
crows from the tropical forests of New Caledonia helped to aid understanding.
Rutz said: "This means we
can test them under highly controlled experimental conditions - but the kind of
experiments we do there, they don't look at how smart these animals are, they
ask what sort of tool behaviour they express naturally."
How did they test for this
ability?
The team used wooden logs with
appealing food buried inside them, which were presented to the crows.
"The only other thing we
provided in the aviary was the plant material, which we knew they naturally
used for tool-making in the wild," explained Rutz.
"So the task was very
simple, we asked our subjects to make tools, then use these tools to extract
the hidden food."
An impressive 10 of the 18
wild-caught birds made tools from the twigs.
It wasn't entirely necessary for
the birds to make tools in order to reach the food, but many of them did so
anyway.
We think the bending helps with
the tool ergonomics," said Rutz.
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