[CT Birds] New caledonia crows
Katz1449 at aol.com
Katz1449 at aol.com
Sat Oct 6 11:49:35 EDT 2007
>From Bev Propen 10/6
I thought all of you advanced birders would find this birding news of
Clever crows are caught on camera
Science reporter, BBC News
Miniature cameras have given scientists a rare glimpse into how New
Caledonian crows behave in the wild.
The birds are renowned for their sophisticated tool-using ability, but
until now, observing them in their natural habitat has proven difficult.
But specially designed "crow-cams" fitted to the birds' tails have shed
light on the creatures, recording some tool-use never seen before.
The research is reported in the journal Science.
New Caledonian crows ( Corvus moneduloides ) are found on the South
Pacific island of New Caledonia.
They can use their bills to whittle twigs and leaves into bug-grabbing
implements; some believe their tool-use is so advanced that it rivals that
of some primates.
Why not just stick a camera to a crow, hitch a ride with it, and get a
crow's eye view of what is going on?
But while these clever crows have been extensively studied in captivity,
looking at their natural behaviour in the wild is tricky.
Christian Rutz, lead author of the paper from the Department of Zoology at
the University of Oxford, UK, said: "These birds are notoriously difficult
to study in the wild.
"They are very sensitive to human disturbance and the terrain in New
Caledonia is very mountainous and forested, so it is difficult to follow
So the team came up with another approach.
"Why not just stick a camera to a crow, hitch a ride with it, and get a
crow's-eye view of what is going on?" Dr Rutz said.
Recent advances in mobile phone technology enabled the researchers to
construct a camera that was small enough to attach to a crow's tail
without impairing its movements.
They attached the 14g (0.5oz) units - which also contained a radio tag to
transmit location coordinates - to the tail feathers of 18 New Caledonian
The footage, broadcasted to the researchers' custom-built receivers,
provided the team with a unique insight into the crows' behaviour -
including some that had never been seen before.
Dr Rutz told the BBC News website: "Before, we thought the crows targeted
their tool use at fallen dead trees where they probe for grubs; but now we
have observed them using tools on the ground - and that has never been
"We also filmed them doing this using a new type of tool, which was very
surprising. We found them using grass stems - and that is interesting
because these stems have very different physical properties from the
sticks and leaves that we knew they use.
"They are using the grass stems on the forest floor, probing the leaf
litter, possibly fishing for ants."
Big juicy grubs
The team is using its video footage to investigate why New Caledonian
crows might have evolved their tool-using abilities. This species of crow
is the only non-primate animal known to create and use new tools.
Dr Rutz said: "What were the ecological circumstances on this one
particular island in the South Pacific that could have fostered the
evolution of this behaviour?"
This technology could really change the way we study wild birds
One idea, he said, was that the behaviour may have evolved in response to
"When we compared situations when the crows did and didn't use tools, we
found two pieces of supporting evidence for this," Dr Rutz said.
"Firstly, the prey encounter rate was surprisingly small: for one hour of
ground foraging a crow would only pick up eight tiny morsels of food - a
blackbird in a garden would be taking up that many items a minute. That
shows maybe foraging without tools is indeed challenging in this habitat.
"Secondly, when you compare the size of the food items they get with and
without tools - when they don't use tools, the food items are very, very
small indeed compared with the food items they extract with the tools.
This again suggests maybe they need to use tools to gain access to this
rich hidden food resource."
The team says its video tracking technique could be used to study other
wild birds that are shy or live in inaccessible habitats.
Dr Rutz added: "This technology could really change the way we study wild
Story from BBC NEWS:
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