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Clever birds.....................

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Old Monday 7th April 2003, 20:34   #1
peter hayes

 
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Clever birds.....................

This is from the BBC web site



First, find a special twig with a curved end. Snap it off the branch
and remove all bark and leaves. Next, pare down the curve and fashion it
into a sharp hook. You are now equipped to go in search of large fleshy
grubs, a tasty morsel but one which likes to remain hidden from view.
The quarry conceals itself deep in leaf litter. However, it responds to
repeated rustling in close proximity by attacking the source of the
disturbance. So you make vigorous repeated probes with the wooden hook
until dinner comes along. Contact! Swiftly, you impale the wriggling
grub and yank it clear of its leafy lair. An impressive feat of hunting
skill by human standards. Except that the sleuth is not a person: all
this ingenious detective work was done by a crow in New Caledonia.

Closer to home, every member of the crow family provides insights that
testify to avian intelligence a cut above average. For example, ravens
can count - an ability lacking in other birds. Here's the proof. Bird
photographers filming nests from hides require an assistant to accompany
them into position. Both enter the hide together so that, when the
assistant emerges and wanders off, the bird assumes the coast is clear
and returns to its nest. Ravens are not so easily fooled. In 1937 Eric
Hosking, a famous bird photographer, required the help of an entire
class of school-children to accompany him into a hide in order to
confound the mathematical skills of a pair of breeding ravens.

Ravens hold another record that could be unique for a bird: they have
been recorded playing in the wild. Their antics, photographed in Wales
in 1980, involved two birds taking it in turn to slide on their backs
down a frozen snow bank. The birds covered about 10ft each time and
returned on a second day for more fun and games. Normally ravens are
encountered singly or in pairs but 800 once came together to feed on the
corpse of a dead whale in Shetland.

Complex social organisation is a hallmark of crow society in general
and certain species spend their entire lives living in groups.
Rookeries, in some cases centuries old, normally consist of about 50
birds but giant conurbations of 16,000 nests have been recorded in
Hungary and 9,000 in Germany. Highly gregarious, rooks from several
colonies merge to form communal winter roosts. Even here, members of the
same pair perch side by side and may sleep together in a prospective
nest. Group behaviour is exhibited throughout the year and 'scouts' are
deployed to warn of danger or to lead the way to good feeding areas.

Despite the impression of massed, homogenous ranks, feeding gatherings
can consist of family groups or may be segregated according to age.
Especially in late autumn and early winter, juveniles regularly form
flocks independent of adults. By and large, life proceeds harmoniously.
However, a code exists and antisocial behaviour is sometimes punished by
death at the hands of peers. So-called rook 'parliaments' are
occasionally convened and although the deeds of the transgressor remain
unclear the bird may be ostracised or, in some cases, pecked to death.

Of all crows, magpies exude a character that, on the one hand, is brash
and inquisitive and, on the other, seems sneaky and dastardly. They
always appear energetic and on the look-out for action. There is no
doubting their bravery since they delight in buzzing birds of prey and
driving them away. Yet, this action is puzzling. Magpies are not
directly threatened and arguably waste energy dive-bombing and harrying
the raptor, sometimes for long periods. Could it be that they are
aggressive by nature and simply spoiling for a fight? Elements of their
social behaviour tend to support this view.

Within non-breeding groups a dominance hierarchy exists. Males are
normally dominant over females. High-ranking birds initiate ceremonial
gatherings by deliberately flying into the centre of established
territories to provoke a response from the owners. The racket from the
commotion sparks a reaction among all the birds in an area and a
gladiatorial contest over territory begins. As many as 225 magpies have
been counted watching the unfolding events. The usual outcome may come
as a surprise: in 95 per cent of cases the troublemaker is evicted.

In recent years magpies have learned another lesson. They have
discovered that it is safer to live in cities and suburbia than in the
countryside. Persecution is almost non-existent in built-up areas,
whereas farmers and country landowners regard the species as a pest and
treat it accordingly. Away from rural areas, magpies are confident and
less shy and, increasingly, seem to be 'born bold'.

However, there is a downside to their curiosity and undoubted
intelligence. They are merciless nest robbers. Even incubating adults
may be attacked and killed. The species sometimes hunts in groups and,
outside the breeding season, has also been recorded attacking birds at
roosts. In one five year study in a suburban part of northern Germany,
100 per cent of eggs and young of some species in a 10 hectare area were
taken, and 64 per cent of open nests were raided. Gorgeous and brainy
magpies may be, but their smartness would be even more appealing if they
weren't quite such a common sight
 
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Old Monday 7th April 2003, 20:48   #2
steve_nova
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Nice to see the Crow family getting some sort of attention even if like the Magpie itself, their reputation is both black and white!
As more work is done on the mechanics of their brains, you can bet that more surprises are to come.
Thanks for the post.
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Old Monday 7th April 2003, 22:10   #3
peter hayes

 
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Couldn't agree more Steve.
 
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