Tools not a sign of evolution to man (From BBC Earth News October 2010)

Young New Caledonian crows learn to use tools by going to "tool-school", where they can observe their parents at work.

These crows are renowned for their extraordinary intelligence and ability to fashion tools to solve problems.

Now a new study has revealed more about how they do it: wild New Caledonian crows live in unusually small family groups, scientists say.

That allows parent birds to take juveniles to tool-using sites, and let young birds play with "grown up" tools.

Talented toolsmiths

Birds belonging to the crow family such as magpies, crows and ravens, known as corvids, are renowned for their innovative behaviour, relatively large brains and general intelligence.

Even among this group, New Caledonian crows (Corvus moneduloides) stand out: they make the most complex tools of any animal yet studied apart from humans.

TALENTED CROWS


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For example, they will evolve and improve the shape of their tools over time, and will fashion left handed or right handed tools.

These tools are usually made to help catch insects and other invertebrates.

Earlier this year, scientists at the Department of Psychology at the University of Auckland, New Zealand discovered that the birds were able to use three tools in succession to reach some food.

However, despite these extraordinary abilities, little is known about how wild New Caledonian crows live, and how they acquire these skills.

To investigate, Jenny Holzhaider and colleagues at the University of Auckland studied the social organisation of New Caledonian crows in their natural habitat on the island of Maré, New Caledonia, which lies in the South Pacific Ocean to the east of Australia and north of New Zealand.

Observations revealed that unlike many other crow species, New Caledonian crows are not highly social.

Instead, they tend to live in small, tight-knit family units comprising two parents and offspring from up to two consecutive breeding years.


Clever crows can use many tools to solve a task
The parents stay together all year and seem to especially tolerate the presence of the juveniles.

"Their social system is based on high quality relationships with a small number of crows, especially immediate family," co-researcher Gavin Hunt told the BBC.

The discovery rules out the idea that New Caledonian crows live in complex social groups, and learn their skills from their peers.

Instead it suggests that the crows develop their tool-using abilities by "keeping it in the family", say the researchers, who publish their findings in the journal Animal Behaviour.

SOURCES


Visit Animal Behaviour to read more about the social structure of New Caledonian crows
What is more, the parent crows appear to go to considerable lengths to ensure their offspring can learn how to fashion and use tools.

"[Juveniles] closely follow and watch their parents' behaviour, are taken to tool using sites, and are 'allowed' to use the tools of their parents," says Dr Hunt.

Structuring their education in this way may also help explain how the crows improve their tools over time, as young crows may learn from their parent's mistakes.