Friday 27 April 2018

Crows use tools to avoid snake

A deadly snake guarding edible treasure presents quite a problem to a hungry crow, but the clever bird used a stick to access the food
A deadly snake guarding edible treasure presents quite a problem to a hungry crow, but the clever bird used a stick to access the food

A deadly snake guarding edible treasure presents quite a problem to a hungry crow - most bird-brains would either stay well away or pay the price for venturing too close.

However scientists in the Pacific have discovered that the Caledonian crows they tested did what humans and chimpanzees would probably do in the same circumstances. They used a tool.

Faced with the snake - or a scary-looking toy version - the crows picked up a long stick and used it to access the food from a safe distance.

However they were not as likely to reach for a stick when the snake was replaced with a teddy bear.

The birds appeared to be evaluating the risk involved, and acting accordingly. Their tool use was said to be "context dependent".

The study, reported in the Royal Society journal Biology Letters, involved 11 wild crows captured on the Pacific island of Mare, New Caledonia.

Blocks of meat were placed a centimetre inside the bars of a box next to either a familiar food bowl, a realistic-looking toy snake or a teddy bear.

Four sticks varying in length from 10 to 25 centimetres were placed in front of the box. In earlier tests without the toys, crows used their bills to pick up the food.

The snake and the bear brought out the birds' natural wariness of anything unusual. But with the snake present, the birds used the sticks more often than when they were faced with the stuffed toy.

Press Association

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