Wednesday, March 28, 2012

Crow Twig Juggling ...

























The willow-leaved (or weeping) pear tree Pyrus salicifolia in our garden has received its annual pruning this week by crows that use its long, pliable twigs as nest material - but each new generation of crows has to learn how to break them off and carry them away. Crows that are new to the game grip the twigs mid-way along their length and simply try to pull them off - which never works because the twigs are tough and very flexible.  But after a few attempts they soon learn that if they grip the twig near its attachment to a larger branch and then use their powerful beaks to bend it sideways it will snap, because the thickened basal end is more brittle. Then a few more hacking blows with that beak and a bit more tugging will usually remove the prize...... 


...... but then they're left holding one end of a long twig, which makes the flight back to the nest very awkward ....


... so they develop a technique of bouncing on the twigs, flapping their wings and tossing their heads to shift their grip towards the middle of the twig. Beginners at this game drop a few before they perfect their technique but after a few attempts ....


...... they become very proficient and shift their grip until .....



.... they have a perfectly balanced and aerodynamically stable load.


Smart birds, crows...

14 comments:

  1. I first came across the Willow-leaved Pear in Calderstones Gardens, Liverpool, many years ago but have rarely seen it since. I think it's a beautiful tree.

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  2. I can only agree, Phil. I've yet to win a game of Kerplunk against these clever corvids.

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  3. Another fascinating post Phil, great observation, Linda

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  4. It's a lovely tree John and ours is just coming into flower. The wood pigeons like to nest in it because they are well hidden inside its tangle of branches. Our tree is 28 years old - I brought it home in a small pot when we first moved in here - and how the topmost branches are level with the bedroom windows: perfect for birdwatching!

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  5. Just hope they never get access to my PIN and credit card Graeme - they'd surely work out how to use them...

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  6. It's fascinating watching birds problem-solving, isn't it Linda? I think the crow family are particularly entertaining...

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  7. Lovely series of shots telling a fascinating story.

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  8. Phil,

    Yet another cracking article. Read it and sat watching Crows and Jackdaws for 30 mins in a tree in my garden but unfortunately they havent done anything clever YET

    John

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  9. Great series of shots Phil. I only see Wood Pigeons pruning the local trees but they are not as adept at getting the balance right for flight.

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  10. Such clever creatures. Great pictures too.

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  11. Thanks swanscot, the crows were back today breaking dead twigs off of a winter-flowering cherry in the garden.

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  12. Hi John, we've got jackdaws nesting in the awning over our back door, making helluva racket every morning. The wood is rotten and they've pecked a hole in the side so they can nest in the cavity inside .... I was supposed to be replacing the awning but now they've moved in that's it for another year..... never mind..

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  13. The wood pigeons in our garden are so portly that I think they could break off the branches of some of the trees just by perching on the end of them John..

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  14. Thanks toffeeapple - they're very entertaining birds...

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