Rooks - Walnuts. How do they crack them?

[ellie2cats]

There is a large walnut tree at the rear of my neighbour's garden and the rooks are busy gathering the walnuts.  Puzzle. How do they crack them?  It has got us puzzled.
Ellie

[ellie2cats]

[Unwashed]

Corvids are smart.  These ones wait at traffic lights for the cars to crush the nuts and then go and pick up the pieces when the lights are red.

[Eristic]

They might also drop them from a great height then clean up.

[1066]

A friend of ours has a walnut tree in their garden and I know various birds and animals all munch on the walnuts (including their 2 dogs!) and they seem to eat most when they are still relatively green i.e. when the cases haven't hardend off and I guess easier to get into. Once the shells are hard its mostly squirrels and rats who get into them

[Maud]

We have a walnut tree near us and the rooks arrive every morning and take the nuts, they then land on the top of our chimney pot (which is capped) and it sounds like they bash them on the cap! Sometimes they drop a walnut and it rolls down the roof.

Also I have seen rooks burying walnuts in the grass clippings that get left when the lawn is cut

[ellie2cats]

Thanks for all your suggestions.  Rooks seem to be pretty clever birds and appear to have the walnut problem solved.