Jackdaws and Cherries

[Unwashed]

The blackbirds typically peck the lot before they're fully ripe.  Some jackdaws will eat a couple, but they're usually much shier than the blackbirds. 

This year the jackdaws have virtually stripped the tree of cherries while they're still completely green and before the blackbirds have taken much interest - but they're hardly eaten a one, they've just snipped the stalk and then deliberately let the green cherry fall to the floor where they leave them.

Why would they do this?  I don't particularly mind because I planted the tree for the birds, but I'd like to understand their behaviour.

[Unwashed]