Jackdaw Cherry Vendetta

Jackdaws in the top of a tree, looking around them
Unripe cherries amidst lots of leaves
Jackdaws pulling cherries off the tree and letting them drop, laughing in a jackdaw way as they do so
Under the tree, littered with fallen unripe cherries

We live by the sea but we don't see many seagulls. Instead we have jackdaws, hundreds of them live near us and are mostly fun to have around. For some reason they take exception to unripe cherries and every summer sit pulling them off the tree one by one. The ground is covered in green cherries. I don't know why they do it, but they must find it satisfying, or fun? Maybe the previous owner of our house was mean to them? They seem perfectly happy with us, no aggression at all.