What is supposed to help are audio screams of birds of prey, but who wants that in the garden?
We are also badly plagued by hordes of small sparrows... At first cute, as they hop around in the garden in groups of 20-40, but the first lettuce harvest was gone, and everything outside is mercilessly shit on... my car looks like a fly agaric mushroom in blue every week :)
What can you do? Nothing and tell yourself: you wanted to live in the countryside, so deal with it :D