Hello Geraldine, did you try to put a few CD in your trees?
Or to put some fake predators on spkes......this did work for me
If you have any bird feed make sure that they are for small birds .hope this will help

It is possible they are looking for cutworms in the grass. We had this problem once. Dealing with the cutworms (Crane fly larva) stopped the rooks as there was nothing in the soil for them to eat.
By the way if there is more than one bird they are rooks or jackdaws. Crows only come in ones.

What are the crows going after? Grubs? Worms? What is drawing them. That's were to focus.

My father used to quote:
A crow in a crowd is a rook,
A rook on its own is a crow!

These are probably rooks or jackdaws and it sounds as though they are doing a good job getting rid of pests. Once they've cleared all they can find they will go elsewhere and you can tidy everything up.

At first I thought they wanted moss but not the case though they are doing a good job of scarifying.I guess they’re looking for grubs or something.I just keep hoping they’ll go on to new pastures.
I don’t have anywhere to hang cds in my front garden.
That’s interesting about what they are there’s usually a couple or three so maybe rooks.
They nest in Scots pine trees just a stones throw from us and they really are nuisances.Don’t know if you remember last year they were bringing their kill to our birdbath so I had to fill it with stones and stop using it for a while.