Regarding the tiles at the lowest part of the eave, right above the fascia board where you see the wavy holes, do yours have flashing that fills in those wavy openings?
If your ridge tiles are not sealed with mortar, you will need to do that. Additionally, if those holes are open, you'll need to install flashing (called bird stops) to cover them.
You can try all the flashy, scary, toxic things that you want, but in the end, mechanical exclusion is the only way to get rid of them 100%.
There may be real damage occurring underneath those tiles to your waterproofing membrane. They will peck and scratch and rot out the paper/membrane.
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