Immature red-tailed hawk. They don’t pose any threat to your property, and they will prey on squirrels. Since you already have a nesting population, not much more you can do except protect them from your neighbors.
Red-Tailed Hawks are a main-stay in American falconry, the species are incredible survivors...
It looks a bit like a young red-tail to me as well, but...every time I try to identify one of these darn things, I see a picture that makes me believe I am wrong!