Why do hawks screech?

I have 2 Redtailed hawks in my backyard & (surrounding area). I frequently hear them screech but today they were soaring low enough to make the dog bark and screeching their heads off. They soon landed in a nearby tree. I can't tell if they are a M&F pair or 2 males struggling for territory. I frequently see them together & when they are, they are screeching. I once saw one of them catch a mouse, or small rat, or something but heard no screech prior to that. Any ideas what's going on?

Thanks,

Maggie

Territorial disputes, courtship, warnings and simple communication with other hawks of the same species.

I am lucky enough to have had pairs of peregrine falcons in the town I work in for the past ten years, or so. They frequently “screech” when the mate is on a kill. It is as if they are asking for a share of the kill and I have witnessed them attempting to “steal” some of the kill from a mate. I have also witnessed a male peregrine “screech” just before attacking a plastic owl, placed on top of a building to scare off pigeons. We no longer have a pigeon problem, but it’s thanks to the peregrines, not the plastic owls.

Thanks Stelco,
I'll try to watch a little closr to see what's going on. I appreciate the info. I'm happy to have themas I've only ever seen one rat here in this heavily wooded suburb. As long as they leave my snkes alone. I think we actually have Indigo snakes. They are rare for this area but I've gotten several pics and neither DH nor I can find the markings of a black racer which should be more likely.
Maggie

Maggie