I confirmed eyasses this evening - I don't know how many there are, I'd assume at least two which would be typical for Coopers, but it's hard to tell. I arrived at the nest at dusk and when I arrived the female was already pulling at a prey item (the item was not visible but she was making obvious pulling movements at a food item). I couldn't see what she was doing with the food at first, but it didn't take long watching before I could see something white moving in the bowl several times.
The feeding appeared to be going on for quite some minutes - I also walked around to the side of the nest and caught one eyas standing near the rim - it let off a poop shot at me. They are quite comical to watch when they get ready to "shoot" - looks like a cannon getting ready to fire.

Actually I was pretty sure that there were chicks up there even before seeing anything - looking up at the nest I could see splatters of white mutes just on the tree trunk and on the sticks not far under the rim - these would have come from young chicks when they're pretty small and can't "shoot" very far. The adults would normally slice off the nest, or at the very least the slices would end up well away from the bowl.
I was quite surprised how big the one I got a good look at looked - it seemed almost a 1/3rd the size of the adult - so they've undoubtedly been down there for a while as I suspected. It was getting dark though so the eyes might play tricks.