Coopers Hawk or Sharp-shinned?

[Julie M.]

This morning I was at Chatfield State Park, and could not differentiate between what I was seeing and hearing.

I only had binoculars available, no camera. It, visually, was positively one or the other, but vocally confusing.
It made a single phrase, nasally call on and off. It would move around from branch to branch, appeared to be an adult, and was otherwise alone for a good 15 minutes.

The closest call I could find was a Coopers Hawk begging call of a chick from AllAboutBirds, but it was more crisp.

Any thoughts?

Julie M.
Highlands Ranch, CO