White and green "hawk" in Sun Lakes, AZ?

by Ray
(Sun Lakes, AZ)

We get a lot of Gambel Quails in our yard but today, sitting atop our Gazebo in the yard, was a mid-sized bird that looked like a hawk. It was about 18 to 24 inches in height. Its color was a light to mid-green but the breast had horizontal "speckles" (don't know what else to call them) across its breast that produced "interrupted lines of speckles" that were alternately green and then white. The nearest bird I could identify via the Internet is a Northern Goshawk but its breast has alternating lines of brownish and white speckles.

Would you have a suggestion as what this bird was?