I viewed this bird flying high just south of Sonora, TX, this past weekend. Cooper's Hawk?
CLOSED: Cooper's Hawk?
The tail has square corners, the flanks are mottled (not streaked like the centre of the breast), and it looks lightweight - so I'd go for Sharp-shinned Hawk, first year.
Res, Thanks for looking at this id and for explaining the important field marks! I really appreciate it.