If about 18 to 24 inches long a Coopers. If 12 to 14 inches a Sharp shinned. Both do birds quite well and without scale and a close look are tough to decipher. I tend to see those spots on the backs of Sharpies more often than the Coopers, but they can happen with both.
It's either a Sharp Shinned or Coopers. I have a friend in town that has one of them killing and eating a Eurasian Collared Dove a week out of his feeders! He swears it's the only hawk there!!!
Without knowing the size, it's hard to say for sure. However, the breast on a juvenile Cooper's Hawk is finely streaked, while the breast on a juvenile Sharp-shinned Hawk is coarsely streaked and barred. The detail in the photo makes me think Sharp-shinned rather than Cooper's.
Here are a few of the pics I took on Christmas morning a few years ago at my house. I think I posted them here then and we probably had the same discussion as we are now but lets try again!!! The ground feeder measures approx 12" long by 8" wide. Probably 2 1/2" deep.