Cooper's Hawk vs. Goshawk

During a recent stroll in the Carleton College Arboretum, Erika and I spied the Cooper's Hawk in the upper photo. The yellow eye and striped underparts indicate the bird is juvenal. Adults have orange eyes and underparts with reddish bars. Our hawk was really large, clearly not the much smaller Sharp-shinned Hawk. Females of both hawks are larger than their males, but there is no overlap in size between species. The breast stripes are not course. Finally, note that the outer tail feathers are clearly shorter than the middle ones. Sharp-shinned Hawks' tails are relatively square-ended.

What about a Goshawk? The photo below was taken in a residential yard in Aberdeen, South Dakota. It is also a juvenal--note the yellow eye. Goshawks are larger than Cooper's Hawks, though it is hard to tell that in two photos. The Goshawk's tail bars are very uneven--note the relatively thin the dark bars--and compare them to the more evenly spaced tail bars on the Cooper's Hawk. The best field mark for a Goshawk is the white eye stripe. The stripe on a Cooper's Hawk is buffy at best. Finally, though hard to see in these photos, the Goshawk's underparts are more buffy than those of a Cooper's Hawk.