This diary is slightly above the level of an open thread. Be prepared for some bad photographs and some bird carnage. Fortunately the quality of the photos makes the carnage less obvious.
Our title references two things. One is an experience I had long ago while doing field work in Phoenix. I stopped to take a look at a raptor flying by and some guy who was passing called out "It's a Cooper's Hawk". I told the friend I was with that, whatever else it was, it was not a Cooper's hawk (it was buteo of some sort). My memory of the details of the event are hazy and the only reason I remember it is that my friend (he was a biologist but definitely not a birder) was quite taken with the phrase and would often repeat it, saying "It's a Cooper's hawk" imitating the rather yokelish accent of that long ago passer by whenever any kind of sizable bird might be seen.
The second reference is to the notorious difficulty of distinguishing Cooper's and Sharp-shinned hawks. The most obvious difference between the two is size but there is overlap and size is not always easy to estimate from a distance.
In recent weeks a Cooper's hawk has been using our feeder as a diner. I've seen it (or them) three times. Twice I've seen it in flight and it is clearly a Cooper's with the rounded corners of the tail. It is also crow-sized and much too larger to be a Sharp-shinned.
However the third sighting was of the bird perched in a water oak, plucking its recently captured prey.
Aside from the inherent interest in seeing predation of this sort first hand, this bird struck me was smaller than the one seen at other times. If it actually was smaller then perhaps it was a male, perhaps paired with the large female? Or perhaps it was a Sharp-shinned? I never got a good look at the tail from an angle where I could see if the corners were rounded or squared off.
This was happening at dusk and I managed to get these first few photos through the spotting scope with the camera zoomed. However it was really too dark for that and I had to reduce the zoom, resulting in the vignette pattern below. I'll note that the hawk appeared to be aware of me (I was at our second floor bedroom window some 40-50 feet away) and glanced in my direction several times.
Eventually moved down the branch a bit so that its front half was obscured. I left it in piece in the gathering gloom at that point.