Its mostly likely a Juvenile Cooper's Hawk, they mainly eat birds. The juveniles in particular seem to be attracted to the commotion of a feeder. While full grown ducks are not usually targeted, they are at risk. Coopers are known to kill other big birds like chickens and pheasants. There was a recent special on Crows on PBS with researchers tagging crows with radio transmitters. Some of the transmitters ended up at the back in a Coopers nest. In the midwest, their favorite food is doves, but will eat anybird that visits your feeders. A couple of weeks ago, I saw one chase a finch and catch it after several figure eights through the trees. It was very impressive to see such a big bird chase a little bird and catch it.

I am also thinking this is a Cooper's Hawk. However, the clincher between immature Cooper's and Northern Goshawk is that the goshawk has brown streaked undertail covers and on a Cooper's the undertail coverts are pure snow white. Although the undertail coverts are not visible, the righthand picture shows the streaking on the breast/belly fading out as it gets closer to the tail, indicating the coverts are probably unstreaked and this is a Cooper's. Also, an immature (1st year) goshawk would appear darker and the streaks on the breast darker and more numerous. Based on all that gibber gabber, I am going with first-year Cooper's Hawk. 1st year NOGO showing undertail coverts. See another link below. Images are not mine but from pbase on the internet. BN Here is a link that might be useful:

Thanks Sterna I was amazed at how big he was for some reason I thought they were smaller I guess he must have been flying low

I cannot really help on this one.May be a Sharp-shinned Hawk. Luc