I'm thinking it's a Sharp Shinned Hawk? They visit my feeder fairly often. How in the world did you convince it to take out a Starling??
I think Bev is right and that is indeed a Sharp-shinned Hawk. They are excellent images. Sharp-shinned Hawks are likely the most common of the small raptors present here in winter, the other relatively common being the Merlin (a falcon). Other raptors that hunt at feeders at this time of year include Cooper's Hawk (similar but larger and much less common), Northern Goshawk (bigger still) and Red-tailed Hawk, and perhaps a few more.
Nice closeups, check out the second pic "full sized" and note the feather wear at the tip of the tail (white feathers aren't as strong as pigmented ones), common I think for this time of year. Your picture shows it nicely.