I'm not particularly good at identifying birds in flight. Gradually, I have picked up a tip or two that helps me out with some flight identifications. This small falcon, has a wing span of 22", and a long tail. It is also known for its ability to hover. Note the rufous tail and little black band at the edge. Looking at Sibley's, I think this is a male.
I am surprised that you can see this much detail on the bird. It was definitely out of range for my camera. It's amazing what a difference favorable lighting can make. If anyone would like to add some tips for identifying a Kestrel in flight, feel free to do so.