I almost lost my kestrel to one of these little killers! Hendrix was tethered on a block perch in the backyard while I was raking leaves. That little bandito blew past me like a bullet and only the fast reactions of Hendrix bailing off his perch and hitting the end of his tether saved his butt.
I am sure the merlin was anticipating the kestrel attempting to flee and corrected her trajectory to intercept Hendrix, but did not calculate the kestrel being stopped short on the end of his leash! She overshot by a few inches and pulled up and over the fence.
If you have bird feeders, it can attract the attentions of these little predators. I get a few calls every year to come "trap" these terrible and cruel killers. I tell people that taking one out will only leave a void his brother/sister/cousin will exploit. In order to discourage them, STOP FEEDING THEIR PREY'S FOOD! When the songbirds wander off to other feeding stations, the merlin/coopers hawk/sharpshin hawk will wander off, too. Resume feeding after a few weeks.
Thanks for posting this pic. It takes a dedicated full time wildlife photographer dozens of hours to get a decent photo of a bird like this. For one thing, as you know, they do not sit still long! And for another, they know when you turn your attention on them for the photo and off they go! Your shot is not only a great illustration, but it's downright artistic! Nice, indeed!