Is this a merlin (Falco columbarius)? I don't think it is a peregrine falcon (F. peregrinus) -- I have seen these with swifter, more intentional flight. Nore an American kestrel (F. sparverius) -- wrong coloration. (Sorry, I don't have a good fix on the size of this bird, it was flying in the distance. Flying back and forth overhead, near the location of the previous image near Trail 10. 9:35:16 am.

Dudley goes for peregrine: "I'm not enough of a raptor person to give you an i.d. on the falcon question, but I would lean toward Peregrine rather than Merlin. Merlins are really small - only a hair bigger than a kestrel - and the western ones are generally quite dark, though I'm sure that varies. This one also has a pronounced dark suborbital patch, which both species have, but the Merlin's is quite a bit smaller than the Peregrine's.Could well be a young one of either; hard to know for sure, for me. But nicely photographed!"