Falcon attacks mailman
The bird in Texas could have been a merlin but since they don't make nests of their own they would have needed to use another bird's nest. Might also have been a Coopers Hawk - they build their own nests in similar kinds of habitat, have a similar profile with falcons, are bigger than Merlins but more streamlined than peregrines. None of the photos showed the profile well enough nor the markings well enough to be sure. I think both Merlins and Coopers Hawks go that far south, but I don't know about nesting ... going to have to do some investigating I think ...