I'm afraid I dissent from KC. In W Mexico we have three pretty similar possibles. Myiozetetes similis hesperis (which this is definitely not - black on the head is different); Megarynchus pitangua caniceps and; Pitangus sulphuratus derbianus (Great Kiskadee). My take is that it is this latter. The birds in the photos just don't have the enormous (for a Tyrannid) beak that it should for the Megarynchus.