Western Kingbird at Naos

Richard Cooke reports seeing a Western Kingbird yesterday afternoon at the parking lot of the STRI Marine Lab at Naos Island, on the Amador Causeway. Even without binoculars, he could see the white outer rectrices. He also noted the olive wash on the chest extending further into the belly than on the typical Tropical Kingbird.
What first called his attention to the bird was its unusual behaviour: skulking in a bush.