Several observers studied the two kingbirds at Cobb SWA in Wellington this morning. The more yellow one was confirmed as Cassin’s by vocalization, as it gave the familiar “cheweer” several times. The other mystery Kingbird stayed close to the Cassin’s, often interacting and perched in the same bush. It vocalized once (unrecognized) but was not recorded.
In Cyberspace, there is a healthy discussion of possibilities by many experts in the ID Frontiers listserve. Consensus is building toward a hybrid combo of some sort. I’ve attached a photo taken this morning. My money is on Thick-billed x Cassin’s, but I usually lose when I gamble. 😎