There are two large and basically yellow and greenish kingbirds in southern Texas and Identifying them can be a bit of a problem unless they call. Under Texan law I believe that you can have hot bamboo inserted under your fingernails for using playback in the Rio Grande Valley, and quite rightly too, given the enormous numbers of birders both resident and visitors there. If everyone subjected the birds to a barrage of songs and calls, the poor birds wouldn’t know whether they were coming or going.
Figuring out the kingbird species based on plumage is really a non-started unless you see them very regularly and so you have to look for a suite of characteristics. Chunky, thick-necked birds with long bills with a prominent hook (variable!) and a deeply forked tail are usually Tropical. Slimmer looking birds with stumpier but thick based bills and lacking a prominent hook (also variable), and a shallow tail fork are likely to be Couch’s – if only they’d sit side-by-side on a wire! They don’t (often) so we are back to diagnostic calls raising the tricky subject of the judicious use of playback.
I sometimes use playback in Québec during migration, usually it is in the form of Black-capped Chickadee alarm calls, find the chickadees and you find the warblers here. In Texas I used it with the kingbirds, just to be sure. A Couch’s at Rockport didn’t seem to need much to start kicking up a racket, two ipod bursts without a speaker was just enough. A Tropical in an urban setting, near McAllen Sewage Farm (the old birding site is now dry by the way) was a bit harder and, although it clearly noted the calling kingbird that it couldn’t see, it wasn’t about to play its hand, or wing, too soon. On the wire it was quiet but it did call when it flew across the road and landed on a fence, thereby confirming the tentative ID, no harm done.
Below is the Couch’s Kingbird photo from Rockport and one I posted earlier. It is followed by another Couch’s, this time from Belize where they seemed to be the default kingbird in open country.
The following photos are of the McAllen Tropical Kingbird followed by some from Panama. I think you can see the differences in the photos, I’d be interested in any comments.
This pair and many others would benefit from a thorough treatment with quality illustrations and a bit more depth that the field guides have room for. Authors and artists off you go…