[All photographs copyright, Gary Nunn 2014] – I found this very interesting, but silent, “yellow-bellied” kingbird at Fort Rosecrans National Cemetery on 23 August 2014. I watched and photographed it for about thirty minutes as it moved between trees in the northeast section of the cemetery. After losing sight of it I could not relocate it again despite many hours searching. Unfortunately it did not vocalize during the time that I watched it – a bit frustrating as I would really liked to have heard it calling!
This seems a bit early to see a Tropical Kingbird here in San Diego County although a quick check through eBird revealed some late August records from further north in California. Certainly based on previous records in the state it seems very much more likely to be a Tropical Kingbird than the exceptional rarity Couch’s Kingbird. However the bill does look very deep and wide at the base. Could it possibly be a Couch’s Kingbird?
The bird appeared to have some disease, possibly a mite infection, in the base of the upper left mandible. The bill base here looks slightly deformed or eaten away a bit behind the left nostril. The feathers around the base of the bill do look to be in poor condition. One other observation I noted when I saw it in flight, and visible in some photographs, is that it has just molted its central rectrices (r1). In fact the bird seems to be in the process of molting. The back and upper chest appear quite faded grayish but with new and much more colorful green feathers coming in on the upper back and breast sides. Similarly the underparts have strongly yellow feathers replacing the older whitish feathers throughout. I believe the photographs of the bird preening under its left wing show a single adult type notched P10 while the P9, and possibly other primaries beneath, appear to be of the rounded juvenal type in shape. Quite noticeable in several of the photographs are orange colored crown-stripe feathers visible among the gray head feathers.
I need to do some more research into aging and molt of Tropical and Couch’s Kingbird to see if this might help in the identification. I believe the two species differ in molt strategy with Couch’s completing prebasic molt on the summer grounds while Tropical completes prebasic molt on the winter grounds. I think without vocalizations this bird might be tough to identify – how I wish it had just called once!