Date: 9/6/25 1:29 pm From: Stan Walens via groups.io <stan.walens...> Subject: Re: [SanDiegoRegionBirding] Encinitas Cuckoo
I’ll jump in here with both feet, looking at the one photo in the initial eBird report, #S271666564, by Jim Colby, Sept. 5 at 3:41 pm.
If there are other photos, I have not seen them.
i am looking on my computer monitor, not a phone screen.
I don’t understand why this bird is being considered a possible black-billed cuckoo.
The bill of a black-billed cuckoo is black from in the nest to adulthood. Uniformly black at all ages—not dusky at the base and then darker elsewhere. The bill of juvenile yellow-billed starts out black and then gradually gets paler and increasingly yellow.
To me, this bill clearly shows yellow. A dark mandible and yellow maxilla are appropriate for yellow-billed.
Now, one might say that the bill really is all black and the apparent lightness is caused by reflections, but it is unlikely that such reflections would exactly match the appropriate black-tipped bill of a yellow-billed, or somehow show exactly the black-tipped/pale-based pattern of a yellow-billed's maxilla.
The orbital ring of hatch-year black-billed is greenish or dusky, according to Pyle’s ID Guide to NA Birds, becoming red after hatch year.
Not yellow. This bird clearly has a yellow orbital ring, and I don’t think that is because of reflections.
The edges of the back feathers are whitish, appropriate for yellow-billed, not grey or buff, as in black-billed.
I think that the apparent brownness of parts of the face, back and some of the wing coverts are because they are in shadow, and the bird is actually fairly extensively and uniformly rufous.
The photo clearly shows the side of the tail, and one can see not the single continuous white outer edge of a black-billed, but the large white discontinuous spots diagnostic for yellow-billed.
The tip of the tail seems to show a thin black subterminal band and large white terminal spot, not the thin white terminal band of black-billed.
This is subjective, but the bill looks larger, both longer and deeper, than I would expect for black-billed cuckoo.
I really don’t see a single feature of black-billed cuckoo in this photo. And I see a number of features diagnostic for yellow-billed.
Stan Walens, San Diego
Sep. 6, 2025; 1:20 pm
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