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The putative Indigo Bunting at Paso Picacho

All,

I have serious reservations about the identification of this individual as a pure Indigo Bunting. We now have several excellent series of photographs showing the extent of white in the lower belly and the blue, white and gray undertail coverts. We can see that the belly patch is not an under-layer of feathers exposed as a new outer layer comes in, but is itself the outer layer.

Indigo Buntings start out as dun-colored birds, and as they molt their dun-colored feathers are replaced by indigo-colored feathers. It’s a patchwork process and they can look quite motley. But they are motley brown and indigo, not white and indigo. Additionally, I don’t know why people are suggesting that the white belly patch on this bird indicates it might be a first-spring individual. First-spring male Indigo Buntings are brown and blue with occasional flecks of white where a feather has been molted but the new feather has not emerged yet. Sometimes in the lower belly, feathers have molted out and we see the white under-layer, but in my experience, it is at most very limited in extent.
So for me, the presence of such extensive a white belly on the Paso Picacho bird is incontrovertible proof of Lazuli Bunting ancestry and puts pure Indigo Bunting hors de combat.
Next, the blue and white undertail coverts do not match the pattern on Indigo Buntings. But this pattern is frequent in Indigo-Lazuli hybrids.
Finally, Eve made some sonograms of the bird singing. To my ears, there is not a single element of that song that is Indigo. The pitch, the timbre and the phrases are spot on for Lazuli.
So, in my opinion, this is a hybrid Indigo-Lazuli bunting. Indeed, if you google images of such hybrids, you’ll find a number of images that match this bird in numerous ways. And so far as I can tell, no images of Indigo Bunting that show such extensive white.
Stan Walens, San Diego
June 9, 2018; 4:30 p.m.

Source: SanDiegoRegionBirding Latest Reports