Thursday, April 12, 2018

Microlocalzonoweirdness


April means a lot of things to a lot of people, but one thing it means around these parts is the departure of the Zonotrichia. Golden-crowned and White-crowned Sparrows make up such a large proportion of the passerine avifauna in northern California for so much of the year, it's always strange to realize one spring day that they are gone until September. Well, nuttalli White-crowned Sparrows don't migrate, but you know what I'm saying.

Both of these birds are common feeder attendants here at Rancho de Bastardos, so of course I am always checking them for a White-throated or a Harris's while I still can, or something even more unexpected...and the unexpected did finally arrive. Last week I was surprised to see the bird pictured above.

This is a newly-arrived migrant that has made a prolonged stopover here at the Rancho. It has been here over a week now, and is easily discernible with the naked eye from the living room. At first I thought it was just a slightly aberrant White-crowned Sparrow, but there is more weird to it than just the almost entirely missing postocular line.


Also surprising is the amount of contrasting white in the throat and malar area, and the thin black crown stripes.


The bill is pinkish, distinctly different from the other orangey-billed White-crowneds that populate the Rancho.


View of the back of the head.


It's a weird bird. I've never seen a great number of White-crowned Sparrows and have never seen one like this. It's the same size as a White-crowned, though does seem bulkier at times. It's definitely not molting, it's a very fresh, bright looking bird. I heard and saw it sing once, and it sounded pretty much like the other White-crowns here.

Right. Don't worry any longer, I will ask The Question you have all been waiting for...is it a hybrid? Could it be that great unicorn of the Zonotrichia, a White-throated X White-crowned Sparrow? An F2 even?

Well, this isn't a quiz bird. Your guess is as good as mine, or better....or potentially far worse, depending on who you are. Let's be honest. I don't have total and complete confidence in identifying it, this is essentially a new bird for me. It's worth mentioning that sometimes the bird gives off a very White-throated vibe, appearing very plump and having a long, flattened crown in profile. If it is "just" a White-crowned, it sure has a lot of mutant characters appearing all at once.

I am inclined to say that this is a hybrid. For reference, I checked eBird of course...there are a total of four White-throated X White-crowned Sparrows with photographs in eBird. One is obviously a Golden-crowned Sparrow and is hopefully being purged as I type this, but the others bear a significant resemblance to this bird. Notably, they all have the minimal (vestigial???) postocular line, though it is such a bold feature on both parent species.

What do you think? In any case, it's fun to have such a weird bird lurking around here at Rancho de Bastardos and have the chance to study it at length.


In case you are wondering, the Golden-crowned Sparrows are looking sharp now. No study required, only appreciation.

1 comment:

  1. Such unholy spawn! You've a knack for attracting bastards.
    Cool bird. The throat, chubbiness, and fluffy lores are all White-throat reminiscent.

    Is it typical with hybrids that hey have vocalizations of one species or the other vs. a mish-mash?

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