Clay-colored and Field Sparrow Hybrid

(my July 2008 ToledoTalk.com post)

Subject: Spizellapalooza
From: Aaron B
Date: Wed, 16 Jul 2008 14:38:11 -0400

Just got back from a successful outing in Lorain County at the Charlemont
Reservation. Since Ethan K found an unusual "Spizella" sparrow at
this preserve a week ago, some interesting developments have taken place.
Originally, this sparrow was thought to be a Clay-colored Sparrow because it
was singing a song almost identical to that of Clay-colored. Since it was
seen with another bird, two follow up attempts to confirm breeding instead
revealed an inconclusive identity for this bird. Scope views and digiscoped
photos taken last week hinted at Field Sparrow but by no means represented
either a "classic" Field Sparrow or Clay-colored Sparrow.

Today, I joined up with Andy J and we attempted to mist net this sparrow
to sample some of its DNA and we managed to capture and release the bird
unharmed. Interestingly, it reacted aggressively to playback of both
Clay-colored AND Field Sparrow. It seemed that it reacted most aggressively
towards Field Sparrow as this was the song that drew it into the net after
just one song broadcast.

Having the bird in the hand was very informative and its plumage
characteristics seem to support our hypothesis that this is a "Clay-colored
X Field" Sparrow hybrid. As far as we know, there are only two published
instances of hybridization between these two sparrow species. For those
interested, the link below is a collection of photos of this bird in
addition to a video with a clear recording of its unusual song:

http://picasaweb.google.com/boone70/SpizellaSparrow?authkey=3tHl2xApLRQ

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Subject: Re: Spizellapalooza
From: Victor F
Date: Wed, 16 Jul 2008 16:41:15 -0700

an interesting development, and equally interesting
as to what the genotype proves to show.

As to the phenotype, Aaron brought to my attention
last Saturday the field images and I provided this
breakdown at that time.

------------------------------------------------------------------------

1. bright pink bill
2. rusty cap set off from pale face
4. pale gray, unstreaked nape

stand back from the computer screen and the bird comes
across as a Field Sparrow, at least from the front.

then there's the

1. prominent lateral throat stripe,
2. a stipling in the crown that appears to be faint streaks,
3. and the heavily streaked back
4. whitish-gray supercilium

which are Clay-colored characters

the auriculars are mostly gray (matching the gray nape) with
a warm upper border (matching the crown) ... typical Field Sparrow.

However, the auriculars are also bordered by a pale supercilium and
submalar setting them off to a degree stronger than normal in Field
and more akin to Clay-colored.

Barest hint of a median stripe is a strike against Clay-colored and
within variation range for Field. The weak, but clearly present white
eye-ring may be within variation for Field but is more typical of
Clay-colored.

and then there is the song

Field = a descending, accelerating, multi-pitch whistled sequence
Clay-colored = a steady, monotone, raspy buzz

Your bird = an accelerating, two-pitch raspy buzz

in any ID one asks whether the observed discrepancies from the
norm are within the range of variation for the species. There are a
couple of characters here that are, to my knowledge, completely
outside the range for either species

1. lateral throat stripe outside of Field
2. bright pink bill, rusty cap outside of Clay-colored

and when the variation falls intermediate between two species
(in this case including vocalizations), one finds the hybrid
explanation as likely as anything else.

Not a conclusion I come to lightly. I am aware of a Dayton area
record from the late 90's where David D observed a Field Sparrow
singing a Clay-colored song. However, that's not the case here.

#bird #nature #ohio