Wayne,
Great info, lots of stuff to ponder. Good east coast birding, Tom
On Thu, Mar 28, 2019, 7:25 AM Wayne Hoffman <whoffman@xxxxxxxx> wrote:
Hi -
Lars has raised some very good points. First, he wrote, "I feel the
Cassiar is a hybrid swarm, not a real subspecies, and one should expect
broad variability." One of the characteristics of a hybrid swarm is
variability in the traits differing between (or among) the parental taxa.
If you have a clear or simple view of what a member of a hybrid swarm
"should" look like, then you are missing the point.
In my opinion, the currently accepted dogma on the relationships between
Junco taxa are oversimplified. American bird taxonomists tend to see
speciation following one model or process: geographic isolation followed
by gradual divergence in isolation, etc. This model seems to do a good job
of explaining species relations in most North American birds, but there are
a handful of groups where "special circumstances" enable speciation to
occur much faster, and sometimes without isolation. "Special
circumstances"might include unusual combinations of migratory behavior and
courtship dynamics, strong disruptive selection on morphology, and
"anomalies" in the groups respective genomes. IMO, these groups include
northern geese (Anser and Branta), prairie grouse, large gulls, the owl
groups Otus/Megascops and Glaucidium, Empidonax flycatchers, Vireos,
Titmice, Gnatcatchers, Juncos, Crossbills, possibly other Fringillid
finches, and probably a few others.
If I remember correctly,a paper was published several years ago reporting
that the different "subspecies" of Junco differed in chromosomal structure.
This takes me back over 40 years to my college genetics courses, where we
studied chromosomal rearrangements in fruit flies. The first implication
(to my knowledge not yet examined in Juncos) is that chromosomal inversions
and translocations often interfere with meiosis when cross-bred, and so can
(but not always) become reproductive isolating mechanisms. If this
happened to be the case with some of the junco taxa, then species limits
might need to be revisited.
Lars also pointed out some aspects of the photographed junco -
particularly pink on flanks - that I think are out of the normal range of
Slate-colored Junco plumage.
Wayne
On 3/27/2019 9:25:57 PM, Lars Norgren <larspernorgren@xxxxxxxxx> wrote:
One of the most striking photos l've ever seen on line was an intergrade
flicker, frontalview, one half of the tail feathers yellow, the other side
of the tail dark orange. I suppose it could have been photoshopped, but
assuming it was real, why couldn't the same happen with Juncos? Will
someone tell me, do eastcoast Juncos regularly have pinkish-buff at the
tail end of their flanks?
On Wed, Mar 27, 2019, 5:23 PM Hendrik Herlyn <hhactitis@xxxxxxxxx> wrote:
I've had a very similar bird at our place in Corvallis in the past few
days that I've been wondering about. The funny thing about my bird is that
its two sides look slightly different from each other. On the right side,
the gray head and chest end in a somewhat concave pattern, and the gray
bleeds along the flanks, with some rufous tinges mixed in toward the rear.
On the left side, the gray head and chest from more of a hooded look, with
gray flanks. So one side resembles a classic Slate-colored (except,
perhaps, for the rufous tones in the flank), while the other side looks
more like Cassiar's - very strange! Unfortunately, the bird has refused to
pose for pictures thus far.
Regarding Bob's bird, I agree with Lars and Dave that it still falls
within the Slate-colored spectrum (to the extent that I'm familiar with it).
Cheers
Hendrik
On Wed, Mar 27, 2019 at 5:06 PM David Irons <llsdirons@xxxxxxx> wrote:
I would call this an immature Slate-colored for the issues Lars raises.
Dave Irons
Beaverton, OR
Sent from my iPhone
On Mar 27, 2019, at 5:00 PM, Lars Norgren <larspernorgren@xxxxxxxxx>
wrote:
Some portion of the cognoscenti will discount this as a Cassiar because
it lacks an Oregon style hood, black clearly delineated from grey flanks, a
convex margin at the upper breast. Also the bright red back...? I have
examined well under a hundred Slate-coloreds in half a century. Others on
this list have looked at thousands. Are the pinkish-buffy flanks OK for
S-c. A similar bird was put up here earlier this year with the same slate
colored foreflank but buff at the rear, the same brown back and nape. Some
said it was well within the range of regular S-c J. I feel the Cassiar is a
hybrid swarm, not a real subspecies, and one should expect broad
variability. Lars
On Wed, Mar 27, 2019, 2:44 PM Robert O'Brien <baro@xxxxxxx> wrote:
My wife just spotted this bird at our feeder. Not a birder, she's
always asking me "What's that bird?", often a song sparrow; but
she hit the jackpot this time. And just in time as these winter
birds/migrants are due to leave before long. I'm not sure I've ever had
one here before, at least that I recognized. And over many years we've
had almost yearly Slate-colored, one or two that returned for a successive
year. Recently there was a OBOL post of a immature female
Slate-colored, so I'm not totally sure of this one. So?
An interesting "subspecies" or is this just a hybridizing contact
zone? And if not a hybrid between 'Oregon' and 'Slate-colored',
what would such a hybrid look like relative to Cassair?
For more on the enigma of the Cassair, see eBird comments at
https://ebird.org/pnw/news/dark-eyed-junco-races-oregon-slate-colored-and-cassiar/
Bob OBrien
Carver OR
--
__________________________
Hendrik G. Herlyn
Corvallis, OR
*"Nature is not a place to visit. It is home." -- Gary Snyder*
