Subject: RE: Forms???? Slate-colored Junco
Date: Oct 31 21:50:00 1998
From: "Jon. Anderson and Marty Chaney" - festuca at olywa.net


"bcbc.holtz" wrote:

>> I am 13 years old and I had a positive "SLATE-COLORED >>JUNCO" come to my feeder today. My book calls the coloring a
>> form. What causes these forms such as the " White-winged" and
>> the "Pink-sided".

Happy Hallow'een, folks,

bcbc.holtz, the forms are 'caused' by birds with similar genetics
breeding within their own groups. The slate-colored forms tend to
mate with their own kind, because the other forms nest in different
areas. Where the two forms nest in the same area, they can cross-
breed (hybridize), and you can get birds that show characteristics of
both 'forms'. This happens with other species in our area, such as
the red-shafted and yellow-shafted forms of the Northern Flicker.

While puttering around today, getting ready for the trick-or-treaters
(we got *zero* kids tonight!!), I had the mist-nets up, and caught
a Slate-colored Junco. This bird was a hatching-year individual,
with light grey plumage, and had just a trace of the rufous/brown
coloration on its back.

Its measurements were not sufficient to distinguish male from female,
but because the plumage was the lighter grey it's likely a female (gets
reported to the Bird Banding Lab as a Hatch-year Unknown sex,
though, cuz' I'm just not sure).

What was interesting, was that there was another Slate-colored Junco
in the yard later in the afternoon. It was much darker grey in plumage,
which makes me think it was likely a male. Quite aggressive toward the
other juncos at the feeder.

Byers, et al. notes that Junco hyemalis hyemalis breeds from Central
and Northern Alaska and west-central B.C. eastward across Canada
to Newfoundland & Nova Scotia, as well as through the Great Lakes
and New England. "Rare but regular west of the Rockies in migration
and in winter".

They have another slate-colored junco, J.h. cismontanus breeding
from south-central Yukon south to central B.C. and west-central
Alberta; winters through western North America.

I am not sufficiently familiar with the 'slate-colored' juncos to distinguish
between these two subspecies. I have to agree with the end of the
following statement in Byers : "Fifteen races described. For convenience
the races are listed under what were formerly the common names of the
different species that were recognised within the complex (Slate-
colored, Oregon, Grey-headed, and White-winged juncos). Within
each group, the races are often very similar and hybridisation is also
common between them, which can make racial identification difficult
or impossible."

I do see the slate-colored types in the yard here in Oly every winter,
and have picked one up in the mist-net about every year or two.
Banded one here last March, as well.

Jon. (Trick-or-Treated as a Cowboy) Anderson
Olympia, Washington
festuca at olywa.net