Hello everyone,
This afternoon, I went in search of the pair of juncos that I mentioned in the
post I made here yesterday about foothills bird activity. I was able to re-find
the pair about 300 yards from where I last saw them yesterday. I was able to
get several record shots of what I now strongly feel is an adult female
WHITE-WINGED X PINK-SIDED JUNCO, as well as her diligent mate, a typical adult
male WHITE-WINGED JUNCO.
Here are the photos, many of which have notes about key features, so just roll
your mouse over the photo and these will appear:
http://www.flickr.com/photos/christian_nunes/
As I described yesterday, these two juncos are associating quite strongly with
each other. They are rarely more than a few meters from one another, and when
one flies to a new tree, the other soon follows. The female bird has a shocking
mix of features from both suspected parent populations. The wing-bars on this
bird are bold and conspicuous. The median and greater secondary coverts that
are tipped in white are predominately gray with no sign of brown hues. The
tertials are also striking, having dark centers and frosty edges that again
lack any brown hues. The sides of the breast and flanks of this bird are a warm
cinnamon color. The head is a pale gray with contrasting dark lores. The hood
is convex on the ventral side, and it contrasts with a brown back on the dorsal
side. The bill is certainly on the large side. Many of these features are
pointed out with notes on the photos. For reference, aikeni= White-winged Junco
and mearnsi= Pink-sided.
I've been able to piece together a little bit more on the historic record of
this pairing. In Miller's (1941) "Speciation in the Avian Genus Junco", he
describes the first example of this pair as being collected on Feb. 6, 1902 in,
how do you like this, Altona, Boulder County, CO. The specimen is in the CU
Museum. Altona, as it turns out, is the corner of Left Hand Canyon Rd and Hwy
36, within spitting distance of Dave Waltman's house! Miller goes on to
emphasize that "of a number of supposed hybrids taken in winter, this is the
only one that is not merely a meanrsi with the white wing spots which may be
considered a "normal" (1.82%) variation of that species." After this bird was
collected in Altona, a team of scientists from the Museum of Vertebrate Zoology
visited what they thought was the likely source location of this pairing, the
mountains of western Powder River County, MT. And of the 30 adult and 9
juvenile juncos they collected near Fort Howe Ranger Station, they considered 3
to have intermediate characteristics between aikeni (the predominant form in
this location) and mearnsi. Subsequent searches of this area in 1985 did not
detect any evidence of hybridization, supporting Miller's hypothesis that
infiltration of mearnsi genes into the breeding range of aikeni is very rare.
The bird I have photographed clearly has several pro-aikeni features, so a
wing-barred variant mearnsi can be ruled out. This bird also has several
features, like the brown back and cinnamon sides of the breast and flanks, that
are not shown by aikeni. These birds seem to be settling in to a particular
area of the forest for now. They will probably be around until the first good
snow storm, at which time I start seeing fewer and fewer White-wingeds in this
particular area. Hopefully I can obtain some better shots.
Christian NunesBoulder, CO
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