Thank you all for your comments.
1) Intergrade vs. Hybrid- The rigid definition is as Bruce describes, with
"hybrid" being ascribed to the interbreeding of two "species", and "intergrade"
as a mixing of two subspecies. But this definition has its flaws, especially
when applied to superspecies like the Dark-eyed Junco. For instance, there are
cases of secondary hybridization between White-winged and Pink-sided Juncos.
They do not have a hybrid zone, or an area of introgression, where you find a
mixture of parental types. A few individuals may turn up in each other's
adjacent ranges and hybridize. In the case of Gray-headed x Pink-sided, there
are several regions, entire mountain ranges, where there are intergrade
populations, with most individuals showing mixed characters. Most cases of
junco hybridization can be described as intergrades. But in some cases, such as
with White-winged x Pink-sided, the cases are so rare that describing the event
as hybridization is perfectly acceptable, as far as I am concerned. The known
rate of hybridization between White-winged and Pink-sided is less than the rate
found in areas of Yellow-eyed x Dark-eyed Juncos. Interesting.
2) Recent sightings of White-winged Juncos- I found one yesterday in a burned
Ponderosa Pine forest in Jefferson Co. It was associating with a Pink-sided. As
others have noted, Pink-sideds and Oregons are moving through. A few scattered
Gray-headeds are turning back up on the breeding grounds. White-wings are
moving out, I think, with a few still around. The birds I have seen recently
have predominantly been hatch-year birds. I haven't seen a spanking adult male
White-winged in a few weeks.
3) Intergrade Pink-sided x Gray-headed- Bruce, I've had your article for a
while and appreciate that someone took the time to publish on that situation. I
used to see a few a winter in AZ, and I see them in CO annually. As I think you
mention, Miller (1941) identified several regions of introgression. These
include several mountain ranges due north of the CO border in WY, as well as
areas of northern UT. Photos:
http://www.flickr.com/photos/christian_nunes/5155736875/
http://www.flickr.com/photos/christian_nunes/5156347106/
4) White-winged Junco Darkness-
Miller made a scale to judge the head darkness of juncos. It ranges from 1-11,
from darkest to lightest. One the dark end are the Oregon types (NOT
Pink-sided!). On the pale end are Pink-sided, White-winged and Carolina. Here's
a little table:
Male Pink-sided: 9-10
Male White-winged: 8-10, typically 9
Male Slate-colored: 6-8, typically 7
Male Montana "Oregon": 4
Male Carolina: 8
Female Pink-sided: 9-11
Female White-winged: 10-11
Female Carolina: 8-10, typically 9
Female Slate-colored: 8-10
>From this data, I ascertain that there is a lot of variation in head color
>between the sexes and between subspecies groups. Some female Slate-coloreds
>are as pale as male and even female Pink-sideds and White-wingeds.
>White-winged males can be as dark as a male Slate-colored (both can be an 8).
>This jives well with my experience with White-wingeds in CO. Some adult males
>are strikingly dark
>(http://www.flickr.com/photos/christian_nunes/3055226426/), young birds are
>not (http://www.flickr.com/photos/christian_nunes/5172728728/). A photo will
>be published in the upcoming Colorado Birds of an adult male White-winged
>specimen that is at the dark end of the spectrum. I can't share those here,
>unfortunately.
Now take a look at the Sibley Guide. I don't have mine in front of me, so can't
tell the page numbers, but there should be Pink-sided next to White-winged,
next to Slate-colored. I would judge Sibley's colors on Miller's darkness scale
as Pink-sided (10), White-winged (9) and Slate-colored (7). He chose to
represent the averages.
5) Tertials-
Jeff wrote:
<In addition, we discussed this on CoBirds a couple months ago; but brown
tertials, even if present, as I understand it, are not an indication of age.
Adult females of all races (according to Pyle) can have brown terts after
hatching year. Shape, however, should be and age indicator. But I didn’t get a
good photo or look at that.>
Well now, I never got on this train. Brown tertials, when present on particular
sub-species, are highly indicative of age. I come to this conclusion from
reading Pyle. It might not be possible to age/sex every single bird, but there
are some things to look at to get a pretty good clue.
During a juncos' first Pre Basic (PB) molt, they can replace 0-3 of their
tertials. This occurs from July-October. Southern subspecies are more likely to
replace all three tertials, northern birds (White-wingeds) less so. So a bird
like this can be reliably aged as a HY because it has replaced one brown-edged
juvenile tertial with an adult gray-edged tertial
(http://www.flickr.com/photos/christian_nunes/5172125607/). This bird hasn't
replaced any tertials, so they are all edged with brown
(http://www.flickr.com/photos/christian_nunes/5172728728/). It is still pretty
clearly a HY bird because of the brown wash, and the brown tertials! Who says
adult female White-winged Juncos have brown tertials? I don't believe that.
White-wingeds are characterized by having less sexual dimorphism than other
subspecies, notable less than the sexual variation in Slate-colored. So, if you
said that brown tertials on a female Slate-colored weren't a reliable
indication of age, I'd agree that that could be a possibility. In Pyle, he
describes After Hatch Year female juncos' tertials as being, "dusky with brown
(western subspecies) to gray (eastern subspecies) edging." I take that to mean
that an adult female Slate-colored, Carolina and White-winged can or should
have gray-edged tertials.
A White-winged, Slate-colored or Carolina Junco that has a mixture of retained
brown-edged juvenile tertials and replaced gray-edged adult tertials can be
reliably aged. I believe I am seeing this effect on Jeff's bird, but it's hard
to say for sure. I would also argue, according to my view on my monitor, that
his bird is of about type 9 or 10 on the color scale, which is more in the
range of White-winged. And also, the white wing-bars on his bird are very thick
and pronounced. I have never seen a variant Slate-colored that has this much
white on the median and greater wing coverts. Despite the apparent small size
(highly relative), I don't see much else to suggest that it's not a
White-winged. Bill color is useful, but maybe not definitive for every
individual. Slate-colored rarely has the whitish-horn colored bill that
White-winged and Carolina Juncos often have. They are much more typically
pinkish, with some duskiness around the nostrils or on then ridge of the upper
mandible. Bill size is diagnostic. Your photos don't give the detail that is
desired to get a good feel for the bill size, but in at least one photo it is
suggestive of White-winged
(http://www.sendpix.com/albums/11032116/16411000000000754107cec347bed66d00c670cb7366/?a=view&i=506344&d=0).
Ok, on with my life! Sheesh.
Christian Nunes
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