Jeff’s photographs depict a plumage (dark hood – gray sides) that I associate with “Cassiar Junco.” In the Sibley Guide to Birds this plumage is called “Slate-colored of the Canadian Rocky Mountains” (see p. 501.) If I had to guess, I would say that about 0.5-1% of the wintering juncos in eastern Colorado are this subspecies (cismontanus). I think many of these are overlooked because they are not well categorized by field guides. Even Peter Pyle’s Identification Guide to North American Birds Part I, which describes this subspecies separately, and provides details on how to age these birds, assigns the common name “Slate-colored Junco” to this taxon. This book is used by banders as a manual for aging birds in the hand.
I am not sure of the significance of the rusty edges to the tertials. Sibley shows this for female Slate-colored, but not males. The only way to judge age on a bird in January would be to have the bird in hand, and to look for retained juvenal feathers. Unlike White-crowned Sparrows, which have a unique plumage for birds in their first basic plumage, juncos molt into adult plumage shortly after fledging. So, by the time the northern birds reach us in winter, they all look like adults through binoculars. In the first few months of life, skull pneumatization may be incomplete, and that would be another way of distinguishing a “hatch-year” (HY) junco from an “after hatch-year” (AHY) junco. This requires handling the bird and careful observation of the skull through the thin skin using strong light and a magnifying glass. However, by January even this method doesn’t work, for a couple of reasons. First, most skulls are completely pneumatized (or ossified) by then. Secondly, by definition, all birds in January are “after hatch-year”, because this aging system that uses terms like HY and AHY refer to the calendar year, not the biological cycle. So, to be clear, even a bird born in 2010 would be AHY in January 2011. If handling the bird (or maybe photographs of a bird at close range with wings and tail spread) determined that a few juvenal feathers are retained from last summer, then this young bird in January would be aged “Second-year” or SY. An alternative aging scheme uses the terms “First-cycle” and “Second-cycle” to refer to the bird’s annual cycle. “First cycle” would be a bird less than a year old. “Second cycle” is a bird in its second year of life, etc. But, beware, in Europe “2cy” does not mean “2nd cycle”. It means “2nd calendar year” – aaargghh. You just cannot win! There is no universally understandable aging system. Oh well. Finally, the common name for Junco hyemalis cismontanus is Cassiar Junco, not Cassiar’s Junco. I don’t mean to criticize, just to clarify. I think it is great that Jeff and others pay attention to bird populations at the subspecies level, and bring these issues to the forefront of birders’ consciousness through Cobirds. Thanks Jeff. Nick Komar Fort Collins CO From: Jeff J Jones Sent: Wednesday, February 02, 2011 9:22 AM To: [email protected] Subject: [cobirds] Cassiar Junco? Hi, Yesterday’s cold brought dozens of Juncos to my feeders with at least 1 good representative of each of the 5 expected subspecies: hyemalis, caniceps, shufeldti, aikenii, and mearnsi (slate-colored, gray-headed, Oregon, white-winged and pink-sided). My recent renewed research into the subspecies expected in Colorado (via Pyle, Sibley, Rising, BNA and JuncoID on the web) has me doubting I have ever seen another potentially expected subspecies, that of cismontanus or the Cassiar’s Junco. Understanding all the discussion on this possible race/hybrid/intergrade and its arguably wide range of plumage characteristics, I believe I had what might be a good candidate for a HY male Cassiar Junco. - Tertials have grown edging; which I believe would make it HY (or first winter) in all Junco cases (but would love to hear feedback if others feel this isn’t always the case) - Grayish flanks with brown tinge - Definite hooded effect; bib coming down below normal concave line of hyemalis nominate subspecies; and hood being somewhat darker than rest; although not as remarkable as Sibley pic might suggest – but that appears to be an extreme. - Brownish wash on mantle - The Oregon group should have brown/cinnamon/pink wash on flanks and no gray; so this should rule out that group as I understand it, and the only choice should be between a hyemalis ssp or cismontanus as I figure it. Anyway, interested in what others might think about this, knowing full well that giants in the field (Floyd, Leukering, Jaramillo, Kaufman, and others) don’t seem to agree on many aspects, and not wanting to start a war here on CoBirds. Just wondering if others feel that I might finally consider the possibility that I have seen a Cassiar in my backyard! J Pictures: http://www.sendpix.com/albums/11020216/160215000000001e83bd6454d7a8606c2c2bf434c1c2/ Thanks Jeff J Jones ([email protected]) Teller County - 8500' - Montane Woodlands -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en. -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
