NOTE: I appreciate Christian responding to the group on this and I hope that if you find this too long you just delete it. If all the experts in their own areas have private conversations about this offline, we all cannot learn from them. And I hope/believe that this is one of the goals of this list. I realize there are also several blogs/forums for discussing such difficult identification, but hope that we can continue to discuss particulars here that are germane to Colorado birders. For example, Limpkin ID issues may not belong here but junco subspecies differentiation seems particularly useful for Coloradans.
Christian, Thanks much for the analysis. And, as I continue to learn the intricacies of Junco race differentiation, allow me to ask a few exploratory questions. First, you mention brown in the tertials. I don't see that. In fact, I went back to the dozens of photos I took in my photo software (where I can blow each photo up as needed; camera has an 11Mpixel resolution) I don't see anything that makes me think brown in its tertials. A couple pictures maybe hint at it, but I think that is just backlighting. I don't remember seeing any brown when looking through binos at 20 feet. Now, this often confounds me as when, in the CFO quiz answer, Tony says something about a photo that I don't remember noticing. I download the photo, import it into my bitmap/photo software; blow it up; look at it from every angle; and I will be darned if I see what he sees. I start thinking, perhaps he has a better resolution picture than the photo quiz that he is using for description, or since he has other angles of the same bird, he knows what should be there - but lots of times I simply cannot find what is being described - such as 'brown tertials'. In either case, I cannot find an indication of brown in this bird's tertials. I say this just to let you know that there is evidence that this is all my color perception problem. J 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. Thanks for pointing out the bit on the presence/absence of lores on aikenii. I will try to get that field mark out of my mind now. And since I didn't get the amount of white in the tail, we are left with size. I didn't think many years ago that one could differentiate the small size differences between the Junco races. But when dozens show up at your feeder for months each winter, it becomes quite easy (once you know to start looking) to spot at a glance the difference between the large and bulky pink-sided and white-winged, for example, and the small Oregon or medium gray-headed/slate-colored. This bird was small; Oregon and slate-colored size. I thought I was getting pics with other juncos in it, but the only one that came close was the one I posted. This bird was also near several dinstinctly slate-colored individuals and appeared to me to be the same size as those. So, interested in knowing if you still feel confident about the white-winged diagnosis? If so, perhaps I can get you to take a different approach and tell me why it can't be a slate-colored? Some percentage of slates have white wing bars of varying degrees as we all know. You also mention the bill color. Is this a reliable field mark for separating hyemalis from aikenii? Pyle says "pale pinkish to whitish" for slate; with no mention for white-winged. On another note, Sibley also states a "pale throat" on white-winged individuals. But I don't find that backed up anywhere else. Is this a generalization also that can't be trusted? The bird I photographed does not seem to have a pale throat or a throat area otherwise differentiated (pic 146a) from the rest. Thanks Jeff J Jones ( <mailto:[email protected]> [email protected]) Teller County - 8500' - Montane Woodlands From: Christian Nunes [mailto:[email protected]] Sent: Monday, March 21, 2011 11:23 AM To: [email protected]; CObirds List Subject: RE: [cobirds] Slate-colored Junco with broad white wing bars - Teller Co Jeff, Your junco is pretty clearly a White-winged. There are a few misconceptions about White-winged Juncos that are exacerbated by modern field guides. One is that they should have dark lores. The other is the color of the head. White-winged Juncos can have contrasting dark lores, or they can lack it. White-winged Juncos can have a head that is as dark as a Slate-colored, or as light as a Pink-sided. These details are misinterpreted by field guides. The monograph on the species (Miller 1941) describes White-winged Junco as lacking dark lores. But the Sibley guide points this out as a useful field mark. They are both right, to some extent, since this feature is simply variable. The head color varies from very pale (Pink-sided gray) to very dark (equal to or darker than Slate-colored). This is a detail that Miller noted, but modern field guides fail to encompass. A Junco with thick white wing-bars, a large, horn-colored bill, and that is gray overall can confidently be called a White-winged here in CO where they are common. The small size is interesting, and in one photo it is quite apparent with the bird standing next to a Gray-headed. Two of the tertials are edged with brown, and the third with gray. It's probably a hatch-year bird. They molt a variable number of tertials in the fall (often 0, often 1, less often 2-3). A bird with retained juvenile tertials at this time of year can confidently be aged, while those with completely replaced gray tertials cannot. I've recently uploaded a bunch of junco photos with a couple confusing hatch-year White-wingeds which can be seen at the end of this set: http://www.flickr.com/photos/christian_nunes/sets/72157609842959747/with/553 7208275/ Christian Nunes [email protected] _____ From: [email protected] To: [email protected] Subject: [cobirds] Slate-colored Junco with broad white wing bars - Teller Co Date: Mon, 21 Mar 2011 10:48:48 -0600 Many juncos moving through Teller County today; slate-colored, Oregon, pink-sided, gray-headed. And several singing. But one caught my eye - a small slate-colored with broad white wing bars on primary and secondary coverts. Bird is smallish - like other slate-coloreds there; definitely smaller than gray-headed and pink-sided - white-winged should be noticeably larger. Lacking contrasting lores that aikenii (white-winged) would have; and throat is not paler as you would expect in aikenii. Didn't get a good read on amount of white in tail feathers. Overall, the bird was darker (slate-colored) that you would expect for white-winged; but I don't think the photos capture the true tone correctly and show it a bit lighter than it looked with naked eyes and binos. Got fair enough pics through the dirty window with sun on it. http://www.sendpix.com/albums/11032116/16411000000000754107cec347bed66d00c67 0cb7366/ Certainly welcome any comments if others feel that this might be an aikenii. Jeff J Jones ( <mailto:[email protected]> [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.
