For the issue of the covert patterning figure 19E and the legend for that
figure suggests an explanation. As for tail length the pictures of the Queens
bird that I saw did not show a fully grown shape and it seems very likely that
it is still growing, making conjecture about relative or absolute tail length
rather hazardous.
Cheers
Phil Jeffrey
Princeton
> On Dec 24, 2015, at 9:10 AM, Shaibal Mitra wrote:
>
> Thanks, Peter, for sharing this.
>
> Although the original hard copy of the article is right here on my shelf, I
> remembered it only dimly until you posted the link.
>
> Among the many characters discussed by the authors are two that I'd like to
> follow up on now, while everything is fresh in our minds. The first involves
> the pattern of the secondary coverts, which in Brewer's Sparrow are described
> as showing pointed black extensions along the shafts, described as absent in
> Clay-colored Sparrow. I had noticed that the Queens bird showed such points,
> and worried about this a little bit until I confirmed that multiple of my
> images of Long Island Clay-colored Sparrows also clearly show this pattern:
>
> https://picasaweb.google.com/109808209543611018404/Spizella#
>
> I don't have an explanation for this discrepancy, but it underscores the need
> to look at multiple characters when trying to distinguish very similar
> species.
>
> The second involves the relative tail length character mentioned in a number
> of posts. Whereas the article does not mention this as a useful field
> character for distinguishing Brewer's and Clay-colored, it is well known that
> these two species collectively differ from Chipping in being longer-tailed,
> relative to body size. This may not be immediately obvious from the table of
> measurements, because the tail length values for Chipping Sparrow are
> basically identical to those for Brewer's and Clay-colored. But the key point
> is that Chipping Sparrow is larger than the other two, as seen most obviously
> in its much greater wing length values. Thus, what might appear to be an
> obscure bander's formula, "wing minus tail" is in fact an elegant way of
> expressing relative tail length, and it is evident from the table that
> Brewer's and Clay-colored are similarly long-tailed compared to Chipping.
>
> Using wing length as a proxy for body size is appealing because these data
> are relatively accessible, but the validity of this approach is restricted to
> closely related species that have similar wing shapes. In the case of the
> Spizella sparrows, I think this is generally true. If anything, I think
> Chipping might be a little be longer-winged (relative to body size) than the
> other two, with a slightly longer primary projection, but I still think
> Clay-colored looks consistently longer-tailed than Chipping in the field and
> suspect that Brewer's does also.
>
> Shai Mitra
> Bay Shore
>
> From: bounce-120008119-11143...@list.cornell.edu
> [bounce-120008119-11143...@list.cornell.edu] on behalf of Peter Reisfeld
> [drpi...@yahoo.com]
> Sent: Wednesday, December 23, 2015 12:59 AM
> To: NYSbirds-L@cornell.edu
> Subject: [nysbirds-l] Spizella sparrows
>
> For those wishing to delve a bit more into this topic, here is an old review
> discussing the range of variation of features within species, and clues to
> help separate them.
>
> http://www.birdpop.org/docs/pubs/Pyle_and_Howell_1996_Spizella_Sparrows_Intraspecific_Variation_and_ID.pdf
>
> Happy winter birding,
>
> Peter
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