Peter B wrote to me offline and pointed out that Sibley does indeed show
an intermediate bird with white belly, at the bottom of page 79, where
he states "A complete range of intermediate birds occurs between white
and dark morph." Re-reading his text under Ross's, p78, "The
combination of dark neck and white belly is not shown by snow goose."
the context is starting to make sense. I mean, David Sibley is a smart
guy, right? (I'm the amateur here!) Technically, the bird I
digiscoped had a WHITE NECK and did not show the combo 'dark neck and
white belly', rather it had a white neck and white belly (only the
breast was dark!) Wish I could remember the neck color of the other 4
white-bellied dark morphs, but I expect all is consistent with Sibley's
statement regarding 'dark NECK and white belly.' You can bet, however,
that I will be watching for dark-necked birds in the future!
Thanks for the comments and discussion.
Fred and Chris Pratt wrote:
> Fun pictures! Looks to me like a lot of Snow Goose and a lot of Blue
> Goose - but with that size and that bill I can't imagine Ross' had
> anything to do with your bird(s).
> I'll stick to pipits.
> Terry Wright wrote:
>> Thanks for pointing to the National Geo guide. It does indeed show
>> this color variant! I've since checked Madge & Burn, Stokes,
>> Audubon Master Guide, Kaufman, etc. and none other, that I own, shows
>> this 'white-bellied blue morph'. As for size, at least one bird was
>> definitely of greater snow size. I've posted a couple digiscoped
>> images here:
>> Fred and Chris Pratt wrote:
>>> This isn't my area of expertise (assuming I have one), but geese
>>> show variations of size and plumage that leave us all guessing. The
>>> National Geographic Guide shows a "blue phase variant" with plenty
>>> of white on the belly, though with only a bit of dark on the neck.
>>> Is it close in appearance to your birds?
>>> I would assume Ross's x Blue hybrids would be smaller than a typical
>>> Blue - but who knows?
>>> Terry Wright wrote:
>>>> Quoting from Sibley's:
>>>> "The combination of dark neck and white belly is not shown by snow
>>>> goose." (The Sibley Guide to the Birds, first edition, Chanticlear
>>>> press, 2000, p78.)
>>>> Either I am misinterpreting this quote or someone forgot to tell
>>>> the snow geese this 'fact', or maybe new color morphs have arisen
>>>> since publication??? Today at the DCWMA we observed at least 5
>>>> individual blue-phase snow geese with white bellies. Could these
>>>> be Snow x Ross' hybrids? They certainly were NOT Ross's Goose! I
>>>> can send pictures to anyone interested in this topic.
>>>> Discussion on this observation most welcome!