[Birdtalk] "Lesser" Canada Goose and "Parvipes"

Mon Mar 3 15:10:49 MST 2008

*Branta canadensis parvipes* are generally referred to as "Lesser" Canada
Goose here in North America.  On the Continent "Lesser Canada Goose" is the
official name for what we here refer to a Cackling Goose (*Branta hutchinsii
*).  Although there is much speculation about the various forms of what the
AOU currently recognizes as eleven subspecies of "white-cheeked geese"
(Canada Goose and Cackling Goose), as with almost any bird, there is no "one
size fits all" match.
Many of the parvipes which migrate through the interior west are dark
breasted, mostly originating from the population breeding around Anchorage,
AK, but can vary in size from "Cackling-like" to larger than any Cackling
Goose subspecies. The safest and surest way of differentiating *parvipes*from
*B.h. hutchinsii* (Richardson's Goose) or *B.h. taverneri* (Taverner's
Goose) is still by head and bill shape/size relationships. Be advised that
there are *B.h.hutchinsii* which can be darker than the "advertised norm,"
and *B.h.taverneri* which are both darker and some lighter than the norm.
Looking at morphological differences in bird populations as a criterion for
subspecies designation can be a slippery slope, considering the endless
possibilities of clinal differences...and yes, using that kind of criterion
it might be possible to come up with 200 variants of white-cheeked geese, as
suggested in the recent two volume work on the subject, but is it valid when
compared to the currently accepted process with other species?  Probably
not.

J. Harry Krueger
Boise, ID
www.IdahoBirds.net <http://www.idahobirds.net/>
http://bird-brio.blogspot.com

On Mon, Mar 3, 2008 at 1:43 PM, Tim Avery <tanager at timaverybirding.com>
wrote:

>  Davis, et all.
>
> Parvipes is part of the complex of "Lesser" Canada Geese.  This going
> along with the assumption that there are multiple forms of the Lesser Canada
> Goose.  Parvipes tending to be on the smaller side.  Since geese flock up we
> often get mixed flock of subspecies which is why when we see many flocks
> there are obvious birds of different size, subtle pattern differences,
> etc..  I mentioned to you on the phone that there was a biologist back east
> who apparently had described over 200 subspecies of Canada Goose at the time
> of his death.  I had heard this from another birder (who I think still
> lingers ont his list).  And there is probably some mount of breeding between
> apparent subspecies based on overlapping breeding grounds.  But this is a
> realm I don't even watn to delve into at the moment.
> When I refer to geese around the Great Salt Lake I often use Great Basin
> (which is also moffiti), Lesser (referring to smaller than moffiti),
> Parvipes (referring to the smallest of the Canada Geese we get, often very
> petite with petite bills), and Dusky (the darker breasted Canada Geese, but
> dusky technically don't occur here, so these birds are likely dark variants
> of lesser?).
>
> It is very confusing, and there isn't any great text or great site that
> really delves into how nasty a complex this probably is.  There are many
> sites with information about Canada/Cackling, but again there is no
> definitive text about it that I am aware of to say what really is what.
>
> That said, I am not saying you didn't see 2 Cackling Geese at Kaysville
> Ponds.  Geese like other birds have wings and tend to move around quite a
> bit and it is very possible that the birds you saw were elsewhere when I was
> at the ponds.  I was simply stating imn my email that we didn't find any
> Cackling Geese, which means nothing in respect to what you saw earlier in
> the week.
>
> I have a pretty good collection of Cackling Goose images on my site (and
> even some of these birds may be odd subspecies of Canada Geese, some are so
> borderline its a tough call):
>
> http://www.timaverybirding.com/photos/thumbnails.php?album=105
>
> However, one general fieldmark I tend to use, it the shape and size of the
> bill.  Cackler's have bills that are short and stubby, they look funny.
> Canada Geese have long bills (take a look through these):
>
> http://www.timaverybirding.com/photos/thumbnails.php?album=104
>
> The best evidence of any Cackling Goose is a photo.  I have mis-identified
> several parvipes in the past as Cackling Geese and it was pictures that
> proved they weren't.
>
> Keep on posting and sharing your sightings, I wish more people would do
> what you do!  Thanks!
>
> Good Birding
>
> Tim
>
>
>
>   ----- Original Message -----
> *From:* David Jensen <dlj11350 at yahoo.com>
> *To:* birdtalk at utahbirds.org
> *Sent:* Monday, March 03, 2008 1:00 PM
> *Subject:* [Birdtalk] "Lesser" Canada Goose and "Parvipes"
>
> Saw Tim Avery's report from Kaysville Ponds. I thought that parvipes
> Canada and "lesser" Canada were the same bird. Have I missed something in my
> hours of nerve-jangling photo studying and reading? I talked with Tim on the
> the phone about two possible cacklers (Hutchinson's) at the ponds but wasn't
> sure what I'd actually seen. I assume I didn't see the cacklers then, and
> that what I saw were a couple of "lesser"/parvipes (?). I think I might be
> getting my goose language all messed up here.
> I'm not very good at this birdtalk site yet and am not sure if my messages
> are getting to the right place. Hope so. Would like to hear back about what
> Tim and Colby think of my nomenclature dilemma. Thanks guys.
> David Jensen
>
>
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