Last weekend, Mike Donahue and I went looking for Gray-bellied Brant
around Padilla Bay, and were able to observe what appeared to be a
family group at fairly close range on the west side of March Point at
low tide. At first we were struck by how different they were from Black
Brant, and then we thought we were looking at an Atlantic/Pale-bellied
Brant family. They showed a marked contrast between the breast and
belly, extensively pale flanks, with very little contrast with the
belly, and less extensive white on the neck. A short time later we found
a large group of brant that contained mostly what I would have called
Atlantic Brant were I on the east coast, as well as, a few Black Brant
mixed in for good comparison.

We were very confused by now, since Mike and I were going by the
illustration in David Sibley's new guide, which was our only source as
to what this undescribed form looked like. (I do recall a description in
the Birds of North America account for Brant describing this form, but I
haven't had time to check it out at the University of Washington
library.) Once home, I poured over what resources I had and recalled
several posting on ID-frontiers in the fall. Here are copies of the
current views of the Puget Sound/ Melville Island Birds, and Brant in
general:

*****
According to Steve Mlodinow:
"Brant: The intermediate form, to my eyes, looks too dark beneath, shows
too
little white on the flanks, and has too much white on the neck. Also,
this
population (per local biologist studying Brant) is considered part of
the
"Pale-bellied" or "Atlantic" Brant group."

also from Steve M.:
A fairly good article on Brant races appeared in Birding World 10:11-15
(1997), entitled Separation of Black Brant, Dark-bellied Brent Goose,
and
Pale-bellied Brent Goose. It does not cover the Melville Island birds,
but
does cover the other taxa.

Notably, the Dark-bellied Brant usually has much less of a white flank
patch
than Black Brant. I suspect that a Pale-bellied X Black Brant hybrid
would
show a far brighter flank patch than Dark-bellied Brant. Also, the
Melville
Island birds wintering in the Puget Sound tend to show a rather
prominent
flank patch, and I suspect this could be used in eliminating
Dark-bellied
Brant.

The Melville Island birds also tend to show a necklace resembling
Pale-bellied Brant rather than the more complete necklace of Black
Brant.

*****
>From David Sibley's website:
Brant Branta bernicla
Black B. b. nigricans
Intermediate B. b. unnamed?
Pale-bellied B. b. hrota
Three subspecies in North America differ subtly in plumage. The status
and identification of the recently diagnosed Intermediate population,
nesting on Melville Island and wintering in Puget Sound, is poorly
known.
[Eurasian race B. b. bernicla could occur in North America, but would
probably be indistinguishable from Intermediate birds and from Black X
Pale-bellied intergrades].

For those interested the URL for the site is:
http://www.sibleyart.com/taxa.htm

*****
>From Angus Wilson:
Taxonomy and Identification of Brant from Melville Island, Canada


The article by Martin Garner that Bill Smith referred to is:

Garner, M. (1998) "Brent Crosses." Birdwatch 78: 29-32. This is a very
accessible, but brief, review of the identification and complicated
taxonomy of Brant (Brent Goose), focusing on exciting possibility that
birds breeding on Melville Island are not hybrids between _nigricans_
and _hrota_ but a distinct subspecies, which Martin terms "Grey-bellied
Brant". There are one or two photos of specimens from the Puget Sound
area showing candidate Grey-bellied Brant along side and Black Brant and
also a candidate photographed in Ireland. [I believe the title "Brent
Crosses" is a play on the name of Britain's first large shopping mall,
Brent Cross, located in Northwest London? Maybe Martin can comment on
this.......]. For information on subscriptions to Birdwatch or to order
back issues visit their web site http://www.birdwatch.co.uk/home.htm

Another important reference is:

Shields, G.F. (1990) "Analysis of mitochondrial DNA of Pacific Black
Brant." Auk 107: 620-623.

The DNA sequence divergence reported in the study provides impetus for
treating the Melville Island birds as a separate taxa rather than hybrid
population.

Lastly, in an article published in The Kingbird, Andy Guthrie and I
review the status of Black Brant on the east coast of North America and
briefly consider the possibility that Grey-bellied Brant might
occasionally occur in east.

Wilson, A. and Guthrie, A. (1999) "Black Brant in New York State."
Kingbird 49(2): 98-106.

With fall already upon us, it seems very appropriate for observers on
the Pacific and Atlantic seaboards as well as western Europe to exchange
photos of the different Brant forms, especially the poorly known
immature plumages. I already have some comparison photos of Black and
Atlantic Brant on my web site and would be very happy to host additional
images from elsewhere, especially of candidate 'Grey-bellied Brant' from
Washington State or British Columbia.

http://www.best.com/~petrel/BBrantNY.html
http://www.best.com/~petrel/GBBRT.html
*****

So, it appears that this form is either an undescribed subspecies or
part of the Pale-bellied 'hrota' group and not an intermediate
population. I'd be interested in others comments on what they have
observed in the field, as far as potential differences between the
lighter bellied brant in Puget Sound, those of the east coast of North
America, and Black Brant. Also, check out the supposed Gray-bellied
Brant http://www.best.com/~petrel/GBBRT.html - when I first looked at
these pictures, I thought Angus was referring to the bird on the far
right of the first picture and agreed that it looked just like the
Gray-bellied Brant Mike and I had seen earlier. Then I realized he was
talking about the one on the left, which to me looks like a very typical
Black Brant!

Lastly, in some British and Dutch 'bird' circles, the Brant is listed as
three species: Branta hrota, Pale-bellied Brent Goose, B. bernicla
Dark-bellied Brent Goose, and B. nigricans Black Brant. Apparently this
is based largely on the phylogenetic species concept, but there is some
evidence that the three forms may be behaving as biological species as
well.

AJ


--
______________________________
Alan J. Knue
bluecrow at home.com
Seattle, WA