I didn’t consider parvipes since it occurs mostly in the western half of
Nebraska; maybe I should have. On the other hand, interior is not at all
common either in Nebraska as far as I know, maybe occurring only in the
Missouri River Valley. Because of that, and because this flock was a bit of
a mixture, but mostly birds I’d call interior, I figured the variation was
an indicator that it was showing intergradation with hutchinsii and derived
from an extensive hybrid zone along the western edge of Hudson Bay. Most of
the flock looked like interior, but the presence of that one Cackling type
(although its bill looks a bit long) and some steep-foreheaded birds would
be what one would expect from a hybrid zone involving Cacklers.
The reference is:
Leafloor, J.O., J.A. Moore, and K.T. Scribner. 2013. A hybrid zone between
Canada Geese (Branta canadensis) and Cackling Geese (B. hutchinsii). Auk
130: 487-500. (In this paper, the authors merge canadensis and interior,
although they note that the Canada types in this hybrid zone are what most
folks call interior).
Maybe too much info, but this is an interesting topic, and it’s fun to take
some time to look at common species!
Nice to hear from you!
Seasonal Reports Compiler
Nebraska Bird Review
From: <NEBirds...> [mailto:<NEBirds...>]
Sent: Sunday, November 12, 2017 7:33 PM
Subject: Re: [NEBirds] Interesting Canada Geese
In my opinion, your photos most likely contain a mix of interior and
parvipes with perhaps a few Cackling Geese. The only one photographed that I
would judge as Cackling is the bird in the photo marked ML75020551.
Mason City, IA
At 07:04 PM 11/12/2017, you wrote:
For Canada Goose aficionados, Iï¿½ve posted pics from Kiwanis Park, Carter
Lake, (just barely in Iowa) of what I believe is a migrant flock derived
from the well-documented hybrid zone between hutchinsii Cacklers and
interior Canadas along the west shore of Hudson Bay, where our eastern
Nebraska hutchies and presumed interiors come from. Iï¿½m very interested in
comments. I found several birds in the flock that I think are intergrades,
but probably 80% at least looked like interiors. Iï¿½d really appreciate
comments! I may be completely wrong, and if so I want to know!
http://ebird.org/ebird/view/checklist/S40473907 Ross Silcock