[birders] Not all small Canada Geese = Cackling

Allen Chartier amazilia1 at comcast.net
Thu Sep 30 09:22:09 EDT 2004


Julie and Birders,

The issue of "runt" Canada Geese has come up in recent years, and I've seen
postings to the effect that this was a potential ID problem based on the
fact that the poster "read it somewhere", which parallels my own personal
memory loss :-)  So, until now, I've been reluctant to forward this idea as
I could not support it with published sources.  So, I appreciate that at the
end of your web page (http://www.umd.umich.edu/dept/rouge_river/goose.html)
you do indeed cite one paper involved:

Leafloor, J.O., C.D. Ankey, and D.H. Rusch.  1998. Environmental effects on
body size of Canada Geese. Auk 115:26-33

It is now possible to view this entire paper as a PDF file on a new site,
called SORA (Searchable Ornithological Research Archive), containing
archives of many ornithological journals, including the Auk.  Go to:
http://elibrary.unm.edu/sora/index.php

As you also point out, Branta canadensis interior also occurs in Michigan.
(B. c. maxima is our beloved Lawn Goose).  I have seen them mostly on Belle
Isle, where many of them have orange neck collars; not a field mark but....
;)  I have reported many of these geese to USFWS over the past 20 years or
so, and all have come from Akimiski Island, or nearby areas of James and
Hudson Bay.  B. c. interior seems to be an annual migrant at Belle Isle in
small numbers, with occasional individuals over-wintering.  October and
November, and again in March, are the best times for goose viewing on Belle
Isle.  B. c. interior is grouped with Canada Goose, not Cackling.  I have
not yet seen what I'd call a Cackling Goose on Belle Isle, but it is always
worth looking.  There have been quite a few reports already this fall from
several areas in Michigan.

I should note that the link to the Utah site I provided in my previous post
gives an excellent overview of the taxonomy, and historical and current
confusions in diagnosing the various subspecies, as well as a table
containing measurements.  It is definitely worth a look.  In addition to
these "runt" B. c. interior geese being possibly confused for Cackling,
there are two other more western "subspecies" that could occur in Michigan
that are both medium-sized, one of which has been assigned to Cackling (B.
c. taverneri) and one of which is assigned to Canada (B. c. parvipes).
There is apparently a specimen of B. c. taverneri in the UMMZ bird
collection from Michigan!

Allen Chartier
amazilia1 at comcast.net
1442 West River Park Drive
Inkster, MI  48141
Website: http://www.amazilia.net
Michigan HummerNet: http://www.amazilia.net/MIHummerNet/index.htm



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