In a message dated 7/22/2004 9:48:50 PM Eastern Daylight Time, David Mozurkewich <> writes:

>Is there a good reference for identifying the subspecies of Canada Goose?
>Does anyone know which subspecies of Canada Goose occur in Maryland and
>what are the relative abundances?

Hi Folks!

Several Maryland briders have been looking at geese for a long time now.  The Yellow Book has some information in Appendix 1, but that is partially out-of-date.  I have seen Cackling Goose in every county except Garrett & Allegany.  The predominant type is "Richardson's" a.k.a. "hutchinsii" and is usually associated with flocks of migrant Canada Geese.  A very few birds found with Snow Goose flocks may be a different subspecies, but I am unwilling to put a name to those yet [they could be "minima"].

There is no one good reference.  The systematics of the Canada Goose group has been problematic since before 1950.  Older literature used scientific names in papers that were just plain wrong because of a mixup in the Type Specimens.  This in part explains why "Richardson's Goose" once called Branta canadensis hutchinsii, and now know as Branta hutchinsii, is not called "Hutchins' Goose". For a very long time the scientific name used was Branta canadensis richardsoni, until someone discovered a mistake in the Type Specimens.

Most of the standard reference books [Kortright, Bellrose, Bent, "Waterfowl of the World"] discuss subspecies and one can not be certain if the name used is correct. Sibley illustrates one of the small Canadas, but gives it the wrong name.

Richardson's Goose is easy to pick out of a flock at a distance, not because of size, but because of coloration. The back is much grayer [not brown] and the chest is much paler. The birds are about 2/3 the size of migrant Canada geese and half the size if resident Canada geese [note: migrant Canadas average smaller than resident Canadas].  The bill is closer to an equilateral triangle in shape than an isoceles triangle. The white cheek patches are typically seperate and do not join under the chin [i.e. the chin is black, not white].  A white neck band may or may not be present [this is not a useful character for identicication].

Just about any flock of 500+ migrant Canadas will have one or two Richardson's.  Typically they are in pairs and any count over 10 is good.  The maximum I have ever seen in a single flock is 26.

If I were to revise the Yellow Book, I would list Richardson's as a regular annual bird [solid black square] in Prince George's, Kent, Caroline, Queen Anne, Talbot, Dorchester and Worcester. It is slightly less common, but not rare, in Cecil, Harford, Baltimore, Howard, Montgomery, and Anne Arundel. Some counties, like Calvert and Washington, just do not get large flocks of migrant Canada geese in winter, so the records are fewer but the species is not unexpected.  I bet there are records for Garrett and Allegany.

Good Birding!

Jim

Jim Stasz
North Beach MD
jlstasz