Mix-and-match

Posted October 22nd, 2010 by kcorliss. Comment (0).

We’ve spoken of the Canada goose (Note: please don’t call them Canadian geese, it’s a pet peeve) complex a few times in this space and the fact it includes a large number of identifiable subspecies with varying morphological traits and sizes. The usual subspecies present locally during the summer months–and thusly, the nesters–are giant Canadas (Branta canadensis maxima). So when fall sets in and we see more subspecies filtering through, it can be an interesting exercise in detailed indentification. The smallest four subspecies, as you’ll recall, were set apart from their brethren a few years ago and given official species status. We now know them as cackling geese (Branta hutchinsii).

presumed cackling goose (left) with Canada goose in flight, K Corliss

Of the four cackling goose subspecies (all are tundra nesters), we get one here in the Heartland with clocklike regularity in both spring and fall–the Richardsonii race. In scientific terms: Branta hutchinsii hutchinii. It really isn’t too tough to differentiate the smaller cackling geese from the local giant Canada geese, even in flight

The only real problem arises when the smallest Canada goose enters the picture, known as the lesser Canada goose (B. canadensis parvipes). But since that particular subspecies is a more Western bird, it shouldn’t be a problem here. In other words, virtually any tiny Canada-goose like goose around here will almost certainly be a cackling goose unless proved otherwise.

Canada goose (walking) with loafing cackling geese, K. Corliss

Now is as good a time as any to scan your local goose flocks for the Mini-Mes. The photo at left is illustrative of the size differential present between the cackling geese and the relatively very large giant Canada goose. Note too the size and shape of their respective bills and heads.

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