Canada Goose and Cackling Goose

by Carl Strang

 

A few years ago the decision was made by the American Ornithologists’ Union (AOU) to recognize a split of the Canada goose into two species. For a long time it has been recognized that Canada geese across the continent form distinct races, distinguishable by nesting geography, body size and proportions, and sometimes minor color variations. They were regarded as all belonging to the same species, however, meaning that the races were really interbreeding or potentially interbreeding populations.

 

One huge physical difference exists between the tundra-nesting varieties and all the rest, however: body size.

 

canada-and-cackling-geese-b

 

The several tundra nesting races, one of which is represented by the birds in the left side of the above photo, are much smaller than more southern varieties as in the birds on the right. The separation by habitat is severe, and the size difference as well, so for the moment there are two recognized species. The little ones are called Cackling Goose officially, while the big ones retain the name Canada Goose. It is possible that there will be further splitting in the future.

 

We see cackling geese here in migration, and sometimes over the winter. At the Blackwell roost I saw a pair early in the winter, but have not spotted them since (though after that roost grew to 3000 birds it would have been easy to miss them). One little bit of my winter behavior study will be to watch out for cacklers and see whether they behave differently from their larger relatives. I will post an update to that study tomorrow.

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