Canada Geese Species

 

 

The Canada geese are back in the Turtle Mountains.  They have been here for a few weeks now, and there may be some in your area as well.  They are one more sign of our changing seasons.  They are also a reminder of how a species, and our understanding of a species may change.    Oh, by the way, they are not all Canada geese anymore.

The Canada goose is the most widely distributed goose in North America.  It breeds from Alaska to Labrador, and unlike other North American geese which breed in the Canadian north, the Canada goose also commonly nests here in the United States, including North Dakota.  Because of its wide range, the Canada goose occupies a wide variety of environmental conditions.

Every high school biology student learns the definition of a species:   a group of naturally interbreeding populations that are reproductively isolated from other such groups.  But a species is a concept:it is not a fixed entity.  The genetics of populations within a species would be expected to differ and change as the populations adapt to their particular environmental conditions.  Those interbreeding populations may become noticeably and measurably different than the other populations:  that is a subspecies.

Perhaps we need to put greater emphasis on the “interbreeding populations.”  As you might expect, many species with large ranges will consist of several subspecies.  As most goose hunters know, biologists recognize several subspecies of Canada goose.  There are other factors that influence the designation of a species or subspecies as well, such as the lineage or phylogeny.  All subspecies within a species should be the descendants of a common ancestral species.   The classifications may change as we gain a better understanding of the species.

Based on recent genetic studies, the American Ornithologists’ Union has split the Canada goose into two species.  That happened a couple years ago.  The larger forms (perhaps seven subspecies) are still the Canada goose (Branta canadensis) while the smaller subspecies (consisting of perhaps four subspecies) are now known as the cackling goose (Branta hutchinsi).  It is going to be a difficult name change for many of us.

Regardless of how these geese are classified, they are still wonderful to watch during their spring migration.  Plus, now have a little better understanding of them than we did a few years ago.

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.



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