It’s time for another installment of my attempts to sort out the Canada/Cackling Goose complex. I recently had nice views of a Lesser Canada Goose (Branta canadensis parvipes).
This bird stood out from the nearby Western Canada Geese by the slightly darker barring on his upper breast. Some populations of this subspecies are considerably darker than this.
Here is the Lesser Canada in front of the larger Western Canada Goose (Branta canadensis moffitti). Note the smaller overall size of the Lesser, and the proportionally shorter neck.
Lesser Canada Goose in profile. The bill is almost half the total length of the head. The upper neck is quite thin.
Compare these Taverner’s Cackling Geese (Branta hutchinsii taverneri) to the Lesser Canada. Taverner’s Cackling has a uniformly thick neck and shorter bill. Notice how the wing tips extend just beyond the end of the tail. Canada Geese have shorter wings.
Here is a Taverner’s Cackling Goose within a flock of Cackling Cackling Geese (Branta hutchinsii minima). Note the longer thick neck and slightly longer bill than those on minima.
Ethical Birder 
Thanks, John. I know there has been a technical article on these recently. But these simple photos clear up the question I had about minima, taverneri, and parvipes in the Willamette Valley.
I now see that Taverner’s Cackling is significantly larger than minima Cackling. I had been seeing flocks of minima with a lot of variation on breast color and confusing myself.
The wing length and neck thickness examples were appreciated field marks to help me separate Taverner’s from Lesser.
This article let me easily identify a recent bird as Taverner’s:
http://www.pbase.com/gregbirder/image/109627756
Good Job!
Greg Gillson
Hillsboro, Oregon