Taverner’s Cackling Goose vs. Lesser Canada Goose

As I continue my study of the white-cheeked goose complex, I often return to the problem of separating Taverner’s Cackling Goose (Branta hutchinsii taverneri) and Lesser Canada Goose (Branta canadensis parvipes). Some sources argue that we shouldn’t be attempting to separate these two in the field until more study is done. Other sources claim to have definitive field marks for each. Some sources contradict each other as to what those definitive field marks are. So here are few photos from my recent goose encounters along with my opinions/guesses about their subspecific identity. I welcome your opinions and comments. (The comment,”Get a life!” is obvious and does not need to be repeated here.)

#1. The length of a goose’s neck appears to vary with the bird’s position, so it is dangerous to judge neck length from a single photo. But the bird on the right appeared consistently longer-necked than the birds on the left. A long thin neck supports the ID of Lesser Canada while the shorter thicker necks suggest Taverner’s Cackling.

#2. The large geese in the background are Western Canada Geese (B.c. moffitti). The smaller bird in front shows a fairly long bill that slopes gently onto the forehead. This head shape is consistent with Lesser Canada Goose.

#3. The bill on this goose is on the short side, and the forehead angles steeply up from the base of the bill. These features, along with the thick neck, suggest Taverner’s Cackling Goose.

#4. The bird on the left looks good for Taverner’s Cackling Goose, with its short bill and very steep forehead. The goose to the right seems to show a gentler slope to the forehead. Is this just an illusion caused by the different neck position, individual variation, or a slightly short-billed Lesser Canada? It is at this point that my eye is drawn back to the gulls, a much easier bunch to sort out.