Can you spot the Cackling Goose in this shot?
|Cackling Goose with Canada Geese. Can you tell which one is the smaller Cackling Goose?|
Here's another shot, perhaps a bit easier now?
|Cackling Goose with Canada Geese, Hunterdon County, NJ (27 Feb 2012)|
In the last shot, the Cackling Goose is the upper rightmost bird. In the first shot it is in the upper center. I took a bunch of shots (none are really great) and in most of the shots it isn't always easy to tell for sure that this bird is much smaller than the others. So while Cackling Goose is generally smaller than Canada Goose, depending on the posture of the birds, this can be very difficult to tell.
I first noticed this Cackling Goose on the back side of the flock as it was moving about, and what first struck me was how the bird had a more silvery-frosted look to the back feathers--more silvery and frosty than the brown and tawny of the Canada Geese (due to lighter feather edgings). I watched it walk up to a very large Canada Goose, and the bird was much smaller. But as I continued to watch it, depending on its posture, and the posture of the birds around it--it wasn't always that much noticeably smaller than some of the other perhaps smaller Canada Geese.
Size and shape of the head and beak are two other important differences between these two similar species--in the second shot you can see the smaller, more rounded head, and the shorter stubbier beak of the Cackling Goose. But again, depending on the angle of the bird, this can be tough to judge as well.
Here are two shots of the Cackling Goose with a Canada Goose. Even with the heads next to each other, in a photo that can be tough to judge. In real life, you may have to watch the birds for a little while to make sure that you are seeing real size and shape differences, rather than artifacts of unique body positions and viewing angles.
|Head size and shape comparison of Cackling (front) and Canada (behind) Geese.|
|Head size and shape comparison of Cackling (front) and Canada (behind) Geese. Not always as obvious as you would hope under even direct comparison!|
So, perhaps the biggest lesson to draw from this is to be careful when looking for Cackling Geese--you can easily overlook them, but you might also be tempted to claim one based on a poor view of a smaller Canada Goose. A good view, from various angles, and in comparison with several other birds may be necessary to be sure that you aren't jumping the gun in your Cackling Goose ID. Size is particularly tricky to judge with these birds, especially through a scope--which often distorts true size even between nearby birds in front of and behind each other.