Nature Note #131: The Call of Cth'ackler

This morning I had the great fortune of spotting not only a life bird, but also getting a fairly rare bird for Massachusetts. The bird I'm referring to is the Cackling Goose (Branta hutchinsii), but upon looking at the two photos below, you probably have noticed something unusual about the appearance of these birds.

For all intents and purposes, a Cackling Goose appears to be a dead ringer for a munchkin-sized Canada Goose (B. canadensis) and to the uninitiated, it could be mistaken for a "baby" Canada Goose. However, we birders know that what a baby goose looks like with its fuzzy yellowish down, peeping voice, and angry, protective parents so to be seeing a "baby" goose at this time of year would be completely unexpected. The Cackling Goose was for a long time considered to be a high Arctic breeding race of Canada Goose in northwestern Canada and Alaska. They themselves can be split into three or four races as well and include the Taverner's, Hutchin's, and Aleutian Cackling Geese. As of 2004, the American Ornithologist Union agreed to the species split after DNA evidence found them to be different enough to warrant differing scientific names. But because they so superficially resemble a Canada Goose, how can you be sure that you have a Cackler and not just a small Canada Goose?

Well if we consider the next two photos below, we can note some similarities and differences that might lead one to conclude that the bird that they are seeing is or isn't a Cackler.

What is your country of origin?

One of these birds is not like the other...

Pretty daunting right? Well first thing's first, when looking at the bird at hand (as opposed to in hand and given the circumstances if one were to hold a goose, you'd probably use your arms more than a single hand) to try to compare it to the nearby birds. 

Size Comparisons: The one reliable thing about geese is that they are gregarious and are nearly always near others of their kind. In the photo above, we can see that while these geese have short necks and are the same size. However, you could well argue that because there are only two of them and with no nearby objects to confirm their size, we don't really know how big they are. But comparing the bottom with the top shows a crucial difference. A key thing to beware is using neck length as a sole indicator. Geese, like many long-necked birds, can extend and retract their necks into a variety of contortions, but it isn't their necks that are magically stretchy. Instead, it is largely their feathers that play the role of maximizing or minimizing the size of the bird's neck, and by extension, its head (no pun intended). The bill of the pair of birds in the above picture are about as long as the head of the bird, while the bird in the picture below has a small, stubby bill. 

Voice: Another key feature is their voice. While a Canada's voice can vary in terms of pitch, generally speaking it is much lower pitched and less yappy than a Cackler. One thing to look out for when you next gaze upon a flock of geese is listen to the pitches of the call notes. Lower pitched calls usually indicate males, while higher pitched ones can indicate females or younger birds.

Range: Finally, one of the best indicators is range. Cackling Geese are generally found west of the Rockies during migration and in the winter, but are increasingly coming east in small numbers either migrating through or wintering in specific areas. Unfortunately, this matters less as Canada Geese as an entire species ranges over much of North America. But, hopefully by using the steps above, one can make an educated guess as it the birds they're seeing.

Nine more species until I reach my goal. Let's hope I can get there soon!