Bird watchers love to keep lists: life lists, state and county lists, year lists, big day lists. So the appearance of a new bird in the region attracts much attention.
A brand new species is here now, ready to be added to any or all of those lists. Its name is the cackling goose.
This addition is different from rare birds like the cave swallow and lark bunting that showed up here recently. It is a species newly separated by American Ornithologist Union taxonomists from a similar appearing common species, the Canada goose. As Ken Abraham of the Ontario Ministry of Natural Resources says, "Nothing has changed except the name! Cackling geese did not suddenly become more abundant here, they didn't change their migration route to accommodate our life lists, and they don't know that they're being watched more closely." They have, in fact, been around all along.
But now this taxonomic decision means that they can be counted.
You know how to identify Canada geese. Until 20 years ago we knew them simply as beautiful birds. They have a black head and neck broken only by a distinctive white chin strap. They often fly in V-formations, and their honking arrival was one of the most pleasant signs of spring.
Unfortunately, many of those geese have become permanent residents and now spend their time soiling and gouging golf courses and other suburban lawns. Others have become tame and beg for handouts. As a result, our favorable view of Canada geese has been compromised.
There are still migrant Canada geese, however, and among them are a few much smaller birds. Those are the cackling geese. Seen with their larger relatives, they appear scarcely more than duck-sized. In overall mass, the cackling geese that appear here are only about 3/4 the size of the Canadas. But the best field mark is the cackling goose's bill. It looks like a snub nose next to that of a Canada goose.
For some years birders had been identifying a small Canada goose subspecies during migration periods. It went under the common names: Hutchins' or Richardson's goose. Those same birds are now called cackling geese.
Field Guide writer David Sibley summarizes how these birds compare with the larger Canadas: "much smaller with a short, stubby bill, relatively round or even square head with steep forehead (vs wedge-shaped head), and relatively short neck." There are also minor color differences, and the cackling goose's voice is slightly higher pitched.
The source of this change brings taxonomy close to contemporary TV crime shows and real life events like the O. J. Simpson trial.
Both taxonomists and forensic criminologists use mitochondrial DNA for identification purposes. While the crime investigators look for similarities, taxonomists look for differences. And although individual changes occur as chance events, they accumulate over time regularly and give a measure of when different organisms separated genetically. In the case of cackling geese, taxonomists found that they split from their larger Canada geese relatives at least a million years ago.
Thus a cackling goose is indeed a different species and deserves its newfound status.
Unfortunately, that does not complete the picture. Despite those DNA differences, birders have neither the equipment nor the opportunity to apply forensics in the field. And problems can arise. Younger Canadas are smaller, as are birds that have had limited food resources on their breeding grounds. Abraham warns, "We are left with identifying cackling geese on poorly quantified and often vague descriptions of size, shape and color."
Despite these problems, some of our top local birders are picking out a few cackling geese from among the half million Canada geese currently migrating through Western New York.
If you visit the Iroquois-Tonawanda-Oak Orchard Wildlife Refuge complex, the ponds that appear below the escarpment parallel to and just south of Route 5, or the shores of Lakes Erie or Ontario, keep an eye out for a few smaller Canada goose look-alikes. There is a good chance that those are cackling geese.