04 February 2009

The Mystery of the Cackling Geese

In 2004 the American Ornithologists Union made a major change to birding in North America by announcing the split of what was formerly known as Canada Geese into two species. The larger of the two was to remain known as Canada Geese, and the smallest four of the eleven or so subspecies in the Canada Goose group would be known as Cackling Geese. This decision was based on genetic evidence that showed little to no interbreeding between these groups. This move was not unexpected by those who had been paying close attention to Canada Geese. The subspecies of Canada Gees were discernible in the field, and various subspecies or groups of subspecies had been elevated to species status in the past. However, it was a big surprise for most of the birding community, because, to be honest, most of us hadn't paid much attention to Canada Geese before.

In Utah, and probably throughout many parts of the U.S., this caused a stir. What was once one of the most common and familiar species in the state was now a pair of strangers. The safe thing to do in this situation was to assume that all previous records of Canada Geese applied to what was still known as Canada Geese, because the most common species here, the Great Basin Canada Goose, was still considered a Canada Goose. However, some records already existed of Cackling Geese in Utah, namely museum specimens. But the Utah Bird Records Committee decided to put the Cackling Goose on the state review list so that any records of this species in the state would be reviewed by a panel of experts.

Now that more people are looking for Cackling Geese, more people are finding them. In the four or five years since the species became a species, there have been over 20 records of Cackling Geese in Utah. However, I think the Records Committee must remain unconvinced, because few records have been submitted to the committee and even fewer have been accepted. Part of the problem, I think, is that the details of Cackling Goose identification were not well worked out. There were conflicting opinions on various websites about the traits that distinguish the largest subspecies of Cackling Goose (Like Taverner's Cackling Goose, seated at right in the photo above, and Richardson's Cackling Goose, in the back of the photo below) from the smallest subspecies of Canada Goose (like the Lesser Canada Goose, in the foreground of the photo below). Thankfully, I think that confusion will soon come to an end. A brilliant article published in the latest issue of North American Birds outlines in thorough detail how to tell the subspecies of Cackling Goose from one another, and from the smallest Canada Geese. I'm hoping that this article will be just the thing to help our knowledge of Cackling Geese advance in Utah and elsewhere. In the meantime, I intend to continue to submit records to the Utah Bird Records Committee until a pattern of occurrence has been established. Based on one year of actively birding in Utah, I think we will soon solve the mystery of the Cackling Geese and realize that this species, although rare, occurs annually in winter in Utah.

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