Cackling Geese at Fairy Lake, Acton

On December 23, 2012, Bradley Bloemendal posted the sighting of at least three Cackling Geese at Fairy Lake in Acton was on the ONTBirds hotline. Next day, I went to check out the report. At that time, there was still a fairly large area of open water on the lake. I counted 330 Canada Geese, 32 Mallards, one American Black Duck, 6 Common Mergansers, and 8 Ring-billed Gulls. I could not distinguish any Cackling Geese among the birds there but they could easily have been present among the geese lined up on the ice off to the west side of the lake. Many had their heads tucked in and size differences were impossible to determine under those conditions. On December 26, I went back and found that much of the formerly-open water had frozen. The Canada Goose count was now down to 130 and those were present in the last open water close to the point in Prospect Park. Among them were four Cackling Geese. As can be seen in the accompanying photo, the Cackling Geese are much smaller than the regular Canada Geese and their bills are stubbier. Their presence was therefore confirmed for Count Week for the Halton Hills Christmas Bird Census that took place on December 27, 2012.

The taxonomy of birds that most people would recognize as Canada Geese has been in debate for many years. Splitting into various races was mentioned by Tavener over 90 years ago. Over the years, the number of recognized races or sub-species has stood at ten to twelve different forms. Distinction between these is blurred at best but size is one of the main features. There is much overlap and intergrading between the races as well as hybridization, not to mention size differences caused by diets and food supply, and thus distinction in the field is nearly impossible. It was no surprise though that American Ornithologist’s Union’s Committee on Classification and Nomenclature decided to split Canada Goose (Branta canadensis) into two species: Canada Goose (B. canadensis) and Cackling Goose (Branta hutchinsii). This became official in 2004 in the 45th supplement to the Check-list of North American Birds. Greater Canada Goose contains six subspecies, namely canadensis [Atlantic], interior [Interior], maxima [Giant], moffitti [Moffit’s], parvipes, fulva [Vancouver], and occidentalis [Dusky]. The smaller Cackling Goose (Branta hutchinsii) group includes the subspecies hutchinsii [Richardson’s], [Bering], leucopareia [Aleutian], taverneri [Taverner’s], and minima. The asiatica are already extinct.

Cackling Geese
Cackling Geese

The Cackling Goose was first recognized as a separate species when Sir John Richardson collected a specimen in 1822 north of Hudson’s Bay. He named it Branta hutchinsii after a man by the name of Hutchins who was employed by the Hudson Bay Company. For this reason, it is sometimes referred to as Hutchins’s Goose but now it is identified as the Richardson’s subspecies of Cackling Goose. The geese at Fairy Lake appear to be of this subspecies as their breasts are light coloured, unlike the Cackling Cackling Goose (minima) which usually has a much darker breast.

Nomenclature of Canada and Cackling Geese is far from settled and we can expect further changes. There has even been a recent proposal that the group be divided into six species with 200 subspecies. This classification would be quite unworkable for field biologists even though DNA analysis might justifiably distinguish that many true species. It is simply not feasible to recognize that number of subspecies without access to DNA laboratory testing. We are only now just learning to separate out the Cackling Geese. Let’s not go too far in the taxonomic splitting exercise. There is always a possibility that while there may be genuinely different genetic groups, the differences may not be enough to separate the species and in the end, we might still be looking at one large but diverse species of Canada Goose.

by W.D. McIlveen
Halton/North Peel Naturalist Club

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