Posted by: Mark Andrew Conboy
For the third winter in a row a peculiar Canada Goose (Branta canadensis) has put in an appearance at Chaffey’s Lock. I first saw this uniquely patterned goose (see picture) over a number of weeks at Chaffey’s Lock in the winter of 2008-09. I subsequently found it paired with a normal-plumaged Canada Goose on a beaver pond in the remote northeast corner of the Massassauga Tract where it was present with its mate and a brood of four goslings in May 2009. In the winter of 2009-2010 I saw it only once at Chaffey’s Lock. The bird was again present among 26 other Canada Geese on December 16, 2010.
Aberrant plumage such as in this goose, can be the result of many factors including hybridization, leucisim, albinism, malnutrition and injury. But it can be difficult to say confidently what the cause of strange colouration in individual birds is without close examination in the hand. Although Canada Geese will hybridize with Snow Geese (Chen caerulescens) to produce offspring that have dark and light patches of plumage, this particular bird doesn’t match the typical hybrid plumage or bill shape very well. That this bird sports the same odd plumage each year suggests that it’s not the result of malnutrition or an injury to growing feathers. Perhaps this goose is either partially leucistic or partially albino. Lecucisim is when a bird lacks black pigment in its feathers. Albinism is when a bird lacks all colouration in the feathers and other tissues. Without a closer look at this goose it is hard to say which of the two it might be, but the pink bill and snow-white feathers suggest a partial albino. A more typical appearance for a leucistic Canada Goose is to have feathers that are not so white but instead are a washed-out brown.
Although colour variations such as albinism are not extremely rare in Canada Geese, this bird is an interesting one because its distinctive plumage means that it is possible to glean some information about the life history of a single bird, even if it is only in glimpses from time to time.