“A Year of Birding in Bloedel” is a column that runs every Friday in the Bainbridge Islander. The project is planned to continue in 52 parts through 2014 to help readers find and identify birds in the island’s garden sanctuary. Beginning with this entry on the Canada geese, each column will also be published here on the Bainbridge Conversation blog each Friday.
The author, Ted Anderson, is a retired professor of biology, having taught at McKendree University (Ill.) for 32 years and for the University of Michigan’s summer biological station for 20 years, where he frequently taught the biology of birds.
Anderson is also the author of “Biology of the Ubiquitous House Sparrow, from Genes to Populations” (2006), and “The Life of David Lack, Father of Evolutionary Ecology” (2013). Ted and his wife Carol have been members of Bloedel Reserve for 7 years. They live in Kingston.
No one requires an introduction to the Canada goose (Branta canadensis), a common year-round resident of the Pacific Northwest. Anyone who has visited parks around our area lakes or Puget Sound is familiar with the unappreciated “calling cards” these geese leave on lawns and paths close to water. Grazing on grass and other terrestrial plants is their primary means of foraging, although they can also be seen tipping up in shallow water like dabbling ducks to feed on aquatic vegetation. At Bloedel they are frequently found grazing in grassy areas near the Bird Marsh, or on the lawns near the Visitor’s Center.
The Canada goose is common throughout much of North America, breeding as far north as Alaska and the Yukon in Canada, and wintering wherever there is permanent open water. Their spring migration in southern Wisconsin inspired Aldo Leopold to proclaim in A Sand County Almanac, “One swallow does not make a summer, but one skein of geese cleaving the murk of a March thaw, is the spring.”
Biologists have long observed that many widespread species vary in size and/or coloration across their broad geographical range. One way in which they have formally recognized these differences is by the naming of subspecies, within-species groups that differ significantly in size and/or coloration. Most subspecific differences are so subtle that they are recognizable only to specialists. Until very recently, however, scientists considered some of the most northern breeding populations, in which adults are only about half the size of our local Canada Geese, to be easily identified subspecies of the Canada goose. These populations are now recognized as a separate species, named the Cackling goose. A wintering Cackling goose has joined the resident Canada geese at Bloedel this winter. Look closely at the foraging flocks of geese for an individual that is only half the size of its compatriots.
The Canada Goose has been successfully introduced into England, where many consider it a pest. In fact, they maintain the Canada goose and the gray squirrel (also introduced from the United States) represent our retaliation for their export of the house sparrow and European starling to the United States.