On the wildside—June, 2013
by Tina Mitchell
Among our best-known waterfowl, Canada Geese often occur in large groups in Colorado’s metropolitan areas but disperse more widely in rural areas. Along the Arkansas River, you can spot pairs or small groups year-round. Their long necks, the contrast between the black head and neck, brown backs, and pale breasts, as well as the white “chin strap” that curves up to the cheeks, make this large waterfowl an easy identification task. Their scientific name is Branta canadensis. “Branta” probably derives from an Anglo-Saxon or Old Norse word meaning “dark or burnt-appearing,” referring to their brown and black plumage; “canadensis” reflects the fact that they historically bred primarily in northern Canada and Alaska.
The classification of birds into species can be a very fluid undertaking, especially in recent years as genetic analyses have become easier to conduct. The Canada Goose “species” offers a good example. Before 2004, scientists considered the species of Canada Goose to be made up of 11 subspecies, ranging in size from really big to surprisingly small. However, DNA analyses, coupled with differences in habitat, voice, and migration, prompted taxonomists in 2004 to declare 4 of the smallest subspecies as their own unique species—the diminutive Cackling Goose. (In the winter, if you see a goose not much bigger than a Mallard and colored like a Canada Goose, you are probably looking at a Cackling Goose.) The subspecies we see year-round in Colorado is the “Giant” Canada Goose, on average weighing 11-12 pounds with a 6-foot wingspan.
Males and females look alike although the males are larger—sometimes, noticeably so. Breeding adults maintain long-time pair bonds, but they can form a new pair after the loss of a mate. They also return to breed in the place where they were raised. The female lays a clutch of 4 – 7 eggs, incubating them for 25 – 28 days. The male stands guard, chasing off interlopers by open-mouthed hissing and pumping his head up and down. Goslings leave the nest within 24 hours of hatching. By that time they can walk, swim, and feed, following the parents wherever they go. While the parents don’t directly feed their young, they defend an appropriate feeding territory and protect their goslings. The young can fly about 7-9 weeks after hatching. Young geese stay with their families through their first winter and typically don’t reproduce until their 2nd or 3rd years.
Almost exclusively herbivorous, Canada Geese have readily adapted to eat not only aquatic vegetation but also agricultural crops and grasses, when they are available—favorites include corn, millet, and oats. In the wild, a single Canada Goose can consume up to 4 pounds of grass in a day, creating as much as 3 pounds of feces each day. One study reported that, on average, an adult Canada Goose poops every 7 minutes. No wonder golf course caretakers who work hard to produce beautiful grassy areas that, coincidentally, are irresistible to Canada Geese consider them to be annoying pests!
You may find it hard to believe today; but at the end of the 19th century, over-hunting had reduced the Canada Goose population to near extinction. In the early 1960s, a concerted effort to rebuild populations began across the nation. Primarily to provide waterfowl hunting opportunities in the state, the Colorado Division of Wildlife began its restoration project in 1955 with a few pairs in the San Luis Valley; in 1957, 40 geese were released near Fort Collins. As numbers increased, geese were captured and moved into new areas. Eggs were taken and incubated to encourage the laying of second clutches. The project started slowly, but eventually ballooned—out of control, some might say today. The principal problem has been that the relocated geese never learned their species’ migratory pathways. Instead they have remained year-round in urban and suburban areas where groomed lawns, parks, golf courses, and artificial lakes provide ideal, delicious habitat. Ironically, since a large portion of the Canada Geese population live in metropolitan areas, they face very little pressure from hunting—the original purpose of the restoration efforts. Add the influx of the smaller subspecies of migratory Canada Geese from the north in the winter, and the numbers of Canada Geese can seem overwhelming in our area. For better or for worse, the Canada Goose population has indeed been pulled back from the brink of extinction.
To learn more about this species, click here.