Northern Prairie Wildlife Research Center
There are 11 different races of Canada geese. All look similar, but differ in size from the three-pound cackling Canada goose to the twelve-pound giant Canada goose. It is this large race, the giant Canada goose, that commonly nested in central and northwest Iowa prior to European settlement. Unregulated hunting and wetland drainage caused their disappearance from the state around 1910. In 1964, the Iowa Department of Natural Resources began reintroducing the giant Canada goose to the state by establishing a captive flock at Ingham Lake in northwest Iowa. Since then, giant Canada geese have been reintroduced across Iowa and now nest in every county.
In Iowa, giant Canada geese begin nesting toward the end of February in the south and in late March in the north. Mated pairs use several ponds and feed primarily on waste grain and tender young plants. Most giant Canada geese nest for the first time when 3-years old, but 25 to 30 percent will attempt to nest when only 2 years old. Adult geese often return to nest in the same area where they first learned to fly. This behavior is called homing.
Giant Canada geese will use almost any body of water and nest on a wide variety of sites including muskrat houses, cattail mats, islands, shorelines, and nest structures. They have even been known to nest on cliffs, in trees, in abandoned heron nests and on permanent duck blinds. Geese can be territorial, especially in the immediate vicinity of the nest site, but will tolerate crowded nesting sites where population densities are high.
The goose lays one 3 1/2-inch long, cream colored egg every 1 to 2 days. Average clutch size is 5 eggs but completed clutches can range from 1 to 12 eggs. Incubation begins the day the last egg is laid and averages 28 days. While the female incubates the eggs, the male remains nearby to help defend the nest from predators. Giant Canada geese seldom renest if their clutch is destroyed during incubation.
The goslings and adults leave the nest together within 24 hours of hatching and do not return to the nest site. They feed by grazing on tender young plants, especially bluegrass, and may move several miles, if necessary, to find suitable browse. Goslings from several broods sometimes group together to form "gang broods". Goslings attain flight 8 to 10 weeks after hatching. Out of an average brood size of 5 goslings, about 3 will survive to flight stage. Adults molt their wing feathers and become flightless about 4 to 6 weeks after the goslings hatch. They regrow their flight feathers in 4 to 6 weeks, depending upon the quality and quantity of food available. Adults remain together year-round and the goslings stay with the pair until the next spring. If one mate dies, the remaining goose will find a new mate by the next nesting season.
We recommend that goose nest structures be placed over water. Geese seem to prefer over-water sites and this enables them to more successfully defend their nests from predators such as raccoons, fox, and coyotes.
When deciding which nest structure to use, select one that fits your budget, is aesthetically pleasing, is appropriate for your wetland, and can be easily maintained. Maintenance is the key to consistent, successful use.