Breeding Biology

Snow geese have reproductive and behavioral characteristics that help ensure successful reproduction in the unpredictable, rigorous and short arctic nesting season.

They are long lived, and can successfully reproduce to 20 years of age and beyond. The maximum lifespan of geese in the wild is not readily measured because they can outlive legbands used to identify individual birds.

Snow geese generally mate for life. However, if one bird dies the other usually finds a new mate relatively quickly. Like other goose species, snow geese do not breed until they are at least two years old.

A female snow goose lays 4-5 eggs. Because of the short nesting season they seldom, if ever, renest if their first clutch is destroyed. Goslings remain with the adults during full migration, winter and the spring return to the breeding grounds, before the family bond is broken.

Like all waterfowl, snow geese undergo a feather molt during the brood rearing period.
During molt they are flightless for about 30 days, and are readily captured for banding and marking.

Because of the short arctic growing season, snow geese begin nesting activities soon after arriving on the breeding grounds. Snow and extended winter weather can delay or prevent nesting. In some years, snow geese do not nest at all - a situation commonly called a "bust" in production.

Arctic nesting geese have adapted to this short nesting period by carrying with them the energy needed to produce and incubate eggs. This energy, in the form of body fat, is critical to successful reproduction.

Research has shown that fat accumulation begins in early spring when geese reach the corn belt of Iowa and Nebraska, and continues as they migrate northward through the Dakotas, Saskatchewan and Manitoba. Snow geese remain on the prairies until late April or early May and then make a non-stop flight across the boreal forest areas of Canada to Hudson Bay and areas north.

Snow geese may gain as much as two pounds, including a pound of fat, during the three-month spring migration. These nutrients are carried to the arctic breeding grounds and used for sustenance, egg production and incubation. They need to have these reserves with them, because there is little food available on the nesting ground when they arrive.

Female snow geese exhibit strong homing behavior and return to nest in the area where they were raised. They quickly sever family bonds and begin breeding activities as soon as the ground begins to clear of snow cover. Pairs stake out claims within the colony: older more experienced pairs often claim the best sites near the center of the colony. Females that nested previously often return to the same nest site.

Snow goose nest success is generally high - more than 90 percent of nests produce at least one gosling. Predation or abandonment is the principal cause of nest failure of loss of eggs. Predators include gulls, arctic and red fox, wolves, polar bear, sandhill cranes, parasitic jaegers and ravens. Caribou also trample nests and eggs, and eat shells.

Once all goslings are hatched, dried and active, the pair leads its brood away from the nest to seek food. Abundant, high quality grass and sedge forage is needed for adults to molt and rebuild body conditioning after breeding, and for goslings to grow so they can fly before the short arctic summer ends and winter sets in.

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