Like most animals, waterfowl (ducks, geese, and swans) select mates for the purpose of reproducing. However, the types of waterfowl pair bonds formed vary considerably among species. Some species pair for life, whereas others invest a lot of time forming new pair bonds each year. Only about 44 percent of waterfowl species — all of which are geese and swans — form life-long pair bonds with the same mate (monogamy). Other waterfowl — mostly ducks — form new bonds each year by finding a new mate.
Canada geese and swans are monogamous and pairs mate for life. They do not form bonds until they are at least two years of age — more commonly three or four. Therefore, geese do not nest and lay eggs until their second year or later; swans typically do not begin laying until their fourth year.
Male geese play a significant role in raising young, including vigilance over and defense of females while they are incubating and brood rearing. If one of the pair dies, the other will eventually re-pair, but this may interfere with or prevent the surviving mate from breeding for that year. Divorce has also been noted in geese, in which pairs will separate. Divorce has been seen in pairs that were unsuccessful in their nesting attempt or in laying and hatching eggs.
Long-term pair bonds are generally observed among species of waterfowl that have large bodies, live longer because of lower annual mortality, exhibit low annual production of young, have slow-maturing young, exhibit high return rates to breeding and wintering sites, and depend on limited food resources on the breeding grounds. These characteristics are typical of geese and swans.
Waterfowl Project Manager
Photo of Canada Geese courtesy of John White