Like most animals, ducks when pairing bonds with members of the opposite sex for survival of their species, this is an innate instinct in all animals, including the human beings. The kind of pairing formed, however, are not what one would think. Duck mating systems vary. Some breeds pair for life, while others pair with a single duck, every year or a season, a behavior that at first thought would seem too tiring and time consuming. Only around 44 percent of duck breeds- form long-term, monogamous bonds. That is, the drakes of the remaining breeds must form new bonds every year by courting a new female.
Monogamy, or partnering for life, is very common for some ducks, but this kind of monogamy only happens during every year or a single season. They are monogamous in that particular mating season, and in the next, the drakes will try to find other ducks to mate. This mating behavior is also called seasonal bonds, or seasonal monogamy wherein new bonds are formed each season. This kind of monogamy happens in about 55 per cent of all duck breeds. In this mating system, partnerships basically form on the wintering areas in their first year, and those bonds are maintained only through egg laying and duck rearing.
Each winter, the drake must find a new duck and maintain a new bond for that particular mating season. Drakes that form seasonal bonds will not participate in rearing the ducklings, but will safeguard the territory around the females during spring, females will instantly find a new drake for that season, and nesting will not be blocked in that year. Seasonal monogamy is very typical for dabbling ducks, diving ducks and sea ducks.
A remarkable twist on seasonal monogamy happens in some tunnel nesters and farm ducks that do not form bonds until their second year. Some researches have proven that some duck couples reunite every year on winter and return to their previous breeding territory. This mating system happened only in breeds that shows strong fascination to both wintering and breeding grounds. Philopatry refers to the behavior which animals return to the exact location, either on the breeding or wintering ground, from the past year, enabling couples to find one another. Re-coupling is also thought to occur in Harlequin and Eider ducks.
The other mating system observed in ducks is polygamy, wherein multiple mating partners can happen. Polygamy is rare among ducks and observed only in 8 percent of breeds, including the Muscovy, Comb, and Maccoa, all of these are stiff-tailed ducks. In this mating system, mating bonds are weak or not formed at all, but instead drakes defend the mating grounds along the shores and engage in complicated courtship to attract the females in the mating grounds. Ducks visit these territories, and the drakes will mate with different ducks.
In North America, the Peking is the only duck to exhibit polygamy, and they are widely used in meat production, and for their eggs.