Duration of mates varies among waterfowl

Since the ponds have become ice free, pairs of mallards, Canada geese and other waterfowl have been swimming and preparing to nest. A pair of mallards and a pair of Canada geese have been swimming in a little pond I walk by daily. Are they the same pairs as last year?

The duration of relationships is not the same for all waterfowl or even all bird species. There are two main types of mating in waterfowl: monogamy and polygamy.

Waterfowl with only one mate are considered monogamous. Waterfowl with more than one mate at a time are considered polygamous.

Only a few species of waterfowl practice polygamy. Both the ruddy duck and muscovy don’t typically form bonds but instead the male defends a territory and breeds with females that enter his territory.

All other waterfowl in North America are considered monogamous. However, there are different types of monogamous relationships. Let’s look at the difference of monogamy in mallards and Canada geese.

The pair of mallards on the pond most likely formed a bond in early winter either on the staging grounds for fall migration or on the wintering grounds. The male decides which hens to court but the hen ultimately chooses her mate.

When the pair leaves the wintering grounds, the hen will lead her mate to the breeding grounds which is often the area she was hatched and raised. At the breeding grounds, the male will defend his mate and her nesting territory, especially from unpaired males who attempt to mate with unguarded females.

Once the hen begins incubating, the drake leaves her to hatch and raise the young. Their monogamous relationship is termed seasonal monogamy since the bond only lasted one season.

One twist to seasonal monogamy is that when the drake leaves his incubating mate, he searches out other breeding opportunities with any female that has lost her nest or mate. If a new subsequent bond is formed within the same season, the drake is practicing serial monogamy.

Then there are Canada geese who practice perennial monogamy because they typically remain together for life. However, if a mate is lost the surviving mate often seeks a new mate.

Canada geese differ from ducks in that they maintain their family structure throughout fall migration, winter and then spring migration. The family breaks up after the adult pair begins nesting on the breeding grounds.

The young then join flocks of other non-breeding geese until they are two or three years old. Then they find a mate at their wintering grounds.

Most large-bodied waterfowl, including swans, form perennial monogamous bonds. Long term bonds are more conducive to large waterfowl because they tend to live longer, have a lower annual mortality, have slower maturing young, have a smaller brood number and a higher philopatry (behavior of returning to the same breeding and wintering grounds).

Some ducks have a unique twist on seasonal monogamy that is not quite perennial monogamy. Goldeneyes, buffleheads, long-tailed, ducks, harlequin ducks and common eiders are suspected of re-pairing with the same mate on the wintering grounds. A strong philopatry to both wintering and breeding sites allows the birds to find each other after separating during the summer.

So there is a good chance that the pair of mallards at the pond has the same female as last year (or a female offspring) but a different drake and there is a good chance the pair of Canada geese is the same too.