By Dale D. Humburg
The Oldest of the Old (Click here to view as a larger image)
As a waterfowl biologist
, I am often asked how long ducks and geese live. Well, it all depends. Survival rates vary considerably among North America's 40-plus waterfowl species. As a rule, larger-bodied waterfowl live longer than smaller birds. Swans generally have the highest survival rates and longest life spans, followed by geese and then ducks. The waterfowl species
most commonly pursued by hunters—dabbling ducks and inland diving ducks—generally live shorter lives than geese and swans. Why? This isn't because of hunting
, as one might suspect. Instead, the answer is closely tied to the birds' habitats and reproductive strategies.
Prairie-nesting dabbling ducks such as mallards
, blue-winged teal
, northern pintails
, and northern shovelers
are prolific breeders subject to boom-and-bust production cycles driven by highly variable wetland conditions on their breeding grounds. These ducks breed during their first year of life, lay large clutches (the number of eggs in a nest), and often renest if their first nest is lost. In many cases, however, less than 20 percent of their clutches ever hatch, and duckling mortality can run 50 percent or more. Research has shown that the most important influences on population growth in these species occur during the 14-week period when hens lay their eggs, incubate their clutches, and raise their broods.
In contrast, northern-nesting Canada geese
reproduce later, lay fewer eggs, and both males and females participate in brood rearing. Studies of nesting Canada geese on western Hudson Bay showed breeding rates of only 7 percent, 15 percent, and 40 percent for two-, three-, and four-year-old birds, respectively. Thus, survival to four years of age and older is essential to ensure population maintenance or growth among these geese.
The rigors of the nesting season result in greater mortality among female than among male waterfowl. That's largely because females must remain on the nest while they incubate their eggs, making them more vulnerable to predators. Male ducks hang around for at least part of the incubation period, but suffer relatively little mortality compared to hens. Female ducks are also solely responsible for leading ducklings to brood-rearing marshes and attending them until they fledge, which also exposes them to predation in ways that drakes never experience. And while hunters harvest more drakes than hens, it's not enough to offset the higher hen mortality that occurs during spring and summer.