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.
Male geese also have higher survival rates than females, but the
disparity between geese and ganders is not as great as between drakes
and hens. Geese have much stronger pair bonds than ducks, and ganders
remain by their mate's side throughout incubation. They also help defend
the nest and aid in raising goslings. However, ganders don't sit on the
nest for most of the day for three to four weeks like female geese, and
therefore are not as directly vulnerable to predation as their mates.
Age is another important factor that influences waterfowl survival. Following a perilous summer on the breeding grounds
, young-of-the-year waterfowl are faced with their first migration
over unfamiliar territory. During this time, these recently fledged birds encounter a new group of predators: hunters.
Immature waterfowl are often the first over the decoys. Band recoveries
suggest that immature waterfowl are harvested at rates 1.25 to 2.5 times higher than those of adult ducks and geese. With natural causes of mortality included, first-year ducks have a survival rate of only 30 percent to 50 percent. First-year geese have a slightly higher survival rate of 50 percent to 70 percent. And while the probability of survival increases for adult birds, at best only about 50 percent to 70 percent of adult ducks and 70 percent to 90 percent of adult geese and swans survive each year.
Waterfowl biologists are keenly aware of the differences in survival among ducks and geese. Longer-lived species with lower reproductive rates such as northern-nesting Canada and white-fronted geese
receive greater attention when hunting regulations are crafted. Populations of prairie-nesting ducks, which rely on abundant wetlands and extensive grasslands, are largely driven by the breeding-season dynamics of nest success and brood survival. That's why Ducks Unlimited focuses much of its resources on conserving habitat
on the prairies and in other breeding areas where large numbers of ducks are raised, while also ensuring that sufficient migration and wintering habitat is restored and protected to sustain their populations throughout their annual cycle. Ultimately, our goal is to protect, restore, and manage landscapes to ensure that ducks and geese survive and reproduce at healthy levels now and in the future.
Dale D. Humburg is chief scientist at DU national headquarters in Memphis.
BIRD BANDING: A Cornerstone of Waterfowl Management Large-scale waterfowl banding began in the 1920s and was the basis for defining the flyway system of waterfowl management. Banding data has been used by biologists for more than 60 years to monitor duck and goose movements and manage harvests.
More than 300,000 ducks, geese and swans are banded each year, mostly on the prairies and other northern breeding areas. In total, roughly 17 million ducks and geese have been banded, and 3 million of these banded birds have been reported, largely by hunters. This information is the basis for much of what we know about waterfowl biology, the rate and distribution of waterfowl harvest and the impact of changing habitat conditions on waterfowl populations.
Hunters can report band recoveries by phone at 1-800-327-BAND (2263), or they can file a report online at pwrc.usgs.gov/bbl. Beginning this year, band recovery certificates that include the species, date, age, sex and location where the bird was banded will be provided electronically.