Renesting behavior is different for each duck and goose species. For example, mallards and northern pintails are more likely to renest than are lesser scaup and gadwall, because mallards and pintails are early nesters. If their first nest fails, they usually still have time left to renest and have the brood gain flight before the end of the breeding and brood-rearing season.
Scaup and gadwall nest three to four weeks later than mallards and pintails, and they renest much less frequently. (Geese nesting in the far north rarely renest because they are subject to even greater time constraints imposed by a particularly short breeding season.)
Age also influences renesting. Older, more experienced hens are thought to arrive on the breeding grounds earlier and initiate a nest sooner than younger birds. Thus, older hens have a longer nesting season. Older birds are also more familiar with local food sources, which are critical in providing nutrients necessary for additional egg production.
Productive wetlands are vital for nesting hens because they provide most of the nutrients required for egg production. If wetlands are scarce due to drought or habitat loss, hens may have a more difficult time finding the necessary resources for renesting. Conversely, waterfowl are more likely to renest during years of high water levels or in years when summer precipitation improves or maintains wetland habitat.
Renesting helps waterfowl offset the effects of nest predation, but it does not guarantee success. Some hens may try to nest several times but will still be unsuccessful. On the other hand, some early-nesting mallards that lose their entire brood of ducklings shortly after hatch may renest, but this is rare.
Renesting comes at a cost. A mallard, for example, requires about 35 days to lay a clutch and incubate it to hatch. By late incubation, a hen is usually very reluctant to leave her nest. For the swift and alert predator, finding a duck nest can include a bunch of eggs and a duck dinner.
This reluctance to leave the nest also makes hens susceptible to being killed by haying and mowing equipment. The more time a hen spends nesting, the greater the probability will be that she will pay the ultimate sacrifice for a chance at hatching a clutch of eggs.
Renesting can be very important for waterfowl production. In many areas, few ducklings would be produced if hens gave up after only one nest attempt. Though the odds of successfully hatching a nest are usually low, the more nests that are attempted, the more nests that will hatch. So, for many hens, if at first you don't succeed, RENEST!
Even for hens that beat the odds and hatch a nest, the battle is far from over. Of the ducklings that hatch, 40 to 60 percent will not survive to reach flight age (approximately 55 to 65 days old).
Duckling mortality is most common during the first two weeks of life. The quality and quantity of wetlands, weather, and predator populations all influence duckling survival. Ducklings fall prey to many different predators, such as mink, turtles, fish, night herons, marsh hawks, gulls, and foxes.