Factors affecting egg viability and incubation time in prairie dabbling ducks

Hatchability declined as unincubated eggs were exposed to longer preincubation delays. This effect was more pronounced at higher ambient temperatures and later in the nesting season, but did not vary with egg size or among duck species. Clutch size may be small later in the year and at lower latitudes owing to the negative effects of date and temperature on the ability of eggs to withstand precincubation delay. Eggs subjected to preincubation delay required about one additional day to hatch. Incubation time was related to egg size in northern shovelers Anas clypeata and in all species combined, but not in blue-winged teal Anas discors or mallards Anas platyrhynchos. Data provide only weak support for the hypothesis that large eggs are costly because they take longer to hatch. -from Author