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In many birds, egg viability declines the longer that eggs remain unincubated (i.e., incubation delay), possibly because of increased levels of microbial infection. Reuse of nests is common in cavity-nesting species and may also increase exposure of eggs to microbes. Starting incubation before the clutch is complete may help protect early-laid eggs from microbial infection. In this study, we tested the effects of nest cleaning, length of incubation delay, and onset of night incubation on growth of microbes on Wood Duck (Aix sponsa) eggshells and examined the effect of microbial infection on hatching success. We used nest boxes that had been cleaned or not cleaned of previous nesting materials and sampled microbes on eggshells during early and mid egg laying and after the start of night incubation. We detected levels of eggshell microbes (101 colony forming units [CFU] egg-1) lower than at more tropical locations (103–4 CFU egg-1). Levels of heterotrophic bacteria were 2.2 times greater in unclea...

Egg viability in birds declines with increasing length of the delay in the start of incubation (i.e., incubation delay) and may be influenced by microbial infection and exposure of eggs to temperatures above physiological zero (>24°C). Onset of incubation during egg laying results in developmental asynchrony of embryos but may help to maintain viability of early-laid eggs. We manipulated incubation delay of Wood Duck (Aix sponsa) eggs and tested for effects of incubation delay and ambient temperature on egg viability and microbial infection. We also examined onset of incubation by egg-laying females. Hatching success declined slowly with increasing length of incubation delay and was very weakly affected by increasing exposure to temperatures >24°C. On average, females began incubation at night 7 days after nest initiation, but egg viability had declined only 8.6% (95% confidence interval: 4.3–15.2) by day 7. Microbial infection of eggshells was not related to length of incubation delay or mean d...

Waterfowl exploit seed resources in agricultural fields to help meet the energy demands associated with migration, thermoregulation, and various life-history activities. Biologists commonly flood agricultural fields to increase the availability of seed for waterfowl and to provide hunting opportunities. Previous studies suggest that flooding may accelerate seed loss; however, simultaneous comparison of seed loss with unflooded fields has not been made. We compared rates of loss between seed contained in wire mesh bags placed in an unflooded agricultural field vs. seed submersed in a flooded field on the Tennessee National Wildlife Refuge from October 2007 to January 2008. Agricultural seed mass declined 40–300% more rapidly in the flooded than in the unflooded field. Corn, soybean, and grain sorghum seed mass declined 42%, 87%, and 46%, respectively, after 12 wk of continuous submersion, which was similar to previous studies that measured seed loss in flooded mesh bags. However, the rate of seed mass loss in unsubmersed mesh bags was 1.3–6.9 times lower than scattered seed lying on the ground under granivore exclosures in a separate experiment. We hypothesize lower rates of seed loss in mesh bags compared to scattered seed may be an artifact of the bags, which are commonly used in seed fate studies. Our results suggest biologists should delay flooding agricultural fields until immediately prior to the arrival of waterfowl and be aware that absolute estimates of seed loss from studies that use mesh bags may be biased negatively.