Comparison of Agricultural Seed Loss in Flooded and Unflooded Fields on the Tennessee National Wildlife Refuge

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.