Abundance and conservation of waste rice for wintering waterfowl in the Mississippi Alluvial Valley

Flooded rice fields are important foraging habitats for wintering waterfowl in the Mississippi Alluvial Valley (MAV). Abundant waste rice in early winter once existed in the MAV (140--490 kg/ha). Research in Mississippi rice fields during autumns 1995--1996 revealed waste-rice abundance decreased 79--99%. Therefore, I developed a sampling design for landscape-scale estimation of resource availability, used the design to estimate waste-rice abundance in the MAV, and conducted pilot experiments evaluating different post-harvest field treatments to conserve waste rice for wintering waterfowl.;I used multistage sampling (MSS) and collected 5,680 core samples from 159 rice fields within 87 farms in Arkansas, Louisiana, Mississippi, and Missouri during September--December 2000--2002. Compared to simple random sampling, MSS was more efficient and cost 33% less. I recommended MSS for estimating abundance of food and other natural resources.;Between 2000--2002, I estimated a 71% decline in mean abundance of waste rice between harvest (x¯ = 271.0 kg/ha, CV = 13%; n = 80 farms) and early winter (x¯ = 78.4 kg/ha, CV = 15%; n = 87). Compared with an estimate used by waterfowl conservationists for habitat planning (1,858 duck use days [DUDs]/ha), carrying capacity of MAV rice fields for waterfowl may be overestimated by 52--83%. I recommended revision of the estimate to 325 DUDs/ha, and monitoring rice harvest dates in the MAV to determine if future surveys are necessary because of increasingly earlier harvests.;I conducted experiments in test plots to evaluate post-harvest practices for conserving waste rice, but results were inconclusive. Based on mean abundances of waste rice by post-harvest practice across the MAV and associated agronomic and environmental benefits, I recommended unmanipulated stubble as a preliminary best management practice. Rice-land managers may desire to roll portions of standing stubble fields to enhance open water areas for waterfowl. Current research has revealed that managed moist-soil habitats in the MAV may provide >6 times the foraging capacity of harvested rice fields. I suggested moist-soil wetlands on public and private lands in the MAV should be increasingly integrated into conservation planning and implementation to improve quality of waterfowl foraging habitats.