Winter management of California's rice fields to maximize waterbird habitat and minimize water use

Abstract

Rice agriculture provides habitat for waterbirds in California's Sacramento Valley, a region that has lost over 90% of natural wetlands. Developed as an agronomic practice, winter-flooding of rice fields also provides habitat for waterbirds but alternatives are needed with predicted declines in water availability. During the winters of 2009–2010 and 2010–2011, we compared waterbird density and water depths of Sacramento Valley rice fields in four post-harvest management treatments that varied in the amount of water used: maintenance flooding, one-time flooding, non-flooded with boards left in water control structures, and non-flooded with boards removed from water control structures. Densities of waterbirds were higher in the flooded treatments compared to non-flooded treatments. One-time flooding provided the most suitable water depths for shorebirds and long-legged waders while maintenance flooding provided the most suitable water depths for dabbling ducks. Our results confirm that the practice of winter-flooding rice fields provides waterbird habitat. However, increased habitat value and potentially less water use could be achieved using a combination of traditional and alternative flooding practices.