Food Selection by Wood Ducks in Relation to Breeding Status

Abstract

Food habits of 155 wood ducks (Aix sponsa) were studied relative to sex, reproductive status, and season during spring and fall in southeastern Missouri [USA]. The diet of breeding females was influenced by reproductive status. Invertebrate consumption by prelaying, laying and postlaying hens was 54, 79 and 43%, respectively. The proportion of animal foods (34%) in the diet of breeding males was similar to those for fall males and females. Breeding hens not only consumed a greater proportion of invertebrates than breeding males, but their diets also contained a greater diversity of animal foods and included a larger proportion of aquatic invertebrates. Of all birds, 88% were surface feeding when collected. Mean water depth at feeding sites increased from 19 cm during spring to 40 cm in the fall. Invertebrates consumed in the fall were predominantly nonaquatic (81%) while those consumed during spring were primarily aquatic (51%) or aquatic-associated (22%). These differences probably resulted from changes in the aquatic ecosystem and invertebrate populations between spring and fall. Shallow water areas (< 30 cm) are important in providing invertebrate foods for breeding wood ducks.