Food Use and Nutrition of Black Ducks Nesting in Maine

Abstract

Based on 32 adult black ducks (A. rubripes) collected during the nesting seasons of 1974-1976, the proportion of macroinvertebrates (as aggregate [average] percent of dry weight) in the diet of males, egg-laying females and postlaying females was 60, 75 and 55%, respectively. Sample sizes were small, and the differences associated with sex and reproductive condition were not significant. Molluskes, isopods, ephemeropteran and odonate nymphs and coleopteran, trichopteran and dipteran larvae contributed 74% of the dry weight and 64% of the gross energy ingested. Data from proximate analyses of 9 invertebrate and 9 plant foods were combined with food habits data to estimate the nutrients available to breeding hens. Females with access to an adequate amount of natural food including invertebrates and the seeds and tubers of aquatic plants would obtain sufficient minerals, protein and energy for reproduction. Food quality does not appear to limit the density of black ducks nesting in Maine.