Abstracts

Presented by Rob Blenk - Email: RHBLENK@UCDAVIS.EDU

Energetic carrying capacity is an integral element of winter waterfowl management at a population level. Understanding the total amount of energy available to waterfowl is dependent not only on knowing the distribution of food on the landscape, but also on the true metabolizable energy content of each food item. Historically, measurements of true metabolizable energy for waterfowl have been obtained using either wild Mallards or domestic ducks as model species. However, documented differences in the internal digestive morphology of waterfowl species suggest that different functional guilds may vary in their digestive efficiency with respect to various food types. Only a single study has assessed true metabolizable energy for a waterfowl species other than Mallards, but this study did not include Mallards as a basis for comparison. I assessed true metabolizable energy of several seed species that differ in their physical characteristics. The true metabolizable energy of each of these seed species are being evaluated for four species representing a diversity of functional guilds within the dabbling duck clade: Northern Pintail (Anas acuta), Mallard (Anas platyrhynchos), Northern Shoveler (Spatula clypeata), and Gadwall (Mareca strepera). Determining whether these species differ in the amount of caloric energy they obtain from common seed foods via captive feeding experiments will provide insight into the appropriateness of generalizing estimates derived from Mallards to other waterfowl species.