Daniel B. Stotts G.W. Pendleton J.E. Hines Vernon D. Stotts D.G. Krementz 1992 The authors estimated laying dates, clutch sizes, and nest success rates of sympatrically breeding populations of American black ducks (Anas rubripes ) and mallards (Anas platyrhynchos ) on Chesapeake Bay islands between 1986 and 1989. Neither average laying date nor clutch size differed between black ducks and mallards. Nest success rates were higher for mallards in 2 of 4 years, but were area dependent. application/pdf 10.1139/z92-035 en Canadian Science Publishing Comparative productivity of American black ducks and mallards nesting on Chesapeake Bay Islands article