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.
Additional publication details
Comparative productivity of American black ducks and mallards nesting on Chesapeake Bay Islands