Effects of Mate Removal on Incubation Behavior and Reproductive Success of Female Wood Ducks

Abstract

Breeding Wood Ducks (Aix sponsa) maintain pair-bonds later into the incubation period than most other species of North American ducks. We tested whether being paired was beneficial to females during incubation by comparing incubation constancy, incubation period, changes in female body mass, and reproductive success in a mate removal experiment. Females were assigned randomly to one of two treatments: paired controls (n = 24) or widowed (n = 21). Mates of females were removed early in incubation (x = day 5), and nests of paired and widowed females were equipped with temperature data loggers to record the presence and absence of incubating females. Paired and widowed females did not differ significantly with respect to incubation constancy, incubation period, body mass, or nesting and hatching success. Paired females, however, tended to produce second broods more often than widowed females. Being paired did not result in advantages to incubating females, but longer attendance by male Wood Ducks may benefit both sexes where breeding seasons are long and future reproductive opportunities (i.e., second broods) are more likely to occur.