POTENTIAL REPRODUCTIVE CONSEQUENCES OF WINTER-DIET RESTRICTION IN MALLARDS

Food restriction during winter may subsequently affect waterfowl repro duction. Therefore, we tested the effects of restricted and ad libitum (control) food availability during winter 1987-88 on reproductive per formance of captive wild-strain and game-farm female mallards (Anas pl atyrhynchos) in Mississippi. Females fed restricted diets weighed less (P < 0.01) at the end of winter but regained mass within 1-2 weeks fo llowing ad libitum feeding. Game-farm mallards on restricted diets ini tiated nesting 3 weeks later (P < 0.001) than did control females. Wil d-strain mallards nested 1 week later than did controls, but no differ ence (P = 0.11) was detected (likely due to small sample size). Means for body mass at nest initiation and other reproductive variables (e.g ., clutch size, egg mass) generally did not differ (P > 0.05) between females fed restricted diets and those fed ad libitum. Few wild-strain females renested, but clutch sizes of game-farm females declined (P < 0.01) after initial nests. Simulation modeling revealed that recruitm ent rates (i.e., n F/breeding F) may decrease 3-15% if free-ranging ma llards were to experience nesting delays of 1-3 weeks. We hypothesize that poor feeding conditions during winter could negatively affect mal lard recruitment primarily through delayed nesting, but replication of our study with wild-strain ducks and other experimental design consid erations is recommended.