Preferences of Mallard Ducklings for Strange Broods of Different Ages

We conducted three experiments on Mallard ducklings Anas platyrhynchos platyrhynchos. In all of them, the dependent variable was the amount of time each subject spent during a 15 min trial with a brood of ducklings of the same age, a brood of one-week old ducklings and a brood of two-week old ducklings. Each brood was composed of six ducklings. It was hypothesized that a preference for an older brood would be demonstrated by the experimental subjects. In Experiment 1 the experimental subjects and the stimulus broods were housed in separate compartments within the same brooder. No significant preferences (P>0.05) among the stimulus broods housed in separate compartments within the same broods were obtained in Experiment 1. In Experiment 2 the stimulus broods were housed separately from the experimental subjects. The brood of same age ducklings and the one-week old brood were preferred to the two-week old brood. In Experiment 3 wooden barriers prevented physical contact between the experimental subjects and the stimulus broods. The two-week old brood and the one-week old brood were preferred to the brood of the same age. This series of experiments and in particular the results of Experiment 3 suggest that Mallard ducklings prefer older broods over broods of the same age.