FEMALE MALLARD MATING PREFERENCES FOR MULTIPLE MALE ORNAMENTS .2. EXPERIMENTAL VARIATION

A study I conducted suggested that female mallards chose males based o n natural variation in individual ornaments, especially the bill. Orna ment manipulations were used to test experimentally whether females we re choosing males based on ornament appearance. Four experiments were conducted: anterior shaving (removed the outer colored part of the hea d, neck and breast feathers), wing patch clipping, bill blackening and bill yellowing. Anterior shaving caused 15 of 16 males to have lower pairing success. Wing patch clipping did not affect pairing success. B ill blackening caused a significant decrease in rank pairing success, and bill yellowing caused a weaker, but not significant, decrease in s uccess. Furthermore, the latter three manipulations had no significant effect on male dominance rank. Taken together with the findings of th e natural variation study, this work shows that female preferences dir ectly select for male ornamentation.