Preferences of female American goldfinches (Carduelis tristis) for natural and artificial male traits

We conducted two experiments to determine mating preferences of female American goldfinches (Carduelis tristis). In the first experiment, females were allowed to choose among four naturally varying males. In the second, females chose among four males wearing either orange, blue, yellow, or no color bands. In experiment 1, females performed more courtship with males that had significantly brighter bills and were brighter overall. In experiment 2, females preferred males wearing orange bands over unhanded males. Blue-banded males ranked second and yellow third, but neither was preferred significantly more often than the unbanded males. A female's preference for a particular band color was weakly associated with her own bill and plumage measures; females with brighter throat feathers and yellower bills preferred orange bands to blue bands. The results suggest that female preferences for orange and yellow may be functional and that females may also have aesthetic preferences.