SEXUAL PARTNER PREFERENCE IN FEMALE ZEBRA FINCHES - THE ROLE OF EARLYHORMONES AND SOCIAL-ENVIRONMENT

This experiment investigated the effects of early estrogen treatment a nd sex composition of the social environment on sexual partner prefere nce in female zebra finches, a pair-bonding socially monogamous specie s. Birds were injected daily with estradiol benzoate (EB) or the stero id vehicle for the first 2 weeks posthatch and then lived in either a unisex (all-female) or a mixed sex group from 40 to 100 days. After 10 0 days birds were implanted with testosterone propionate and given thr ee kinds of tests: tests with a stimulus female, two-choice mate prefe rence tests with male and female stimuli, and colony tests to assess p airing preference in a more naturalistic context. Both EB and unisex h ousing independently resulted in a preference for females (masculinize d preference) in the two-choice tests, but only females with both EB t reatment and unisex living were more likely to pair with females in th e colony tests. Sexual partner preference, a key sexually dimorphic co mponent of mate choice, appears to be organized by sex steroids in thi s pair-bonding species, but in a manner that may be mediated by the so cial environment. (C) 1996 Academic Press.