SOUND-PRESSURE LEVELS AND SONG PREFERENCES IN FEMALE RED-WINGED BLACKBIRDS (AGELAIUS-PHOENICEUS) (AVES, EMBERIZIDAE)

Female red-winged blackbirds (Agelaius phoeniceus) were tested for res ponse to songs of male red-winged blackbirds differing in sound-pressu re level (SPL) of playback. Subjects gave significantly more copulatio n-solicitation displays in response to playback of songs at 85 dB SPL than to playback of the same songs at 72 dB SPL. The strength of the p reference, as judged by the ratio of response to high and low SPL play back (1.15:1), was lower than that of preferences for high SPL shown b y insects and anurans. Female red-winged blackbirds responded preferen tially to a conspecific song relative to a heterospecific imitation, e ven when the imitation was presented at an SPL 13 dB higher than that of the conspecific song. By contrast, female redwings did not maintain a preference for multiple conspecific song types over single types wh en the single song types were presented at the higher SPL. These resul ts are compatible with KLUMP & GERHARDT's (1987) suggestion that the i ntensity independence of female preferences varies with the relative b enefit females obtain from each preference.