Female preference for the songs of older males and the maintenance of dialects in brown-headed cowbirds (Molothrus ater)

摘要: Female preferences for local song types have been implicated in the maintenance of dialects songbirds. Such can be assessed by copulation solicitation displays (CSDs) females response to playback male songs. We used CSDs determine if female brown-headed cowbirds (Molothrus ater) Sierra Nevada California discriminate between yearling and adult vocalizations based on two vocal characteristics that often distinguish songs these age classes, incomplete renditions dialect flight whistle 'unique', unshared perched types. predicted stronger responses because yearlings are rarely involved copulations observed although they sexually mature. Eleven estradiol-treated trapped Convict were more stimulated complete whistles recorded from either adults or than typical yearlings. Females also found shared stimulating 'unique' These sexual appropriate consistent with hypothesis use differences classes as cues their choice mates. Furthermore would create selection pressure young males conform culture. Mainly a learning constraint hatching year, do not development repertoires until start second season when years old. The deficits serve uncheatable indicators age, turn is likely correlate genetic quality, which may explain preference reliably identify older males. This system shows signal honesty maintained developmental constraints rather high cost alone.