The PMCA's innovative new Purple Martin dawnsong cd. This cd is highly successful in attracting Purple Martins to potential colony sites. It contains 60 minutes of loud, uninterrupted, Purple Martin dawnsong, the nocturnal song that adult males sing to attract subadults.
The Purple Martin Conservation Association is excited to announce the availability of the most unique accessory yet developed for attracting martins: a 60-minute cassette of Purple Martin Dawnsong. Dawnsong is the unique set of vocalizations that adult (ASY = "after-second-year") male martins emit during the predawn hours of spring while flying high above their colony sites or while perched nearby. It is a loud, continuous series of chirps presented in a syncopated series of about seven to nine notes repeated over and over. Its function is the attraction of nocturnally-migrating subadult (SY = "second year" or yearling) martins to a singing male's colony site.
Dawnsinging is not a group chorus. Each male flies his own path in slow, wide circles about 500 feet up, singing his own unique song. It is estimated that the sounds from a morning of dawnsong project across at least 30 square miles of ground and perhaps 100 cubic miles of air, as early morning acoustics are the best for sound transmission.
By attracting more colony members, a dawn-singing male is attempting to leave more offspring during a single summer's breeding effort by increasing his opportunity of engaging in forced extrapair copulation with the mates of the subadult males he attracts. Since the migration of subadults lags behind that of the earliest adults by at least 4-6 weeks, adult males don't begin their dawnsinging until about the time that subadults begin migrating through their area.