The PMCA`s dawnsong recording has helped thousands of folks become martin landlords. Adult Purple Martin use "dawnsinging" to attract young martins to there colony site. playing the recording for one or two hours before dawn is recommened, but can be played any time of the day during the two- to four-month period when migrating martins are arriving. Any martin within range will be lured to investigate. Comes with complete instructions for use. A sixteen-page instructional booklet included with each CD. Produced at the library of Natural Sounds of the Cornell Laboratory of Ornitholoy from master tapes provided by Dr. Eugene S. Morton of the Smithsonian Institute. Produced in collaboration with the PMCA. The CD is 74 minutes in length.