Best daytime Purple Martin attraction tool! This CD was produced by the Macaulay Library at Cornell Labs of Ornithology. This is the best sound on the market. Use this to attract martins to your site! With the purchase of this item, you will receive a three month subscription to the Purple Martin Conservation Association, limited to one free subscription per household. Purple Martin Market Place offers high-quality items for martin enthusiasts. Buy with confidence knowing that we have directed the development of much of the merchandise and what we offer has been approved by the Purple Martin Conservation Association. Profits generated support the PMCA’s conservation, education, and research programs.