Enjoy this 40-minute cassette of loon call identification

"Voices of the Loon" is a 1980 cassette produced by The North American Loon Fund (N.A.L.F.).

From the YouTube description:

Clearly, the N.A.L.F. asked themselves how they could make this cassette more annoying than to simply have the two or three sounds loons make repeated over and over for close to an hour; their solution was to call Robert J.