"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. Lurtsema, a Boston-based public radio broadcaster who was famous throughout New England for his unique, buttery voice and his often Shatner-esque delivery.
It takes Lurtsema almost a half hour to explain the four sounds loons make to the listener, clearly enjoying the sound of his own voice, at times even slowing down the recordings to make sure the audience can hear every detail of the so-called "tremolo." He goes on to explain that there are people who record loons every season and use those recordings to extrapolate such things as territorial disputes, breeding patterns, and family movements. Because of course there are.