The Macaulay Library contains nearly 175,000 recordings of life on Earth, dating back almost a century. Digitizing the library's audio collection, based at the Cornell Lab of Ornithology, took 12 years, with the result equaling about 10 terabytes of data to total 7,513 hours of run time. Of course, that just scratches the surface of animal life--and focuses a bit on birds more than other creatures--with "only" about 9,000 species represented but, now, with the thing safely housed on servers, it becomes that much easier to add to it with the help of regular folks with an iPhone or whatever.
Cornell has a handy guide to/best-of the library up right now.
Earliest recording: Cornell Lab founder Arthur Allen was a pioneer in sound recording. On a spring day in 1929 he recorded this Song Sparrow sounding much as they do today.
Best candidate to appear on a John Coltrane record: The indri, a lemur with a voice that is part moan, part jazz clarinet
Most spines tingled: The incomparable voice of a Common Loon on an Adirondacks lake in 1992
Most erratic construction project: the staccato hammering sounds of a walrus under water.
Listen to the remaining recordings, the other 8,996 or so species doing their thing, at www.MacaulayLibrary.org.