Weblink 5.1
Caption: A BBC documentary "Ludwig Koch and the Music of Nature"
Link: www.bbc.co.uk/archive/archive_pioneers/6505.shtml

Weblink 5.2
Caption: A recording by Albert R. Brand in 1937 (Herringull, Canada), available at the Macaulay Library
Link: macaulaylibrary.org/audio/flashPlayer.do?id=3288

Weblink 5.3
Caption: A (focused) recording by Arthur A. Allen in 1947 (Gray-necked wood-rail, Panama), available at the Macaulay Library
Link: macaulaylibrary.org/audio/flashPlayer.do?id=914

Weblink 5.5
Caption: A gramophone publication by the Cornell Lab of Ornithology "An Anthology of Over 200 American Bird Songs"
Link: closetcurios2.blogspot.com/2008/05/anthology-of-over-200-american-bird.html

Weblink 5.6
Caption: A gramophone publication by two of Peter Paul Kellogg’s disciplines, Jerry and Norma Stillwell, "Bird Songs of Dooryard, Field and Forest"
Link: closetcurios2.blogspot.com/2009/07/bird-songs-of-dooryard-field-and-forest.html