Henslow's sparrow
Chapter 3: Why and How Birds Sing
Subchapter: What birds hear
From page 41 in the book.
Photo by Wil Hershberger
♫130. Songs of one male, 22 simple hiccups over about a minute's time. June 2, 2008. Prairie State Park, Mindenmines, Missouri. (1:05)
♫131. One of those songs first at normal speed, then slowed four times, then eight times, increasingly revealing the intricacies in what our limited ears hear as an especially simple song. (0:06)