Least flycatcher
Chapter 6: Song Learning Often Creates Complex Songs and Large Repertoires
Subchapter: Song complexity
From page 79 in the book.
Photo by Brian E. Small
♫361. A simple, eighth-of-a-second Che-BEK! May 20, 2012. Quabbin Park, Ware, Massachusetts. (3:25)
♫362. Example 2. June 20, 2013. Ear Falls, Ontario. (9:10)