Context:

Steve mentions owning this book which contains bird sounds with a built-in speaker. He discusses how his kids like it and how he tried to use it to test the Merlin app, but the compressed audio quality meant Merlin couldn't identify the birds from the book's speaker.

Context:

Steve cites this book by historian Dan Flores when discussing that there are only five species of birds with global populations exceeding one billion (including English sparrow, a type of gull, and European starling). This fact was later questioned by the ornithologists as difficult to verify with confidence.