too literal, but thanks!
Some things I picked from it.
“Singing for status was an all-consuming passion, and fanciers often competed using wild-caught goldfinches and chaffinches.”
“He was especially interested in how birds acquire their song, and he was the first to recognise that songs weren’t hard-wired in the brain, as most people believed, but that learning was the key to a bird’s singing success”
Basically the cage bird sings to keep from being eatan.