birdman vs copilot

birdman

noun
  • an aviator. 

  • A man who works with birds. 

  • A mythological creature that is part man and part bird. 

copilot

noun
  • A backup or assistant pilot of an aircraft. 

verb
  • To serve as relief or assistant pilot. 

How often have the words birdman and copilot occurred in a corpus of books? (source: Google Ngram Viewer )