airman vs birdman

airman

noun
  • A pilot of an aircraft. 

  • A naval seaman, especially one in the U.S. Navy, who works on and/or handles aircraft. 

  • A member of an air force. 

  • A person of a rank in the U.S. Air Force above airman basic and below airman first class. 

birdman

noun
  • an aviator. 

  • A man who works with birds. 

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

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