oner vs rare bird

oner

noun
  • An extraordinary individual. 

  • A small marble of little worth in children's games. 

  • A long one-take shot, or equivalent animated segment simulating a one-take shot 

  • A conker that has won one match. 

rare bird

noun
  • An unusual or exceptional person or thing. 

  • Used other than figuratively or idiomatically: see rare, bird. 

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