merlin vs peregrine falcon

merlin

noun
  • A small falcon, Falco columbarius, that breeds in northern North America, Europe, and Asia. 

  • A cytoskeletal protein active in the suppression of tumors. 

peregrine falcon

noun
  • A medium-sized, very swift falcon, Falco peregrinus, that hunts small birds. 

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