kestrel vs peregrine falcon

kestrel

noun
  • Any of various small falcons of the genus Falco that hover while hunting. 

  • The common kestrel, Falco tinnunculus. 

peregrine falcon

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

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