kestrel vs peregrine

kestrel

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

  • The common kestrel, Falco tinnunculus. 

peregrine

noun
  • The peregrine falcon. 

adj
  • Wandering, travelling, migratory. 

  • Lacking essential debility. 

  • Not native to a region or country; foreign; alien. 

  • Extrinsic or from without; exotic. 

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