beast of prey vs bird of prey

beast of prey

noun
  • A carnivorous animal that hunts for its food, especially one that preys on vertebrates. 

  • A predatory person, savagely cruel and ruthless in their treatment of others. 

bird of prey

noun
  • A carnivorous bird that hunts for its food, especially one that preys on vertebrates. 

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