cushat vs turtle dove

cushat

noun
  • A pigeon, wood pigeon or ring dove. 

turtle dove

noun
  • Any of several (species of) birds, called by this traditional name, mainly in the genus Streptopelia, of the family Columbidae (doves and pigeons, which also included the extinct passenger pigeon, dodo, and solitaire). 

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