culver vs kereru

culver

noun
  • A dove or pigeon, now specifically of the species Columba palumbus. 

  • A culverin, a kind of handgun or cannon. 

kereru

noun
  • The New Zealand pigeon (species Hemiphaga novaeseelandiae). 

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