cervid vs wapiti

cervid

noun
  • Any animal (such as the deer) of the family Cervidae 

wapiti

noun
  • The American elk (Cervus canadensis). It was formerly considered to be in the same species as the European red deer, which it somewhat exceeds in size. 

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