hart vs roe deer

hart

noun
  • A male red deer or one of related species. 

  • A male deer, especially the male of the red deer after his fifth year. 

roe deer

noun
  • A small, nimble Eurasian deer with no visible tail, a white rump patch, and a reddish summer coat that turns grey in winter, the male having short three-pointed antlers (Capreolus capreolus and Capreolus pygargus). 

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