Eurasian bittern vs bittern

Eurasian bittern

noun
  • A bittern found in Europe, Asia, and Africa, Botaurus stellaris. 

bittern

noun
  • The saline substance added to soy milk to coagulate it as a primary step in the production of tofu. 

  • Several bird species in the Botaurinae subfamily of the heron family Ardeidae. 

  • The liquor remaining after halite (common salt) has been harvested from saline water (brine). 

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