fauna vs mammal

fauna

noun
  • Animals considered as a group; especially those of a particular country, region, time. 

  • A book, cataloguing the animals of a country. 

mammal

noun
  • An animal of the class Mammalia, characterized by being warm-blooded, having hair and producing milk with which to feed its young. 

  • A vertebrate with three bones in the inner ear and one in the jaw. 

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