kitten vs wolf cub

kitten

noun
  • A young rabbit, rat, hedgehog, squirrel, fox, beaver, badger, etc. 

  • A moth of the genus Furcula. 

  • A term of endearment, especially for a woman. 

  • A young cat, especially before sexual maturity (reached at about seven months). 

verb
  • To give birth to kittens. 

wolf cub

noun
  • A young wolf. 

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