kitten vs moorhen

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. 

moorhen

noun
  • A female red grouse, Lagopus lagopus scotica. 

  • Any of various medium-sized water birds of the genus Gallinula, of the rail family, that feed in open water margins. 

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