bluebelly vs western fence lizard

bluebelly

noun

  • Sceloporus occidentalis, a North American lizard. 

  • A Yankee; a Union soldier during the American civil war. 

western fence lizard

noun

  • Sceloporus occidentalis, a North American lizard. 

How often have the words bluebelly and western fence lizard occurred in a corpus of books? (source: Google Ngram Viewer )