guano vs peat

guano

noun
  • Coccothrinax borhidiana, a variety of palm tree indigenous to Cuba. 

  • Dung from a sea bird or from a bat. 

peat

noun
  • Soil formed of dead but not fully decayed plants found in bog areas, often burned as fuel. 

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