redhead vs redpoll

redhead

noun
  • red-headed vulture (Sarcogyps calvus) 

  • A person with red hair. 

  • red-headed bunting (Emberiza bruniceps) 

  • red-headed titi (Callicebus regulus) 

  • red-headed woodpecker (Melanerpes erythrocephalus) 

  • A North American duck (Aythya americana) highly esteemed as a game bird. 

  • A kind of milkweed (Asclepia curassavica), with red flowers, formerly used in medicine. 

  • Chinese red-headed centipede (Scolopendra subspinipes mutilans) 

  • A kind of 800-watt lamp. 

redpoll

noun
  • Any of various finches in the genus Acanthis (syn. Carduelis), which have characteristic red markings on their heads. 

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