eared seal vs northern fur seal

eared seal

noun
  • A seal belonging in the Otariidae family; a fur seal or a sea lion, differing from the true seals in having small, visible ears and the ability to walk on land. 

northern fur seal

noun
  • A fur seal of the species Callorhinus ursinus (formerly Arctocephalus ursinus), of the northern Pacific. 

How often have the words eared seal and northern fur seal occurred in a corpus of books? (source: Google Ngram Viewer )