ululate vs yip

ululate

verb
  • to produce a rapid and prolonged series of sharp noises with one's voice. 

  • to howl loudly or prolongedly in lamentation or joy 

yip

verb
  • to bark with a sharp, high-pitched voice 

noun
  • a sharp, high-pitched bark 

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