pettychaps vs western Orphean warbler

pettychaps

noun
  • Any of several species of small European passerine songbirds, including the willow warbler (Phylloscopus trochilus), the chiffchaffs (Phylloscopus spp.), and the western Orphean warbler (Sylvia hortensis). 

western Orphean warbler

noun
  • Sylvia hortensis, an Old World warbler. Now sometimes Curruca hortensis. 

How often have the words pettychaps and western Orphean warbler occurred in a corpus of books? (source: Google Ngram Viewer )