Was my grandfather a heron?

My grandfather, David Windsor Davis Sr. was born 5 Jul 1893 at 41 Garn Cross Street in Nantyglo, Wales. At the time of his birth, his father was a grocer and the family lived above the store. Below is a picture we took of the building when we were in Wales.

His birth certificate lists his name as "David Windsor Cranog Davies." I don't know the significance of the name Cranog. Only one other brother, John Ivor, had an additional name, "John Ivor Crynant Davies." Cranog is a Welsh boy's name and means heron; a wading bird with grey and white plumage.