What are two ways that the birds got represented as monsters in "The Raven"?

Ghastly grim and ancient raven wandering from the Nightly shore, Tell me what thy lordly name is on the Nigh

Then upon the velvet sinking, I betook myself to linking
Fancy unto fancy, thinking what this ominous bird of yore-
What this grim, ungainly, ghastly, gaunt and ominous bird of yore
Meant in croaking "Nevermore."

"Prophet!" said I, "thing of evil!–prophet still, if bird or devil!-