Hmm.. that's a tough one. I think you are on the right track calling it a falcon - definitely one of the birds of prey. Best known peregrine falcon has such white-grey feathers, but it has grey, not black, beak and distinct "helmet".

Hen harrier has white-grey feathers everywhere, including top of the head, but it has yellow beak.

Praire falcon maybe? Still yellow accents that are missing on the sculpture but it is the closest one I could find.