Yes, MARABOUS is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, R 1, A 1, B 3, O 1, U 1, S 1.

Is it a valid word?

MARABOUS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

large African black-and-white carrion-eating stork; its downy underwing feathers are used to trim garments
the downy feathers of marabou storks are used for trimming garments

Also: marabou stork, leptoptilus crumeniferus.