Pied Coucal (Centropus ateralbus)

huge black bird with ivory-colored neck and part of head; black face and bill and red eye; long, ragged-looking tail; sharp, mechanical "tuk" call repeated as if in agitation; in flight, splayed primaries and long tail made the birds look prehistoric; four birds in all; clambered about mid-story vegetation and I noted zygodactyl feet; small white patch on forewing -- perhaps the alula?