Beaded bottles surmounted by birds are usually the prerogative rulers. Their contents may be known only to their owners, for such decoration–like the beaded crowns that “contain” rulers’ prepared heads–suggests awesome presences, set apart and distinguished form more benign substances. Knowledgeable herbalists (whose iron staff with birds recall this beaded bird bottle-stopper) specialize in preparing healing liquids, oti (hot liqueurs mixed with sacred woods, snakes, roots, leaves, insects, or other items). Bottling and then dressing power in beads and sequins has been most fully articulated among the Fon- and Aja-speaking peoples to the west Yorubaland, the Bantu peoples of Central Africa, and their descendants in the Americas, most especially in the vodou world of Haiti and among African-Americans in the South. However, this custom also occurs among Yoruba peoples.
Source: Drewal, H., Mason, J. (1998). “Beads, Body, and Soul – Art and Light in the Yoruba Universe”, Los Angeles: UCLA Fowler Museum of Cultural History. page 225