Bijago or Bidyogo is the language of the Bissagos Archipelago of Guinea-Bissau. Bidyogo is the "dominant mother tongue of the archipelago population", though it is not used in schooling there, a role that has been taken over by Kiriol since the 1990s. There are some difficulties of grammar and intelligibility between dialects, with the Kamona dialect being unintelligible to the others.
The Kajoko dialect is one of the few in the world known to use a linguolabial consonant, the voiced stop [d̼] (or, given that it behaves as a labial consonant, [b̼]), in its basic sound system.
Bijago is highly divergent. Sapir (1971) classified it as an isolate within the West Atlantic family. However, Segerer showed that this is primarily due to unrecognized sound changes, and that Bijago is in fact close to the Bak languages. For example, the following cognates in Bijago and Joola Kasa (a Bak language) are completely regular, but had not previously been identified:
Olson, Kenneth S.; Reiman, D. William; Sabio, Fernando; da Silva, Filipe Alberto (2009). "The voiced linguolabial plosive in Kajoko". Chicago Linguistic Society. 45 (1): 519–530.
Segerer, Guillaume (2000). "Lʼorigine des Bijogo: hypothèses de linguiste". In Gaillard, Gérald (ed.). Migrations anciennes et peuplement actuel des Côtes guinéennes. Paris: LʼHarmattan. pp.183–191.
Segerer, Guillaume (2002). La langue bijogo de Bubaque (Guinée Bissau). Louvain and Paris: Editions Peeters.
Segerer, Guillaume; Lionnet, Florian (2010-12-04). 'Isolates' in 'Atlantic'. Language Isolates in Africa. Lyon.
