The Bijagos Archipelago, a West African biodiversity hotspot.

The Bijagos Archipelago is located off the coast of Guinea Bissau in West Africa, and consists of around 88 islands and islets. The archipelago is particularly known for its extensive mangrove forests, the population of hippos that roam free on Orango, and the culture of the local Bijógo communities which is strongly influenced by local wildlife. However, among ornithologists and ecologists the Bijagos Archipelago is also known as being part of the East Atlantic Flyway for migratory shorebirds and the complexity of its tidal flats.

The gradient of mangrove forests, intertidal mudflats and subtidal waters (Jannes Heusinkveld/University of Groningen).

The cluster of islands was formed from the ancient delta of the Rio Grande and Rio Geba rivers. The archipelago spans an area of almost 13,000 km2and only 20 out of the 88 islands and islets are inhabited all year round. The capital of the archipelago is Bubaque and is also the most populated island of the archipelago. The archipelago is a designated RAMSAR site since 2014 and was recognized as a UNESCO Biosphere Reserve in 1996 due to its large variety in ecosystems. The archipelago consists of large mangrove forests, intertidal mudflats, complex gulley systems, large subtidal areas, rocky shores, savanna plains, palm forests and semi-dry forests. Due to this high diversity in ecosystems, it is not surprising that the archipelago is high in biodiversity and hosts many endemic species. 

As it is located along the migratory pathway of migratory shorebirds – the East Atlantic Flyway – the Bijagos is one of the West African sites where migratory birds from as far north as the Arctic spend their winter. During the boreal winter months, the Bijagos homes between 600.000 to 900.000 waders, including 116.000 bar-tailed godwits, 90.000 red knots and 13.000 whimbrels. The total number of bird species occurring within the archipelago is estimated to be 283. Not only is the Bijagos archipelago diverse in bird species, it also homes a large variety of other species. In total, 29 mammal species occur within the boundaries of the archipelago, of which the hippopotamus is without a doubt the most famous one. Other mammal species include bottlenose dolphins, the African manatee, African clawless otters and a large variety of (fruit) bat species. The islands also home a variety of herpetofauna. The beaches of the many islands and islets provide nesting sites for five different sea turtle species. The southern islands provide nesting sites for an estimated 7.000 to 37.000 green sea turtles every year. As 88% of the archipelago consist of subtidal waters, the archipelago also is an important area for fish. In total 155 fish species have been documented within the Bijagos, of which 42 are cartilaginous fishes (i.e. sharks and rays). The Bijagos is possibly an important nursery area for many pelagic fish, shark and ray species. The area was also famous for the last observations of sawfish within the West African region, which has completely disappeared over the last decade.

Throughout history the people of the Bijagos are known to be independent, even during times of intensive slave trade or colonial times. The local communities have strong land-based beliefs, inspired by local wildlife like sawfish and hammerhead sharks. The archipelago has an estimated population of 25.000 people, of which most speak their own ethnic language and the Portuguese-based Creole language, which is also commonly spoken throughout the rest of Guinea Bissau. The faith of the local communities was, and still is, key to why large parts of the archipelago are still pristine. In their faith, areas and even whole islands have been designated as sacred areas, limiting or even banning commercial and subsistence activities. 

The edge of an intertidal mangrove area just before low tide (Laura Govers/University of Groningen).

Published by Guido Leurs

Marine predator ecology, specialized in shark and ray research.

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