---
title: "The tides that make Guinea-Bissau's islands a haven for wildlife"
description: "Off the coast of Guinea-Bissau, the Bijagós Archipelago is shaped by some of West Africa's largest tides, which expose vast mudflats twice a day and sustain huge flocks of migratory birds and one of Africa's great sea-turtle nesting grounds. Last year it was named a UNESCO World Heritage site."
category: "Science"
category_url: https://newsparlor.com/category/science
author: "Sofia Russo"
published: 2026-07-17T04:36:00.000Z
updated: 2026-07-17T04:36:00.000Z
canonical: https://newsparlor.com/article/bijagos-archipelago-tidal-biodiversity
tags: ["biodiversity", "guinea-bissau", "conservation", "tides", "birds"]
---
# The tides that make Guinea-Bissau's islands a haven for wildlife

Off the coast of Guinea-Bissau, the Bijagós Archipelago is shaped by some of West Africa's largest tides, which expose vast mudflats twice a day and sustain huge flocks of migratory birds and one of Africa's great sea-turtle nesting grounds. Last year it was named a UNESCO World Heritage site.

Twice a day, the sea around a scattering of low islands off the coast of Guinea-Bissau draws far out and then rushes back, laying bare and then drowning immense expanses of mud and sand. That relentless tidal rhythm is the engine of one of West Africa's richest wild places: the Bijagós Archipelago, a chain of dozens of islands and islets whose exposed flats teem with life.

The tides here are unusually large, reaching several metres, far greater than along most of the West African coast, [as highlighted in imagery from NASA's Earth Observatory](https://science.nasa.gov/earth/earth-observatory/a-tide-fueled-trove-of-biodiversity-in-guinea-bissau/). When the water retreats, it uncovers mudflats that become vast feeding grounds, and when it returns it replenishes the mangroves and channels that thread between the islands. This constant exchange of salt water, fresh water and sediment underpins an ecosystem of remarkable productivity.

## A refuelling station for migratory birds

For hundreds of thousands of shorebirds, the archipelago is a lifeline. Each year, great numbers of sandpipers, plovers and other waders, many travelling along the East Atlantic Flyway from breeding grounds as far away as northern Europe and the Arctic, gather on the exposed flats to feed and rest. Conservationists rank the Bijagós among the most important sites in the world for these migrants, which depend on such places to refuel on their long journeys between continents.

The mudflats offer them an abundance of the worms, molluscs and small creatures that emerge as the tide falls, a moveable feast timed to the rhythm of the sea. Lose such a stopover, and the birds that rely on it can suffer across their entire range, thousands of kilometres away.

## Turtles, mangroves and more

The islands are also a stronghold for sea turtles. A marine national park within the archipelago hosts one of the largest concentrations of nesting green turtles on the African continent, with tens of thousands of nests laid each year on its beaches. As everywhere, only a tiny fraction of hatchlings survive to adulthood, which makes major nesting sites like this one all the more precious.

Fringing the islands, dense mangrove forests filter the water, hold the coastline together and shelter young fish, while the surrounding waters support dolphins, manatees and important fisheries. It is this interlocking web, mudflat, mangrove and open sea, that makes the archipelago so valuable, and so distinctive.

## Recognition and risk

In 2025, UNESCO added the Bijagós Archipelago to its World Heritage list, recognising the global importance of its coastal and marine ecosystems and describing it as a rare kind of place on Africa's Atlantic coast. The designation is a mark of prestige, but it does not by itself remove the threats the islands face.

Local communities harvest shellfish from the same mudflats the birds depend on, a livelihood that must be balanced against conservation. Pollution, pressure on fisheries and the prospect of industrial activity offshore all pose risks, as does climate change, which threatens low-lying islands with rising seas and may disrupt the delicate timing on which migratory species rely.

For now, the Bijagós remains a powerful reminder of how physical forces, in this case the simple, twice-daily pull of the tide, can create the conditions for extraordinary abundance. Protecting it means safeguarding not just a remote corner of West Africa, but a vital link in journeys that span the globe.