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Lake Chad is remarkable in many respects. For one thing, it's situated on the edge of the Sahara Desert, providing a vital source of water to human and wildlife communities alike. It's also changed dramatically in size over the years; once measuring as large as 9,700 square miles (25,000 sq. km), it has also been as small as 965 square miles (2,500 sq km) during this century. The lake is freshwater, despite evaporation rates that are four times as high as rainfall in the region. And it's extremely shallow--rarely more than 23 feet (7 m) deep. The lake supports a growing human population as well as millions of birds and a number of mammals, reptiles, and amphibians.
Lake Chad drains an area of about 965,000 square miles (2.5 million sq. km). Because conditions in the region are so hot and dry, leading to high rates of evaporation, the lake would likely be saltwater if it weren't for several factors. One is that the heavier salts flow out through underground passages, preventing salt buildup in the lake. Another is that the lake receives large freshwater inputs from the nearby Adamaoua Plateau. The ecoregion includes the Hadejia-Nguru wetlands to its west. Swamps occupy the margins of the lake, and dense floating vegetation covers the shallow waters. This shallow lake expands dramatically with seasonal floods, providing a vital refuge for migrant paleartic birds and other animals.
Up to a million wintering ducks congregate on Lake Chad each year, making it the third most important area for migratory waterbirds in West Africa. Actual numbers of birds vary year to year, depending on the size of the lake and on wetland conditions elsewhere in West Africa. The ecoregion supports two near-endemic birds, the rusty lark and the river prinia. Other birds include the marbled teal, which is occasionally seen on Lake Chad and in northern Chad and is thought to be declining worldwide. Ruffs are common here, with over one million seen on the lake at one time. A few populations of elephant, kob, and red-fronted gazelle still live in sections of the Chad Basin. Although other large mammals and crocodiles have been hunted out by humans, smaller mammals (such as the endemic Lake Chad gerbil), smaller reptiles, and amphibians remain.
About 11 million people live in the Chad Basin, and their domestic cattle, goats, and sheep have come to replace much of the native wildlife. Overfishing and hunting have led to declining animal populations, pollution threatens wildlife habitat, and diversion of water for agriculture and industrial uses may further reduce lake levels. For more information on this ecoregion, go to the World Wildlife Fund Scientific Report. All text by World Wildlife Fund © 2001
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