Drying out

Along the southern edge of the Sahara there is a grassland region called the Sahel. This is where millions of hungry migrants find food after crossing the desert.

But overgrazing by cattle has done terrible damage to the Sahel – the soil has been eroded, the plants are disappearing and the whole region is drying up. 

This has made the Sahara desert wider, and some birds – such as sand martins – now find it much harder to cross. Sand martins no longer visit Europe in the same numbers they did fifty years ago.