From March to May, many species make their annual prenuptial migration towards breeding grounds in the north. The numbers of these birds passing through the Park depend on the weather, but also on the water levels in the marshes. These visitors generally stop to feed and to replenish their fat reserves before continuing their journey north, effectively using the Camargue as an avian service station.
Other species end their journey here, staying in the Camargue to breed. Large colonies of herons and egrets nest in the trees, whereas terns, gulls and avocets take up residence on the lake islands. Several species of passerine can be found singing and nesting in the reed beds and in trees, bushes and hedges throughout the Park.-