Merja Fouwarate is a marshland located in the North of Morocco, on the Atlantic coast, close to the Sebou estuary; it belongs to a large complex of marshes which occupied the Gharb plain and are actually drained in their majority for agricultural purposes. This wetland is richly vegetated and favorable to several water bird species, both as breeding habitat and migration stopovers. The last severe droughts which affected Morocco reduced drastically these habitats and their bird populations were therefore reduced; but since the beginning of this century, abundant rainfall insures therefore to this wetland good flooding and a rich bird population. That why we planned a weekly monitoring of the bird population, which was held between August 2009 and August 2010 and permitted to study the phenology and the reproduction cycle of the waterbirds. The majority of waterbird species remain in relatively low numbers, but the great importance of this site is due to the presence of several species globally or regionally threatened. Among them, Anatidae are represented with eleven species, two of them (Marbled Teel and Ferruginous Duck) are listed in the global Redlist and have significant breeding populations in the site. Three other species nest in this site and the others are visitors. According to our study the importance of Anatidae populations, as well as Ardeidae and Rallidae, assign to this wetland an international importance, thanks to several Ramsar criteria (1, 2, 4 et 6). This wetland was already included in the Moroccan Master Plan of Protected Areas, as 'Site of Biological and Ecological Interest'.