Diet of non-breeding wildfowl Anatidae and Coot Fulica atra on the Perthois gravel pits, northeast France

Abstract

Gravel pits are important habitats for wintering waterbirds, yet food selection by wildfowl wintering at these wetlands has seldom been studied. Here we describe the diet of eight dabbling and diving duck species, and also of Coot Fulica atra, at the Perthois gravel pits in northeast France. The pits form part of a broader Ramsar area and are in themselves of national importance for several Anatidae. From 343 guts collected, the gross diet of the nine bird species corresponded to that reported in the literature for these waterbirds on other types of inland wetlands, though Pochard Ayhtya ferina were almost exclusively granivorous here whereas earlier studies found that they fed more on invertebrates. All nine bird species ingested seeds, often in abundance, though in addition to Pochard only Teal Anas crecca and Mallard A. platyrhynchos could be considered as being true granivores. Two species (Spiny Naiad Naïas marina and Small Pondweed Potamogeton pusillus) were consistently among the most consumed seeds in eight out of nine bird species. The importance of these plant species may be typical to gravel pit in this study area. Animal prey was also well represented in the gut samples, and this study especially highlights the importance of Bryozoan statoblasts in waterbird diet. Management implications for gravel pit areas are suggested.