Geographical and temporal patterns in the diet of pintail Anas acuta, wigeon Anas penelope, mallard Anas platyrhynchos and teal Anas crecca in the Western Palearctic

Dabbling ducks are important quarry species, and as a result, they are relatively well studied. Over the last century, considerable effort has been made to describe their diet and food requirements. In this review, we compile present knowledge about the diet of four widespread dabbling ducks (wigeon, pintail, mallard and teal) in the Western Palearctic. Previous diet research has a spatio-temporal bias towards autumn/winter and the western parts of Europe. The limited number of studies from the breeding season reveals an increase in invertebrates in the diet compared to other seasons, but with some differences between adults and ducklings. Adult ducks eat a larger proportion of benthic invertebrates, whereas ducklings feed relatively more on emerging invertebrates. The most important plant species (seeds) based on frequency occurrence was found to vary with a geographic gradient. Carex spp., Hordeum vulgare and Hippuris vulgaris are common in the diet of birds at northern latitudes, whereas taxa such as Oryza sativa, Potamogeton pectinatus and Scirpus spp. are common in the south. The reviewed studies are based on the contents of different parts of the digestive system and on a variety of methods to quantify food items. The variations in sampling techniques and shortage of articles from the breeding season and some geographic regions highlight the need for future studies. In the future, it is important to standardize sampling techniques to improve the possibility to compare studies and to obtain a more representative view of the diet of dabbling ducks in Europe.