Spatial and temporal variation in the diet of Marbled Teal Marmaronetta angustirostris in the western Mediterranean

Abstract

Capsule This globally threatened species is less dependent on invertebrates and more dependent on seeds than other ducks. Aims To assess seasonal variation in Marbled Teal diet at two of the most important wetlands for the west Mediterranean population. Methods Faecal samples from El Hotba, Morocco (19 in October, 28 in May) and Veta Ia Palma, Doñana (19 in August, five from July broods) were analysed. Gut contents of six birds from Veto Ia Palma (September—October were analysed. Results At El Hotba, small seeds (especially Ruppia) and green plant material (especially charophytes) were the dominant faecal components in May and October. The proportion of invertebrates did not change, but more Corixidae and less Chironomidae were consumed in May. At Veta Ia Palma, Ruppia seeds were dominant in August, but Ephydridae, Chironornidae, Coleoptera and other insects were dominant in faeces from July broods. Significantly fewer Coleoptera but more Foraminifera were recorded in August. The overall proportion of invertebrates at El Hotba in May and October was higher than at Veto a Palma in August, but lower than in July broods. Corixidae were dominant in May, Ephydridae in July broods, unidentified insects, Ostracoda and Foraminifera in August and Coleoptera in October. Gut contents from Veto Ia Palma confirmed the dominance of Ruppia seeds in the post-breeding diet. Conclusion Marbled Teal differs in its ecology from the better-known north-temperate ducks. With the exception of ducklings, they are less dependent on invertebrates and rely on small seeds more than north- temperate ducks.