The diet of the Marbled Teal Marmaronetta angustirostris in southern Alicante, eastern Spain

Abstract

We present a study of the diet of the globally threatened Marbled Teal Marmaronetta angustirostris in the southern Alicante wetlands, the most important site for the European population. We analysed the gut contents of 64 fully-grown teal collected between 16 June and 24 November from 1992 to 2000, and 31 ducklings (29 of the newly hatched age class Ia) collected between 18 May and 16 July from 1994 to 1998. The ducklings died following rescue from a concrete irrigation channel, and all but 4 fully-grown teal died in various mortalities. We also analysed 20 faecal samples collected from fully-grown teal in July-August in 1999 and 2000, plus faecal samples collected from five broods after their rescue from the channel. Seeds (72% by aggregate percent of gullet volume), supplemented by invertebrates (21%) dominated gut samples from fully-grown teal. The most important food item was Scirpus litoralis seeds (43% by aggregate percent of gullet volume) consumed mainly when floating on the water surface. The importance of invertebrates was probably underestimated owing to the poor quality of gut samples. Chironomid larvae and pupae, Corixidae and their eggs, ants, ostracods and amphipods were the most abundant invertebrates by volume. Green plant material (probably Potamogeton pectinatus) was abundant in July faeces. There were no clear seasonal trends in diet, perhaps because of the poor quality of most gut samples and variation between years in the seasonal patterns of abundance of different seeds and invertebrates. Ducklings fed mainly on invertebrates, especially chironomid adults and pupae, Coleoptera, Corixidae and ants. They consumed more green plant matter than seeds.