Feeding patch selection by herbivorous Anatidae: the influence of body size, and of plant quantity and quality

摘要: Recent findings suggest that herbivores select feeding sites of intermediate biomass in order to maximise their digestible nutrient intake as the result trade-off between forage quality and quantity (‘forage maturation hypothesis'). We propose a reformulation this hypothesis which recognises trade-off, but also underlines constraints due body mass (i.e. metabolism digestive constraints, size apparatus) can lead variations grazing patterns. tested latter experimentally three species herbivorous Anatidae different mass: wigeon Anas penelope (in our study c. 620 g), barnacle goose Branta leucopsis (c. 2000 greylag Anser anser 3500 g). Each was separately from 0600 0930 hours, an enclosure with mosaic patches grass heights: short, medium tall. The behaviour, location patch) each individual were recorded every 5 minutes. Our results show important interspecific differences rates resulting site selection: fed fastest on shortest swards, selected short higher quality. Tall provided highest dry matter rate protein for geese, they preferred these swards. These choices allowed birds nitrogen rather than thus underline importance major currency foraging decisions Anatidae. Since two extreme sward heights (instead one), give support role cause patch selection