Discrimination factors Δ δ13C and Δ δ15N between food and various tissues of four herbivorous Anatidae species.

Source -tissue discrimination was measured experimentally in captive Bewick Swans Cygnus columbianus bewickii (A) and mallards Anas platyrhynchos (B); diet and egg tissue- feather discrimination was determined in free-living Barnacle Geese Branta leucopsis (C) and Pink-footed Geese Anser brachyrhynchos (D). Herein, droppings were used as proxies for ingested food. Between-species differences were examined with t-test,*marks a difference at p-levelx gives sample size for the respective species. Individual species values are provided in Table S2.