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-level<0.05, nx gives sample size for the respective species. Individual species values are provided in Table S2.