Coastal wetlands are heterogeneous systems with multiple inputs and complex interactionswithin local food webs. Interpreting such complexity is limited by incomplete knowledgeof trophic interactions among organisms. Although widely recognized as secondary consumersand predators of intertidal macroinvertebrates, shorebirds can also consume lower-trophic-levelfood sources, and frequently forage in adjacent supratidal habitats. To ascertain potential trophiclinks between overwintering shorebirds and alternative non-standard food sources, we collectedcarbon and nitrogen stable isotope data of shorebirds and benthic organisms from 4 coastal wetlandsalong the Eastern Atlantic: Tejo Estuary, Portugal; Sidi-Moussa, Morocco; Banc d’Arguin,Mauritania; and Bijagós Archipelago, Guinea-Bissau. Using dual-isotope Bayesian mixing models,we evaluated the relative importance of intertidal benthic macroinvertebrates and 3 otherpotential food sources (biofilm and seagrass rhizomes from intertidal areas, and saltpan macroinvertebrates)in the diet of wintering shorebirds. Although intertidal macroinvertebrates form themain part of most shorebird species’ diet, our data revealed that supratidal saltpans can contributeto >30% of the biomass ingested by several shorebird species. Seagrass rhizomes represented>10% of the diet of several species in Banc d’Arguin and in Sidi Moussa. Little stint Calidris minutaappears to consume biofilm on all 3 wetlands where they were sampled, which is the first timebiofilm consumption by shorebirds has been detected along the East Atlantic Flyway. Empiricalevidence for generalized consumption of alternative food sources by intertidal avian predatorsshow the greater complexity and food web connectivity in and of intertidal habitats, and also withthe surrounding habitats.