Niche partitioning is a strategy whereby specialization allows species with similar ecological requirements to coexist. This is particularly important for organisms exploiting specific food resources, such as migratory birds at stopover and nonbreeding sites. However, the relative interplay between niche sharing and segregation among resident and migratory species at the same site has been challenging to quantify. We carried out conventional dietary (i.e. feces), as well as δ13C and δ15N stable isotope analyses of blood samples, on eight migratory and resident shorebirds (Charadriidae and Scolopacidae) in a Ramsar site of international importance for shorebirds in southern Brazil during the Nearctic winter. We assessed interspecific trophic niche variation and overlap to uncover the potential relationships between dietary and/or isotopic composition and species’ functional traits. We hypothesized that shorebird species should differ in they prey consume and segregate along at least one dimension, and predicted that migratory species would exhibit broader trophic niches. Limited trophic niche overlap was observed between most species: most migrants had diets comprised of intertidal prey, while most residents had diets composed by freshwater, grassland, or supralittoral prey. Niche overlap was, in general, higher and isotopically more variable between residents than migrants. Finally, diet dissimilarities were negatively correlated with the degree of isotopic similarity between species. Our results reveal distinct degrees of trophic and isotopic partitioning among migratory and resident shorebirds. There was no evidence that similarity of morphological traits or migratory status was related to similarity of diet or the isotopic niche of species. Resource partitioning and dietary variability and morphological differences seems to allow coexistence of resident and migratory shorebirds. In this scenario, high prey availability combined with recent declines in shorebird abundance can relax potential competition, facilitating species coexistence via niche overlap in a dynamic, yet critical, site for shorebirds in the Western Hemisphere.