Foraging Activity and Capture Rate of Large Nearctic Shorebirds Wintering at a Tropical Coastal Lagoon

Abstract

Abstract. Winter foraging ecology of Marbled Godwit (Limosa fedoa), Long-billed Curlew (Numenius americanus), Whimbrel (Numenius phaeopus) and Willet (Tringa semipalmata) was studied in relation to conspecific density at Estero de Urias, a tropical coastal lagoon in northwestern Mexico. Specifically, the effect of ecological factors in relation to individual prey capture rates for Marbled Godwits and both Numenius spp. was examined. There was a consistent, inverse relationship between conspecific density and foraging activity, but the slope differed among species. The inverse relationship suggests that conspecific density was an important determinant of individual foraging behavior and habitat use across species. For Marbled Godwits, prey capture rate was positively correlated with conspecific density and water depth, but negatively correlated with tidal height, at least during spring tides. In contrast, for both Numenius spp., prey capture rate was significantly higher for territorial birds and tactile f...