Foraging Behavior and Diet of Northward Migrating Bar-Tailed Godwits (Limosa laponica) and Great Knots (Calidris tenuirostris) at a Key Stopover Site

Sunghoon Choi, Sung-Ryong Kang, Sang-im Lee, Jae Min Lee, Baek-Jun Kim


After the completion of the Saemangeum reclamation, the Geum Estuary has emerged as a key feeding and rooting site (staging site) for shorebirds in South Korea. However, there has yet to be any study conducted on the behavior and diet of shorebirds in this region. In this study, we first compared behavior and diet of two representative shorebird species with different morphologies, Bar-tailed Godwits (Limosa laponica) and Great Knots (Calidris tenuirostris) that co-occur in the tidal flat of Yubu Island near the Geum Estuary. During the April to May of 2016, using a camera equipped with a telescope, we recorded 36 individuals during low tide. Behavior was significantly different between the two shorebird species (Chi-square test, P = 0.037), although feeding success rate was similar between the two species (ANOVA, P > 0.05); the Bar-tailed Godwit showed more probings and less peckings than the Great Knot. In addition, Bar-tailed Godwits walked less (ANOVA, P < 0.001) and were less alert (ANOVA, P < 0.005) than Great Knots. On the other hand, diet composition was significantly different between them (Chi-square test, P = 0.010); Both species fed mainly upon Mollusca but the Great Knot fed on noticeably more Annelida (lugworms) than the Bar-tailed Godwit. Among Mollusca, both species consumed more gastropods than bivalves (ANOVA, P < 0.001).

Based on these results, it is thought that Bar-tailed Godwits may save energy through less pecking together with less walking and less being alert, since it fed on less food than Great Knots. These results on behavior and diet will be helpful for conservation of the two species in the Geum Estuary tidal flats, a key stopover site of many shorebirds in the East Asian-Australasian Flyway (EAAF).


Bar-tailed Godwits; behavior; diet; Great Knots; Yubu Island Bar-tailed Godwits; behavior; diet; Great Knots; Yubu Island.

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