Diet and Foraging

The Spoon-billed Sandpiper primarily feeds on marine invertebrates in brackish and marine intertidal mudflats and estuaries. However, during the breeding season, it shifts to freshwater and terrestrial food sources, including invertebrates and small fish. On breeding grounds usually feeds around freshwater pools. It feeds in shallow water and soft, wet mud by moving head to both sides; it also picks at food items from water and mud surface; it performs a drill-like action with bill tip in mud, bill held slightly open.

Microhabitat for Foraging

Information needed.

Food Capture and Consumption

The Spoon-billed Sandpiper primarily employs a specialised foraging technique known as 'sweep-stitching', among a range of feeding techniques. This behavior involves sweeping its spoon-shaped bill through the mud to detect prey by touch rather than sight. The bill’s sensitive structure enables the bird to capture small invertebrates even in turbid waters, making this technique particularly effective in shallow pools where the prey congregate (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ). This method of foraging is crucial for maximizing feeding efficiency in the dynamic mudflat ecosystems on which the Spoon-billed Sandpiper depends during its non-breeding season.

The morphology of the bill was described in detail by Burton (58 Burton, P. J. K. (1971). Comparative anatomy of head and neck in the Spoon-billed Sandpiper, Eurynorhynchus pygmeus and its allies. Journal of Zoology (London) 163:145–163. Close ) but at the time there was little information on feeding behavior. Kelly et al. (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ) described six major feeding strategies by the Spoon-billed Sandpiper. Information was collected during all stages of the annual cycle. These were 'selective pecking', 'sweep-stitching', 'burst stitching', 'stabbing', and 'spear-hunting or hammering', where the bird attacks often a larger prey item from a higher vantage point (grandstanding) with its sharp and pointed bill tip. 'Hoovering' was less commonly and only locally observed (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ). Rather unexpectedly, feeding techniques were not strikingly different from other Calidris sandpipers. 'Sweep-stitching' was the most distinctive technique but this appears to be an extreme variation of stitching commonly used by other calidrids. The bill shape is most likely used as a magnifying pressure sensor in muddy waters with a large congregation of Herbst corpuscles (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ).

The following foraging movements were regularly observed and described by Kelly et al. (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ): 'Concertinaing', where a bird thrusts the head forward and holds it still to scan while the body catches up, 'Grandstanding', where a bird stands tall with the head stretched high to scan for prey, 'Pirouetting', where a grandstanding bird rotates on the spot, 'Jumpback', where a bird jumps backward then stands alert, scanning for prey where it was originally standing, and 'Transiting', where a bird moves rapidly between suitable prey microhabitats, often while concertinaing.

On the breeding grounds, the Spoon-billed Sandpiper primarily consumes aquatic and terrestrial invertebrates, including Coleoptera, Hymenoptera, and Diptera, small seeds, insect larvae, small aquatic amphipods, with occasional coastal marine prey supplementing its diet. Research on the breeding grounds confirmed a high proportion of small spiders Linyphiidae (E. Lappo personal communication 2023). Diet of chicks estimated to comprise mainly flies (Diptera, 60%), as well as Trichoptera, Hymenoptera, and Carabidae beetles (35%), and seeds of plants (c. 5%) (31 Tomkovich, P. S. (1991). Three-year study of breeding Spoon-billed Sandpiper. Asian Wetland News 4:17. Close , 54 Collar, N. J., A. V. Andreev, S. Chan, M. J. Crosby, S. Subramanya, and J. A. Tobias, Editors (2001). Threatened Birds of Asia: The BirdLife International Red Data Book. BirdLife International, Cambridge, UK. Close ).

During the non-breeding season, its diet shifts predominantly to reflect the availability of prey in coastal mudflats, focusing on small marine invertebrates, including shrimp, amphipods, and polychaete worms, which form the core of its dietary intake, and also small fish (20 Kelly, C., C. Zöckler, B. Scampion, and E. E. Syroechkovskiy (2017). Hammer, filter or microphone: How does the spoon-billed sandpiper calidris pygmaea use its bill to feed?. Wader Study 124:99–111. Close ). The prey items can vary in size widely. Larger items like shrimps, crabs and small fish have been observed more regularly in Jiangsu Province (45 Lu, X., H. Yang, T. Piersma, L. Sun, Q. Chen, Y. Jia, G. Lei, L. Cheng, and X. Rao (2022). Food resources for Spoon-billed Sandpipers (Calidris pygmaea) in the mudflats of Leizhou Bay, southern China. Frontiers in Marine Science 9:1005327. Close ). Regional variations in diet composition are common, largely influenced by the availability of local food resources. In Leizhou Bay (Zhanjiang, China), small crustaceans – particularly shimps, amphipods and cumaceans are the primary prey items. While small fish and crabs are also consumed in smaller quantities, the rich biodiversity of benthic invertebrates in the mudflats is supported by the adjacent mangrove ecosystems, which likely enhance habitat complexity and food availability (45 Lu, X., H. Yang, T. Piersma, L. Sun, Q. Chen, Y. Jia, G. Lei, L. Cheng, and X. Rao (2022). Food resources for Spoon-billed Sandpipers (Calidris pygmaea) in the mudflats of Leizhou Bay, southern China. Frontiers in Marine Science 9:1005327. Close ). In the Gulf of Mottama (Myanmar), polychaetes are especially abundant within the mixed sand-mud substrates and serve as the main food source for the Spoon-billed Sandpiper. Other prey, such as small crabs and insect larvae, also contribute to its diet, especially during low tide when these organisms become more accessible on the exposed mudflats (36 Aung, P. P., S. Moses, N. A. Clark, G. Q. A. Anderson, G. M. Hilton, G. M. Buchanan, C. Zöckler, and R. E. Green. (2020). Recent changes in the number of Spoon-billed Sandpipers Calidris pygmaea wintering on the Upper Gulf of Mottama in Myanmar. Oryx 54(1): 23–29. Close ).

Information needed.

Information needed.

Information needed.

Information needed.