Sandpipers are a diverse group of wading birds belonging to the Scolopacidae family, renowned for their specialized foraging habits along shorelines, mudflats, and wetlands. They are highly adapted to their environment, relying on a keen sense of touch and specific bill structures to locate food hidden beneath the surface. Their diet reflects their migratory lifestyle, providing the necessary energy for long-distance travel and the protein needed for successful reproduction.
The Core Diet: Aquatic and Terrestrial Invertebrates
The vast majority of a sandpiper’s diet consists of invertebrates harvested from intertidal zones and damp terrestrial areas. Along coastlines and estuaries, the primary prey are infaunal and epifaunal marine organisms, including small crustaceans (amphipods, copepods, and tiny shrimp) and mollusks (clams and snails). They also consume burrowing polychaete worms extracted from the mudflats. This concentrated source of protein and fat is essential for maintaining their high metabolic rates.
Inland species, or those foraging away from saltwater, focus on terrestrial and aquatic insects and their larvae. Common prey includes the adults and larvae of flies (such as midges, brine flies, and shore flies), small beetles, spiders, and occasionally grasshoppers or crickets. These soft-bodied invertebrates are gleaned from the surface of marsh vegetation or picked from the soil in damp fields.
A significant food source for some sandpipers is intertidal biofilm, a thin layer composed of diatoms, microbes, and organic detritus that accumulates on wet sediment surfaces. For species like the Western Sandpiper, this biofilm can contribute substantially to their daily energy intake, sometimes accounting for nearly half of their total diet. Plant material, such as seeds and grains, is occasionally consumed, but this is a secondary food source used when invertebrate prey is scarce, especially during winter.
Specialized Feeding Behaviors and Bill Adaptations
Sandpipers are recognized for their primary method of locating food: probing or “drilling” into the soft substrate. They repeatedly insert their thin, flexible bills into the mud or sand, often moving in a sewing-machine-like motion. This technique allows them to find prey completely hidden from view deep within the sediment.
This probing ability is facilitated by a unique biological adaptation: a high concentration of specialized sensory structures at the bill tip. These mechano-receptors, called Herbst corpuscles, are housed within tiny sensory pits under the bill’s keratin layer. The corpuscles detect minuscule pressure gradients and vibrations caused by the movement of buried invertebrates, allowing the bird to “feel” its prey without seeing it.
The morphology of the bill is directly linked to the bird’s foraging niche. Species with longer, more curved bills are specialized for deep probing, accessing infaunal prey buried far beneath the surface.
Conversely, shorter-billed species forage in shallower areas, relying more on visual hunting to pick epifaunal prey from the surface. This variation in bill length can lead to resource partitioning between sexes, such as female sandpipers with longer bills probing for deeper prey than their male counterparts.
Seasonal and Habitat Influences on Sandpiper Meals
The composition of a sandpiper’s diet shifts based on geographic location and the time of year. Coastal sandpipers or those on migration routes often rely heavily on marine-derived resources, such as worms and small crustaceans from tidal flats. In contrast, those utilizing inland freshwater habitats predominantly consume aquatic and terrestrial insects and their larvae.
Seasonal changes impose different energetic demands that the diet must meet. During the breeding season, the diet prioritizes readily available, high-protein food sources, primarily insects and their larvae, to support nesting and raising chicks.
Before migration, sandpipers undergo hyperphagia, a period of intense feeding, to build up fat reserves. They opportunistically consume energy-dense prey like invertebrate larvae and amphipods to fuel long, non-stop flights between hemispheres.