Small birds darting along the ocean’s edge are a common and captivating sight for beachgoers. These energetic avian residents move with a rhythm synchronized to the waves, often sparking curiosity about their identity. While various shorebirds inhabit coastal environments, one species is particularly known for its prevalence in this unique dance with the surf.
Identifying the Beach Runners
The most frequently observed bird exhibiting this wave-chasing behavior is the Sanderling (Calidris alba). This small wading bird typically measures 7 to 8 inches long, with a 14-inch wingspan. In non-breeding plumage, common on beaches, Sanderlings appear pale, with grayish-white underparts and light gray upperparts, blending with the sand; they also possess a stout, straight black bill and black legs. A unique physical characteristic is their lack of a hind toe, an adaptation believed to aid swift movement across sandy surfaces. While other small sandpipers or plovers might be seen, the Sanderling’s specialized adaptations and widespread presence make it the primary “beach runner.”
The Secret Behind Their Scramble
Sanderlings engage in their characteristic wave-chasing behavior as an efficient foraging strategy, following receding waves to snatch small invertebrates exposed or brought to the surface by the turbulent water. Their diet primarily consists of minute marine creatures such as mole crabs, amphipods, small bivalves, and marine worms. As a wave washes ashore, it stirs up these organisms; as it pulls back, Sanderlings quickly run into the wet sand to probe with their bills. Their swift movements and probing bills are well-adapted for this dynamic environment, allowing them to maximize access to newly uncovered food items before the next wave arrives. This constant advance and retreat is directly linked to their feeding success in the intertidal zone.
A Wider World: Beyond the Shoreline
Beyond their familiar presence on temperate and tropical sandy beaches, Sanderlings are long-distance migrants, undertaking journeys between their breeding grounds in the High Arctic tundra and warmer wintering areas across nearly every continent except Antarctica. These migratory routes can span vast distances, with some individuals traveling between 3,000 to 10,000 kilometers annually. During the breeding season in the Arctic, their diet shifts to include insects and some plant material. Outside of this period, they are gregarious, often forming large flocks on coastal mudflats or sandy beaches. Sanderlings, like many other shorebirds, rely on healthy coastal ecosystems and undisturbed habitats for both foraging and resting throughout their extensive migratory routes.