Small, fast-moving birds darting along the edge of the ocean are a common sight on sandy beaches worldwide. These energetic flyers are generally known as shorebirds or waders, a diverse group that includes the families of plovers and sandpipers. They inhabit the narrow zone between the water and the land, where the constant motion of the waves provides a rich feeding ground. Typically comparable to a sparrow in size, their rapid movement patterns make them easily recognizable.
Identifying the Most Common Shorebirds
The species most recognized for its behavior on North American beaches is the Sanderling, a small sandpiper often observed in groups. In its non-breeding plumage, seen for much of the year, the Sanderling appears exceptionally pale, sporting light gray feathers above and a stark white underside that blends seamlessly with dry sand. This species is one of the “peeps,” a collective term for several small sandpipers, and is easily identifiable by its black bill and legs.
Other small sandpipers, such as the Semipalmated or Least Sandpiper, may also be present, sometimes displaying slightly darker or more mottled brown-gray plumage. Plovers, like the Semipalmated Plover, are another common sight, distinguished by their rounder body shape and a short, stout bill. Many shorebirds, including the Sanderling, adopt richer rufous or rusty tones on the head and breast during the spring and summer breeding season before migrating north to the Arctic tundra.
The Unique Behavior of Running with the Waves
The shorebird behavior that captures the most attention is their frantic, synchronized running back and forth with the tide. This constant motion is a highly efficient foraging strategy executed along the swash zone. As a wave pulls back, the water temporarily exposes small marine invertebrates that were buried in the wet sand or disorients them, making them easier to catch.
The birds rush down to the retreating water line to probe the wet sand with their bills, snatching up newly exposed prey like mole crabs and amphipods. They must quickly retreat up the beach to avoid the next incoming wave, repeating the dash as the water recedes again. This high-energy pursuit fuels their high metabolism, which is necessary for species that undertake extensive migrations between the Arctic and southern continents. Specialized leg and foot structures, such as the Sanderling’s lack of a hind toe, allow for this rapid mobility on the shifting, wet substrate.
Key Differences Between Plovers and Sandpipers
While both plovers and sandpipers are shorebirds, they belong to different families and display distinct adaptations for foraging. The most apparent difference lies in their beak structure; plovers possess a short, relatively stout bill well-suited for a run-and-peck feeding technique. Sandpipers, conversely, typically have longer, more slender bills, which are designed for probing or “stitching” deep into the sand or mud to locate hidden prey by touch.
Their foraging movements also differ significantly. Plovers are visual hunters that use a characteristic stop-start motion, running a short distance, abruptly pausing to scan for prey movement, and then pecking at the surface. Sandpipers, especially Sanderlings, are characterized by their continuous, frantic running and probing action. Plovers tend to have larger eyes relative to their head size, reflecting their reliance on sight for hunting. Their bodies also appear rounder and more robust compared to the generally more elongated form of sandpipers.