Scurry birds. That’s the nickname friends have coined for the small flock of sanderlings (Calidris alba) they see while walking the beach at La Jolla Shores. It’s an apt name for birds that spend most of their day running to and fro in a characteristic “bicycling” action along the sand-surf border. While watching the tides and foaming waves, sanderlings feel the wind and its direction, then turn accordingly like beach strollers who run from the incoming water to keep their feet dry. Appearance-wise, sanderlings have a chubby sparrow-size body covered in plumage that spans the spectrum from white to gray to black. Sounds blah, but a dearth of color does not translate to a lack of visual impact or personality. This understated, shaded feathering is the secret to why they can blend seamlessly with their background, be it sand, kelp wrack or seafoam. How these chameleons vanish in plain sight has everything to do with attitude, literally. Sanderlings always face the oncoming surf, with head angled down and black beak hard at work probing the sand for prey. At this orientation, and when viewing the birds from a distance, only the snow-white belly plumage is visible, which matches the water’s foamy edge. When the next wave begins making its way onto shore, sanderlings scurry back up the beach. From this angle, their tan coloration blends with the terrestrial environment and shadowing of light from the sun. Unlike many other shorebirds with chopstick-like beaks, sanderling beaks are short and stout, limiting the depth to which they can dig in the sand. Feeding behavior is called “run-pause-snatch,” which pretty much sums it up. Think of a chicken (peck, peck, peck, scurry, scurry, scurry), and you have the picture. Sanderlings travel in small clusters, both for safety and companionship. If potential threats are comfortably at bay, it’s business as usual. One courageous wader runs toward the wet sand. Shortly thereafter, another follows suit until the rest of the group runs or walks to catch up and feed on tiny crustaceans in the surf line or near the mounds of kelp wrack. Sometimes they walk near a lump of kelp to pick off seaweed flies. When absolutely necessary, sanderlings fly, but if so, flight times are short-lived. It only takes being surprised by a sudden big wave, a jogger or a shrieking child for the birds to take wing. They fly low and seaward, but circle back, returning to their habitat further up or down the beach, where they get back to business foraging in a new location. Flight is also integral to sanderlings’ mating rituals. The distinct display begins with the birds, flying low, maintaining a head-down position while holding the body parallel to the ground. Next, while still in midair, the head shifts from side to side while the wings flutter rapidly, and the sequence ends with a brief glide. This demonstration, which lasts up to a couple of minutes, resembles that of a hummingbird. Couplings result in tiny sand-colored eggs that hatch after about a month. Some young become year-round residents; others disperse. Either way, most sanderlings return to their birthplace to nest. As an aside, nesting sanderlings may pretend to be injured as a way to appear less palatable to predators (a pretty neat trick). Wetlands are a favorite habitat for sanderlings, but the birds are now most common along ocean coasts. They may also be found on sandy beaches of inland lakes, prairie potholes and even the arctic where they nest near moist tundra or ponds. Since 90 percent of our wetlands have been dredged for urban use (for example, Mission Bay was originally a wetland), sandy beaches like La Jolla Shores have become critical habitats for sanderlings, birds seemingly borne of sand and sea.
