Wintering Coastal Shorebirds

     In winter over the years, I have gone to the Atlantic Ocean coast in New Jersey many times to see what birds winter on the sandy beaches, rock jetties and salt marsh mud flats.  I 've seen a small variety of gulls on the beaches and jetties and clapper rails and more gulls on the flats.  But my main interest has been the intriguing, little shorebirds that nest in the Arctic and winter in specific niches in those shoreline habitats, including sanderlings on beaches, purple sandpipers and ruddy turnstones on jetties and dunlin on flats.
     Beaches, jetties and mud flats are all open habitats with little, if any, vegetation.  But shorebirds have long ago adapted to those "barren" environments to spend winters searching for invertebrate food, with a minimum of competition for it.  Shorebirds exploit natural and human-made niches that few other species of birds will. 
     These shorebirds escape the attention of peregrines and merlins, both bird-catching falcons, by blending into their open surroundings.  Sanderlings are light-gray and white, which camouflages them on beaches.  Purple sandpipers and turnstones are mostly darkly feathered, which makes them nearly invisible on jetties.  And dunlin are mostly dull-brown on top, which camouflages them on mud.  But if those falcons see through the shorebirds' camouflage and dive on them, the shorebirds take wing in speedy, erratic flight to avoid being caught by those swift hawks.  
     All these little shorebirds depend on the actions of the ocean to get their invertebrate food.  Wind-pushed waves, washing up the beaches, bring in various organisms that little gatherings of sanderlings, which are a kind of sandpiper, pick up with their beaks and consume as the water slides down the beach again because of gravity.  It is entertaining and amusing to see these little sandpipers running up the beaches on their black legs as fast as they can before incoming wavelets, then running down the beaches after the receding water and picking up invertebrates as they go.  This they do most all day, every day through winter.
     It's equally intriguing to see congregations of sanderlings flying low along beaches and breakers to a new feeding spot on a beach.  They race a few feet above the water and sand, turning this way and that in unison, then abruptly pitch down to a beach to feed on invertebrates and other tidbits washed in by the incoming wavelets.     
     Jetties are human-made lines of boulders extending a couple hundred yards into the ocean.  Their purpose is to protect the sandy beaches from being washed away by the power of waves, or breakers, as their called.
     Purple sandpipers and ruddy turnstones have long adapted to wintering along rocky shorelines.  There blue mussels and a few types of green vegetation flourish, which offer living space to a variety of small invertebrates, as on naturally rocky coasts. 
     These jetties give  small, scattered groups of purple sandpipers and turnstones more feeding space in winter.  They ingest invertebrates living among the mussels and plants, and eat tiny edibles that get dumped on the boulders by waves and lodged between the mussels and vegetation.
     When the tide goes out salt marsh channels to the ocean because of the moon's gravity, flocks of wintering dunlin, which are a kind of small sandpiper, walk along the exposed mud flats in salt marshes to get invertebrate food sheltering in the mud.  They poke their bills into the mud to pull out invertebrates until the tide of water comes back up the channels into the marsh, covering the flats.     Occasionally, the dunlin will take flight in one big flock, swirl over the salt marshes a few times, which is exciting too see, then land on the flats again and immediately begin feeding.  
     Each of these interesting shorebird species, wintering along the Atlantic Coastline, has its own niche for gathering food, with a minimum of competition.  And each kind is a joy to watch along the seashore in winter.