MIGRANT SEMI-PALMATED SANDPIPERS

      Semi-palmated sandpipers are sparrow-sized shorebirds that have camouflaging brown and dark-mottled feathering on top, and black legs and beaks.  They nest on the Arctic tundra, by the Arctic Ocean, in Canada and Alaska, but winter along the seacoast beaches and mud flats of South America.  

     Each May, semi-palms migrate north, and south each August and September, both times through much of the inland United States, and along its Atlantic Ocean shorelines.  And semi-palms, along with other kinds of shorebirds, have at least two major feeding places along the Atlantic coast in northeast North America, one going north and the other going south.

     In May, horseshoe crabs spawn on sandy beaches of estuaries and other back waters of North America, off the North Atlantic Ocean.  Many thousands of horseshoe crabs, for example, spawn on the sandy beaches of Delaware Bay in May.  Each female, attended by a male or two who fertilizes her greenish eggs, buries thousands of tiny eggs an inch or so in the sand.  Thousands each of a few kinds of shorebirds, including red knots, ruddy turnstones and semi-palmated sandpipers, plus many locally nesting laughing gulls, gorge on many of those little eggs.  Swarms of shorebirds put on fat to sustain their migrations to the tundra to raise young.              

     Perhaps startled by a hunting peregrine falcon or merlin, whole hordes of shorebirds sometimes take flight from beaches at once, swirl in flight together in tight, zig-zagging flocks over beaches and water, and land again on a beach like peanuts being tossed across the sand.  Immediately, those thousands of shorebirds feed again on horseshoe crab eggs in the sand.  Those massed, flying groups of birds, that briskly sweep this way, then that, are exciting and inspiring to see.

     In July, August and September, hundreds of thousands of post-breeding, south-bound semi-palmated sandpipers, and other kinds of shorebirds in lesser numbers, feed on the abundant, three-eight of an inch mud shrimps, and other species of invertebrates, that live on the great mud flats of the Bay of Fundy in Nova Scotia.  When the tide goes out, which it does twice a day, swarms of shorebirds cover much of those flats to ingest millions of invertebrates, while they can.  And when the tide comes in, shorebirds retreat before the rising waters to rest, digest, preen their feathers and socialize.    

     Migrating semi-palmated sandpipers do so in great flocks that settle in certain places to consume large numbers of invertebrates to have the energy to continue their migrations north or south.  On the beaches of Delaware Bay and the mud flats of the Bay of Fundy, semi-palms and other kinds of shorebirds make exciting spectacles of themselves while they feed on invertebrates.  But within a couple of weeks that have all the body fat they need to push on, ending the great shows of themselves.          

               

    

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