Ringed Plovers in North America

     I remember when I was a young boy walking across a plowed field in Lancaster County, Pennsylvania farmland in March.  Suddenly, a bird I didn't see flew up almost at my feet and low across the field yelling "kill-dee, kill-dee".  I was startled at the time and later learned that the bird was a killdeer, a kind of inland plover.
     As a middle-aged adult, I was visiting beaches on Assateague Island, Virginia.  I read that Wilson's plovers raise young on coastal beaches as far north as Virginia.  Since I never saw one to that point, I set out on a beach on Assateague to find one.  As I walked along a beach, I soon spotted a pair of them, right where they were supposed to be.  Each bird of the pair had one black ring on its chest and a thick, black beak, typical characteristics of their species.
     There are four kinds of ringed plovers in North America that I have seen.  They are all look-alikes, demonstrating their common ancestry from one ancestral species.  All species are more or less dark on top, for camouflage against soil or sand, white below with one or two black rings on their chests, depending on the kind.  All of them eat invertebrates from the soil or sand, but in different niches which caused the various species in the first place.  And all of them, being shorebirds, lay four eggs in a clutch on the ground.         
     Killdeer plovers are the most common and biggest of ringed plovers in North America.  And they are the only type of ringed plover that lives and nests inland throughout most of North America. Their upper parts are brown to blend into bare soil to be invisible, which they are until they move.  And this is the only species, when adult, that has two black rings on its chest.  Young killdeer have one ring like their cousins. 
     Killdeer hatch young on gravel bars along inland waterways, which are their original nesting niches.  But, being adaptable, they also hatch young in bare ground fields, and on gravel driveways, parking lots, railroad beds and flat, gravel roofs, all of which are human-made habitats.  The young have to jump off the roofs to get food in nearby lawns and fields.
     Semi-palmated plovers breed on the Arctic tundra.  They migrate twice each year through much of the Lower 48 and Canada to get to their nesting territories in summer and to the coastal beaches and mud flats of the southern United States and Mexico for the winter.
     Semi-palms have brown feathering on top and short bills.  I sometimes see little groups of them along puddles in flooded fields where they search for invertebrates and put on more fat before continuing their migrations.  
     Piping plovers look much like semi-palms, except they are lighter in color, which camouflages them on sandy beaches where they nest.  There are two populations of piping plovers, one that rears offspring on beaches of the North Atlantic and another that hatches youngsters along rivers in the Central United States and Canada.  The Atlantic beach piping plovers have been reduced in numbers because of a reduction in nesting habitat.  Many beaches along the North Atlantic are used for human recreation, which doesn't allow successfully nesting piping plovers and least terns.  Piping plovers winter along sea coasts of the South Atlantic and the Gulf Coast.
     Limited numbers of Wilson's plovers raise young on beaches along the Gulf Coast and the Atlantic Ocean north to Virginia.  And this species winters on beaches from the Caribbean to northern South America.
     Ringed plovers have traits that show their common ancestry.  They are shorebirds, and like most species in their family, they are camouflaged and hard to spot.  But they are interesting to experience when found.