Migrant Shorebirds in a Bare-ground Field

     In the afternoon of October 2, 2015, I drove to a few places in Lancaster County, Pennsylvania cropland in search of migrant shorebirds in partly-flooded fields and pastures.  We had a couple days of rain and I knew from past experience what low-lying fields and meadows would collect water into puddles.  Most of the places I visited were not at all inundated, but one bare-ground field, a harvested corn field, had pools in it.  I knew, without looking, shorebirds would be in that field to rest and eat invertebrates emerging from the saturated soil to avoid drowning.  I stopped and saw no birds at all with my own eyes.  But with the aid of my16 power binoculars, there they were!  There was a small variety of shorebirds in that partly-flooded field!  All those brown or gray shorebirds were so well camouflaged on the bare ground that I would not be able to see any until they moved, flew or were noticed through binoculars.  That camouflage protects them well against hawks and other predators.
     I estimated over a hundred killdeer plovers on the mud and around the pools in that field.  Some of them probably were local birds that nested in Lancaster County, but others were migrants.  All of them were in that bare-soil habitat to eat earthworms and other kinds of invertebrates emerging from the ground to avoid drowning.  That gathering of killdeer, spread loosely across the field, probably attracted the other species of shorebirds to that human-made habitat.
     By scanning my field glasses across the field, I counted six black-bellied plovers, which are light-gray on top, and six American golden plovers.  And I saw several pectoral sandpipers and a few least sandpipers.  All the other kinds of shorebirds here were mostly brown on top.  And all species were either standing at rest facing into the wind or walking about and pulling invertebrates from the soggy soil. 
     Interestingly, the black-bellied plovers were the largest of these shorebirds, followed by the golden plovers, killdeer, pectorals and least sandpipers, in that order of size.  But they were all equal in importance as migrants that rested and fed in a built habitat here in civilized Lancaster County before continuing their migrations south to avoid the northern winter.
     All these species, except the killdeer, raised young on the treeless Arctic tundra in summer when the sun never "sets" that far north.  And all these species, including the killdeer, are adapted to open country, including prairies, cow pastures, mud flats, beaches and bare-ground fields.
     The black-bellied plovers were the most unusual migrants in that field.  They either don't come through this county much on north-bound or south-bound migration, or we just don't often see them because they land temporarily in local places that few people think to look for birds.
     Those five kinds of shorebirds were interesting on that field of bare soil and corn stubble while they were here.  Only a few of the killdeer might stay through winter in this county, but they were all exciting, and brought a bit of the wild to civilized Lancaster County.