When driving through Lancaster County, Pennsylvania farmland every August, September and into October, I watch for migrating sandpipers and plovers around rainwater puddles in Lancaster County, Pennsylvania fields and meadows, both of which are human-made habitats. Much rain fell locally in late-summer and fall of 2018. I knew there would be many pools in farmland that would attract tired, hungry southbound shorebirds ready to feed on invertebrates they pull from mud and shallow water at the edges of puddles in fields and pastures. Then, well fed and rested, those sandpipers and plovers will continue their migrations southward to their wintering territories.
In fall, over the years, I have seen several different kinds of shorebirds in partly flooded Lancaster County farmland, but the species I see most abundantly are least sandpipers, lesser yellowlegs, which are a kind of sandpiper, solitary sandpipers and killdeer plovers. On August 20 of this year, for example, I saw about a dozen shorebirds around and in an average-sized, living-room-sized pool in a partly bare meadow of short grass near the rural road I was on. I counted four lesser yellowlegs and four solitary sandpipers wading on their long legs in the puddle, three sparrow-sized, short-legged least sandpipers on the edge of the water and a killdeer plover trotting over the mud near the water. Developing different lengths of legs and beaks because of genes, these shorebird relatives feed in different niches around water, which reduces competition for food among them.
Shorebirds are camouflaged in their open niches with little or no cover. Yellowlegs, for example, are gray, which blends them into the still waters they extract food from. Least sandpipers and killdeer are brown on top to blend them into mud around that shallow water.
On August 21, I saw five least sandpipers in mud, and tiny puddles made by the hoof prints of cattle trampling down the short grass in another pasture. It was interesting to think how those small sandpipers coming south from their nesting territories on the Arctic tundra found that little patch of mud and hoof-sized pools where they probed their beaks into the mud after invertebrates to ingest.
About the end of August, I found a dozen local killdeer plovers around long, water-filled ruts made by a tractor in a field of one-foot-tall soybean plants. Those brown and white plovers were stunning standing by the puddles bordered by dark-green soybean foliage. Killdeer were in that field when it was devoid of vegetation; before the soybean plants sprouted. Those shorebirds stayed around the flooded ruts in that field as the crop plants grew. And there the birds picked up and consumed a variety of invertebrates.
On September 6, I visited an outdoor ice-skating pond, that had a couple of inches of rainwater in it, in a large short-grass meadow. Several killdeer trotted and stopped, trotted and stopped, between the muddy edge of the water and the lush grass as they watched for edibles. About a dozen least sandpipers walked in half-inch-deep water and ate tiny invertebrates from the mud and water. And around eight lesser yellowlegs waded in deeper parts of the pool and poked the water and mud for invertebrates. Again there was a diversity of shorebirds because of at least a few niches in and around that shallow pond in the midst of a larger sea of grass.
Toward the end of September, I spotted several shorebirds in a few shallow rain puddles in a half-denuded short-grass pasture. There were about a dozen least sandpipers scurrying along the edges of the shallow pools, one lesser yellowlegs walking through the middle of a puddle and a few killdeer trotting over the mud by a temporary, shallow pond. All were feeding as fast as they could to build up fat and resources for the next part of their migration.
And on the sunny afternoon of October 1 of this year, I happened to spot a sky-reflecting trickle of clear rainwater flowing through a low crease in a harvested corn field that was replanted with winter rye.that will enrich the soil and hold it down against erosion. The long rows of beige corn stubble and two-inch tall, lush-green rye sprouts were bathed in sunlight. At least three killdeer were picturesque standing in the trickle, surrounded by a human-made, sun-soaked and pretty habitat of corn stubble and rye shoots.
Hundreds of south-bound shorebirds rest and feed by puddles in many fields and pastures in autumn in southeastern Pennsylvania. There they find food and rest, and we humans can enjoy their presence and activities, and think about where they came from and where they are going. They are exciting to experience on human-made habitats.
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