Using Human Influences

     About 4:40 one afternoon in Mid-November I stopped at a two-acre, human-made impoundment in Lancaster County, Pennsylvania to see what kind of aquatic life was visible among the couple hundred mallard ducks resting on that pond.  A great blue heron stood tall and stately on a hand rail of a dock as I drove up to the impoundment.  But within seconds, it flew to the water's edge and waded in the shallows to stalk for fish.  I knew there were at least goldfish in the pond because I saw them earlier in the year.  Goldfish are native to Asia, but were introduced to America as ornamental fish.  However, in ponds this size, they certainly would spawn, producing various sized fish that are food for herons and a variety of other fish-eating creatures.       
     Some of the mallards were already paired and engaging in courting and mating activities.  Other mallards were resting on the water.  But at dusk all those ducks will fly up from the water to land in harvested cornfields for much of the evening to eat corn kernels missed by harvesters.
     While watching the mallards and the heron for a few minutes, I was reminded of a one-acre, built pond closer to home that currently has about 180 mallards resting on it everyday.  And there a male belted kingfisher daily hunts small fish from the pond's surface.  The kingfisher either perches on a tree limb or the top of an outdoor light to watch the water for prey.  Or this bird will hover into the wind over the water while watching for small fish.  When he spots a victim, he dives into the water beak-first to snare it in his long, sharp bill.  He then flies to a perch to consume his catch. 
     As I left the two-acre impoundment a few minutes later, I saw two red-tailed hawks flying close together low over a field and land beside each other on a power tower.  At first I thought they were a mated pair because red-tails start their courting in December or early in January.  But then I noticed they were fighting over a dead rock pigeon that one of those raptors held in its talons.  Within a minute, the hawk without the pigeon apparently gave up the scrap and flew off the tower, leaving the lucky one with its catch.
     Rock pigeons are originally from Eurasia, where they nested on rock cliffs.  But some of them were brought to the United States by the first European colonists as domesticated meat and egg birds, and as ornamentals.  Some of them escaped captivity in America and have been populating farmland and cities ever since.    
     Red-tails are native to this continent and mostly prey on rodents.  But in this county's intensely cultivated cropland, few rodents can exist,  So red-tails turn to whatever is common in cropland, including pigeons that are successful and abundant in local farmland because they nest and roost in barns and under bridges (built cliffs) and feed on seeds and grain in harvested fields.  
     People have a large impact on Earth today.  Most every acre of land in Lancaster County, for example, is used to serve humans.  But creatures that can benefit from those same acres have a future.  Being adaptable is a key to their success.