RETENTION BASIN WILDLIFE

     Today, retention basins are required by law in the United States.  They are designed to control storm-water runoff, and retain soil.  These human-made basins are like shallow ponds, except some basins aren't always filled with water, making them more like wetlands.  Still, clumps of cattails, certain grasses, arrowhead plants and other kinds of emergent plants grow in many retention basins, providing food and shelter for a variety of adaptable, water-loving creatures, particularly in summer.
     Mallard ducks and Canada geese raise young on and around some retention basins.  The ducklings swim as a group across the water and mostly consume protein-filled invertebrates.  Goslings, however, ingest tender alga, duckweed, grasses and other kinds of vegetation, as do their parents.  There is little competition for food between these species of related waterfowl.
     Pairs of red-winged blackbirds hatch babies in grassy nurseries attached to cattail stalks above the normal water level in many retention basins.  Striking, black male red-wings perch on swaying cattails and repeatedly sing "konk-ga-reeeee", while raising their wings to show off their red shoulder feathers to attract females and repel other male red-wings.  Male and dark-striped, camouflaged female red-wings flutter among cattails and grasses to collect insects to feed their young that resemble their mothers.    
     Green frogs sit, camouflaged, along the edges of shallow water in some basins and wait to snare invertebrates with their tongues.  Those frogs, from nearby ponds or streams, entered watery basins during dewy nights or rainy days.  Males belch and gulp lustily to attract females to them for spawning in the shallows.  But some basins dry before the tadpoles grow legs and lungs and leave their nurseries.
     Fish can't survive permanently in retention basins because of the possibility of their drying out, killing the fish.  But green herons, and raccoons come to those basins to hunt green frogs and tadpoles.  The herons blend into the cattails and grasses as they stalk their amphibian prey by day.  Raccoons sneak along basin shores at night to hunt frogs.
      A few painted turtles survive in some basins where they consume aquatic plants and insect larvae.  They, too, came from ponds and smaller waterways, but probably leave those basins that dry out.
     Muskrats live in some basins where they dine on cattail roots, grasses and other kinds of vegetation.  These mammals either burrow into the banks of a basin for shelter or build a home of cattails and grasses in the middle of the basins.
    A small variety of common, attractive dragonflies, including green darners, white-tailed and twelve-spotted dragonflies, sweep swiftly over water-filled basins as they do ponds to catch a variety of flying insects to eat.  Some of these dragonflies might also spawn in some basins' shallows, but those basins might dry before the dragonfly larvae can leave the water.  
     Colorful, energetic American goldfinches come to cattails to gather fluff to make their petite cradles in nearby sapling trees.  These handsome, little birds help make retention basins more lively.
     Crack willow trees, multiflora rose and other kinds of woody vegetation grow in some retention basins that are not mowed or manicured.  There a few each of song sparrows, northern cardinals and gray catbirds raise youngsters.  And the sparrows and catbirds, along with red-wings, move along the muddy edges of water-filled basins in search of invertebrates to consume.  
     Groups of handsome and trim barn swallows and tree swallows cruise swiftly over inundated retention basins after mosquitoes and other flying insects.  These small, stream-lined birds are entertaining to watch swooping and diving among their fellows, without collision, low over the water.
Barn swallows nest in nearby barns while tree swallows do so in close by tree cavities and bird boxes.
Bird boxes around retention basins would attract tree swallows to those basins to rear offspring.
     Killdeer plovers live on mowed lawns around some retention basins near larger parking lots.  These attractive inland shorebirds ingest invertebrates living in the lawns and along the shores of the basins.  
     Some larger lots have raised islands of gravel or mulch that surround planted trees in those lots.  Some pairs of killdeer hatch young on that gravel or mulch where vehicles can't reach and few people notice.       
     Killdeer eggs, chicks and adults are camouflaged in their somewhat barren habitats.  They are nearly impossible to see, until they move.  
     Being like shallow ponds or marshes, retention basins are valuable to several kinds of wildlife.  But some basins can be risky to certain species because they might dry out.  Still, all basins are interesting for us to visit and study. 

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