A Successional Wetland

     For a couple of hours yesterday, May 28, I visited a half-acre, successional wetland, closely surrounded by deciduous thickets of bushes and young trees in southeastern Pennsylvania.  This swamp of shallow water and lush, green vegetation was more open and sunny with cattails and red-winged blackbirds five years and more ago.  But a variety of wetland plants, both emergent and covering the edges of the water, and their annual dropping of foliage has filled in what might have been a shallow pond years ago.  And some of the wildlife in this wetland reflect that succession, over the years, from pond to swamp.  Little wetlands like this are uncommon habitats in southeastern Pennsylvania, but also of beauty and interest.  And homes for certain aquatic creatures.
     Skunk cabbage plants still grow in this wetland from the days when this area was a wooded bottomland with constantly moist soil.  The large skunk cabbage leaves gather adequate sunlight in shaded woods, but those plants also adapt to more plentiful sunlight.
     A few each of cattail and arrowhead plants remain from when this wetland was more open and sunny.  And I saw a couple of male red-winged blackbirds around those remnant cattails as reminders of the past when cattails were prevalent here, and the place where the red-wings hatched.
     Several kinds of wetland-adapted bushes and young trees lean over the shallow water from all the shorelines, and emerge from inch-deep water.  This woody vegetation includes the shrubby speckled alders and red-twigged dogwoods, and red maple, silver maple and crack willow trees.  
     Those plants provide nesting sites for a variety of small, nesting birds, including permanent resident northern cardinals, song sparrows and American goldfinches, and summering gray catbirds, chipping sparrows, yellow warblers and common yellowthroat warblers, all of which I saw one or two of in the couple hours I visited that wetland.  The cardinals and chippers are there simply because of the shrubbery to nest in.  But the other species seem to prefer nesting by water as well as in bushes in woodland edges.  Song sparrows and catbirds even walk and hop along narrow, muddy shores like sandpipers in search of invertebrates to eat.  Yellow warblers seem attracted to willows around water and common yellowthroats like bushes near water. 
     All these small bird species, except goldfinches, catch invertebrates to feed their nestlings and themselves during warmer months.  Algae that grows abundantly in water is part of the goldfinches' food, as well as a variety of seeds.  Song sparrows, chipping sparrows and catbirds snare many invertebrates from the ground, but the rest of these birds get that same type of food from the foliage of shrubbery and trees.             
     I saw at least a few purple grackles reaching down with their beaks from the edges of the water and woody stems of alder shrub islands for invertebrates in the water and wet soil.  A species of lawns, some grackles also act like shore birds, getting much of their food from the water's edge.  These blackbirds with beautiful, iridescent-purple sheen on their black feathers have large, sharp beaks for snaring insects, spiders and other kinds of invertebrates, plus tadpoles and other aquatic creatures from shallow water.  Predatory grackles help make small, inland waters come alive.
     I saw a pair of tree swallows perched on twigs for a minute in that little wetland, and sweeping over it to catch and ingest flying insects.  They probably have a clutch of eggs in a tree hollow in bordering woods.
     Several pretty painted turtles of various sizes in that little wetland rested on emergent stubs of dead trees and a fallen log to bathe in the warming sunlight.  Duckweed from the water surface was stuck to their drying shells as their body heat rose in the sunshine to the point when these cold-blooded reptiles would have the energy to hunt food and carry out other activities.  These water turtles mostly feed on aquatic plants, snails, submerged insect larvae, tadpoles, dead animals and other edibles in the water.
     And, although I didn't see any, I heard several male green frogs and a few male bull frogs belching and moaning respectively from the shelter of emergent plants in the shallows.  Because there are no fish in the stagnant, inch-deep water of this wetland, the camouflaged frogs and their tadpoles have a better chance of survival.  But I did see a green heron stalking along the shoreline in search of frogs to catch and eat or feed to its young in a stick nursery in a nearby woodland.  A great blue heron will probably stalk frogs in this woodland swamp as well.  And raccoons and mink probably are along this frog haven at night to catch some of those burping, groaning amphibians.
     There will be a small variety of dragonflies catching flying insects over the shallow water of this wetland later in summer.  At this time, however, many of them are nymphs on the bottom of the water catching and consuming tadpoles and aquatic invertebrates.
     Eventually this wetland will fill in with decaying leaves and soil and succeed back to a bottomland woods as it was in the beginning.  Frogs, painted turtles, dragonflies and other water creatures will have to move out of this spot.  And more woodland critters will move in.  But that's part of natural succession of life.  Life is always changing; never stagnant.