Exploring bird habitats of the salt marsh

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By Staff Brunswick Beacon

Today, we will find birds in salt marsh habitat. As an ecology lesson—and just for fun—let’s start at an altitude of 200 miles, as if were are a naturalist on the space shuttle, and zoom in.

Ah! There is North America! It is part of the zoogeographic region know as the Nearctic. Scientists have divided the world into six major zoogeographic regions based on their uniqueness and location. If our bird is not a resident, it may be a Neotropical migrant, that breeds in North America but overwinters in the Neotropical region that includes Southern Mexico, Central America, the Caribbean, and South America.

We zoom in farther and find the Brunswick County coastline. Ah! We are looking the edge of the South Atlantic Coastal Plain. Those danged scientists with their obsession for order have developed 99 North American “ecoregions” that are biologically distinct in terms of climate conditions, topography, soil types, and plant communities.

Nearer Earth we find the Cape Fear River where it spills into the sea. We are now looking at an expansive, stunningly beautiful estuary. Beautiful even with the man-made spoils islands because they are frequently covered by shorebirds and waders.

The Cape Fear River estuary, partially enclosed by riverbanks and barrier islands, is the place where fresh river water mixes with salt water, a place of transition from land to sea and from fresh to saltwater. The dynamics of this estuary are ever changing. They are influenced by river flow and tides and yet protected by barrier islands and maritime forest from the full force of the ocean and storms.

We now arrive at our final destination. Dang! We are ankle deep in the muck of a salt marsh. Oops, I meant to land us on the shore.

The salt marsh is the Lower Cape Fear’s most important habitat and richest in nutrients. Forming large treeless meadows of grass on the protected side of our barrier islands they serve as invaluable foraging habitat for land animals and nurseries for fish and mollusks.

The marsh has several zones. The upper zone edge includes southern red cedar, marsh elder, silverling, wax myrtle and sea oxeye. The next zone includes salt-meadow hay, black-needle rush, and glasswort, which then leads into smooth cordgrass (spartina) in the intertidal zone. Woven in the spartina and mudflats are tidal creeks and pools that remain at low tide (pannes).

Because of its high salt tolerance, spartina is essentially without competition and predators except for grasshoppers. That is when it is alive. When it dies, spartina is broken down into detritus, the base of the salt marsh food web, by fungi and bacteria. This base allows our sounds and estuaries to be so rich in seafood. Of course, Ospreys and us humans enjoy being at the top of this food web!

In addition to providing nutrients, spartina is a keystone species in the salt marsh habitat because it has roots to hold the soil thereby minimizing the impact of storm surges and floods, it provides footing for oysters and mussels, and it is a home to a small snail called the Periwinkle that lives and feeds on algae. The Periwinkle crawls up and down the stalk, staying above the water.

Tidal creeks rise and fall flooding the marsh before retreating. The rhythms of twice daily high and low tides are big happenings—possibly as big as the opening of a buffet line at restaurant giving a senior citizen’s discount. This rhythm controls the lives of most marsh inhabitants and those that crawl in or fly in just for the food. They are adapted to these cycles. Their lives depend on it.

Oops! I almost forgot to look for birds. The first bird we see is sitting on top of a Sea Oxeye. Sometimes called a Sea Daisy, the oxeye’s colorful yellow flowers grace our barrier islands when in bloom.

The bird is a Seaside Sparrow, a permanent resident of our salt marsh. The other bird is a very happy Black-bellied Plover that has nabbed a lugworm. The plover is migrating through our area and just stopped in for a snack. Wonder what wine goes well with lugworms? I should call one of those reality shows and ask.

Other salt marsh inhabitants, usually seen best at low tide, include fiddler crabs crawling in the mud and their predators: waders, shorebirds, gulls, skimmers, and oystercatchers feeding around tidal creeks and flats. Also, raccoons show up to forage at night.

Clapper Rails are marsh birds much desired by birders. It is usually easy to hear them and sometimes, if you wait and watch from an overlook, one will walk by. High tides, especially the highest during the year that are called “marsh hen tides”, are the best times to look for clappers. The rails may be seen walking along the edge of the flooded marsh or in raised areas in the marsh—keeping up with those stalk-climbing snails—otherwise known as rail food.

The importance of the salt marsh cannot be overemphasized. In addition to the nutrients and protection provided to fish, shellfish, and the other visitors at the smorgasbord, the marsh also filters water and provides protection from floods and storm surges.

Loss of Louisiana marshes was a recipe for disaster during Hurricane Katrina. A few hundred miles away, my favorite Texas coastal birding site was near the landfall of Rita and was saved from saltwater intrusion by its salt marsh.

Development is a constant and growing threat to the salt marsh; otherwise, the main threat is from sewage, chemicals, pesticides, and other pollutants washed down our rivers from upstream that harm the food web and affect the livelihood of commercial fishermen and our feathered friends.