Saugatuck Harbor Natural Area

NATURAL COMMUNITIES OF THE SAUGATUCK HARBOR NATURAL AREA

Great Lakes Shore and Beach: Although the beach is attractive to people, it is too hot and unstable for most plants, animals, and even insects. Therefore, the main forms of wildlife seen on the beach are migratory shorebirds. Herring Gulls are plentiful and feed off dead fish and other materials washed up by the waves. Less commonly seen on the beach are plovers, sandpipers and terns. The Common Tern and Forster’s Tern are listed as threatened species (T) under protection in the Endangered Species Act of the State of Michigan.

beach birds 6-30-10 Ellie Scholtz (8)

Coastal Sand Dunes: Coastal Sand Dunes along the eastern shore of Lake Michigan were formed by the action of wind and water on sand deposits left behind by the glaciers. The dunes in the SHNA and surrounding area are all within the boundaries of Michigan’s designated Critical Dunes which are protected by state law and regulated by the Michigan Department of Environmental Quality.   The dunes on the northern part of the SHNA are small because they were formed fairly recently in geological times, and because they were stabilized within living memory by the planting of beach grasses. Stabilization of these dunes has lead to a more varied habitat, including a Jack pine forest where Prairie Warblers (Michigan Endangered (E)) nest. Bank Swallows have recently begun to colonize some eroded dune faces in the interior. Foraging Northern Harriers (MI-SC) have been seen. Many other birds nest or forage on the property, and additional species arrive during fall and spring migrations. Many of these birds are found on the list of plants and animals of Michigan Coastal dunes (CLICK HERE).

Wind continually moves the sand on the surface of bare dunes. When plants begin to grow on the dunes, they slow the wind and sand accumulates around them. When this happens to dune grasses, they not only continue to grow above the sand, but their roots continue to grow beneath the surface and begin to hold and stabilize the sand. Sand Cherry shrubs are also tolerant of sand burial and are found not far from Lake Michigan on the SHNA. Cottonwood trees also expand their root systems when buried by sand, so they tend to be the first trees on the dunes. They can be seen in the SHNA as small clusters surrounded by grasses.

Some plants you may notice near the SHNA trails are wild strawberries and blackberries. Milkweed is fairly common and attracts monarch butterflies which you may see them flying about near the plants. Clusters of yellow flowers are conspicuous on the dunes in the SHNA. Hairy puccoon appears early in the year. Late summer yellow flowers are more likely St John’s Wort which is considered an invasive.

Many animals are found in the Saugatuck Harbor Natural Area. Deer are common. Red fox dens have been seen, but the animals are pretty secretive. Raccoons and woodchucks are present, but they are more common near the river and the Oxbow Lagoon. The Eastern Hognose Snake is the most common snake in the natural area. It is harmless, but when threatened it may raise its head and flatten it in a cobra-like attitude. Alternately it may flop on the ground and “play dead”.

More information on dune formation can be found on the DNR site (CLICK HERE) and the MNFI site (CLICK HERE).  Some research on dune formation in the region of the SHNA is described (CLICK HERE).

 

Interdunal Wetlands: As the name implies, an interdunal wetland is a wetland formed in low-lying areas within open dunes or between dune ridges along the Great Lakes. Although the water levels in the wetlands fluctuate with water levels in Lake Michigan, the interdunal wetlands in the SHNA have been in the same locations for at least a century and perhaps longer. Interdunal wetlands around the Great Lakes are considered to be globally imperiled because of their rarity and because factors such as coastal development make them vulnerable to extinction throughout their range. Protection of these wetlands provided an important impetus for setting aside the surrounding area as a natural area.

wet interdunalEScholtz 6-12-11 035

These unique wetlands provide critical habitat for rare species such as Blanchard’s Cricket Frog (MI-T) and a rare wetland wildflower called Zigzag Bladderwort (also MI-T). Both have been documented in the SHNA, and, according to MNFI, this site is one of just three known locations for Zigzag Bladderwort in Michigan. The interdunal wetlands also provide stopover foraging for migratory shorebirds along the coast of Lake Michigan. More information on interdunal wetlands can be found (CLICK HERE).

 

Great Lakes Marsh: This is a wetland plant community which is restricted to the shorelines of the Great Lakes and their major connecting rivers. This type of marsh includes a number of different subcommunities such as emergent cattail/bulrush marsh, submergent marsh, wet sedge meadows, and lowland shrub habitats. These occur along the north and west sides of the Oxbow Lagoon inside the boundaries of the SHNA, as well at the N and NE end of the Oxbow Lagoon on Tallmadge Woods property. These marshes provide primary breeding and feeding habitat for water birds (ducks, geese, herons, cranes, rails) and song birds like the marsh wren and yellow warbler. These marshes were at one time the only known location of Hibiscus moscheutos along the lower Kalamazoo River near Saugatuck. This large native marsh wildflower is relatively rare in Michigan. The marshes of the SHNA and surrounding area include potential nesting and stopover habitat for other birds of concern as well as two turtles: the Spotted Turtle and Blanding’s Turtle (both MI-T). A list of plants and animals found in Michigan wetlands is given (CLICK HERE).  These marshes are threatened by the multiplication of an invasive form of Phragmites (giant reeds). These plants are crowding out the native vegetation and destroying the native habitat. They grow so densely that few species can use them for nesting or foraging. Control measures are being undertaken.

SwampRoseMallow-Basin AScholtz


Riparian Shoreline and Adjacent Marshes. The western and northern shores of the Oxbow Lagoon provide very important habitat for the local population of Blanchard’s cricket frog (MI-T). For this reason, and because the shorelines are wet and marshy, they are not accessible from trails within the natural area. However, there is a short trail originating in the “Basin” area which leads to the northern end of the Oxbow Lagoon. Here calling cricket frogs can frequently be heard during May and June. Their call consists of a rapid series of metallic clicks, somewhat like the sound of two marbles shaken together. Great Blue Herons and Green Herons may be seen in this area feeding along the marshy shores. Muskrats make their homes along the shoreline and may be seen swimming in the vicinity. In late summer and early fall migrating egrets may make this a stopover point.

In areas of the shore which are not so wet, there are numerous small flowering plants including lobelia, gentians, ladies tresses and trailing wild bean (MI-SC).

 

 
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