(adapted from Wetlands and Wildlife, Brooks et al. 1993)

Wetlands provide important and sometimes critical habitats for many plants and animals. An estimated one-third or more of all endangered or threatened species in the United States depend on wetlands for survival. Wetland ecosystems provide important nesting, wintering, and feeding sites for many wildlife species. In fact, wetland ecosystems are one of the most productive wildlife habitats in Pennsylvania.

Most people associate species such as waterfowl, herons, beavers, muskrats and river otters with wetlands. These species are termed obligate wetland species because they depend on or are obligated to inhabit wetlands for survival. Many other species of wildlife use wetlands. Some do so extensively. Because, these species are not as dependent on wetlands for their survival, we call this group of animals facultative wetland species. Good examples of facultative species include the black bear who use Pocono wetlands extensively and ring-necked pheasants who use wetlands as escape areas when available.

Birds

An estimated 150 species of birds are wetland dependent or obligate wetland species in the United States. Countless others use wetlands or are facultative wetland species (Figure 15 - Song Sparrow. Source: Cole et al. 1996).

Waterfowl

Ducks can be divided into three groups based on similarities in ecological requirements: dabbling ducks, diving ducks and sea ducks (Figure 16 - Blue-winged Teal. Source: Cole et al. 1996). Dabbling ducks get their name from the way they feed in wetlands. Dabblers generally are surface-feeding ducks that display the unique tipping or dabbling for their food. They also sit high in the water and are able to burst into flight without running on the water surface. Pennsylvania’s most abundant dabblers are mallards and black ducks. In contrast, diving ducks are so named because of their ability to dive and swim underwater in search of submerged plants or animals for food. Diving ducks sit low in the water and have large powerful legs that are situated far back on their bodies. This positioning of their legs makes them excellent swimmers, but it also means they are awkward on land and must run on the water surface before they can fly. Familiar diving ducks in Pennsylvania include the common and hooded mergansers, buffleheads and the less abundant goldeneyes, redheads and ruddy ducks. Sea ducks, such as scoters and eiders, spend most of their time in coastal wetlands.

Two species of geese found in Pennsylvania are Canada and Snow geese. Canada geese are the best known and the most abundant. Canada geese are the birds people think of when envisioning V-shaped flocks flying in formation and foretelling the changing seasons. Canada geese nest throughout the state; whereas, snow geese are only migrants on their way to either their breeding or wintering grounds. Canada geese are very sociable, and readily land in fields where flocks can feed on pastures and croplands.

Tundra swans are our only native swan and are considered migrants in Pennsylvania. They are magnificent. Large flocks winter on the Chesapeake Bay, which brings their flight pattern through our state. Tundra swans are basically surface feeders; their long necks enable them to reach surface plants as well as submerged plants.

Shorebirds and Wading Birds

Shorebirds and wading birds display unique adaptations for feeding and breeding. Both shorebirds and wading birds feed by walking along and visually stalking their prey in shallow waters or along the edges of lakes, ponds, rivers or wetlands (Figure 17 - Killdeer. Source: Cole et al. 1996).

Few shorebirds nest in Pennsylvania, although many migrate through the state. In fact, shorebirds are more migratory than any other group of North American birds. Shorebirds include species such as plovers (including the common killdeer), rails, and sandpipers. Migrant shorebirds move frequently to exploit food sources, escape predators and to continue their migratory treks.

Songbirds and Raptors

Wetland dependent songbirds and raptors include the red-winged blackbird, marsh wren, Louisiana waterthrush, song sparrow, swamp sparrow, belted kingfisher, northern harrier (marsh hawk), osprey, bald eagle and others (Figure 18 - Broad winged hawk. Source: Cole et al. 1996).

Gamebirds

Gamebirds is a term refers to birds pursued recreationally in hopes of harvesting for consumption (Figure 19 - American Woodcock. Source: Cole et al. 1996). The four most important species in Pennsylvania are: American woodcock, ruffed grouse, wild turkey and ring-necked pheasant. These four species are good examples of facultative wetland species with recreational and economic value.

The American woodcock has perhaps the best link with wetlands. The woodcock uses its long bill to probe the soil and turn leaves to find earthworms and other soft-bodied organisms. Woodcock favor wooded feeding areas which include damp or wet soils where earthworms are likely to be found close to the surface.

Ruffed grouse, the Pennsylvania state bird, are predominantly birds of brush-stage forests. Good year-round grouse range contains at least three habitat types: brushy and low-growing ground cover for feeding young birds and for supplying summer and fall foods; mature deciduous woodlands for nesting and providing fall, winter and spring foods; and low-growing evergreens such as spruce, hemlock and mountain laurel for winter cover. Wetlands sometimes provide several of the habitat types needed by grouse. Alder thickets provide brushy areas and food, and wet meadows provide a good insect source to feed young poults. Forested and shrub wetlands that contain conifers provide excellent winter cover and contribute many valuable foods.

The eastern wild turkey is the largest of Pennsylvania gamebirds and generally is considered a forest species, but two wetland habitat types are frequently used by turkeys. The first is wet meadows. Turkeys, especially young poults, use wet clearings containing grasses and forbs because these sites have herbaceous foods and an abundance of protein-rich insects. The second most frequently used habitat is spring seeps. Temperatures of the groundwater flowing from the seeps are above freezing, and the areas remain open throughout the winter. Vegetation and insect life found in these seeps provide the critical foods during a stressful time of year.

The ring-necked pheasant is not native to Pennsylvania. Since first released in 1915, they have, until recently, inhabited much of the state. Pheasants, considered chiefly as a farmland wildlife species, use available wetlands for both food and cover. Insects are an important food source for pheasants, as well as for turkeys and grouse. Wet meadows, when available, are good sources of this nutrition. Wetlands become especially important during the fall and winter season because they provide excellent escape and thermal cover as well as food.

Mammals

Five familiar species of medium-sized furbearing mammals use wetlands and other aquatic resources extensively in Pennsylvania. Four of these can be considered obligate species (beaver, muskrat, mink and otter). These species have adapted their anatomy, physiology and behavior to a life in and around water. The fifth species, raccoon, is often associated with wetland and riparian areas, but can survive in upland habitats. All of these species produce valuable fur, and thus are sought by trappers. However, due to low population numbers, there is (since 1952) a closed season on river otter in the state. Restoration activities for the river otter are taking place. Wetland furbearers have fascinating life histories which make them enjoyable to observe and study.

Few species other than humans are able to manipulate their environment like the beaver. They cut trees, create openings, build dams and dig canals (Figure 20 - Beaver Dam. Photo by R.P. Brooks). Dams are designed to provide ample water for safety, food, transportation and storage. The entire complex is called a beaver flowage. Flowages abandoned by beavers evolve into beaver meadows. In effect, a colonizing beaver is the beginning of a new wildlife community characterized by elements of wetland, riparian and upland habitat.

The lodge and dam are good basking areas for snakes and turtles, and frog and salamanders breed in shallow waters. Mink, raccoons and green herons search for frogs, crayfish and other prey along marshy and riparian edges. Insects above the water attract swallows and flycatchers by day and bats at night. Dead trees harbor insects that are fed upon by woodpeckers. Holes made by woodpeckers are potential nesting sites for a variety of cavity-nesting birds. Some kinds of birds like the alder flycatcher, Louisiana waterthrush and wood duck are closely tied to beaver flowages.

Bordering the dam, small meadows resulting from felled trees provide habitat for deer, rabbit and hares. Turkey and grouse hens lead their young through such clearings in search of insects. These sunlit clearings have a rich herbaceous layer that supports high density populations of meadow voles, and certain other small mammals. In turn, these popular prey species are sought by hawks and owls, and ground-born predators like red and gray foxes. Thus, the beaver creates habitat that is used by a variety of wetland and upland wildlife species.

Muskrats

Muskrats, another rodent with construction skills, builds two types of shelter, depending on the characteristics of the ecosystem. Houses, or lodges, are constructed in shallow water (less than half a meter [2 feet] deep) surrounded by the emergent vegetation found in marshes and backwater coves. The second type of shelter, burrows, are dug when suitable banks (clay soils) are available along streams and the edges of marshes, ponds and lakes.

Mink, River Otter and Raccoon

Mink, a member of the weasel family, are found in a variety of wetland and riparian habitats that remain relatively undisturbed by human activities. They use logjams, root masses and rock crevices along shorelines for their dens. Mink hunt along the edges of waterbodies for almost any kind of vertebrate animal, including muskrats, small mammals, birds, reptiles, amphibians and fish.

River otter populations have declined from historic levels. Trapping (prior to 1952 when the season was closed), water pollution and habitat loss contributed to this decline. Only the northeastern Pocono region supported a healthy population. This large, carnivorous weasel prefers undisturbed riparian and lake habitats where it can find fish and crayfish, its primary food items. Recent reintroduction efforts have returned river otters to several other watersheds throughout the state.

Raccoons feed on many of the small vertebrates (frogs, fish, mice) and large invertebrates (crayfish, mussels, grasshoppers) found along the shores of wetlands, streams and ponds. However, their diet is more omnivorous because they also eat berries, nuts, corn and other types of plant foods. Raccoons tolerate disturbances by humans more so than other wetland furbearers. They can survive successfully in suburban and urban developments.

Other Wetland Mammals

Other species of mammal that use wetlands are not as well known. The water shrew is at home in the water and along streambanks. Another insectivore, the semi-aquatic star-nosed mole, searches for food both in water and in underground tunnels that penetrate saturated soils. The southern bog lemming, despite its name, is not restricted to bog-like environments. It can be found in old fields, forest clearings and young-growth forests.

Reptiles and Amphibians

Although reptiles evolved primarily on drier lands, some species have reverted back to dependence on aquatic habitats. Species such as the painted turtle and northern water snake live in water, but lay their eggs high and dry on land. Thus, reptiles and amphibians differ in their use of wetlands. Both groups rely on wetlands and other water bodies for survival. Even the smallest of temporary ponds (sometimes called vernal ponds), only 3 meters (10 feet) in diameter, that are dry for much of the year, are critical habitat for these species. How do you think the loss of wetlands in Pennsylvania has impacted these species?

Fish

About 30 species of fish are known to use inland, freshwater wetlands in Pennsylvania some time during their life cycle. Fish such as sunfish and catfish will nest in the shallow open-water areas of wetlands, ponds and reservoirs. Other species such as bass, pickerel and pike require vegetated habitats with dense stands of emergent and submergent plants on which to lay their eggs and raise their young.

Wetlands connected to other water bodies, such as streams, lakes and estuaries, are more likely to contain a variety of fish species, particularly those that move to and from deep waters and shallow waters for feeding and breeding. The salt marshes along estuaries and the floodplains along larger rivers are among the most productive habitats in the world because they serve as spawning and nursery areas for many commercially important species of finfish and shellfish. Tides and floods continually replenish the nutrients used by plants, invertebrates and fish dwelling in these wetlands. Nutrients in short supply can reduce the kinds of species that can live in small, inland wetlands.

Invertebrates

Invertebrates are the most abundant and varied of all wetland animals, at least those that we can see without the aid of a microscope. Invertebrates inhabit both aquatic and terrestrial environments. From an ecological point of view, invertebrates are associated with nearly all other animals as food, predators, parasites and/or competitors for available resources or space.

Aquatic invertebrate fauna have an important role in the decomposition of dead plant and animals material in wetlands. Crane fly larvae and earthworms are two examples. Invertebrates are also important pollinators of plants, such as wetland orchids. Microscopic invertebrates provide food for larger invertebrates called macroinvertebrates. In turn, these macroinvertebrates such as crayfish, mayflies, dragonflies, damselflies, caddisflies and stoneflies are major staples in the diets of other wetland wildlife such as fish, amphibians, shorebirds, songbirds, waterfowl and insectivorous mammals. Invertebrates are integral parts of any food web (Figure 23 - Source: N. Obel).

Many familiar plants grow in wetlands. Blueberries and cranberries are examples of wetland plants that we favor. You already know that wetlands have been classified according to the dominant plant types found there. You also know the importance of plants in wetland functions such as chemical transformation. Plants are able to uptake nutrients and toxins and transform them. The plants in a wetland are the basis for all other life forms which exist there. They offer shelter and food to insects, birds, mammals, fish, reptile and amphibians. They are the primary producers. Animals that feed on them are called secondary consumers. Plants are the base of any food web (Figure 23 - Source: N. Obel).

Some wetland plants only occur in wet areas and others may occur in wet or dry areas. There is a special classification system for plants which assigns an indicator status (OBL - obligate; FAC - facultative; etc.) to each species depending on how often they are found in wet areas (see Appendix 2).

Many wetland plants have special adaptations that enable them to live in water. Because the sediments in many wetlands become anaerobic (low in oxygen), the roots of some wetland plants have evolved air spaces, called aerenchyma, which allow oxygen molecules to move from the emergent portions of the plant to the underwater roots (Figure 24 - Aerenchyma. Source: Tiner 1998. Reprinted with permission.). Trees, such as the bald cypress of southern swamplands, have evolved prop roots with pores called lenticels. The prop roots are above the tidal or flood zone and supply oxygen to the submerged roots. Oxygen diffuses to the roots and can cause soil oxidation around the root producing a rust color in the soil horizon. Some wetland plants produce seeds during the dry season and others may produce buoyant seeds which can float to the banks to take root.

Submergent and floating plants: pondweeds, wild celery, water milfoil, fanwort, water lilies, water shield, yellow pond lily, duckweed (common animals: deer, swan, coots, grebes, newts, bass and tadpoles).

Emergent plants: cattail, woolgrass, reed canary grass, sedges, rushes, bulrushes, pickerel weed, burreed (common animals: muskrat, small mammals, dabbling ducks, bitterns, rails, sparrows, frogs and tadpoles).

Shrubs: alder, high bush blueberry, viburnums, rhododendrons, dogwoods (common animals: beaver, bear, otter, snowshoe hare, woodcock, common snipe, green heron, waterthrushes, and other warblers).

Trees: elms, green and black ash, swamp white oak, hemlock, black spruce, red and silver maple (common animals: bear, raccoon, woodduck, black duck, osprey, wood turtle, wood frog, red-backed salamanders).

Wetland or Hydric Soils

Wetland soil is both the medium in which many of the wetland chemical transformations take place and the primary storage area of available chemicals for most wetland plants (Mitsch and Gosselink 1993). The Natural Resources Conservation Service (NRCS) defined wetland soil, or hydric soil, as "a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part". There are two types of soils you might find in a wetland, ones with a high organic content and ones with a high mineral content. Organic soils develop in wetlands that are covered in water for a significant portion of the year. Plant decomposition is slowed under the anaerobic conditions and results in the accumulation of organic materials such as peat. Soils with a high mineral content are found in wetlands that are inundated by surface waters carrying sediments for part of the year. Oxygen diffuses into these soils to hasten decomposition. Thus, the organic matter decomposition in these areas occurs at a rate even with the accumulation, leaving the minerals behind. These soils can be identified based on color using a standard color chart, such as a Munsell Color Chart (Figure 26 - Source: Munsell Color 1992. Courtesy of GretagMacbeth, LLC. Reprinted with permission.). These soils are characteristically gray, greenish, or blue-gray as a result of a process called gleying which is the result of the chemical reduction of iron, a common element in soils. Soils that are seasonally flooded, or alternately wet and dry, develop a mottled appearance. Mottles are often orange/reddish-brown or dark reddish-brown/black and are formed because of the oxidized spots of iron and manganese oxides in an otherwise reduced environment.

The 10 species were chosen to represent a wide range of taxa, feeding levels and habitat uses that span the plant composition and degree of disturbance found in the wetlands of the northeastern U.S. Selected species include: bullfrog (Rana catesbeiana), muskrat (Ondatra zibethicus), meadow vole (Microtus pennsylvanicus), red-winged blackbird (Agalaius phoeniceus), American woodcock (Philohela minor), common yellowthroat (Geothlypis thrichas), green heron (Butorides striatus), wood duck (Aix sponsa), wood frog (Rana sylvatica) and southern redback vole (Clethriononmys gapperi). The species have been arranged in order according to preferred vegetative cover type (Table 1). See Appendix 3 for the habitat suitability model for each species. After completing the suitability models for each species, the students can develop a wildlife community profile. This profile can be used to compare sites and produce a visual representation of the wildlife community at each site (Figure 27).

The students should break into groups of three. Each group will be given a model to score based on pictures and description of an ecosystem. Enough information will be available in the description of the wetland so the students will be able to score each factor. This in-class exercise is intended to acquaint the students with these models so they will be prepared to use them in the field when following the CWC protocol.

1) At least three observers should independently score each site. The score for each variable will be calculated as an average of the independent scores of each observer. If the score difference is greater or equal to 0.3 units, observers must discuss that variable and reduce the difference to a value that is equal to or less than 0.3 before averaging their scores.

2) Each model contains an equation to calculate overall HSI value.

3) A site may be ranked from multiple perspectives, depending on the species model being used. Consider, for example, an open water site with grass-like herbaceous vegetation along the shore. When ranking the model for the meadow vole, focus mainly on evaluating the grassy shore rather than the open water (because the meadow vole would not be found in the open water). The wood duck, on the other hand, will use both the open water and vegetated shore, therefore focus on all portions of the site. Life history information is included at the beginning of each model.

4) It is important to score all species for each site. After the scores are computed for each species, a graph can be produced to display the relative ranking.