Wildlife of the Mid-Atlantic: A Complete Reference Manualby John H. Rappole
The Mid-Atlantic is a geographically and biologically diverse region, ranging from the sandy coastal beaches and blackwater swamps of southeastern Virginia to the boreal bogs and spruce-fir forests of northern Pennsylvania and the highest peaks of West Virginia's Appalachian Mountains. Scientists identify six distinct geologic provinces in the area, along with four
The Mid-Atlantic is a geographically and biologically diverse region, ranging from the sandy coastal beaches and blackwater swamps of southeastern Virginia to the boreal bogs and spruce-fir forests of northern Pennsylvania and the highest peaks of West Virginia's Appalachian Mountains. Scientists identify six distinct geologic provinces in the area, along with four climatic zones. As John H. Rappole explains, these varied landforms and climates create the environment for the variety of wildlife found in the region.
This well-illustrated volume is the most comprehensive and up-to-date guide to the wildlife of Pennsylvania, New Jersey, Delaware, Maryland, Virginia, and West Virginia. Approximately 550 species are described, including all birds, mammals, reptiles, and amphibians known to inhabit the area, excluding open ocean species. Each species is illustrated and a distribution map is included with every entry. The species accounts contain a physical description, data on habitat and distribution, habits, diet, reproduction, conservation status, and one or more key references.
Sections cover the major habitat types in the region (including descriptions and photos), physical geography, climate, and conservation challenges. In addition, the book has a glossary of nearly 400 technical terms. An appendix contains descriptions of casual, accidental, hypothetical, and extinct species, an index allows readers to locate specific information quickly, and a thorough bibliography suggests additional reading.
Written by a respected scientist, Wildlife of the Mid-Atlantic provides the only complete summary of information on all the terrestrial species of the area, based on the most recent research. Designed to meet the needs of professional as well as nonprofessional readers, it is an essential resource for all natural history enthusiasts, from students to teachers, from birders to ornithologists, and from avid outdoors people to armchair naturalists.
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The Mid-Atlantic region, for the purposes of this work, includes Pennsylvania, Virginia, West Virginia, New Jersey, Delaware, Maryland, and the District of Columbia (Figure 1). This area encompasses an impressive array of habitats and topography, ranging from the sandy coastal beaches and blackwater swamps of southeastern Virginia to the boreal bogs and spruce-fir forests of northern Pennsylvania and the highest peaks of West Virginia's Appalachian Mountains. In line with this diversity, the region has an extraordinary richness of terrestrial vertebrate fauna: 72 amphibian species; 62 reptiles; 81 mammals; and 331 birds. "Terrestrial" in this case means those that spend most or all of their life cycle on land, and thus excludes most pelagic vertebrates, e.g., seabirds, whales, and sea turtles, as well as fish. Some anomalous species are included, like the Hellbender and sirens, which are aquatic in all life cycle phases, because to exclude them would be to fall just short of complete coverage for the Amphibia.
An additional purpose of this book is to summarize the conservation status and major problems confronting vertebrate populations in the Mid-Atlantic. This part of the country has experienced anthropogenic effects as radical as any on earth over the four centuries since European settlement began, and these changes have had profound effects on the area's wildlife. For instance, moose, lynx, bison, elk, cougars, wolves, Trumpeter Swans, Whooping Cranes, Passenger Pigeons, and Carolina Parakeets were part of the terrestrial vertebrate fauna when Lederer first pushed his westward explorations to the peaks of the Blue Ridge Mountains in the late 1600s (Talbot 1672). Thomas Lewis surveyed northern Virginia's Shenandoah-Rockingham county line in the mid-1700s, recording not only the large mammals and birds observed, but the dominant tree species as well, providing a glimpse of what the primeval forest must have been like in the Appalachians (Lewis 1746). Now, in the early twenty-first Century, few old growth stands of any habitat type remain in the region: Cook's Forest in northwestern Pennsylvania and Swallow River Falls State Park in the Cumberland of western Maryland serving as two notable exceptions. Structurally, at least, it makes quite a difference whether a forest is composed of trees 23 m (710 ft) in diameter at breast height (dbh) or even larger, as was the case in pre-settlement times, versus today in which few trees exceed a meter in dbh. Unfortunately, we can only surmise what difference these structural dissimilarities might make in terms of the vertebrate communities.
Most early explorers and settlers had things on their mind other than the extraordinary natural diversity surrounding them, and made few notes on animals or plants that weren't edible or dangerous. For instance, John Lederer, a German explorer, made three trips to the Blue Ridge Mountains in the late 1600s, in which he catalogued the presence of deer, elk, buffalo, wolves, and mountain lions, but little else in the way of wildlife (Talbot 1672). Mark Catesby's (17311743) superb The Natural History of Carolina, Florida and the Bahama Islands provided the first extensive treatment of terrestrial vertebrate species for North America, which included not only paintings of each animal and plant discussed, but a brief natural history account as well. His volumes include accounts for 103 birds, 8 mammals, 3 amphibians, and 28 reptiles. Although Catesby's volumes focused on areas south of the Mid-Atlantic, he lived for some time in Virginia, and most of his accounts are relevant for species from the Mid-Atlantic region.
Another relatively early study of Mid-Atlantic natural history is that provided by Thomas Jefferson (1784). Although comprised largely of lists, Jefferson's book catalogued some of the major flora and fauna of Virginia, which included West Virginia at the time of his writing. Works like that of Catesby, Jefferson, William Bartram (1791), and other early naturalists (cf Linzey 1998, Johnston 2003) allow us to establish a baseline of at least some of what existed in temperate eastern North America at that time, nearly two centuries after initial colonization.
The first detailed life history accounts of terrestrial, Mid-Atlantic vertebrates were done on the birds by Alexander Wilson (18081831), assisted by George Ord and Charles Lucien Bonaparte. Audubon's work (18401844) also focused mainly on birds, and included information from many different parts of North America beyond the Mid-Atlantic. His Quadrupeds of North America provided paintings and detailed life history accounts for 37 species of mammals, most of which are, or were, found in the Mid-Atlantic (Audubon and Bachman 18461854). David Johnston (2003) has provided an excellent summary of historical natural history literature for the region. He too focused on birds, and the State of Virginia, but he identifies many of the main historical natural history references pertinent for the entire region. His work, and that of other studies summarizing historical literature for other major taxa (e.g., Linzey's 1998 The Mammals of Virginia and Green and Pauley's 1987 Amphibians and Reptiles in West Virginia) make clear that systematic efforts to catalog all of the terrestrial vertebrates within the Mid-Atlantic, and to provide the details of the life history for each species, are really a twentieth century phenomenon. Only recently have detailed life history accounts been completed for most of the terrestrial vertebrates of North America. For birds, such accounts became available through the Birds of North America project, which began with publication of the Barn Owl account in 1992 and was completed with the Dark-eyed Junco account (#716) in 2002 (Poole and Gill 19922002). The American Society of Mammalogy's (19692004) "Mammalian Species" was begun in 1969, with publication of the account for Waterhouse's Leaf-nosed Bat, and currently stands at 760 accounts, covering most North American mammals as well as many from elsewhere in the world. The national herpetological societies have no comparable program, but Petranka's (1998) Salamanders of the United States and Canada presents an outstandingly thorough treatment for all members of that group.
Up-to-date life history summaries for members of the major taxa of terrestrial vertebrates (i.e., birds, mammals, reptiles, and amphibians) do not exist for all the states in the region. Those that do exist, however, are excellent. These include Green and Pauley's (1987) Amphibians and Reptiles in West Virginia; Martof et al.'s (1980) Amphibians and Reptiles of the Carolinas and Virginia; Linzey's (1998) The Mammals of Virginia; White and White's (2002) Amphibians and Reptiles of Delmarva; Merritt's (1987) Guide to the Mammals of Pennsylvania; Webster et al.'s (1985) Mammals of the Carolinas, Virginia, and Maryland; and Hulse et al.'s (2001) Amphibians and Reptiles of Pennsylvania and the Northeast. Wildlife of the Mid-Atlantic is an attempt to take the next step, pulling together summaries from the detailed life history accounts along with distributional and conservation information from state treatments. No publication effort prior to this book presents detailed information on all the terrestrial vertebrates in the Mid-Atlantic region in a single volume, including life history summaries, distribution maps and depictions (photo or drawing), conservation information, and a source in the literature where students can turn for additional information.
Six major geologic provinces are found in the region: 1) Coastal Plain, 2) Piedmont, 3) Blue Ridge, 4) Ridge and Valley, 5) Appalachian Plateau, and 6) Central Lowlands. The Coastal Plain stretches 3,500 km (2,200 mi) along the edge of the continent from Massachusetts to the Mexican border, forming the boundary between land and ocean. In the Mid-Atlantic, the southern end of this province is about 200 km (120 mi) wide at the Virginia-North Carolina border, although it narrows sharply and disappears at its northern end in central New Jersey where the Piedmont extends to the ocean shore. Several of the great cities of the Mid-Atlantic, such as Richmond, Washington, Baltimore, and Philadelphia, are located along the boundary between the Coastal Plain and Piedmont provinces, known as the "Fall Line." Here rivers like the James, Delaware, and Potomac flow out of the hard bedrock of the rolling Piedmont onto the sediments of the level Coastal Plain, and waterfalls mark the head of navigation.
The Appalachian Mountains are the predominant physiographic characteristic of the Mid-Atlantic, and the Piedmont Province forms the easternmost of the 4 provinces that are essentially subcategories of this single geological feature (Piedmont, Blue Ridge, Ridge and Valley, and Appalachian Plateau). The hills of the Piedmont extend westward from the Fall Line to the base of the Blue Ridge Mountains in Virginia, Maryland, and southern Pennsylvania, and to the mountains of the Ridge and Valley of Pennsylvania and New Jersey. The Blue Ridge is a long, narrow province consisting of a single ridge or series of parallel ridges and valleys running generally from southwest to northeast 885 km (550 mi) from Carlisle, Pennsylvania, to north Georgia. North and west of the Blue Ridge is a wider series (up to 130 km) (80 mi) of higher ridges and deeper valleys that also run southwest to northeast; these constitute the Ridge and Valley Province, which extends nearly 2,000 km (1,200 mi) from the St. Lawrence River at the Canadian border to central Alabama. West and north of this province are the steep hills of the Appalachian Plateau, covering most of West Virginia and western Pennsylvania. A sixth province, the Central Lowlands, occurs in only a small portion of our region, namely that part of Pennsylvania bordering Lake Erie, where Presque Isle and the city of Erie are located.
Four major climatic zones occur in the Mid-Atlantic: 1) the Austral is characterized by hot summers, mild winters, and moderate precipitation, and is found only in southeastern Virginia; 2) the Carolinian is characterized by hot summers, cool winters, and moderate precipitation, and covers the Piedmont region and valleys of the southern Appalachians; 3) the Alleghenian is characterized by warm summers, cold winters, and moderate precipitation, and covers most of the Appalachian Highlands; and 4) the Canadian is characterized by cool summers, harsh winters, and moderate precipitation, and is found only at the highest elevations in our region.
The varied landforms and climates of the Mid-Atlantic create the basis for the diversity of plant and animal communities or "habitats" that occur here. Specific associations or communities of plants and animals constitute a habitat for a given species, and, with experience, one can learn to recognize these communities and know which organisms to expect in them. However, there are differences among the classifications for the living environment provided by biologists. For instance, C. Hart Merriam (1894) recognized 3 major "life zones" for the Mid-Atlantic based on temperature (isotherms for the mean temperature of the 6 hottest weeks of the year): Lower Austral, Upper Austral, and Transitional (Figure 5). Dice (1943) modified this system, replacing the "life zone" classification with "biotic provinces." In doing so, he used characteristics of temperature, topography, and soil to define "province" boundaries, similar in many cases to those drawn by Merriam. Thus his "Austroriparian Province" roughly matches Merriam's "Lower Austral"; his "Carolinian" approximates Merriam's "Upper Austral"; and his "Canadian" is similar to that of Merriam's "Transitional." These and similar attempts to apply subjective taxonomic rules lumping large numbers of ecological communities together retain interest because they reflect reality at a gross level. For instance, there is no doubt that something of considerable ecological significance occurs in southeastern Virginia, where many
species of animals reach the northern extremity of their distribution along the boundary of Dice's "Austroriparian Biotic Province." For this reason, terms from the various attempts at community classification at continental scales, like "Austroriparian" and "Transitional," remain in common natural history parlance, long after their theoretical basis has been more or less discredited. The fundamental problem with these various organizational efforts is that no single principle or set of principles can explain the distributions of all organisms, because the distribution of each species is the result not only of factors affecting all other species in its community, e.g., changes in climate and topography, but also of factors unique to itself, e.g., the length of time that it has existed as a species, and the various chance mutations through which it has evolved over that period. To cite extreme examples, one must take into consideration the breakup of Pangaea 200 million years ago to understand the current distribution of Hellbenders (Cryptobranchidae), which are found only in China, Japan, and the eastern United States, while the breeding distributions of more than 150 species of birds have changed in a matter of decades in response to global warming (Mathews et al. 2004).
To avoid these complications, while recognizing some utility in terms of community classification, ecologists have reverted to strictly descriptive mapping of the major plant communities. Like the higher-level groupings discussed above, and for the same reasons, these plant community classifications are not always indicative of the animal communities that they contain. Nevertheless, they have the virtue of being largely objective in that they reflect mapping exercises of major plant associations. Perhaps the most widely used of these classifications is that developed by Küchler (1975) (Figure 6). His classification includes nine principal habitat types for the Mid-Atlantic region: Northern Cordgrass Prairie; Northeastern Spruce-Fir Forest; Beech-Maple Forest; Mixed Mesophytic Forest; Appalachian Oak Forest; Northern Hardwoods; Northeastern Oak-Pine Forest; Oak-Hickory-Pine Forest; and Southern Floodplain Forest. It is important to note that Küchler's habitat map is titled, Potential Natural Vegetation of the United States (Küchler 1975). Thus he shows what he believes would be present in the region, if humans had not modified the habitats. Of course, humans have modified every habitat, so what you find at any given site could range anywhere from a hundred-year-old oak forest to a parking lot. Almost all sites are in some seral stage short of the climax vegetation communities whose distribution is hypothesized in Küchler's map. Also, global warming has caused rapid change in the distribution of some communities, a process that is in progress at a rate scientists are only beginning to understand.
In defining a habitat classification for the Mid-Atlantic region, I follow a modification of Küchler's system. I add three major habitats that his classification does not address: Coastal Waters and Shoreline, Agricultural and Residential, and Freshwater Wetlands; also, I combine several of his deciduous forest classifications into a single broadleaf forest category.
Coastal Waters and Shoreline—The coastal marine habitat can be broken into three major subdivisions, each with its own characteristic group of species: 1) Pelagic (open ocean) and Bays; 2) Beaches and Dunes; and 3) Estuaries, Saltmarshes, and Tidal Flats.
Freshwater Wetlands—Lakes, ponds, impoundments, rivers, and marshes. The defining characteristic is the presence of fresh water, which stimulates the growth of such plants as cattails, sedges, and bulrushes. Freshwater wetlands are among the most endangered of habitats in our region, perhaps because they tend to limit human economic activities, and so are dammed, dredged, drained, channeled, and filled out of existence. Those that remain serve mainly as conduits for waste.
Grassland—Most of what now occurs of this habitat in our region has been created by human activity, such as the grasslands now covering reclaimed strip mines in Pennsylvania's Clarion County, the broad pasture lands of Virginia's Piedmont, or Delaware's hayfields, although natural coastal cordgrass prairies still occur along the immediate coast, especially in places like Brigantine and Barnegat marshes in New Jersey. The primeval forests of the eastern U.S. are legendary, where supposedly at the time of Captain John Smith, "a squirrel could travel from the coast to the Mississippi, and never touch the ground." Nevertheless, the fact that there were extensive areas of grassland has been well documented. Wayland (1989), for instance, reports that much of the broad Shenandoah Valley was grassland at the time of the arrival of the first European settlers, perhaps maintained by Indians with fire. At least one bird was native to grasslands, the Heath Hen, an eastern subspecies of the Greater Prairie-Chicken (Tympanuchus cupido), now extinct.
Broadleaf Deciduous and Mixed Forest—Five of Küchler's (1975) forest communities are lumped within this designation including the Beech (Fagus)-Maple (Acer) Forest as found near Sharon and New Castle in western Pennsylvania; the Mixed Mesophytic Forest of maple, beech, oak, tulip poplar, and horse chestnut found in much of the Appalachian Plateau of West Virginia; Appalachian Oak Forest (and formerly American Chestnut), which covers the lower slopes of the Appalachian Highlands of Virginia, Maryland, Pennsylvania, and New Jersey; Northeastern Oak-Pine Forest, otherwise known as the "Pine Barrens" of central and southern New Jersey; and Oak-Hickory-Pine Forest found throughout most of the Piedmont. The reason for lumping these different plant communities together is that they are quite similar in terms of the animal communities they support—at least in their current stage of recovery from nineteenth century clearing.
Northern Mixed Hardwoods—Maple, birch, beech, hemlock, and white pine forest, often referred to as "Transitional Forest" (from C. Hart Merriam's classification), as in transition from the primarily deciduous forests of the temperate portions of the continent to the mainly coniferous forests of the boreal regions.
Highland Coniferous Forest— This forest type is referred to as Northeastern Spruce-Fir Forest by Küchler (1975), and actually represents an outlier of the vast Holarctic boreal forests that cover much of Canada, Siberia, and northern Europe. During the Wisconsin glaciation (22,00010,000 years before the present), this habitat covered vast areas, and extended hundreds of kilometers southward. Now, it remains only in small isolated patches at high elevations, e.g., above 1200 m (4000 ft) in the southern mountains of our region, lower in more northern latitudes.
Southern Floodplain Forest—Like the previous forest type, southern floodplain forest is an outlier in our region (of Dice's "Austroriparian Biotic Province" and Merriam's Lower Austral Zone), representing the northernmost extent of the great southeastern bottomlands that once choked every river with tangled swamps and bayous along the Coastal Plain from southeastern Virginia all the way to east Texas, but now persist only as remnants. The upland longleaf pine/palmetto savanna of the Austroriparian, principal habitat of the endangered Red-cockaded Woodpecker, is now even more rare than the bottomland forest in our region.
Agriculture and Residential—Unfortunately, many of the beautiful and unique habitats of the Mid-Atlantic States have been converted to these universal types: a corn field looks pretty much the same in coastal Maryland as it does in Iowa, or Ecuador for that matter, and plowed dirt is plowed dirt, no matter where you find it. These habitats share common species in many parts of the world—such as Norway Rats, Rock Pigeons, and House Mice. Still, some species native to the region's aboriginal grasslands and woodlands, e.g., the Meadow Vole, Northern Leopard Frog, and Smooth Greensnake, can still be found in "improved" pastures, orchards, suburban lawns and gardens, and similarly altered environments.
Wildlife and Conservation Issues for the Mid-Atlantic Region
There is considerable debate concerning the effects of humans on North American biota prior to European colonization, e.g., the role of Homo sapiens in large mammal extinctions during the late Pleistocene and early Holocene, 10,000 years ago (Martin and Klein 1984, MacPhee 1999). In contrast, basic facts associated with anthropogenic influence on the biota since Europeans first established permanent settlements on the continent are well documented, including the following: 1) forest cover in the eastern United States declined from >90% in 1600 to about 30% in 1900, recovering to almost 60% at present (Powell and Rappole 1986), although almost none is old growth forest; 2) widespread extirpation of species resulting from hunting by the early 1900s, with recovery subsequent to protection for some species, e.g., Diamond-backed Terrapin, White-tailed Deer, and Wild Turkey; 3) extensive poisoning of river systems by pollutants, e.g., DDT and acid rain, with subsequent ripple effects on species up through the food chain; 4) drastic reduction, regional extirpation, or elimination of species resulting from intentional or unintentional introductions of species from the Old World (e.g., Chestnut Blight Fungus and Dutch Elm Fungus); 5) shifts in breeding distribution of 150 species of migratory birds resulting from global climate change (Matthews et al. 2004).
Extinction of species like the Carolina Parakeet and Passenger Pigeon is emblematic of the profound environmental changes that have taken place resulting from human influence. Among the data summarized in this book are the species-by-species conservation assessments performed by state Natural Heritage programs and departments of natural resources. All the states in the Mid-Atlantic follow The Nature Conservancy's suggested rankings of degree of threat to wild populations (S1 = Critically Imperiled, S2 = Imperiled, S3=Vulnerable, etc.). Of the 546 species of birds, mammals, reptiles, and amphibians in the Mid-Atlantic, 287are considered to be imperiled in one or more of our states. Furthermore, many are considered as already extirpated from the region (e.g., Gray Wolf, Martin, Whooping Crane, Heath Hen, Eskimo Curlew) (Appendix 1). These data show that the problem of vertebrate species decline and disappearance in the Mid-Atlantic is much more profound than the short list of species known to be extinct might indicate. Analysis of the known or suspected reasons for the decline and/or disappearance of these species is informative. These are discussed below. For some species, the reasons are obvious. Trumpeter Swans, Elk, and Whooping Cranes were eliminated by human hunting for food; American Martens and Fishers were eliminated by trapping for sale of pelts; wolves and mountain lions by predator removal programs, often subsidized by government bounties. However, for many species, the reasons are not obvious. For instance, 162 species of migratory birds that occur in the Mid-Atlantic region have been listed as S1, S2, or S3 in one or more states, are extinct or extirpated, or have been found to have undergone significant declines in the region or throughout their range, based on National Breeding Bird surveys (DeGraaf and Rappole 1995). For some of these birds, regional loss of breeding habitat seems like the obvious cause. However, for migratory species with complex life cycles, significant parts of which may be spent thousands of kilometers from the Mid-Atlantic in areas with their own conservation problems, it is very hard to know whether observed declines are the result of breeding ground threats, wintering ground threats, or threats to critical habitats somewhere in between (Robbins et al. 1989, DeGraaf and Rappole 1995, Rappole 1995).
Habitat Change During One or More Phases of the Life Cycle for Migratory Species—Thirty-one species of migratory birds are listed as S1, S2, or S3 in the region for which the reasons for decline are not obvious (Table 1). Such declines are not restricted to the Mid-Atlantic, but have been recorded for many migratory birds across their entire continental ranges (DeGraaf and Rappole 1995). The complex life cycles of migrants, in which populations are dependent on different habitats in widely separated geographic areas at different times of the year, make identification of the specific portion of the life cycle responsible for the decline difficult. Many researchers have suggested that fragmentation of breeding habitat is responsible (Askins et al. 1990), and, in fact, there is good evidence from several studies to indicate that size of a piece of habitat is positively correlated with numbers of breeding pairs ("Area Effect") (Robbins et al. 1989). However, as Rappole and McDonald (1994, 1998) point out, loss of transient or wintering habitat could provide a sound explanation for this observation. In addition, amount of habitat for many forest-related migrants has actually increased in the Mid-Atlantic region; yet populations of many such species continue to show declines (Rappole 1995).
Loss of Old Field and Grassland Habitat—There were few areas of extensive grassland in eastern North America prior to European colonization (Küchler 1975). This situation changed rapidly during the 1800s as human populations expanded rapidly westward, replacing forest with farm fields and various stages of second growth (Powell and Rappole 1986). Many species of flora and fauna responded quickly to this change in habitat, expanding their ranges into the Mid-Atlantic where they had not previously been recorded, e.g., Bachman's Sparrow, a bird originally of southeastern pine savanna (Dunning 1993), and Bewick's Wren, whose precolonization distribution presumably was restricted to the Great Plains and western North America (Kennedy and White 1997) . By the 1920s, various economic and social forces began to cause small farms in the Mid-Atlantic and elsewhere in eastern North America to be abandoned, and by the late 1900s, large areas of grassland and old field habitat had reverted to forest or been converted to intensive agriculture or urban use, resulting in the increasing rarity or disappearance of many members of open habitat and early seral stage communities (Askins 2000) (Table 1).
Disturbance and Loss of Coastal Breeding Habitat—Coastal habitats of the Mid-Atlantic in general, and wetlands in particular, are under intense pressure. The waterways, marshes, beaches, dunes, and other habitats unique to the immediate coast are being developed for residential housing and recreation at an extremely rapid rate (Carter 1988). In addition, those habitats not actually developed are increasingly subjected to intense disturbance, either directly by people (e.g., recreational beach traffic) or by increased populations of predators associated with increased human use, including dogs, cats, and introduced species, e.g., feral pigs (Rappole 1982). Coastal wetlands are also subject to pollution from agricultural runoff, industrial waste, poultry farms, and human sewage from the immediate vicinity, or brought to the coast by the region's major rivers (Carter 1988). One of the more ironic sources of human coastal disturbance is that provided by those conducting beach surveys for nesting by endangered sea turtles. These surveys are conducted in spring and summer at night along several of the region's barrier-island beaches, usually by vehicles driven along the shore above high-tide line, destroying preferred nesting sites for beach-nesting shorebirds (e.g., Wilson's Plover, American Oystercatcher, Least Tern) (Rappole 1982).
Hunting—Destruction of wildlife populations for personal or market consumption is not currently a serious threat to North American vertebrate fauna, with the possible exception of the Black Scoter. However, hunting and trapping caused complete or near-complete extirpation of many Mid-Atlantic species during the 1800s and early 1900s. Eastern populations of some species decimated by hunting or trapping are recovering or have recovered (e.g., Snowy Egret, White-tailed Deer, American Beaver, Canada Goose); some, however, are extinct (e.g., Passenger Pigeon, Carolina Parakeet), regionally extirpated (e.g., Elk, Bison, Timber Wolf, Cougar, Whooping Crane, Trumpeter Swan), or have never fully recovered (e.g., Short-billed Dowitcher, Hudsonian Godwit, American Avocet).
Highland Forest and Bog Disappearance—In many parts of the Mid-Atlantic, boreal forest and bogs remain as scattered remnants of the most recent Ice Age, persisting only at higher elevations. Where these exist, they provide relatively isolated islands of habitat, home to unique assemblages of animals and plants that are quite vulnerable to disturbance. Several threats affect these habitats, including logging, acid rain, mining, spruce budworm, and wooly adelgid infestation (Little 1995), causing local disappearance of boreal wildlife communities. To these threats must now be added the influence of rapid global warming, which is likely to change the climate sufficiently in the next century to cause many remaining boreal sites in the Mid-Atlantic to be replaced by more temperate habitats (Matthews et al. 2004).
Conversion of Flood Plain Forest—Like boreal forest, flood plain forest is restricted in distribution by its very nature; although perhaps more like a peninsula or isthmus than an island, these are the aboriginal habitats lining the region's waterways (Küchler 1975). Often such sites present the richest soils for crops and timber products, as well as the most pleasant sites for recreational homes. As a result this habitat is threatened by logging and clearing for agriculture, and by residential development, in much of the Mid-Atlantic, threatening the natural communities associated with it as well (Noss et al. 1995).
Roosting/Breeding Cave Destruction and Disturbance—Like migratory birds, several bat species are dependent on widely separated areas and habitats at different times of the year. These localities are often caves where large portions of the known regional population of a species can be found in a relatively few sites. In addition to the normal kinds of disturbance threatening Mid-Atlantic habitats, e.g., pollution and development, bat caves are extremely vulnerable to simple human trespass. Spelunkers, visiting and exploring caves, can cause massive bat die-offs as a result of disturbing breeding mothers, forcing abandonment of newborn offspring (Tuttle 1979), or starvation of bats awakened from hibernation at winter roosts, causing depletion of precious fat stores (Brady et al. 1982).
Wetland Destruction or Pollution—Wetland communities are especially vulnerable, not only because they are highly prized for both residential and agricultural development, but also because the habitats that replace them are completely unsuitable for most community members. In addition, of course, wetlands can be made uninhabitable for wildlife by pollution as well, often occurring far from the site where the pollutants collect. As a result, wetland drainage and despoilation are among the most serious environmental problems in the United States in general, and the Mid-Atlantic in particular (Noss et al. 1995). As is clear from Table 1, more species are endangered by threats to this habitat type (81) than from any other single cause.
Control of Human, Crop, Livestock, or Fisheries Predators—Vertebrates that pose direct potential threats to human life, or to resources valued by humans, have been subjected to intense and extremely effective control measures in the past. Kercheval (1925) for instance, reported that 256 wolf heads were turned in for bounty in Augusta County, Virginia in 1750. Thus, Gray Wolves, Red Wolves, and Mountain Lions have long been extirpated from the Mid-Atlantic, while Timber Rattlesnake populations have been decimated. In addition, such predators on livestock and fisheries as Golden Eagle, Double-crested Cormorant, and Common Merganser continue to be persecuted in parts of their range.
Pet Trade Collecting—Some rare amphibians and reptiles are especially prized by collectors, who will not hesitate to pay large amounts for specimens. Wood Turtles, for instance, bring $35$200 per animal, and illegal collecting has resulted in complete extirpation of the species from several waterways (Hammerson 2003).
Landscape change is a part of natural history. Huge changes occurred during the last advance of the Wisconsin ice sheet into Pennsylvania 22,000 years ago and its subsequent retreat a few thousand years later (Sevon and Fleeger 1999). Vast regions of habitat stretching thousands of kilometers were completely obliterated or pushed southward hundreds of kilometers. Nevertheless, such changes are not quite the same as those resulting from the human effects discussed above. For one thing, anthropogenic changes can occur over a matter of decades rather than millennia; for another, they can be quite insidious and difficult to document, if, nonetheless, pervasive; and lastly, and perhaps most importantly, they are not inevitable. Once we know what effects we are having on our environment, we have a choice.
Meet the Author
John H. Rappole is a Research Scientist at the Smithsonian National Zoological Park's Conservation and Research Center. He is the author of twelve books, including Birds of the Mid-Atlantic Region and The Ecology of Migrant Birds.
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