As the Paleozoic Era gave way to the Mesozoic, some 225 million years ago (MYA), an ovoid upwarping of Earth's crust developed in what is now northern Arizona. Reinforced during the Laramide Orogeny (the formation of the Rockies, 70 MYA), this broad ridge was eventually covered by layers of Mesozoic and Tertiary sediments (both erosional and volcanic). Late in the Tertiary Period, the Miocene-Pliocene Uplift (stretching from about 15-5 MYA) lifted the entire Colorado Plateau and its rim of mountain ranges another 5000 feet, increasing stream erosion across the Province. Rising on the west side of the Continental Divide, the Colorado River flowed westward and gradually southward to enter the Sea of Cortez; en route, it crossed northern Arizona, entrenched in the younger sediments that covered the Kaibab-Coconino ridge. As the Colorado Plateau rose beneath it, the river was forced to cut down through this ridge of Paleozoic rock (and the upper layer of the ancient Precambrian basement that lies beneath it). Augmented by the wet climate of the Pleistocene (2 to 0.01 MYA), the Colorado thereby sculpted the Grand Canyon, the most spectacular chasm on our planet.
The ridge itself, oriented NNW to SSE, has since been uncovered by erosion. Streams from its eastern edge drain directly into the Colorado (or into the Little Colorado south of the Grand Canyon), while its northwest flank drains to the Colorado via Kaibab Creek and its southwest flank feeds the Cataract River, another tributary of the Colorado. The exposed ridge is composed primarily of Kaibab limestone overlying Coconino sandstone; that portion north of the Grand Canyon is known as the Kaibab Plateau while its segment south of the Canyon is referred to as the Coconino Plateau. The rock strata of the plateau, deposited during the Permian Period, form the upper layers of the Grand Canyon
The Kaibab Plateau rises to elevations that exceed 9200 feet, supporting a rich forest of fir, spruce and aspen, giving way to ponderosa pine and then pinon-juniper woodlands at lower elevations. The Coconino Plateau is 7400 feet above sea level at the south rim of the Grand Canyon and gradually lowers toward the west, south and east; it is covered primarily by ponderosa pine parklands. South of the Coconino Plateau, the landscape is dominated by the high peaks and scattered cones of the San Francisco Volcanic Field, including Humphreys Peak (12,633 feet), the highest point in Arizona.
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Kamis, 12 Juli 2012
Selasa, 10 Juli 2012
Front Range Oasis
While those of us who live along the Colorado Front Range enjoy abundant sunshine and a mild, semiarid climate, there is plenty of aquatic habitat along the urban corridor. One of the best places to observe water-loving birds and mammals is South Platte Park, which stretches across the river's floodplain from the northern edge of Chatfield Reservoir State Park to the outskirts of downtown Littleton. A mosaic of ponds, lakes, wetlands, meadows and riparian woodlands, the Park is accessed by a paved bikeway, its parallel walking path and a number of adjoining trail loops. An Interpretive Center, west of Santa Fe Drive and north of Mineral, introduces visitors to the varied fauna and flora of the Park.
On this mild, clear morning, the refuge was teeming with birds, including many that non-Coloradans might not associate with our State. A dozen American white pelicans moved among the lakes or fished in the shallows, joined by a large number of double-crested cormorants, scattered great blue herons, a pair of snowy egrets, a flotilla of common mergansers, noisy flocks of Canada geese and a varied assortment of ducks (primarily mallards, gadwall and wood ducks). Tree and barn swallows swooped above the ponds, a Swainson's hawk circled overhead, belted kingfishers chattered along the river and a wide assortment of songbirds moved among the trees and cattails; these included yellow warblers, common yellowthroats, American and lesser goldfinches, western wood pewees, northern orioles, house wrens, northern flickers, downy woodpeckers and those ever-vocal red-winged blackbirds. A lone black-crowned night heron, spooked from his shadowy haunt, was my final sighting of the morning.
Though represented only by fox squirrels, cottontails and black-tailed prairie dogs this morning, a variety of mammals also inhabit the Park and are best seen at dawn or dusk. Among these residents are mule and white-tailed deer, red fox, coyotes, beaver, muskrats, raccoons, striped skunks, meadow voles and deer mice; mountain lions and black bear are potential visitors but are rarely encountered.
On this mild, clear morning, the refuge was teeming with birds, including many that non-Coloradans might not associate with our State. A dozen American white pelicans moved among the lakes or fished in the shallows, joined by a large number of double-crested cormorants, scattered great blue herons, a pair of snowy egrets, a flotilla of common mergansers, noisy flocks of Canada geese and a varied assortment of ducks (primarily mallards, gadwall and wood ducks). Tree and barn swallows swooped above the ponds, a Swainson's hawk circled overhead, belted kingfishers chattered along the river and a wide assortment of songbirds moved among the trees and cattails; these included yellow warblers, common yellowthroats, American and lesser goldfinches, western wood pewees, northern orioles, house wrens, northern flickers, downy woodpeckers and those ever-vocal red-winged blackbirds. A lone black-crowned night heron, spooked from his shadowy haunt, was my final sighting of the morning.
Though represented only by fox squirrels, cottontails and black-tailed prairie dogs this morning, a variety of mammals also inhabit the Park and are best seen at dawn or dusk. Among these residents are mule and white-tailed deer, red fox, coyotes, beaver, muskrats, raccoons, striped skunks, meadow voles and deer mice; mountain lions and black bear are potential visitors but are rarely encountered.
Jumat, 06 Juli 2012
Colorado's Black Canyon
Near the end of the Mesozoic Era, as the Cretaceous Sea retreated to the southeast, Colorado was a relatively flat landscape of wetlands, sandhills and primitive forest. Then, about 70 million years ago (MYA), pressure within the North American craton crumpled up the Rocky Mountains, pushing ancient Precambrian rock up through the overlying Paleozoic and Mesozoic sediments.
As soon as they formed, the forces of erosion began to act on these new mountains, filling the intervening valleys with debris. About 35 MYA, volcanism developed in central and southwestern Colorado, lifting the West Elk and San Juan Mountains; the copious ash, pumice and lava from these eruptions also coated the valleys and basins of that region. By 10 MYA, the Gunnison River had formed; rising on the west side of the Continental Divide, in the Sawatch Range, and receiving large tributaries from the West Elk Mountains, to its north, and the San Juans, to its south, this river flowed west to join the Colorado. Entrenched within the erosional and volcanic debris that had settled across the broad, intervening basin, the Gunnison was forced to cut into a ridge of Precambrian gneiss and schist, east of present day Montrose, that was buried within the sediments. Since that time, the river has sculpted the Black Canyon of the Gunnison from that ancient rock, a process that was augmented during the cooler, wetter climate of the Pleistocene.
Almost 50 miles in length, the Black Canyon is up to 2720 feet deep and 1100 feet across at its rim; at river level, it is much narrower, only 40 feet wide in one area. The Painted Wall, on the north flank of Black Canyon, is named for the light-colored lava rock that laces its surface and is the tallest cliff in Colorado, dropping 2250 feet. Within the canyon, the Gunnison River drops 43 feet per mile, a grade that is almost six times steeper than the Colorado River's course within the Grand Canyon. Named for its shaded walls, hidden from the sun by its deep and narrow topography, the Black Canyon of the Gunnison is protected within a National Park that stretches along its middle (and most spectacular) 14 miles. Farther west, the Gunnison is thought to have carved Unaweep Canyon through the Uncompahgre Plateau, later diverted northward by a landslide to join the Colorado west of Grand Junction (see my blog on 12-27-10).
As soon as they formed, the forces of erosion began to act on these new mountains, filling the intervening valleys with debris. About 35 MYA, volcanism developed in central and southwestern Colorado, lifting the West Elk and San Juan Mountains; the copious ash, pumice and lava from these eruptions also coated the valleys and basins of that region. By 10 MYA, the Gunnison River had formed; rising on the west side of the Continental Divide, in the Sawatch Range, and receiving large tributaries from the West Elk Mountains, to its north, and the San Juans, to its south, this river flowed west to join the Colorado. Entrenched within the erosional and volcanic debris that had settled across the broad, intervening basin, the Gunnison was forced to cut into a ridge of Precambrian gneiss and schist, east of present day Montrose, that was buried within the sediments. Since that time, the river has sculpted the Black Canyon of the Gunnison from that ancient rock, a process that was augmented during the cooler, wetter climate of the Pleistocene.
Almost 50 miles in length, the Black Canyon is up to 2720 feet deep and 1100 feet across at its rim; at river level, it is much narrower, only 40 feet wide in one area. The Painted Wall, on the north flank of Black Canyon, is named for the light-colored lava rock that laces its surface and is the tallest cliff in Colorado, dropping 2250 feet. Within the canyon, the Gunnison River drops 43 feet per mile, a grade that is almost six times steeper than the Colorado River's course within the Grand Canyon. Named for its shaded walls, hidden from the sun by its deep and narrow topography, the Black Canyon of the Gunnison is protected within a National Park that stretches along its middle (and most spectacular) 14 miles. Farther west, the Gunnison is thought to have carved Unaweep Canyon through the Uncompahgre Plateau, later diverted northward by a landslide to join the Colorado west of Grand Junction (see my blog on 12-27-10).
Senin, 25 Juni 2012
The Lena River Delta
On satellite imagery, the Lena River Delta on the northern coast of Siberia gives the appearance of a fan coral, its braided channels and numerous lakes forming an intricate pattern across the Arctic tundra. It is this landscape of countless pools and waterways that attracts huge congregations of loons, grebes, shorebirds and waterfowl to this 11,600 square mile wetland to nest and raise their young during the brief Arctic summer.
The Lena River, the second largest stream in Siberia, rises a few miles west of Lake Baikal, flowing northward and gradually eastward for 2700 miles to its delta on the Laptev Sea. There it delivers tons of sediment each year, gradually enlarging and enriching the delta which is also an important spawining area for Arctic fish. Nesting birds of note include red-necked grebes, four species of loon, whooper and tundra swans, bean geese, black brant, king and Steller's eiders, long-tailed ducks, Ross's and Sabine's gulls and numerous shorebird species. Of course, willow grouse, rock ptarmigan, snowy owls, peregrine falcons and a wide variety of Arctic songbirds also inhabit the delta. Resident mammals include gray wolves, Arctic fox, wolverines, least weasels, stoats, lemmings, tundra voles and reindeer; beluga whales, walruses and a variety of seals often visit the area.
Fortunately, most of this vast tundra wetland is protected within the Lena River Delta Nature Reserve, the largest nature preserve in Russia. Visited only by the most adventurous naturalists, this spectacular but remote site is relatively free of human disturbance; nevertheless, the Lena, like all rivers on our planet, is tainted by pollutants from agriculture, mining, industry and sewage and their long term effects on the delta ecosystem is yet to be determined.
The Lena River, the second largest stream in Siberia, rises a few miles west of Lake Baikal, flowing northward and gradually eastward for 2700 miles to its delta on the Laptev Sea. There it delivers tons of sediment each year, gradually enlarging and enriching the delta which is also an important spawining area for Arctic fish. Nesting birds of note include red-necked grebes, four species of loon, whooper and tundra swans, bean geese, black brant, king and Steller's eiders, long-tailed ducks, Ross's and Sabine's gulls and numerous shorebird species. Of course, willow grouse, rock ptarmigan, snowy owls, peregrine falcons and a wide variety of Arctic songbirds also inhabit the delta. Resident mammals include gray wolves, Arctic fox, wolverines, least weasels, stoats, lemmings, tundra voles and reindeer; beluga whales, walruses and a variety of seals often visit the area.
Fortunately, most of this vast tundra wetland is protected within the Lena River Delta Nature Reserve, the largest nature preserve in Russia. Visited only by the most adventurous naturalists, this spectacular but remote site is relatively free of human disturbance; nevertheless, the Lena, like all rivers on our planet, is tainted by pollutants from agriculture, mining, industry and sewage and their long term effects on the delta ecosystem is yet to be determined.
Jumat, 22 Juni 2012
Australia's Great Basin
The Lake Eyre Basin of east-central Australia is a vast topographic bowl within which streams drain toward the lowest part of the basin, never reaching the sea. Covering 440,000 square miles from southwestern Queensland to South Australia and from the southeastern corner of the Northern Territory to the northwestern edge of New South Wales, most of it is dry, desert landscape through which ephemeral streams lead to Lake Eyre, in the southwest corner of the Basin. Nearly dry and coated with salt flats most of the time, the lake fills only twice each Century (on average); composed of a large northern basin connected to a smaller southern basin by the Goyder Channel, Lake Eyre covers 3700 square miles and has an average depth of less than 10 feet (when full) The lowest point of the lake basin, in Belt Bay of the northern portion, is 50 feet below sea level while the rim of the lake is 30 feet below the level of the sea.
The Lake Eyre Basin began to form about 200 million years ago, when Australia was part of Gondwanaland. Tectonic forces caused the crust of this region to subside and, within another 100 million years, an arm of the sea invaded the basin; when uplift occurred along the northern and eastern margins of the basin, the sea drained away and rivers flowed across the region, depositing sediments on their way to the ocean. During the middle of the Pleistocene, about 1 million years ago, uplift along the southern rim closed off the basin and all streams fed Lake Diers, the much larger predecessor of Lake Eyre (as Lake Bonneville preceded the Great Salt Lake in the U.S.). As the climate became warmer and drier late in the Pleistocene and into the Holocene, the flow through the rivers diminished and eventually became sporadic. Today, what little water reaches the lake is via three primary river systems: the Georgina River from the north, the Diamantia River from the northeast and Cooper Creek from the east. Most streams from the west and northwest dry up before reaching Lake Eyre.
During those rare periods when monsoon rains or tropical storms fill Lake Eyre, this remote oasis attracts huge flocks of shorebirds, terns and Australian Pelicans that nest on the islands and feed in the shallows; how these birds know that the distant lake is full remains a mystery. Lake Eyre National Park stretches along the east shore of the northern lake, just a short 435 mile drive north from Adelaide. Major towns within the Lake Eyre Basin include Alice Springs, Mt. Isa, Longreach and Broken Hill.
Selasa, 19 Juni 2012
The Congo River
Almost 3000 miles long and second only to the Amazon in its annual flow volume, the Congo River curves counterclockwise through the Democratic Repbulic of the Congo, taking in tributaries from a watershed that exceeds 1.5 million square miles. The Upper Congo, known as the Lualaba River, receives the Luvua River from Lake Mweru, on the Zambian border, and flows northward, gathering the waters of other streams from Lake Tanganyika, to its east. Alternately placid and turbulent, the Lualaba reaches Kisangani following a sixty mile course of rapids known as Boyoma Falls (formerly Stanley Falls).
From Kisangani to Kinshasa, at the west end of the Malebo Pool, the 1000 mile stretch of the Middle Congo is wide and navigable, receiving large tributaries such as the Lomami, from the south, the Aruwimi, from the east, and the Ubangi, from the northeast; just upstream from the calm, deep Malebo Pool, the Kasai River enters from the southeast. Below Kinshasa, Livingston Falls, 90 miles of rapids and cataracts, make the Congo unpassable once again; to bypass this stretch, the Matadi-Kinshasa Railway was constructed in the 1890s. From Matadi to the Atlantic Ocean, the river is broad and navigable and its braided delta begins just west of Boma; the Congo's total elevation drop, from Lake Mweru to this delta, is just over 3000 feet.
Crossing the equator twice and winding through the second largest tropical rainforest on our planet, the Congo evokes a sense of adventure, mystery and hidden danger. Long before humans tainted its name with the atrocities of colonialism and slavery, this mighty river nourished and cleansed the Heart of Africa, connecting its lush savannas and dense forests to the distant sea; that role will surely continue long after we have plundered the natural bounty of our native Continent.
From Kisangani to Kinshasa, at the west end of the Malebo Pool, the 1000 mile stretch of the Middle Congo is wide and navigable, receiving large tributaries such as the Lomami, from the south, the Aruwimi, from the east, and the Ubangi, from the northeast; just upstream from the calm, deep Malebo Pool, the Kasai River enters from the southeast. Below Kinshasa, Livingston Falls, 90 miles of rapids and cataracts, make the Congo unpassable once again; to bypass this stretch, the Matadi-Kinshasa Railway was constructed in the 1890s. From Matadi to the Atlantic Ocean, the river is broad and navigable and its braided delta begins just west of Boma; the Congo's total elevation drop, from Lake Mweru to this delta, is just over 3000 feet.
Crossing the equator twice and winding through the second largest tropical rainforest on our planet, the Congo evokes a sense of adventure, mystery and hidden danger. Long before humans tainted its name with the atrocities of colonialism and slavery, this mighty river nourished and cleansed the Heart of Africa, connecting its lush savannas and dense forests to the distant sea; that role will surely continue long after we have plundered the natural bounty of our native Continent.
Senin, 18 Juni 2012
Missisquoi NWR
As heat and humidity grip much of the country over the next few months, those of us in the Midwest and Southeast will look for escapes to cooler, northern climes. For naturalists, one option is a visit to Missisquoi National Wildlife Refuge, in northwest Vermont.
The Missisquoi River rises in the uplands of northeast Vermont, loops westward through southern Canada and then returns to Vermont to enter Lake Champlain along its northeastern shore. There it has created a delta of marshlands, channels, mudflats and islets, providing ideal nesting and feeding grounds for migrant and resident waterfowl, shorebirds, waders, rails and wetland songbirds. Established in 1943, the Missisquoi NWR now protects the delta, the adjacent Big Marsh Slough and parcels of northern forest. At least 300 species of birds visit the refuge throughout the year and nesting species include ospreys, great blue herons, least bitterns, black terns, common goldeneyes, soras and Virginia rails, among many others.
Missisquoi NWR is located NNW of Swanton, Vermont, which is just west of I-89 (Exit 21). Like most of our National Wildlife Refuges, it is accessible from dawn to dusk every day of the year; the refuge Visitor Center is open M-F and most Saturdays from mid May through October. Adventurous visitors might want to rent a canoe in Swanton and explore the refuge marshlands from the cool waters of Lake Champlain.
The Missisquoi River rises in the uplands of northeast Vermont, loops westward through southern Canada and then returns to Vermont to enter Lake Champlain along its northeastern shore. There it has created a delta of marshlands, channels, mudflats and islets, providing ideal nesting and feeding grounds for migrant and resident waterfowl, shorebirds, waders, rails and wetland songbirds. Established in 1943, the Missisquoi NWR now protects the delta, the adjacent Big Marsh Slough and parcels of northern forest. At least 300 species of birds visit the refuge throughout the year and nesting species include ospreys, great blue herons, least bitterns, black terns, common goldeneyes, soras and Virginia rails, among many others.
Missisquoi NWR is located NNW of Swanton, Vermont, which is just west of I-89 (Exit 21). Like most of our National Wildlife Refuges, it is accessible from dawn to dusk every day of the year; the refuge Visitor Center is open M-F and most Saturdays from mid May through October. Adventurous visitors might want to rent a canoe in Swanton and explore the refuge marshlands from the cool waters of Lake Champlain.
Minggu, 17 Juni 2012
Glacial Lake Souris
Near the end of the Pleistocene, 10-15,000 years ago, large meltwater lakes formed along the retreating edge of the Continental Ice Sheet. One of these, Lake Souris, extended from north-central North Dakota into Manitoba, intermittently connecting with Glacial Lake Agassiz, to its east.
All of these lakes expanded and contracted depending upon their interconnections, the regional climate and the rate of meltwater production. Dammed by tongues of ice or moraines of glacial debris, some would occasionally break through their retaining wall, sending a torrent of water across the flat landscape of the Northern Plains. One such event involved Glacial Lake Regina of southern Saskatchewan, which flooded southeastward into Lake Souris; the broad, shallow channels of this flood remain evident today and are partly occupied by the Upper Souris River and its major tributary, the Des Lacs River.
East of Minot, the Souris River now enters the former lake bed of Glacial Lake Souris, following it north and gradually eastward to merge with the Assiniboine River of southern Manitoba; Lake Souris, itself, eventually drained into Lake Agassiz, which contracted into Lake Winnepeg after drainage opened to the north. National Wildlife Refuges now line the Des Lacs and Souris Rivers which, as we saw last summer, may still flood across the Pleistocene channels and lake beds when a deep winter snowpack is followed by heavy spring rains.
All of these lakes expanded and contracted depending upon their interconnections, the regional climate and the rate of meltwater production. Dammed by tongues of ice or moraines of glacial debris, some would occasionally break through their retaining wall, sending a torrent of water across the flat landscape of the Northern Plains. One such event involved Glacial Lake Regina of southern Saskatchewan, which flooded southeastward into Lake Souris; the broad, shallow channels of this flood remain evident today and are partly occupied by the Upper Souris River and its major tributary, the Des Lacs River.
East of Minot, the Souris River now enters the former lake bed of Glacial Lake Souris, following it north and gradually eastward to merge with the Assiniboine River of southern Manitoba; Lake Souris, itself, eventually drained into Lake Agassiz, which contracted into Lake Winnepeg after drainage opened to the north. National Wildlife Refuges now line the Des Lacs and Souris Rivers which, as we saw last summer, may still flood across the Pleistocene channels and lake beds when a deep winter snowpack is followed by heavy spring rains.
Sabtu, 16 Juni 2012
The Flathead River
The Flathead River of northwest Montana rises via three primary forks. The North Fork heads in the mountains of southeast British Columbia and then flows south along the western edge of Glacier National Park. The Middle Fork rises in the Rocky Mountains, northwest of Great Falls, winding northwest and then westward to join the North Fork. The South Fork also rises in the Rockies, more directly west of Great Falls, and flows NNW, where it enters Hungry Horse Reservoir before merging with the combined North and Middle Forks. The primary channel of the Flathead River then enters the Rocky Mountain Trench, a broad valley formed by downwarping of the crust as mountains rose to its east and later occupied by Pleistocene glaciers. Flowing southwestward and then southward, the river passes Kalispell, Montana, and enters Flathead Lake; the Stillwater, Whitefish and Swan Rivers also feed the lake.
The largest natural freshwater lake (by area) in the western Lower 48, Flathead Lake initially formed from glacial meltwater behind a terminal moraine that was deposited late in the Pleistocene; the lake valley was also inundated by Glacial Lake Missoula as it expanded and retreated 30-15,000 years ago (see my blog on 4-2-12). Exiting the southwest corner of its lake, the Flathead River snakes southward across a landscape of plateaus and ridges before flowing westward through a rugged canyon to join the Clark Fork River.
The upper forks of the Flathead have all been designated National Wild & Scenic Rivers and are among the most remote and least disturbed streams in our country. Nevertheless, the North Fork faced possible contamination from proposed coal mining and gas production in southeastern British Columbia over the past few decades; fortunately, an agreement between the U.S. and Canada has, for now, blocked that "development."
The largest natural freshwater lake (by area) in the western Lower 48, Flathead Lake initially formed from glacial meltwater behind a terminal moraine that was deposited late in the Pleistocene; the lake valley was also inundated by Glacial Lake Missoula as it expanded and retreated 30-15,000 years ago (see my blog on 4-2-12). Exiting the southwest corner of its lake, the Flathead River snakes southward across a landscape of plateaus and ridges before flowing westward through a rugged canyon to join the Clark Fork River.
The upper forks of the Flathead have all been designated National Wild & Scenic Rivers and are among the most remote and least disturbed streams in our country. Nevertheless, the North Fork faced possible contamination from proposed coal mining and gas production in southeastern British Columbia over the past few decades; fortunately, an agreement between the U.S. and Canada has, for now, blocked that "development."
Sabtu, 09 Juni 2012
Dry Rivers on the High Plains
Most of the rivers that cross the High Plains of the American West would hardly be recognized as creeks farther to the east. While the primary rivers that rise in the mountains, including the Missouri, Yellowstone, Platte and Arkansas Rivers deserve their title, many of the smaller rivers, heading on the High Plains Province itself, are dry for much of the year, transmitting water only after episodes of torrential rain or rapid snowmelt. Among these sandy channels are the upper tributaries of the Niobrara, Republican and Smokey Hill watersheds.
Cut off from Pacific moisture by the Continental Divide and located far from the Gulf of Mexico, the High Plains only receive copious precipitation when powerful storms draw in moisture laden air from the east, events that most often occur from February through June; indeed, this geophysical province receives less than 20 inches of precipitation each year. Yet, if we study the High Plains topography, we find that these meager conduits have managed to carve ridges, hills and valleys from the otherwise level plain, suggesting that they were more substantial streams in the past. In fact, during the Pleistocene Epoch (2 million to 10 thousand years ago) the regional climate was much cooler and wetter, giving rise to rivers that, in today's climate, have withered to channels of sand, prairie grass and scattered stands of cottonwood trees.
As with other ecosystems across our globe, it is impossible to understand the current geography without an appreciation for natural history and the region's underlying geology. In the case of the American High Plains, Pleistocene rivers sculpted the Tertiary deposits and underlying Cretaceous Sea sediments into the landscape that we find today; feeble and intermittent streams now occupy the valleys that those rivers left behind.
Cut off from Pacific moisture by the Continental Divide and located far from the Gulf of Mexico, the High Plains only receive copious precipitation when powerful storms draw in moisture laden air from the east, events that most often occur from February through June; indeed, this geophysical province receives less than 20 inches of precipitation each year. Yet, if we study the High Plains topography, we find that these meager conduits have managed to carve ridges, hills and valleys from the otherwise level plain, suggesting that they were more substantial streams in the past. In fact, during the Pleistocene Epoch (2 million to 10 thousand years ago) the regional climate was much cooler and wetter, giving rise to rivers that, in today's climate, have withered to channels of sand, prairie grass and scattered stands of cottonwood trees.
As with other ecosystems across our globe, it is impossible to understand the current geography without an appreciation for natural history and the region's underlying geology. In the case of the American High Plains, Pleistocene rivers sculpted the Tertiary deposits and underlying Cretaceous Sea sediments into the landscape that we find today; feeble and intermittent streams now occupy the valleys that those rivers left behind.
Jumat, 08 Juni 2012
Rock Squirrels on the Piedmont
Rock squirrels have long been common residents of canyons throughout central and western Colorado and of the varied rock formations that rise along the base of the Front Range foothills. Our largest ground squirrel is easily recognized by his attractive salt-and-pepper coat and his large bushy tail. Most often seen lounging on rocks early or late in the day, these omnivores consume a wide variety of plant materials (nuts, fruits, vegetation) in addition to insects, carrion, bird eggs and even small mammals on occasion. Two litters are produced each year (mid spring and late summer) and, though they retire to their dens for most of the winter, they store food and are not true hibernators, becoming active during periods of mild weather.
Over the past few decades, rock squirrels have ventured onto the Colorado Piedmont and High Plains, following river channels from their original homeland in the foothills and lower mountains. Their expansion has been well documented along the Cache la Poudre River, in northern Colorado, and along the Arkansas River, from Pueblo all the way to the Kansas border. In all of my years hiking along the South Platte, I had not encountered rock squirrels until this week, when I saw a pair at the major rapids area in South Platte Park (just east of the golf course).
Though I am not familiar with scientific studies regarding their dispersal, I suspect that rock squirrels are spreading eastward due to both opportunism and human encroachment on their native habitat. Suburbs have increasingly pushed into the areas just west of the Dakota Hogback as well as along the primary canyons that incise the foothills. In addition, we humans have lined our river channels with rocky embankments, protecting our homes while producing new living quarters for the rock squirrels. Of course, over time, their presence becomes a nuisance as their digging and foraging creates havoc for human engineers and gardeners; once viewed as fascinating residents of our foothill parks, they are now despised as invasive varmints to be trapped or killed.
Over the past few decades, rock squirrels have ventured onto the Colorado Piedmont and High Plains, following river channels from their original homeland in the foothills and lower mountains. Their expansion has been well documented along the Cache la Poudre River, in northern Colorado, and along the Arkansas River, from Pueblo all the way to the Kansas border. In all of my years hiking along the South Platte, I had not encountered rock squirrels until this week, when I saw a pair at the major rapids area in South Platte Park (just east of the golf course).
Though I am not familiar with scientific studies regarding their dispersal, I suspect that rock squirrels are spreading eastward due to both opportunism and human encroachment on their native habitat. Suburbs have increasingly pushed into the areas just west of the Dakota Hogback as well as along the primary canyons that incise the foothills. In addition, we humans have lined our river channels with rocky embankments, protecting our homes while producing new living quarters for the rock squirrels. Of course, over time, their presence becomes a nuisance as their digging and foraging creates havoc for human engineers and gardeners; once viewed as fascinating residents of our foothill parks, they are now despised as invasive varmints to be trapped or killed.
Selasa, 05 Juni 2012
Front Range Drought
Following a lackluster snow season and spotty rain throughout the spring, Colorado's Front Range is tinder dry and wildfires have become a significant problem, especially for residents of foothill communities. Over the past two days, the fire risk has increased dramatically as hot, dry, southeast winds have raked the area; while the humidity has increased a bit with this upsloping wind flow, little precipitation has developed and "dry thunderstorms" threaten to ignite more fires.
Along the urban corridor, the winds are producing a welcome "wind-chill," making the mid afternoon heat feel less intense than it might on a calm day. A stroll along the South Platte revealed water levels lower than I have encountered in many years; with much of its flow diverted for irrigation and water supply, the shallow river attests to the ongoing drought in much of the State. On the positive side, the sluggish stream attracted a variety of birds from the parched fields and woodlands, including yellow warblers, belted kingfishers, spotted sandpipers, killdeer, swallows, great blue herons and mother ducks (mallards and wood ducks) with their broods in tow.
There is some hope that the gusty, upsloping winds will produce showers and thunderstorms overnight but, even if they do, a widespread, soaking rain is not expected. As often occurs along the Front Range, the precipitation will be spotty in nature, with some areas enjoying a cloudburst and others left in the windblown dust. In reality, a significant break from our ongoing drought will probably not occur until the late summer Monsoon pumps moisture up from the Desert Southwest. Let's hope that annual relief arrives early, rescuing the Front Range from what appears to be a destructive wildfire season.
Along the urban corridor, the winds are producing a welcome "wind-chill," making the mid afternoon heat feel less intense than it might on a calm day. A stroll along the South Platte revealed water levels lower than I have encountered in many years; with much of its flow diverted for irrigation and water supply, the shallow river attests to the ongoing drought in much of the State. On the positive side, the sluggish stream attracted a variety of birds from the parched fields and woodlands, including yellow warblers, belted kingfishers, spotted sandpipers, killdeer, swallows, great blue herons and mother ducks (mallards and wood ducks) with their broods in tow.
There is some hope that the gusty, upsloping winds will produce showers and thunderstorms overnight but, even if they do, a widespread, soaking rain is not expected. As often occurs along the Front Range, the precipitation will be spotty in nature, with some areas enjoying a cloudburst and others left in the windblown dust. In reality, a significant break from our ongoing drought will probably not occur until the late summer Monsoon pumps moisture up from the Desert Southwest. Let's hope that annual relief arrives early, rescuing the Front Range from what appears to be a destructive wildfire season.
Senin, 21 Mei 2012
River Relief
Those of us who frequently travel across the Great Plains or the Glaciated Plain of the Upper Midwest are usually glad to encounter river valleys, which break the monotony of the flat terrain. In these areas, the primary channel and its tributaries have carved a mosaic of hills, ridges and valleys from the plain, necessitating dips and curves in the route of our journey.
Beyond the topographic relief, these river valleys harbor rich, moist soil, supporting a wide variety of vegetation, offering a sharp contrast from the cropfields, grasslands and sparse woodlands of the adjacent plains. Visually appealing to human travelers, these corridors also attract regional wildlife that utilize them to nest, roost, feed or to escape the harsh conditions on the plain. Indeed, naturalists know that wildlife viewing is significantly more productive along these ribbons of life than it is on the flat terrain that surrounds them; even open-country species tend to congregate near river valleys, a vital source of water and cover.
Of course, river corridors also appeal to those of us who take an interest in regional topography, providing insight into the evolution of Earth's landscape. Unless one is a robotic traveler, oblivious to the environment through which they move, rivers, like mountain ranges and lakes, give us a sense of place and direction, a natural perspective by which to gauge our progress.
Beyond the topographic relief, these river valleys harbor rich, moist soil, supporting a wide variety of vegetation, offering a sharp contrast from the cropfields, grasslands and sparse woodlands of the adjacent plains. Visually appealing to human travelers, these corridors also attract regional wildlife that utilize them to nest, roost, feed or to escape the harsh conditions on the plain. Indeed, naturalists know that wildlife viewing is significantly more productive along these ribbons of life than it is on the flat terrain that surrounds them; even open-country species tend to congregate near river valleys, a vital source of water and cover.
Of course, river corridors also appeal to those of us who take an interest in regional topography, providing insight into the evolution of Earth's landscape. Unless one is a robotic traveler, oblivious to the environment through which they move, rivers, like mountain ranges and lakes, give us a sense of place and direction, a natural perspective by which to gauge our progress.
Minggu, 20 Mei 2012
Vulture Heaven at Eagle Bluffs
As a consequence of the lowest water levels that I have ever encountered at Eagle Bluffs Conservation Area, dead carp lined the central channel, providing a feast for numerous turkey vultures. Usually seen soaring above the countryside, these large scavengers had gathered on the mudflats and levees to partake in the bounty of rotting fish.
Of course, the low water was also beneficial to great blue herons, great egrets and green-backed herons, concentrating their prey in the shallow pools. Other highlights included a large number of wood ducks, the attentive females ushering their broods across the calm waters, and an unusual abundance of migrant shorebirds for late May. Cormorants and diving ducks were noticeably absent but small groups of coot, blue-winged teal and mallards plied the shallows or huddled on the shorelines. Throughout the evening, a steady background chorus was provided by bullfrogs, green frogs, cricket frogs, killdeer and indigo buntings as white-tailed deer emerged from the woods to browse the marshlands and crop fields.
Since the Missouri River is still fairly high, I suspect that the low water at Eagle Bluffs reflects an artificial drawdown, often utilized to mimic natural fluctuations that foster the welfare of native floodplain vegetation while discouraging the invasion of alien species. Whatever the cause, the drought-like conditions surely favor the hunters and scavengers; for the time being, it's vulture heaven at Eagle Bluffs.
Of course, the low water was also beneficial to great blue herons, great egrets and green-backed herons, concentrating their prey in the shallow pools. Other highlights included a large number of wood ducks, the attentive females ushering their broods across the calm waters, and an unusual abundance of migrant shorebirds for late May. Cormorants and diving ducks were noticeably absent but small groups of coot, blue-winged teal and mallards plied the shallows or huddled on the shorelines. Throughout the evening, a steady background chorus was provided by bullfrogs, green frogs, cricket frogs, killdeer and indigo buntings as white-tailed deer emerged from the woods to browse the marshlands and crop fields.
Since the Missouri River is still fairly high, I suspect that the low water at Eagle Bluffs reflects an artificial drawdown, often utilized to mimic natural fluctuations that foster the welfare of native floodplain vegetation while discouraging the invasion of alien species. Whatever the cause, the drought-like conditions surely favor the hunters and scavengers; for the time being, it's vulture heaven at Eagle Bluffs.
Jumat, 18 Mei 2012
Superior's Northwest Coast
Just north of downtown Duluth, Interstate 35 ends and becomes Minnesota Route 61 that hugs the northwest coast of Lake Superior, all the way to the Canadian border. Providing spectacular and ever-changing views of the lake, this road also yields access to a chain of State Parks, most of which surround rivers that rise in the hill country to the west and rumble down to Lake Superior.
A few of these Parks deserve special mention. Gooseberry River State Park, a few miles north of Two Harbors, is accessed by an excellent network of trails that lead past a series of beautiful waterfalls, lead out to cliff-top views of the lake and river valley or take the visitor down to the rocky shore. Temperance River State Park, just north of Taconic Harbor, provides spectacular evidence of the erosive force of moving water; this turbulent stream has cut a deep, rugged gorge through the Precambrian volcanic bedrock, producing waterfalls, whirlpools and polished rock formations. Just shy of the Canadian border, Grand Portage State Park, stretching along the Pigeon River, provides access to Pigeon River Falls, the highest waterfall in Minnesota (120 feet). Finally, a scenic rest-stop, a few miles north of the town of Grand Portage, offers an awe-inspiring view of Lake Superior, its coastal hills, the offshore Susie Islands and the distant silhouette of Isle Royale, stretching across the northeastern horizon.
While towns, marinas, resorts and industrial ports are also spaced along Superior's Northwest Coast, they do not begin to detract from its fabulous natural landscape and the abundance of State Parks, State Forests and dedicated Wilderness could keep any naturalist entertained for months, if not years. Our only regret is that we had too little time to explore that scenic wonderland.
A few of these Parks deserve special mention. Gooseberry River State Park, a few miles north of Two Harbors, is accessed by an excellent network of trails that lead past a series of beautiful waterfalls, lead out to cliff-top views of the lake and river valley or take the visitor down to the rocky shore. Temperance River State Park, just north of Taconic Harbor, provides spectacular evidence of the erosive force of moving water; this turbulent stream has cut a deep, rugged gorge through the Precambrian volcanic bedrock, producing waterfalls, whirlpools and polished rock formations. Just shy of the Canadian border, Grand Portage State Park, stretching along the Pigeon River, provides access to Pigeon River Falls, the highest waterfall in Minnesota (120 feet). Finally, a scenic rest-stop, a few miles north of the town of Grand Portage, offers an awe-inspiring view of Lake Superior, its coastal hills, the offshore Susie Islands and the distant silhouette of Isle Royale, stretching across the northeastern horizon.
While towns, marinas, resorts and industrial ports are also spaced along Superior's Northwest Coast, they do not begin to detract from its fabulous natural landscape and the abundance of State Parks, State Forests and dedicated Wilderness could keep any naturalist entertained for months, if not years. Our only regret is that we had too little time to explore that scenic wonderland.
Selasa, 15 Mei 2012
Western Lake Superior
Facing an off-week and yearning to get back to the North Country after our memorable journey across the Upper Peninsula of Michigan, last September, my wife and I decided to head for western Lake Superior. We left Columbia yesterday afternoon, driving north across the Glaciated Plain of northern Missouri and eastern Iowa, stopping for the night in Iowa City. This morning, we resumed our journey, dropping into the Mississippi Valley at Marquette, Iowa, and then paralleling the broad river and its wooded islands along the Wisconsin (eastern) shore. Scenic bluffs rise along both sides of the Mississippi Valley in this "Driftless Area" of the Upper Midwest, which was spared the erosive force of Pleistocene Glaciers.
Protected within the Upper Mississippi National Wildlife Refuge, access to the Mississippi and its varied riparian habitats is rather limited (except for boaters). However, Goose Island County Park, just south of La Crosse, Wisconsin, provided an excellent opportunity to study the floodplain wetlands, backwater bays and eastern channel of the river; birding was excellent at the Park. North of La Crosse, we cut away from the Mississippi for a more direct route to Duluth, Minnesota, where we are spending the night on that city's restored waterfront.
In the coming days, we plan to explore the northwest coast of Lake Superior and the Apostle Islands region of northern Wisconsin. So far, wildlife encounters have been limited to bald eagles, sandhill cranes, common loons, gulls, aquatic turtles and a host of waterfowl and songbird species. But we are now in wolf and moose country and I look forward to the possibility of seeing (or hearing) those North Country residents amidst the spectacular landscape that adjoins America's grandest Lake.
Protected within the Upper Mississippi National Wildlife Refuge, access to the Mississippi and its varied riparian habitats is rather limited (except for boaters). However, Goose Island County Park, just south of La Crosse, Wisconsin, provided an excellent opportunity to study the floodplain wetlands, backwater bays and eastern channel of the river; birding was excellent at the Park. North of La Crosse, we cut away from the Mississippi for a more direct route to Duluth, Minnesota, where we are spending the night on that city's restored waterfront.
In the coming days, we plan to explore the northwest coast of Lake Superior and the Apostle Islands region of northern Wisconsin. So far, wildlife encounters have been limited to bald eagles, sandhill cranes, common loons, gulls, aquatic turtles and a host of waterfowl and songbird species. But we are now in wolf and moose country and I look forward to the possibility of seeing (or hearing) those North Country residents amidst the spectacular landscape that adjoins America's grandest Lake.
Selasa, 08 Mei 2012
The Mackenzie River
Rising at the west end of Great Slave Lake in Canada's Northwest Territories, the Mackenzie River flows northwestward for almost 1100 miles to the Beaufort Sea. Un-dammed and winding through Subarctic and Arctic wilderness, its wide, braided channel is just the final conduit of a massive watershed that covers 20% of Canada, extending from northeast British Columbia, northern Alberta, northwest Saskatchewan and the western Yukon to the massive Mackenzie River Delta, the 12th largest on our planet. If one includes its most distant tributaries, this river system exceeds 2600 miles in length (the longest in Canada) and drains a watershed of almost 700,000 square miles.
To the southwest, the Peace and Athabaska Rivers rise on the east side of the Continental Divide in the northern Canadian Rockies; these large streams merge to form a large inland delta along Lake Athabaska, which drains to Great Slave Lake via the Slave River. Leaving Great Slave Lake, the Mackenzie River picks up meltwaters from the Mackenzie Mountains (to its west) via the Liard River system and then receives flow from Great Bear Lake, to its east, the largest lake in Canada. At its braided delta, just east of the Richardson Mountains, the Mackenzie discharges copious amounts of relatively warm, fresh, nutrient-rich water into the Arctic Ocean; this annual discharge, the 14th largest on Earth, dramatically affects the regional ecosystem, allowing boreal woodlands to extend well north of their usual range and increasing the diversity of plants and animals across the ever-changing delta. Beluga whales gather here in spring to molt in the mild river current and the countless, shallow lakes provide ideal breeding habitat for shorebirds, tundra swans and snow geese. Resident mammals include black bears, barren ground grizzlies, Arctic fox, Arctic wolves, caribou, moose, musk ox and a massive number of muskrats.
However, all is not well in this seemingly pristine wilderness. Dams on tributaries of the Mackenzie have reduced flow through its primary channel and are diminishing the annual floods that are crucial to the welfare of its delta ecosystem. In addition, worrisome levels of mercury have been found in the river over the past few years, the product of mining and power plant effluent across the watershed. Of course, as with other Arctic ecosystems, global warming may dramatically affect the natural diversity of this magnificent yet fragile landscape.
To the southwest, the Peace and Athabaska Rivers rise on the east side of the Continental Divide in the northern Canadian Rockies; these large streams merge to form a large inland delta along Lake Athabaska, which drains to Great Slave Lake via the Slave River. Leaving Great Slave Lake, the Mackenzie River picks up meltwaters from the Mackenzie Mountains (to its west) via the Liard River system and then receives flow from Great Bear Lake, to its east, the largest lake in Canada. At its braided delta, just east of the Richardson Mountains, the Mackenzie discharges copious amounts of relatively warm, fresh, nutrient-rich water into the Arctic Ocean; this annual discharge, the 14th largest on Earth, dramatically affects the regional ecosystem, allowing boreal woodlands to extend well north of their usual range and increasing the diversity of plants and animals across the ever-changing delta. Beluga whales gather here in spring to molt in the mild river current and the countless, shallow lakes provide ideal breeding habitat for shorebirds, tundra swans and snow geese. Resident mammals include black bears, barren ground grizzlies, Arctic fox, Arctic wolves, caribou, moose, musk ox and a massive number of muskrats.
However, all is not well in this seemingly pristine wilderness. Dams on tributaries of the Mackenzie have reduced flow through its primary channel and are diminishing the annual floods that are crucial to the welfare of its delta ecosystem. In addition, worrisome levels of mercury have been found in the river over the past few years, the product of mining and power plant effluent across the watershed. Of course, as with other Arctic ecosystems, global warming may dramatically affect the natural diversity of this magnificent yet fragile landscape.
Rabu, 02 Mei 2012
Natural Afghanistan
For the past decade, Afghanistan has evoked images of war, political corruption and civil strife. It seems appropriate to shift gears and focus on the natural landscape of that isolated but starkly beautiful region of our planet.
Consulting a map, one finds that the country of Afghanistan is pear-shaped, aligned northeast to southwest; the narrower part, complete with a thin stem of territory that pokes eastward to China, is to the northeast while its broader portion is to the southwest, abutting Iran, western Pakistan and southern Turkmenistan. The high spine of the Hindu Kush, the westernmost extension of the Himalayas, bisects the northeastern half of the country, curving from its northeastern frontier to the heart of Afghanistan; some peaks in easternmost Afghanistan soar above 25,000 feet while elevations gradually decrease toward the west. On either side of this natural divide, numerous streams have carved a maze of ridges, canyons and valleys from the Hindu Kush massif, giving rise to four major river systems.
The Kabul River drains the southeast edge of the Hindu Kush, flowing through the capitol city before cutting through the Spin Ghar Range along the border with Pakistan, where it joins the Indus River. The Helmand River and its tributaries drain the southwestern and western flanks of the Hindu Kush, crossing the southwest plateau region of Afghanistan and eventually flowing westward into Iran. The Hari Rud, rising along the northwest side of the massif, also flows westward into Iran while the Amu Darya, fed by mountain glaciers of the Hindu Kush, snakes westward across the fertile plain of northern Afghanistan, forming its border with Tajikistan, Uzbekistan and Turkmenistan (east to west) before angling northwestward into the latter country. With the exception of the Kabul River, which reaches the sea via Pakistan's massive Indus River system, the rivers of Afghanistan, heavily utilized for irrigation in this dry landscape, eventually disappear into the desert sands of Iran and Turkmenistan.
Consulting a map, one finds that the country of Afghanistan is pear-shaped, aligned northeast to southwest; the narrower part, complete with a thin stem of territory that pokes eastward to China, is to the northeast while its broader portion is to the southwest, abutting Iran, western Pakistan and southern Turkmenistan. The high spine of the Hindu Kush, the westernmost extension of the Himalayas, bisects the northeastern half of the country, curving from its northeastern frontier to the heart of Afghanistan; some peaks in easternmost Afghanistan soar above 25,000 feet while elevations gradually decrease toward the west. On either side of this natural divide, numerous streams have carved a maze of ridges, canyons and valleys from the Hindu Kush massif, giving rise to four major river systems.
The Kabul River drains the southeast edge of the Hindu Kush, flowing through the capitol city before cutting through the Spin Ghar Range along the border with Pakistan, where it joins the Indus River. The Helmand River and its tributaries drain the southwestern and western flanks of the Hindu Kush, crossing the southwest plateau region of Afghanistan and eventually flowing westward into Iran. The Hari Rud, rising along the northwest side of the massif, also flows westward into Iran while the Amu Darya, fed by mountain glaciers of the Hindu Kush, snakes westward across the fertile plain of northern Afghanistan, forming its border with Tajikistan, Uzbekistan and Turkmenistan (east to west) before angling northwestward into the latter country. With the exception of the Kabul River, which reaches the sea via Pakistan's massive Indus River system, the rivers of Afghanistan, heavily utilized for irrigation in this dry landscape, eventually disappear into the desert sands of Iran and Turkmenistan.
Kamis, 12 April 2012
Bald Knob NWR
Many nature buffs are familiar with National Wildlife Refuges such as Horicon, Squaw Creek and Aransas. But there are many others that evade the attention of the general public, some of which are close to home and readily accessible. One such refuge is Bald Knob NWR, just east of Searcy, Arkansas (and south of Bald Knob), at the western edge of the Coastal Plain. Established less than 20 years ago to protect wetlands along the Little Red River, this refuge blends with the the Henry Gray/Hurricane Lake WMA, to its east; spring flooding along the White and Little Red Rivers often precludes entry to southern and eastern sections of the combined preserves.
Characterized by agricultural fields, man-made ponds, sloughs and bottomland timber, the Bald Knob NWR is accessed by a network of graveled roads and earthen trails, most of which run atop levees. On my visit this morning I encountered mixed flocks of ducks and coot, migrant shorebirds, numerous killdeer and a flock of at least 100 American white pelicans; as is typical, the pelicans waited for mid-morning thermals before taking to the air and soaring above the refuge. The highlight of my visit was provided by a lone peregrine falcon that repeatedly strafed and spooked the waterfowl.
Access to Bald Knob NWR is best achieved from the city of Bald Knob, a few miles northeast of Searcy on US Highway 67. From the downtown area, turn south on Hickory St., which becomes Coal Chute Road, the northern entry road for the refuge; during periods of spring flooding, this may be the only route of access.
Characterized by agricultural fields, man-made ponds, sloughs and bottomland timber, the Bald Knob NWR is accessed by a network of graveled roads and earthen trails, most of which run atop levees. On my visit this morning I encountered mixed flocks of ducks and coot, migrant shorebirds, numerous killdeer and a flock of at least 100 American white pelicans; as is typical, the pelicans waited for mid-morning thermals before taking to the air and soaring above the refuge. The highlight of my visit was provided by a lone peregrine falcon that repeatedly strafed and spooked the waterfowl.
Access to Bald Knob NWR is best achieved from the city of Bald Knob, a few miles northeast of Searcy on US Highway 67. From the downtown area, turn south on Hickory St., which becomes Coal Chute Road, the northern entry road for the refuge; during periods of spring flooding, this may be the only route of access.
Rabu, 11 April 2012
White River NWR
The bad news? White River NWR is currently flooded and almost totally inaccessible to humans without boats. The good news? White River NWR is currently flooded and is almost totally inaccessible to humans. How refreshing to discover that we have at least one portion of a major river that has not been channelized, dammed or corralled by levees for the benefit of human recreation. And, of course, letting rivers flood is essential to protecting what little remains of bottomland forests along the Mississippi Valley and elsewhere on our planet.
Established in 1935 to protect wintering habitat for waterfowl as well as this remaining tract of swamp forest, White River NWR hosts up to 350,000 ducks and geese each winter and is home to a wide range of wildlife, including American alligators, black bears, bald eagles and, possibly, ivory-billed woodpeckers. Though my observations were limited to fringe areas today, graveled roads and five trails provide access to the heart of the refuge when conditions permit. For those who have not visited in the past, I suggest a stop at the refuge Visitor Center, in St. Charles, Arkansas, to obtain maps and to find out what areas might be open to the public; some sections are closed from November through February to protect wintering waterfowl from human disturbance.
Nearly 90 miles long and up to 10 miles wide, White River NWR harbors a vibrant ecosystem; in addition to the vast bottomland, hardwood forest are numerous lakes, ponds, sloughs, bayous and marshlands. Wading birds, especially common and varied during the warmer months, are present throughout the year, as are barred owls, pileated woodpeckers, belted kingfishers and red-headed woodpeckers. In spring, prothonotary warblers, scarlet tanagers, yellow-breasted chats, yellow-billed cuckoos and a host of other summer songbirds add color to the deep, dark woods.
Established in 1935 to protect wintering habitat for waterfowl as well as this remaining tract of swamp forest, White River NWR hosts up to 350,000 ducks and geese each winter and is home to a wide range of wildlife, including American alligators, black bears, bald eagles and, possibly, ivory-billed woodpeckers. Though my observations were limited to fringe areas today, graveled roads and five trails provide access to the heart of the refuge when conditions permit. For those who have not visited in the past, I suggest a stop at the refuge Visitor Center, in St. Charles, Arkansas, to obtain maps and to find out what areas might be open to the public; some sections are closed from November through February to protect wintering waterfowl from human disturbance.
Nearly 90 miles long and up to 10 miles wide, White River NWR harbors a vibrant ecosystem; in addition to the vast bottomland, hardwood forest are numerous lakes, ponds, sloughs, bayous and marshlands. Wading birds, especially common and varied during the warmer months, are present throughout the year, as are barred owls, pileated woodpeckers, belted kingfishers and red-headed woodpeckers. In spring, prothonotary warblers, scarlet tanagers, yellow-breasted chats, yellow-billed cuckoos and a host of other summer songbirds add color to the deep, dark woods.
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