Waterton Canyon, which incises the foothills southwest of Denver, represents the South Platte's final journey through the Rocky Mountains before it rumbles onto the Colorado Piedmont. Harboring a wealth of scenic rock formations and home to a wide variety of Transition Zone flora and fauna, the canyon has long been a popular destination for hikers, birders, fishermen and naturalists. Over the past decade or so, it has also become a mecca for bikers and joggers, now comprising at least 75% of the visitors.
While these trail athletes surely enjoy the pristine landscape, at least in a holistic sense, I doubt they pay much attention to the varied plants and animals, focused as they are on distance and time. As they turdge along, gasping and spitting, or whiz by on their trail bikes, I often wonder if they could identify even a handful of species that inhabit the canyon. They surely notice the bighorn sheep, for which this refuge is well known, but a fleeting glance is probably sufficient.
In this age of obesity, I certainly have no objection to aerobic exercise. But I suspect these bikers and joggers choose Waterton Canyon for its graded climb and known distance (6 miles to the Strontia Springs Dam); of course, they also enjoy group exercise and avoid the heavy auto traffic that occurs in other foothill canyons. Some might conclude that I envy the youth and vitality of these athletes (which is surely true to some extent) but I am more inclined to pity their lack of interest in nature's bounty. Dogs are not permitted in Waterton Canyon in order to protect the bighorn sheep; perhaps we should limit its use as an athletic training site in order to protect the natural milieu.
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Jumat, 13 Juli 2012
Rabu, 11 Juli 2012
Prairie Racerunners
Closely related to the six-lined racerunner of the Mid-Atlantic and Southeastern U.S., the prairie racerunner is found from northwestern Indiana and southern Wisconsin, westward to southern Wyoming and southward to Arkansas, West Texas and New Mexico. Favoring dry, sandy soil and hot weather, these lizards inhabit prairie grasslands, abandoned farms, glades and rocky hillsides; attracted to disturbed areas, they are known to spread along power line swaths and railroad lines. Here in Colorado, prairie racerunners are abundant from the High Plains to the shrub zone of the lower Front Range foothills.
Emerging from hibernation in late April or May, prairie racerunners are best observed during the morning and early afternoon hours of June and July, dashing across trails or clearings and disappearing into clumps of vegetation to snare prey or to avoid predators. Their long tail, twice the length of their body, is thought to serve as a counter-balance as they zig-zag at speeds up to 18 miles per hour. Mating occurs by late spring and five eggs are generally produced; as with most lizards, the hatchlings are miniature replicas of the adults and must fend for themselves. While a second brood may be produced within a few weeks, adult prairie racerunners begin to hibernate by late August or early September; the young, needing more time to generate fat stores, wait until late September or October to settle in their winter burrows (depending on their home latitude).
Feasting on a wide variety of insects and other invertebrates during their brief season of activity, prairie racerunners may fall victim to grassland hawks, prairie falcons, burrowing owls, fox, coyotes, roadrunners, magpies and a variety of snakes. Using shallow burrows during the warmer months, they dig a deeper channel with a terminal chamber for their prolonged hibernation; during that time, in sharp contrast to their frenzied life above ground, their metabolic rate falls dramatically and they rely on fat deposits to fuel their survival. If they make it through their first winter, adult prairie racerunners are thought to have a natural life span of 4-5 years.
Emerging from hibernation in late April or May, prairie racerunners are best observed during the morning and early afternoon hours of June and July, dashing across trails or clearings and disappearing into clumps of vegetation to snare prey or to avoid predators. Their long tail, twice the length of their body, is thought to serve as a counter-balance as they zig-zag at speeds up to 18 miles per hour. Mating occurs by late spring and five eggs are generally produced; as with most lizards, the hatchlings are miniature replicas of the adults and must fend for themselves. While a second brood may be produced within a few weeks, adult prairie racerunners begin to hibernate by late August or early September; the young, needing more time to generate fat stores, wait until late September or October to settle in their winter burrows (depending on their home latitude).
Feasting on a wide variety of insects and other invertebrates during their brief season of activity, prairie racerunners may fall victim to grassland hawks, prairie falcons, burrowing owls, fox, coyotes, roadrunners, magpies and a variety of snakes. Using shallow burrows during the warmer months, they dig a deeper channel with a terminal chamber for their prolonged hibernation; during that time, in sharp contrast to their frenzied life above ground, their metabolic rate falls dramatically and they rely on fat deposits to fuel their survival. If they make it through their first winter, adult prairie racerunners are thought to have a natural life span of 4-5 years.
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.
Senin, 09 Juli 2012
Monsoon Relief
Returning to our Littleton, Colorado, farm today, I found that early monsoon rains have revitalized the landscape. Indeed, over the past few days, heavy rains have moved northward across the Front Range, bringing much needed rain to the tinder-dry mountain forests and welcome moisture to the urban corridor. While some flooding, mudslides and sinkholes developed, the storms have reduced the wildfire risk to some degree and, so far, have not ignited any new fires.
The annual monsoon rains of the American Southwest result from a southerly flow that brings in moisture from both the Gulf of California and the Gulf of Mexico. The engine for this wind pattern is high pressure over the Southern Plains that generally develops by early July and persists through much of August; winds move clockwise around that atmospheric ridge, sweeping moisture northward along its western rim. Showers and thunderstorms are usually confined to the Desert Southwest and Four Corners Region early in the season, reaching the Colorado Front Range by late July and August. Thanks to the dome of drought that has plagued the south-central and southeastern U.S. for several weeks, the Monsoon got an early start and Colorado, caught in its own drought after a mild, snow-starved winter and a warm, dry spring, has received an early and very welcome gift.
Unfortunately, the monsoon flow will be shut off for the rest of this week as high pressure builds in from the West, bringing another round of hot, dry weather to the State and blocking the southerly stream of moisture. When the Southwest Monsoon might generate more relief is anyone's guess but its typical arrival date is still a week or two away.
The annual monsoon rains of the American Southwest result from a southerly flow that brings in moisture from both the Gulf of California and the Gulf of Mexico. The engine for this wind pattern is high pressure over the Southern Plains that generally develops by early July and persists through much of August; winds move clockwise around that atmospheric ridge, sweeping moisture northward along its western rim. Showers and thunderstorms are usually confined to the Desert Southwest and Four Corners Region early in the season, reaching the Colorado Front Range by late July and August. Thanks to the dome of drought that has plagued the south-central and southeastern U.S. for several weeks, the Monsoon got an early start and Colorado, caught in its own drought after a mild, snow-starved winter and a warm, dry spring, has received an early and very welcome gift.
Unfortunately, the monsoon flow will be shut off for the rest of this week as high pressure builds in from the West, bringing another round of hot, dry weather to the State and blocking the southerly stream of moisture. When the Southwest Monsoon might generate more relief is anyone's guess but its typical arrival date is still a week or two away.
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).
Rabu, 20 Juni 2012
Colorado's Beetles & Wildfires
After dealing with an overwhelming pine beetle blight for the past few years, Colorado residents now face what, so far, is a devastating fire season. A modest winter snowpack, combined with a dry spring, has set the stage for lightening and human-induced forest fires. In addition, the presence of so many dead pine trees will surely exacerbate that threat.
Our human-centric view of nature often leads to false conclusions about man's role in the occurrence of "natural disasters." Many are quick to blame fire-suppression policies for both the beetle blight and the wildfires while others see the hand of God, a biblical punishment for the ills of human society . But natural wildfires play a vital role in the maintenance of forest ecosystems, clearing out dead wood, opening the canopy and allowing the seeds of certain trees (lodgepole pines, for example) to germinate. In like manner, pine bark beetles attack stressed or diseased trees and their massive infestations, which probably occur every century or so, restore forests with a diverse assembly of young, healthy trees. While it is an unwelcome sight for residents and tourists, the remnant landscape of dead or burned trees is a necessary stage in the life of a forest; unfortunately, when viewed from the perspective of our brief human life span, it appears all too permanent.
Aspen trees, which spread by suckering and take advantage of clearings in the coniferous forests, will likely be the primary beneficiaries of these "disasters" in the short run. Humans who chose to reside in western forests are among the primary victims, losing pristine scenery if not their homes. Like those who live on barrier islands or along river floodplains, they were taking a chance; most will be philosophical, acknowledging the risk that comes with living in the Colorado mountains and respecting the natural forces that, over the centuries, mold our landscape.
Our human-centric view of nature often leads to false conclusions about man's role in the occurrence of "natural disasters." Many are quick to blame fire-suppression policies for both the beetle blight and the wildfires while others see the hand of God, a biblical punishment for the ills of human society . But natural wildfires play a vital role in the maintenance of forest ecosystems, clearing out dead wood, opening the canopy and allowing the seeds of certain trees (lodgepole pines, for example) to germinate. In like manner, pine bark beetles attack stressed or diseased trees and their massive infestations, which probably occur every century or so, restore forests with a diverse assembly of young, healthy trees. While it is an unwelcome sight for residents and tourists, the remnant landscape of dead or burned trees is a necessary stage in the life of a forest; unfortunately, when viewed from the perspective of our brief human life span, it appears all too permanent.
Aspen trees, which spread by suckering and take advantage of clearings in the coniferous forests, will likely be the primary beneficiaries of these "disasters" in the short run. Humans who chose to reside in western forests are among the primary victims, losing pristine scenery if not their homes. Like those who live on barrier islands or along river floodplains, they were taking a chance; most will be philosophical, acknowledging the risk that comes with living in the Colorado mountains and respecting the natural forces that, over the centuries, mold our landscape.
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.
Kamis, 07 Juni 2012
Denver's Monster Storm
Late yesterday afternoon, a line of thunderstorms developed across northeastern Colorado, a typical occurrence in early summer. One of these was a tornadic monster that stretched from Castle Rock to the area just east of Denver International Airport.
While such storms usually move rapidly off to the east, this storm, unaffected by steering winds, sat in place throughout the evening, dropping torrential rain, producing large hail and spawning several tornados. In fact, by 10 PM, the massive thunderstorm began to drift southwest and then northwest, eventually stretching along the foothills west of Denver. Though radiation cooling generally causes Front Range storms to dissipate after sunset, this one continued to intensify and, by midnight, was illuminating the sky with incessant cloud-to-cloud and cloud-to-ground lightening.
Its final push across Metro Denver triggered severe thunderstorm and flash flood warnings from the National Weather Service. Here in Littleton, we received heavy rain and an inch or two of pea-sized hail; some areas reported golf ball sized hail and the region south and east of Denver, impacted twice by the same storm, received up to five inches of rain. Exiting the Front Range by 2 AM, the massive storm had put a significant dent in our drought and had produced the most spectacular light show that I have ever witnessed. Of course, for those impacted by large hail, flooding and tornados, the memories of this unusual weather event will be less positive.
While such storms usually move rapidly off to the east, this storm, unaffected by steering winds, sat in place throughout the evening, dropping torrential rain, producing large hail and spawning several tornados. In fact, by 10 PM, the massive thunderstorm began to drift southwest and then northwest, eventually stretching along the foothills west of Denver. Though radiation cooling generally causes Front Range storms to dissipate after sunset, this one continued to intensify and, by midnight, was illuminating the sky with incessant cloud-to-cloud and cloud-to-ground lightening.
Its final push across Metro Denver triggered severe thunderstorm and flash flood warnings from the National Weather Service. Here in Littleton, we received heavy rain and an inch or two of pea-sized hail; some areas reported golf ball sized hail and the region south and east of Denver, impacted twice by the same storm, received up to five inches of rain. Exiting the Front Range by 2 AM, the massive storm had put a significant dent in our drought and had produced the most spectacular light show that I have ever witnessed. Of course, for those impacted by large hail, flooding and tornados, the memories of this unusual weather event will be less positive.
Rabu, 06 Juni 2012
A Morning Chat
On this bright, cool morning, we opted for a hike through the South Platte Valley, looping past several lakes that border the river channel. In one area, the trail crosses a brushy ridge with scattered groves of cottonwoods and it was there that I heard the unmistakable "song" of a yellow breasted chat, more like a loud, rambling conversation. Indeed, though classified as a warbler (our largest), the chat acts more like a thrasher or a catbird, skulking in the shrubbery and delivering its litany of seemingly unrelated calls and noises.
Solitary for most of the year, yellow breasted chats summer across the Lower 48, preferring riparian woods and brushy hillsides. Nests are placed in low shrubs and these common birds would probably go unnoticed were it not for the male's tendency to sing from an exposed perch, his bright yellow chest and abdomen glowing in the early summer sun. Here in Colorado, chats are especially common along streams of the lower foothills where they feast on insects and berries. While some winter along the East Coast of the U.S., most yellow breasted chats head to Mexico or Central America for the colder months.
This morning, our songster was accompanied by house wrens, lesser goldfinches, yellow warblers, song sparrows, black-billed magpies, broad-tailed hummingbirds, a Say's phoebe, northern flickers and those ubiquitous robins and house finches. Double-crested cormorants moved among the lakes, fishing for their breakfast, while great blue herons, a black-crowned night heron, flocks of Canada geese and squadrons of ducks passed overhead. But it was the chat that made our morning, delivering his strident lecture to all who cared to listen.
Solitary for most of the year, yellow breasted chats summer across the Lower 48, preferring riparian woods and brushy hillsides. Nests are placed in low shrubs and these common birds would probably go unnoticed were it not for the male's tendency to sing from an exposed perch, his bright yellow chest and abdomen glowing in the early summer sun. Here in Colorado, chats are especially common along streams of the lower foothills where they feast on insects and berries. While some winter along the East Coast of the U.S., most yellow breasted chats head to Mexico or Central America for the colder months.
This morning, our songster was accompanied by house wrens, lesser goldfinches, yellow warblers, song sparrows, black-billed magpies, broad-tailed hummingbirds, a Say's phoebe, northern flickers and those ubiquitous robins and house finches. Double-crested cormorants moved among the lakes, fishing for their breakfast, while great blue herons, a black-crowned night heron, flocks of Canada geese and squadrons of ducks passed overhead. But it was the chat that made our morning, delivering his strident lecture to all who cared to listen.
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, 07 Mei 2012
From Tropical Heat to Upslope Chill
After wilting in central Missouri over the last two days, enveloped in tropical heat and humidity, I arrived along the Colorado Front Range late this afternoon under low clouds and scattered showers; the temperature was 45 degrees F. These two weather extremes were produced by the same Pacific storm system; ahead of the front, muggy air was pumped into the Midwest from the Gulf of Mexico while, behind it, a plume of moisture was swept westward through the cool air. Since this flow is counterclockwise around the storm's central low, the moisture arrived from the northeast, the classic upslope direction for Metro Denver. Cooling and condensing as it rose across the western landscape, the plume dumped its cargo of moisture across northeastern Colorado.
Over the past 24 hours, Metro Denver received a half inch of rain in most areas while higher elevations to the west and south collected .75 inch or more, a welcome respite from the recent drought. Checking the foothills as I arrived from the east, it was obvious that the upslope shroud was beginning to lift though jet traffic was still landing to the north and likely offering a bumpy descent through the showers and virga. Our Littleton farm clearly benefited from the moisture, having taken on the untidy overgrowth that promises plenty of yard work this week.
As the system continues to move eastward, the muggy air and thunderstorms will be confined to the Eastern Seaboard and high pressure will reclaim the Heartland, bestowing warmth and sunshine for the days ahead. Here along the Front Range, the wind will shift to the south-southwest, a downsloping direction for Metro Denver; we expect sunshine, mild temperatures and a chance to dry out.
Over the past 24 hours, Metro Denver received a half inch of rain in most areas while higher elevations to the west and south collected .75 inch or more, a welcome respite from the recent drought. Checking the foothills as I arrived from the east, it was obvious that the upslope shroud was beginning to lift though jet traffic was still landing to the north and likely offering a bumpy descent through the showers and virga. Our Littleton farm clearly benefited from the moisture, having taken on the untidy overgrowth that promises plenty of yard work this week.
As the system continues to move eastward, the muggy air and thunderstorms will be confined to the Eastern Seaboard and high pressure will reclaim the Heartland, bestowing warmth and sunshine for the days ahead. Here along the Front Range, the wind will shift to the south-southwest, a downsloping direction for Metro Denver; we expect sunshine, mild temperatures and a chance to dry out.
Selasa, 24 April 2012
Sage Grouse Saga
Greater sage grouse, the largest grouse in North America, inhabit sage grasslands of the Intermountain West, from Colorado to the Columbia Plateau and from southern Alberta to southern Utah. Closely tied to their habitat, these grouse feed solely on the sage plant in the winter while supplementing that diet with a variety of forbs, insects and grasses during the warmer months. Unlike many game birds, they do not possess a muscular crop and cannot digest hard seeds.
Come spring, sage grouse gather in clearings (known as leks) at dawn and dusk, where the dominant males attract mates with ritualized strutting, tail fanning and a variety of noises from their air sacs; most of the females mate with only one or two of the performers. Nests are placed on the ground and females are solely responsible for both incubation and protection of the young; six to twelve eggs are generally produced. Able to forage soon after birth, the young are vulnerable to a wide range of predators, including snakes, prairie falcons, crows, magpies, badgers, coyotes, bobcats and owls.
Once abundant across the American West, greater sage grouse have long been threatened by habitat loss; their population, estimated to have been about 16 million in the early 1900s, has fallen to less than 500,000 today, a drop of 97% over the past century. The loss of sage grasslands to mining, ranching and oil production has been primarily responsible for this decline and efforts to list the greater sage grouse as an Endangered Species have been successfully blocked by Western Governors and their Federal colleagues. Perhaps a 99% population decline will be more convincing.
Come spring, sage grouse gather in clearings (known as leks) at dawn and dusk, where the dominant males attract mates with ritualized strutting, tail fanning and a variety of noises from their air sacs; most of the females mate with only one or two of the performers. Nests are placed on the ground and females are solely responsible for both incubation and protection of the young; six to twelve eggs are generally produced. Able to forage soon after birth, the young are vulnerable to a wide range of predators, including snakes, prairie falcons, crows, magpies, badgers, coyotes, bobcats and owls.
Once abundant across the American West, greater sage grouse have long been threatened by habitat loss; their population, estimated to have been about 16 million in the early 1900s, has fallen to less than 500,000 today, a drop of 97% over the past century. The loss of sage grasslands to mining, ranching and oil production has been primarily responsible for this decline and efforts to list the greater sage grouse as an Endangered Species have been successfully blocked by Western Governors and their Federal colleagues. Perhaps a 99% population decline will be more convincing.
Kamis, 19 April 2012
Back from Argentina
Swainson's hawks are back from their winter in Argentina. Working on our Littleton, Colorado, farm today, I observed several of these large buteos cavorting overhead, soaring, hovering and stooping, as if to display their pleasure in having completed a long migration. Indeed, making a roundtrip journey of more than 4000 miles each year, Swainson's hawks travel further between breeding and wintering grounds than any other American raptor (with the possible exception of Arctic breeding peregrine falcons).
Monogamous, these hawks are highly territorial during the breeding season and their high-pitched calls are commonly heard from the time of their arrival in spring until their chicks are fledged. Nests are generally constructed in large, solitary trees in open country and may be used repeatedly over the years. The female incubates the eggs and the male brings food during that time; once the chicks hatch, both parents hunt for food, which generally consists of small mammals, reptiles and birds throughout the breeding cycle. During the rest of the year, Swainson's hawks, despite their size, are known to prefer insects, feasting primarily on grasshoppers and dragonflies.
The summer breeding range of Swainson's hawks extends from western Minnesota, Iowa and Missouri to the Pacific Coast and from western Canada to northern Arizona, New Mexico and Texas. Though a bit smaller than red-tailed hawks, their long wings give them an eagle-like appearancer in flight and their plumage pattern (especially in the common white-phase subspecies) aids identification. By August, their territorial instincts have abated and Swainson's hawks begin to congregate in large flocks, drifting southward on their two month journey to the pampas of Argentina; there they have long been threatened by the use of DDT and other pesticides, highlighting the importance of international cooperation in efforts to conserve migratory birds. Fortunately, this practice has diminished and populations of this majestic buteo seem to have stabilized across most of its breeding range.
Monogamous, these hawks are highly territorial during the breeding season and their high-pitched calls are commonly heard from the time of their arrival in spring until their chicks are fledged. Nests are generally constructed in large, solitary trees in open country and may be used repeatedly over the years. The female incubates the eggs and the male brings food during that time; once the chicks hatch, both parents hunt for food, which generally consists of small mammals, reptiles and birds throughout the breeding cycle. During the rest of the year, Swainson's hawks, despite their size, are known to prefer insects, feasting primarily on grasshoppers and dragonflies.
The summer breeding range of Swainson's hawks extends from western Minnesota, Iowa and Missouri to the Pacific Coast and from western Canada to northern Arizona, New Mexico and Texas. Though a bit smaller than red-tailed hawks, their long wings give them an eagle-like appearancer in flight and their plumage pattern (especially in the common white-phase subspecies) aids identification. By August, their territorial instincts have abated and Swainson's hawks begin to congregate in large flocks, drifting southward on their two month journey to the pampas of Argentina; there they have long been threatened by the use of DDT and other pesticides, highlighting the importance of international cooperation in efforts to conserve migratory birds. Fortunately, this practice has diminished and populations of this majestic buteo seem to have stabilized across most of its breeding range.
Jumat, 06 April 2012
Mountain Bluebirds
By April, mountain bluebirds are returning to Colorado, having wintered on the Southern High Plains or in the Desert Southwest. The sky blue males are the first to arrive, searching for nest cavities which they use to attract a mate; those settling in the foothills, canyons and mountain valleys must compete with western bluebirds and violet-green swallows for those treasured sites.
Once the grayish females arrive, mountain bluebirds pair off and begin their nesting activities; while the males provide token assistance, the female takes charge of the nest construction, most often tucked within a tree cavity but sometimes in a rock crevice or a gap in an old cabin. Favoring open woodlands, mountain bluebirds may be found from the ponderosa parklands of the Colorado foothills to the krummholz at the alpine timberline; those that nest at lower elevations sometimes raise a second brood later in the summer.
Mountain bluebirds breed and summer in the mountain ranges of western North America, from Alaska to New Mexico. Like other bluebirds, they usually hunt from a perch, dropping to the ground to snare insects; they also snatch their prey in mid-air and mountain bluebirds often hover above their quarry before striking. During the colder months, all bluebird species supplement their diet with berries. Mountain bluebirds are especially nomadic in late summer and early autumn, regularly appearing on the Great Plains and, occaionally, in the eastern U.S.
Once the grayish females arrive, mountain bluebirds pair off and begin their nesting activities; while the males provide token assistance, the female takes charge of the nest construction, most often tucked within a tree cavity but sometimes in a rock crevice or a gap in an old cabin. Favoring open woodlands, mountain bluebirds may be found from the ponderosa parklands of the Colorado foothills to the krummholz at the alpine timberline; those that nest at lower elevations sometimes raise a second brood later in the summer.
Mountain bluebirds breed and summer in the mountain ranges of western North America, from Alaska to New Mexico. Like other bluebirds, they usually hunt from a perch, dropping to the ground to snare insects; they also snatch their prey in mid-air and mountain bluebirds often hover above their quarry before striking. During the colder months, all bluebird species supplement their diet with berries. Mountain bluebirds are especially nomadic in late summer and early autumn, regularly appearing on the Great Plains and, occaionally, in the eastern U.S.
Kamis, 22 Maret 2012
Pine Grosbeaks
Pine grosbeaks are among my favorite Colorado birds. Though widespread throughout the mountains and higher foothills, these large, colorful finches are not often seen by the casual hiker. However, once encountered, pine grosbeaks are amiable birds, allowing close approach and observation.
Residents of open coniferous forests, from Alaska to northern New England and southward through the mountain corridors of the West, these hardy birds pair off during the breeding season but spend most of the year in sizable flocks, roaming about in search of favorable seed crops. Easily recognized by their large size, stocky build, long tail and undulating flight pattern, the adult males have rose-colored plumage while females and juveniles are mostly gray with olive or burnt orange patches on their head and tail (all have white bars on their black wings). Like many northern finches, pine grosbeaks are irruptive, wandering erratically during the winter months and may turn up almost anywhere across the northern half of the U.S., where they feed in deciduous woodlands as well.
Here in Colorado, pine grosbeaks are best found in open forests of pine, fir and spruce, from the higher foothills to timberline. One wonders how their welfare and distribution will be affected by the extensive pine beetle blight that has decimated northern and central regions of our mountainous terrain.
Residents of open coniferous forests, from Alaska to northern New England and southward through the mountain corridors of the West, these hardy birds pair off during the breeding season but spend most of the year in sizable flocks, roaming about in search of favorable seed crops. Easily recognized by their large size, stocky build, long tail and undulating flight pattern, the adult males have rose-colored plumage while females and juveniles are mostly gray with olive or burnt orange patches on their head and tail (all have white bars on their black wings). Like many northern finches, pine grosbeaks are irruptive, wandering erratically during the winter months and may turn up almost anywhere across the northern half of the U.S., where they feed in deciduous woodlands as well.
Here in Colorado, pine grosbeaks are best found in open forests of pine, fir and spruce, from the higher foothills to timberline. One wonders how their welfare and distribution will be affected by the extensive pine beetle blight that has decimated northern and central regions of our mountainous terrain.
Rabu, 21 Maret 2012
Morning at the Canyon
Facing another mild, sunny morning along the Colorado Front range, I headed to Deer Creek Canyon Park in the foothills of southwest Metro Denver. There I was greeted by cool, fresh air, the usual mix of wild residents and, for most of the visit, the joy of solitude.
As I hiked through a spectacular landscape of yucca-studded grasslands, Gambel's oak, mountain mahogany, junipers and scenic rock formations, I encountered scrub jays, Townsend's solitaires, rufous-sided towhees, ravens, canyon wrens and, of course, the ubiquitous chickadees, robins and juncos; mule deer were abundant and Colorado chipmunks scurried across the trail. At the top of the first ridge, which commands a magnificent view of the canyon and of rock formations to the east, I was rewarded by the sight of a golden eagle, soaring above the foothills that flank Deer Creek Canyon.
In another month, these permanent residents will be joined by black-headed grosbeaks, green-tailed towhees, Lazuli buntings, lesser goldfinches, blue-gray gnatcatchers, yellow-breasted chats, white-throated swifts, Virginia's warblers and other summer residents. Blue grouse will also return to this refuge during the warmer months, having spent the winter on higher mountain slopes, feasting on conifer needles and berries. Of course, I will also come back to welcome these seasonal residents to their summer home in Colorado.
As I hiked through a spectacular landscape of yucca-studded grasslands, Gambel's oak, mountain mahogany, junipers and scenic rock formations, I encountered scrub jays, Townsend's solitaires, rufous-sided towhees, ravens, canyon wrens and, of course, the ubiquitous chickadees, robins and juncos; mule deer were abundant and Colorado chipmunks scurried across the trail. At the top of the first ridge, which commands a magnificent view of the canyon and of rock formations to the east, I was rewarded by the sight of a golden eagle, soaring above the foothills that flank Deer Creek Canyon.
In another month, these permanent residents will be joined by black-headed grosbeaks, green-tailed towhees, Lazuli buntings, lesser goldfinches, blue-gray gnatcatchers, yellow-breasted chats, white-throated swifts, Virginia's warblers and other summer residents. Blue grouse will also return to this refuge during the warmer months, having spent the winter on higher mountain slopes, feasting on conifer needles and berries. Of course, I will also come back to welcome these seasonal residents to their summer home in Colorado.
Senin, 19 Maret 2012
More like March
After a week of summer-like weather across most of the U.S., cooler air has moved east of the Continental Divide. Nevertheless, sunny skies and minimal wind in Metro Denver sent me down to the South Platte Valley for a morning hike.
Not fooled by the recent mild conditions, buffleheads and common goldeneyes still joined the Canada geese, mallards, shovelers, gadwall and pied-billed grebes on the valley ponds and lakes. Other signs of March included the loud, seasonal calls and drumming of northern flickers and nest building by a pair of black-billed magpies; the latter couple took a break from their work to harass a red-tailed hawk that had perched in a nearby cottonwood.
Perhaps the most potent reminder that we are still in early spring is the forecast for snow flurries overnight. Indeed, March is the snowiest month along the Front Range urban corridor and, lest we get too anxious for an end to winter, we must remember that April snowfall ranks just behind that of March. Fortunately, such upslope snowstorms are interspersed with mild, sunny weather and, except for the damage to flower beds, spring snows are easy to take. There are truly no bad months for outdoor exploration along the Colorado Front Range.
Not fooled by the recent mild conditions, buffleheads and common goldeneyes still joined the Canada geese, mallards, shovelers, gadwall and pied-billed grebes on the valley ponds and lakes. Other signs of March included the loud, seasonal calls and drumming of northern flickers and nest building by a pair of black-billed magpies; the latter couple took a break from their work to harass a red-tailed hawk that had perched in a nearby cottonwood.
Perhaps the most potent reminder that we are still in early spring is the forecast for snow flurries overnight. Indeed, March is the snowiest month along the Front Range urban corridor and, lest we get too anxious for an end to winter, we must remember that April snowfall ranks just behind that of March. Fortunately, such upslope snowstorms are interspersed with mild, sunny weather and, except for the damage to flower beds, spring snows are easy to take. There are truly no bad months for outdoor exploration along the Colorado Front Range.
Rabu, 08 Februari 2012
Flying with Pterosaurs
Since heavy snow still covers most of the Front Range trails, we opted for a visit to the Denver Museum of Nature & Science today. Long famous for its wildlife dioramas, this magnificent institution has recently received kudos for its recovery of numerous Pleistocene fossils from a lake bed near Snowmass, Colorado; the skeletal remains of mammoths, mastodons, ancestral camels, ancestral bison and numerous other animals were unearthed last summer before the reservoir was refilled.
Today, we arrived just in time to see an IMAX film produced by National Geographic and narrated by the renowned naturalist, David Attenborough. Given the odd title of The Flying Monsters, apparently chosen to attract young visitors, this 3-D film covered the natural history of pterosaurs, from their initial appearance in the Triassic, some 200 million years ago, until their disappearance at the end of the Cretaceous, 65 MYA. Thought to have evolved from lizards that used webbed limbs to glide between trees, pterosaurs had an elongated digit on each forefoot which was connected to the ipsilateral leg by a thin membrane. Early pterosaurs were not much larger than lizards while giraffe-sized pterodons had appeared by the late Cretaceous; through the course of their evolution, pterosaurs lost their long tails and developed a limited ability to walk on their hands (located at the bend of each wing) and feet, offering some capacity to feed on land as well as in the air. Some pterodons, equipped with a large head fin, also may have preyed on fish, sailing across the surface of the sea.
While pterosaurs disappeared with terrestrial dinosaurs, at the end of the Cretaceous, the film suggested that their demise may not have been solely related to a massive meteor strike; rather, the rise of birds, more agile on land and in the air, may have sealed their fate. Though pterosaurs were extinct for almost 65 million years before humans appeared, the film provided a splendid introduction to those fascinating creatures and, through the magic of 3-D photography and computer animation, allowed the audience to fly with them.
Today, we arrived just in time to see an IMAX film produced by National Geographic and narrated by the renowned naturalist, David Attenborough. Given the odd title of The Flying Monsters, apparently chosen to attract young visitors, this 3-D film covered the natural history of pterosaurs, from their initial appearance in the Triassic, some 200 million years ago, until their disappearance at the end of the Cretaceous, 65 MYA. Thought to have evolved from lizards that used webbed limbs to glide between trees, pterosaurs had an elongated digit on each forefoot which was connected to the ipsilateral leg by a thin membrane. Early pterosaurs were not much larger than lizards while giraffe-sized pterodons had appeared by the late Cretaceous; through the course of their evolution, pterosaurs lost their long tails and developed a limited ability to walk on their hands (located at the bend of each wing) and feet, offering some capacity to feed on land as well as in the air. Some pterodons, equipped with a large head fin, also may have preyed on fish, sailing across the surface of the sea.
While pterosaurs disappeared with terrestrial dinosaurs, at the end of the Cretaceous, the film suggested that their demise may not have been solely related to a massive meteor strike; rather, the rise of birds, more agile on land and in the air, may have sealed their fate. Though pterosaurs were extinct for almost 65 million years before humans appeared, the film provided a splendid introduction to those fascinating creatures and, through the magic of 3-D photography and computer animation, allowed the audience to fly with them.
Selasa, 07 Februari 2012
Snow on Snow
Leaving a nearly snowless winter in Missouri, we arrived at our Littleton farm and found it adorned with more than 15 inches of white powder; fortunately, my Tacoma pickup was able to navigate the long, uphill driveway and it was just a short trudge to the backdoor.
Out on our property, Townsend's solitaires, robins and bushtits feasted on juniper berries while chickadees, flickers and house finches moved among the bare deciduous trees, undaunted by the heavy snow. Our resident fox and raccoons may den up for a few days but we'll soon see their tracks across the blanket of white. Down on the South Platte, ducks and geese crowded the river, feeding along and beneath the relatively warm, open waters.
Another cold front passed through Colorado overnight and, though only a dusting was expected, five more inches were left behind. Enjoying a snowy winter landscape for a change, my wife and I took a walk through the residual flurries as the clouds began to dissipate and patches of blue opened above the Front Range. Milder, sunny weather is forecast for the rest of this week and the intense Colorado sun will soon take a toll on our beautiful gift of the season.
Out on our property, Townsend's solitaires, robins and bushtits feasted on juniper berries while chickadees, flickers and house finches moved among the bare deciduous trees, undaunted by the heavy snow. Our resident fox and raccoons may den up for a few days but we'll soon see their tracks across the blanket of white. Down on the South Platte, ducks and geese crowded the river, feeding along and beneath the relatively warm, open waters.
Another cold front passed through Colorado overnight and, though only a dusting was expected, five more inches were left behind. Enjoying a snowy winter landscape for a change, my wife and I took a walk through the residual flurries as the clouds began to dissipate and patches of blue opened above the Front Range. Milder, sunny weather is forecast for the rest of this week and the intense Colorado sun will soon take a toll on our beautiful gift of the season.
Jumat, 06 Januari 2012
The Raton Basin
Driving along I-25 between Walsenburg, Colorado, and Raton, New Mexico, one enjoys spectacular scenery, including lofty peaks, high mesas and rugged canyons. One would certainly not imagine that this area was once a basin!
Yet, back in the Cretaceous, some 100 million years ago, when Tyrannosaurus rex and his cohorts roamed the planet and a broad seaway stretched from Texas to western Canada, a geologic basin extended across this region, tilted upward to the west; marine shale, known as Pierre Shale, covered the floor of the basin, deposited by the Cretaceous Sea. As the Rockies began to rise and the sea retreated to the south and east, coastal sands settled on the shale and have since hardened into the sandstone of the Trinidad Formation. Then, toward the end of the Cretaceous, a delta ecosystem spread across the region, destined to yield the shales, siltstones, sandstones and coal seams of the Vermejo Formation; coal has been mined from this formation since the 1800s and methane has been retrieved since the 1980s. As the Cretaceous gave way to the Tertiary Period, alluvial debris from the rising mountains covered the area, the source of conglomerates that now comprise the Raton Formation; harboring pockets of coal, this Formation is famous for its exposure of the K-T boundary, within which a high level of iridium supports the theory that a catastrophic meteor impact ended the Cretaceous and wiped out the dinosaurs. Finally, during the Paleocene, alluvial sands and muds of what is now the Poison Canyon Formation covered any remaining evidence of the underlying geologic basin.
Since then, in concert with continued uplift along the Rocky Mountain corridor, granite intrusions pushed up into the sediments, later to be uncovered by erosion to reveal the spectacular Spanish Peaks of southern Colorado, complete with Eocene-Oligocene lava dikes that formed as these massive plutons rose. In the late Miocene, about 9 million years ago, the Raton-Clayton Volcanic Field developed across northeast New Mexico, spreading thick pools of basalt across what is now the Colorado-New Mexico line. This hard cap of basalt protected the underlying Tertiary and Cretaceous sediments, yielding a chain of high mesas that stretch from the base of the Rockies to the Oklahoma Panhandle, separating the watersheds of the Arkansas and Cimarron Rivers.
Yet, back in the Cretaceous, some 100 million years ago, when Tyrannosaurus rex and his cohorts roamed the planet and a broad seaway stretched from Texas to western Canada, a geologic basin extended across this region, tilted upward to the west; marine shale, known as Pierre Shale, covered the floor of the basin, deposited by the Cretaceous Sea. As the Rockies began to rise and the sea retreated to the south and east, coastal sands settled on the shale and have since hardened into the sandstone of the Trinidad Formation. Then, toward the end of the Cretaceous, a delta ecosystem spread across the region, destined to yield the shales, siltstones, sandstones and coal seams of the Vermejo Formation; coal has been mined from this formation since the 1800s and methane has been retrieved since the 1980s. As the Cretaceous gave way to the Tertiary Period, alluvial debris from the rising mountains covered the area, the source of conglomerates that now comprise the Raton Formation; harboring pockets of coal, this Formation is famous for its exposure of the K-T boundary, within which a high level of iridium supports the theory that a catastrophic meteor impact ended the Cretaceous and wiped out the dinosaurs. Finally, during the Paleocene, alluvial sands and muds of what is now the Poison Canyon Formation covered any remaining evidence of the underlying geologic basin.
Since then, in concert with continued uplift along the Rocky Mountain corridor, granite intrusions pushed up into the sediments, later to be uncovered by erosion to reveal the spectacular Spanish Peaks of southern Colorado, complete with Eocene-Oligocene lava dikes that formed as these massive plutons rose. In the late Miocene, about 9 million years ago, the Raton-Clayton Volcanic Field developed across northeast New Mexico, spreading thick pools of basalt across what is now the Colorado-New Mexico line. This hard cap of basalt protected the underlying Tertiary and Cretaceous sediments, yielding a chain of high mesas that stretch from the base of the Rockies to the Oklahoma Panhandle, separating the watersheds of the Arkansas and Cimarron Rivers.
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