Native to North America, muskrats are semi-aquatic rodents that inhabit wetlands and streams across the Continent; hunted and trapped for their dense fur and meat, they have also been introduced in Eurasia and South America. When spotted on lakes and ponds, muskrats are often mistaken for beaver; however, they are significantly smaller (weighing 5 pounds or less) and are easily identified by their long, narrow tail.
Muskrats dig dens in the banks of streams, canals and lakes or construct mounds of aquatic vegetation and mud; in either case, multiple entrances to the lodge chamber, both above and below the water line, permit escape routes from predators and access to aquatic food when the surface water is frozen. Primarily nocturnal and active throughout the year, muskrats feed on a wide variety of plant material and also consume amphibians, snails, turles and fish; they, themselves, are potential prey for coyotes, fox, otters, mink, raccoons, snapping turtles, snakes, eagles, herons and owls.
Breeding from late winter through late summer, muskrats are both polygamous and highly territorial. Females may produce up to five litters each year, with 6-10 kits per litter; as with cottontails, the young mature rapidly and females born in spring may breed by late summer. On the other hand, female muskrats chase off their youngsters when a new litter is about to arrive and often kill those that refuse to leave. Though muskrats may damage levees and dikes, especially during periods of overpopulation, their activity opens up dense cattail marshes for waterfowl and their abandoned dens provide homes for raccoons, mink and aquatic snakes; as avid birders know, Canada geese often nest atop muskrat lodges.
Friday, March 30, 2012
Thursday, March 29, 2012
An Odd Mix of Spring
Out back last evening, it looked, felt and smelled like late April. The lilacs and honeysuckle were in bloom, dandelions and violets speckled the lawn and the trees were nearly leafed out; even the late-leafing sycamores and black walnuts had a modest canopy of green. Toads were trilling, honey bees buzzed across the flower beds and a band of thunderstorms loomed to the west.
Yet, there were missing pieces to this late April scene. While our permanent avian residents moved about the yard, they were still joined by wintering juncos and white-throated sparrows. Many other birds, usually present in mid spring, were conspicuous by their absence; there were no chimney swifts in the evening sky, no house wrens singing in the twilight and no gray catbirds scouring the shrub line. Colorful warblers were not flitting about the shade trees and no northern orioles or indigo buntings had arrived to compete for attention with our resident cardinals and blue jays.
While plants, amphibians, reptiles and hibernating mammals have responded to the exceptionally warm spring and are well ahead of their usual spring schedule, migrant songbirds are attuned to the light cycle and will leave their winter haunts at the same time each year, regardless of the weather up north. After all, awaiting their departure from Mexico or the Gulf Coast, they have no clue that the Midwest landscape is well ahead of schedule, a product of summer-like warmth. They will arrive when they usually do and our winter residents will depart in concert; whether either group will take heed of the altered landscape is something we'll never know.
Yet, there were missing pieces to this late April scene. While our permanent avian residents moved about the yard, they were still joined by wintering juncos and white-throated sparrows. Many other birds, usually present in mid spring, were conspicuous by their absence; there were no chimney swifts in the evening sky, no house wrens singing in the twilight and no gray catbirds scouring the shrub line. Colorful warblers were not flitting about the shade trees and no northern orioles or indigo buntings had arrived to compete for attention with our resident cardinals and blue jays.
While plants, amphibians, reptiles and hibernating mammals have responded to the exceptionally warm spring and are well ahead of their usual spring schedule, migrant songbirds are attuned to the light cycle and will leave their winter haunts at the same time each year, regardless of the weather up north. After all, awaiting their departure from Mexico or the Gulf Coast, they have no clue that the Midwest landscape is well ahead of schedule, a product of summer-like warmth. They will arrive when they usually do and our winter residents will depart in concert; whether either group will take heed of the altered landscape is something we'll never know.
Wednesday, March 28, 2012
The Porcupine Caribou
Named for the Yukon River tributary that drains most of their range, the Porcupine Caribou Herd inhabits northeastern Alaska and the northern Yukon Territory of Canada. According to the last official count, in the summer of 2010, the herd is now composed of about 169,000 individuals, making this one of the most spectacular concentrations of migrant mammals on our planet.
After wintering in mountainous regions south and east of the Brooks Range, the Porcupine Caribou begin their spring migration in March, led by cows and yearlings (bulls and juveniles follow a few weeks later). Using three primary routes across the Brooks Range of Alaska and British Mountains of the northern Yukon, pregnant cows reach the North Slope by late May and calving begins, synchronized to reduce the impact of predation by wolves, grizzlies and golden eagles; the formation of nursery groups and the rapid development of calves (able to run within 24 hours) also serve to diminish loss of the newborns. As the bulls and juveniles arrive, the caribou assemble in huge herds, feeding on the nutritious tundra and moving about to escape hordes of mosquitoes.
By late July, the Porcupine herd begins to leave the vast tundra plain and heads to the northern foothills of the Brooks Range where they now endure biting flies (warble and nose-bot flies) that deposit larvae in their hide and nostrils, respectively. The fall migration ensues by late August and the 2-week rut occurs in October, as frenzied bulls forego eating to gather and impregnate their harem. While some of the herd remains within the Brooks and British Mountains, most head for the Richardson and Ogilvie Mountains of the Yukon Terrority, in the upper reaches of the Porcupine River. Their neighbors, the Central Arctic Caribou herd, numbering about 20,000 individuals, have a much shorter migration, wintering in the Brooks Range and summering on the Coastal Plain. Both herds are threatened by global warming and by human development across their territories, especially the ongoing political pressure to drill on the Arctic NWR.
After wintering in mountainous regions south and east of the Brooks Range, the Porcupine Caribou begin their spring migration in March, led by cows and yearlings (bulls and juveniles follow a few weeks later). Using three primary routes across the Brooks Range of Alaska and British Mountains of the northern Yukon, pregnant cows reach the North Slope by late May and calving begins, synchronized to reduce the impact of predation by wolves, grizzlies and golden eagles; the formation of nursery groups and the rapid development of calves (able to run within 24 hours) also serve to diminish loss of the newborns. As the bulls and juveniles arrive, the caribou assemble in huge herds, feeding on the nutritious tundra and moving about to escape hordes of mosquitoes.
By late July, the Porcupine herd begins to leave the vast tundra plain and heads to the northern foothills of the Brooks Range where they now endure biting flies (warble and nose-bot flies) that deposit larvae in their hide and nostrils, respectively. The fall migration ensues by late August and the 2-week rut occurs in October, as frenzied bulls forego eating to gather and impregnate their harem. While some of the herd remains within the Brooks and British Mountains, most head for the Richardson and Ogilvie Mountains of the Yukon Terrority, in the upper reaches of the Porcupine River. Their neighbors, the Central Arctic Caribou herd, numbering about 20,000 individuals, have a much shorter migration, wintering in the Brooks Range and summering on the Coastal Plain. Both herds are threatened by global warming and by human development across their territories, especially the ongoing political pressure to drill on the Arctic NWR.
Tuesday, March 27, 2012
Future Exotic Terranes
The continents of planet Earth are composed of central, "stable" platforms to which smaller "exotic terranes" have accreted and from which other segments of crust have rifted away. In fact, the central platforms (or cratons) are, themselves, composed of ancient segments that fused together early in geologic history and possess aborted rift zones that could reactivate in the future.
Exotic terranes are segments of continental crust that either rifted from a larger land mass or formed above oceanic hotspots, mid-oceanic ridges or subduction zones as volcanic islands. Moving with the surrounding oceanic crust, they accrete to another continent where the intervening oceanic crust subducts into a trench. Looking at the current geologic map of our planet, we can thus identify land masses that will become exotic terranes in the future (as long as the current plate movements and subduction zones do not change).
Examples include Southern California and the Baja Peninsula, which are moving NNW with the Pacific Plate toward the Aleutian Chain of Alaska, the Hawaiian Islands, which are moving toward the Kamchatka Peninsula of Siberia, and the Galapagos Islands, which are moving eastward on the Nazca Plate toward Ecuador. If the East African Rift continues to develop, southeastern Africa will become a large exotic terrane that could swivel northeastward to join India or might drift eastward and attach to Southeast Asia. Of course, all of these projections will be wrong if the current oceanic spreading zones shut down or if new continental rifts develop; we should find out in 80 million years or so.
Exotic terranes are segments of continental crust that either rifted from a larger land mass or formed above oceanic hotspots, mid-oceanic ridges or subduction zones as volcanic islands. Moving with the surrounding oceanic crust, they accrete to another continent where the intervening oceanic crust subducts into a trench. Looking at the current geologic map of our planet, we can thus identify land masses that will become exotic terranes in the future (as long as the current plate movements and subduction zones do not change).
Examples include Southern California and the Baja Peninsula, which are moving NNW with the Pacific Plate toward the Aleutian Chain of Alaska, the Hawaiian Islands, which are moving toward the Kamchatka Peninsula of Siberia, and the Galapagos Islands, which are moving eastward on the Nazca Plate toward Ecuador. If the East African Rift continues to develop, southeastern Africa will become a large exotic terrane that could swivel northeastward to join India or might drift eastward and attach to Southeast Asia. Of course, all of these projections will be wrong if the current oceanic spreading zones shut down or if new continental rifts develop; we should find out in 80 million years or so.
Monday, March 26, 2012
Double-Dip of Winter
Lest we forget it is still March, wintery weather lingers in the Pacific Northwest and, thanks to a Canadian front, has re-invaded the Great Lakes and Northeast. Cloudy skies, chilly rain and snow showers will dominate those areas for the next few days while, between the dips, summer warmth persists across the Heartland, from the Central Plains to the Gulf Coast.
Despite the proximity of winter's advance, current forecasts suggest that neither trough will affect the mild (if not hot) spring that is entrenched from the Southern Rockies to the Southeast. Rather, the high-riding jet stream is expected to remain in Canada and warm air will return to New England by the end of the week.
After almost two weeks of summer-like weather, many under the central ridge of high pressure are tempted to plant the tomatoes. Nevertheless, here in Missouri, the historical risk of frost runs through mid April and we may yet encounter winter's final gasp before the heat is here to stay.
Despite the proximity of winter's advance, current forecasts suggest that neither trough will affect the mild (if not hot) spring that is entrenched from the Southern Rockies to the Southeast. Rather, the high-riding jet stream is expected to remain in Canada and warm air will return to New England by the end of the week.
After almost two weeks of summer-like weather, many under the central ridge of high pressure are tempted to plant the tomatoes. Nevertheless, here in Missouri, the historical risk of frost runs through mid April and we may yet encounter winter's final gasp before the heat is here to stay.
Sunday, March 25, 2012
The Garth Wetlands
Stretching across the Bear Creek floodplain in north Columbia, Missouri, the Garth Nature Preserve harbors one of the best urban wetlands that I have yet to encounter. Accessed by a fine network of trails, it is visited primarily by joggers, dog-walkers and couples focused more on their conversation than on the natural beauty that surrounds them. For those of us who care to look, there is always much to see.
This morning I found the flora and fauna to be well ahead of schedule, as is occurring across much of North America in the midst of our ongoing heat wave. The rosy glow of redbuds brightened the greening woodlands while a background chorus was provided by northern flickers, chorus frogs, trilling toads and red-winged blackbirds. Though the latter songsters are commonly heard in late March, they were joined by the distinctive chortle of leopard frogs, the scattered call of cricket frogs and, if I was not mistaken, the deep croaks of a few groggy bullfrogs. Aquatic turtles were abundant, peering from the shallows or basking on mats of vegetation and a lone water snake wound through the cattails. Eastern bluebirds, tree swallows and eastern phoebes feasted on a new generation of insects and a pair of red-tailed hawks cavorted overhead, already well into their nesting season.
While all ecosystems offer unique sightings during each season of the year, wetlands are especially interesting in the spring as amphibians and reptiles emerge from their winter slumber and colorful birds return from the south to nest and raise their young. Of course, this riot of life is fueled by the insect hordes, most of which overwintered as eggs, pupae or larvae in these same marshlands.
This morning I found the flora and fauna to be well ahead of schedule, as is occurring across much of North America in the midst of our ongoing heat wave. The rosy glow of redbuds brightened the greening woodlands while a background chorus was provided by northern flickers, chorus frogs, trilling toads and red-winged blackbirds. Though the latter songsters are commonly heard in late March, they were joined by the distinctive chortle of leopard frogs, the scattered call of cricket frogs and, if I was not mistaken, the deep croaks of a few groggy bullfrogs. Aquatic turtles were abundant, peering from the shallows or basking on mats of vegetation and a lone water snake wound through the cattails. Eastern bluebirds, tree swallows and eastern phoebes feasted on a new generation of insects and a pair of red-tailed hawks cavorted overhead, already well into their nesting season.
While all ecosystems offer unique sightings during each season of the year, wetlands are especially interesting in the spring as amphibians and reptiles emerge from their winter slumber and colorful birds return from the south to nest and raise their young. Of course, this riot of life is fueled by the insect hordes, most of which overwintered as eggs, pupae or larvae in these same marshlands.
Saturday, March 24, 2012
Mt. Salina
Having driven across the Great Plains on many occasions, I have come to know the cities and towns, their respective exit numbers and, most importantly, the amenities that they offer for the traveler. In addition, as a naturalist, I have come to recognize these human oases by their surrounding terrain (yes, the Great Plains harbor a mix of topography).
One of these natural landmarks is a small but prominent mesa just east of Salina, Kansas. While it has an elevation of only 1500 feet or so, it rises almost 300 feet above the city and its immediate surroundings. Nameless on the few maps that I have checked, I have christened it Mt. Salina and have noted that this erosional remnant rises south of the Smoky Hill River, near its junction with the Saline River.
While not nearly as majestic as Pikes Peak and other famous landmarks across the American West, this mesa must have played a significant role in guiding early settlers and native Americans to regional settlements and their vital water resource (though I profess no historical knowledge in this regard). As for myself, I am always glad to catch site of Mt. Salina when I head west on I-70, a sign that I have put a significant dent in my journey across the Plains.
One of these natural landmarks is a small but prominent mesa just east of Salina, Kansas. While it has an elevation of only 1500 feet or so, it rises almost 300 feet above the city and its immediate surroundings. Nameless on the few maps that I have checked, I have christened it Mt. Salina and have noted that this erosional remnant rises south of the Smoky Hill River, near its junction with the Saline River.
While not nearly as majestic as Pikes Peak and other famous landmarks across the American West, this mesa must have played a significant role in guiding early settlers and native Americans to regional settlements and their vital water resource (though I profess no historical knowledge in this regard). As for myself, I am always glad to catch site of Mt. Salina when I head west on I-70, a sign that I have put a significant dent in my journey across the Plains.
Thursday, March 22, 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.
Wednesday, March 21, 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.
Tuesday, March 20, 2012
The Caspian Sea
A remnant of the Paratethys Sea, the Caspian Sea is the largest inland body of water on Earth. Covering more than 143,000 square miles, it was cut off from the Black Sea when the Caucasus Mountains rose some 6 million years ago, a product of the Red Sea opening which forced (and continues to force) the Arabian Plate to collide with the Eurasian Plate. Retaining some salinity from the Paratethys, the Caspian Sea has become a massive basin lake, receiving inflow from more than 130 freshwater rivers but having no outlet to the sea; 80% of the inflow is via the Volga River while the combined flow of the Ural and Kura Rivers adds another 15%.
Since this inflow is primarily from the north and northwest shores of the Caspian Sea, its relatively shallow northern waters (only 20 feet deep) are fresh while the deeper waters of its southern section (exceeding 3000 feet in some areas) have a salinity that is 1/3 of that found in our oceans. Kara-Bogaz-Gol, a large lagoon on its eastern shore (within Turkmenistan) has been nearly cutoff by sandbars and receives inflow only during periods of high water in the Caspian Sea; the lagoon's waters, subject to intense evaporation, have a salinity that is 10 times that of sea water. Today, five countries border the Caspian Sea: Russia on the northwest, Kazakhstan on the northeast, Azerbaijan on the southwest, Turkmenistan on the southeast and Iran on the south; except for the Caspian Depression to its north, the Caspian Sea is rimmed by highlands and its surface elevation, while variable, is about 92 feet below sea level.
While lush wetlands are spaced along its western and southern shores, the Caspian Sea is bordered by desert on its northern and eastern coasts; of special interest is a region of geothermal mud domes along part of the Azerbaijan coast, a testament to plate subduction in that area. Famous for a magnificent diversity of birdlife (especially during migrations), its prized sturgeon caviar and its endemic Caspian seals (thought to have arrived when the Paratethys connected to the North Sea), this unique and varied ecosystem is threatened by both global warming and industrial pollution (especially from oil and gas production). Since it is rimmed by five countries, the effort to protect this ecological treasure is especially challenging.
Since this inflow is primarily from the north and northwest shores of the Caspian Sea, its relatively shallow northern waters (only 20 feet deep) are fresh while the deeper waters of its southern section (exceeding 3000 feet in some areas) have a salinity that is 1/3 of that found in our oceans. Kara-Bogaz-Gol, a large lagoon on its eastern shore (within Turkmenistan) has been nearly cutoff by sandbars and receives inflow only during periods of high water in the Caspian Sea; the lagoon's waters, subject to intense evaporation, have a salinity that is 10 times that of sea water. Today, five countries border the Caspian Sea: Russia on the northwest, Kazakhstan on the northeast, Azerbaijan on the southwest, Turkmenistan on the southeast and Iran on the south; except for the Caspian Depression to its north, the Caspian Sea is rimmed by highlands and its surface elevation, while variable, is about 92 feet below sea level.
While lush wetlands are spaced along its western and southern shores, the Caspian Sea is bordered by desert on its northern and eastern coasts; of special interest is a region of geothermal mud domes along part of the Azerbaijan coast, a testament to plate subduction in that area. Famous for a magnificent diversity of birdlife (especially during migrations), its prized sturgeon caviar and its endemic Caspian seals (thought to have arrived when the Paratethys connected to the North Sea), this unique and varied ecosystem is threatened by both global warming and industrial pollution (especially from oil and gas production). Since it is rimmed by five countries, the effort to protect this ecological treasure is especially challenging.
Monday, March 19, 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.
Sunday, March 18, 2012
Ground Turbulence
My regular trips between Missouri and Colorado are usually a bit tiring but today's journey was especially difficult. After leaving Columbia in a balmy haze this morning, I encountered a southwest wind in eastern Kansas which strengthened with every mile to the west, all the way to the Front Range. Though the skies were mostly sunny and I had neither supercells nor snow to complicate my travel, nine hours of bone-jarring turbulence was more than enough.
While the strong wind was my sole problem through eastern and central Kansas, dust plumes and tumbleweed armies posed additional distractions across the dry landscape of the High Plains. Fortunately, no trucks were overturned by the winds and few RV's ventured across the Great Plains today, a wise response to the high wind advisory. Though strong winds are common across this region, today's wind field is especially widespread and is posing a major fire threat from New Mexico and West Texas to Nebraska. Gusty winds along the Front Range have enveloped Denver in a pall of dust and a large wildfire is currently burning in northeast Colorado.
Today's strong winds are the product of a potent low over Wyoming (attached to a deep trough over the western U.S.) and a massive area of high pressure over the eastern States. Counterclockwise winds around the low are combining with clockwise winds at the edge of the high pressure dome, leading to a strong south-southwesterly flow over the Great Plains. The leading edge of the trough is forecast to cross the Rockies overnight and, here in Metro Denver, we'll experience cool, showery weather for the next few days. Meanwhile, as the front moves eastward, these strong winds will precede it, raking the Midwest and igniting thunderstorms as Gulf moisture enters the mix.
While the strong wind was my sole problem through eastern and central Kansas, dust plumes and tumbleweed armies posed additional distractions across the dry landscape of the High Plains. Fortunately, no trucks were overturned by the winds and few RV's ventured across the Great Plains today, a wise response to the high wind advisory. Though strong winds are common across this region, today's wind field is especially widespread and is posing a major fire threat from New Mexico and West Texas to Nebraska. Gusty winds along the Front Range have enveloped Denver in a pall of dust and a large wildfire is currently burning in northeast Colorado.
Today's strong winds are the product of a potent low over Wyoming (attached to a deep trough over the western U.S.) and a massive area of high pressure over the eastern States. Counterclockwise winds around the low are combining with clockwise winds at the edge of the high pressure dome, leading to a strong south-southwesterly flow over the Great Plains. The leading edge of the trough is forecast to cross the Rockies overnight and, here in Metro Denver, we'll experience cool, showery weather for the next few days. Meanwhile, as the front moves eastward, these strong winds will precede it, raking the Midwest and igniting thunderstorms as Gulf moisture enters the mix.
Friday, March 16, 2012
Marsh Madness
While college basketball fans are focused on their brackets, a more natural madness is unfolding across our wetlands. Chorus frogs and spring peepers have entered the peak of their breeding season and their loud calls ring across the marsh. Joining the frenzy are the season's first insects, rising from the ponds and lakes, hoping to mate before encountering hungry tree swallows, eastern phoebes, eastern bluebirds or reawakening bats.
The hysterical calls of flickers and red-bellied woodpeckers also echo across the wetlands and the impatient, deafening calls of red-winged blackbirds signal the onset of their nesting season. Rafts of ducks and coot add their voices to the chorus while stately great blue herons wade through the shallows, feasting on the tree frogs and other hapless victims. While the color explosion of late spring birds and plants has yet to materialize, a greening landscape spawns the joy of rebirth across the March wetlands.
This year, following a mild winter and fueled by a warm early spring, the marsh madness is especially intense. Though a cold wave could dampen that enthusiasm, the tide of spring has been unleashed and any half-hearted invasions by winter will be quickly rebuffed by the higher sun and longer days. As snakes emerge, insects swarms explode and summer birds arrive, the madness will intensify and nature's season of renewal will reign until an autumn chill invades the marsh.
The hysterical calls of flickers and red-bellied woodpeckers also echo across the wetlands and the impatient, deafening calls of red-winged blackbirds signal the onset of their nesting season. Rafts of ducks and coot add their voices to the chorus while stately great blue herons wade through the shallows, feasting on the tree frogs and other hapless victims. While the color explosion of late spring birds and plants has yet to materialize, a greening landscape spawns the joy of rebirth across the March wetlands.
This year, following a mild winter and fueled by a warm early spring, the marsh madness is especially intense. Though a cold wave could dampen that enthusiasm, the tide of spring has been unleashed and any half-hearted invasions by winter will be quickly rebuffed by the higher sun and longer days. As snakes emerge, insects swarms explode and summer birds arrive, the madness will intensify and nature's season of renewal will reign until an autumn chill invades the marsh.
Thursday, March 15, 2012
May in March
We awoke in Cincinnati this morning under clear skies and enveloped in balmy air; the temperature was 60 degrees F. By mid morning, as we prepared to return to Missouri, the leading edge of a storm system arrived with intense lightening, torrential rain and pea sized hail.
Taking the northern route through Indianapolis, we managed to dodge most of the severe weather, and continued west under puffy white clouds in a hazy, blue sky; stopping for gas in western Indiana, we stepped from our air-conditioned car into summer-like heat. All across the till plains, meadows were greening, barren fields shimmered with the purple of henbit and early fruit trees were in bloom. Canada geese were nesting along the farm ponds, killdeer raced along the shallow sloughs and mourning doves cuddled on the powerlines, swaying in a mild, south breeze.
After crossing another band of storms in eastern Missouri, we arrived in Columbia to find the magnolias and wild cherries in bloom and the community in full summer mode. Though only mid March, the foliage is typical of early April and the warm, humid air evokes the feel of May. Unless a few Canadian fronts invade the Heartland over the coming months, we'll be sick of summer by June.
Taking the northern route through Indianapolis, we managed to dodge most of the severe weather, and continued west under puffy white clouds in a hazy, blue sky; stopping for gas in western Indiana, we stepped from our air-conditioned car into summer-like heat. All across the till plains, meadows were greening, barren fields shimmered with the purple of henbit and early fruit trees were in bloom. Canada geese were nesting along the farm ponds, killdeer raced along the shallow sloughs and mourning doves cuddled on the powerlines, swaying in a mild, south breeze.
After crossing another band of storms in eastern Missouri, we arrived in Columbia to find the magnolias and wild cherries in bloom and the community in full summer mode. Though only mid March, the foliage is typical of early April and the warm, humid air evokes the feel of May. Unless a few Canadian fronts invade the Heartland over the coming months, we'll be sick of summer by June.
Wednesday, March 14, 2012
Geophysical Provinces of Ohio
Though known primarily for its rolling farmlands, Ohio is a mosaic of geophysical provinces, defined by underlying geology, tectonic uplift and the erosive power of Pleistocene Glaciers. From a broad perspective, the State overlaps two major provinces; the northwestern 60% of Ohio lies within the Central Lowlands of North America while the southeastern 40% is occupied by the Appalachian Plateau. The border between these two geophysical regions runs SSW, from the northeast corner of Ohio to the Ohio River Valley at the southern edge of the State.
The Appalachian Plateau, composed of Carboniferous sandstones, limestones and shales, was lifted with the Southern Appalachian Mountains as North America and Africa collided during the formation of Pangea, some 300 million years ago. While the Plateau's western edge has been obscured by glacial erosion in northeastern Ohio, it stands out as a prominent escarpment through the southern half of the State, rising 500 feet above the adjacent lowlands. The Central Lowlands within Ohio are comprised of four sub-provinces: the Lake Plain, the Glacial Till Plains, the Ohio Valley and a small segment of the Interior Low Plateaus; the latter, unglaciated province, characterized by glades and karst landscapes, extends from Adams County, in southwestern Ohio, southward and then westward through Kentucky, western Tennessee, southern Indiana and southern Illinois.
The Lake Plain of northern Ohio is a swath of flat terrain south of Lake Erie, representing the post-glacial extent of Lake Warren, Lake Erie's larger predecessor; it is underlain with Devonian sedimentary rocks which have since been covered by glacial till and sandy lake deposits (though these rocks are exposed along the Lake Erie shoreline, in major river valleys and on Ohio's Lake Erie islands). South of the Lake Plain, the gently rolling farmlands of central and west-central Ohio occupy the Till Plains, molded by a number of post-glacial streams that flow southward to the Ohio River; beneath the thick layer of till are Silurian (western Ohio) and Devonian (central Ohio) sedimentary rocks, deposited in shallow seas from 400-350 million years ago. Finally, in the southwest corner of Ohio, ancient Ordovician limestones and shales, 500 million years old, have been sculpted into the hilly terrain of Greater Cincinnati by the erosive force of glacial meltwater and the continued action of post-glacial streams; harboring fossils of trilobites, brachiopods and other early marine invertebrates, these are the oldest exposed rocks in the State.
The Appalachian Plateau, composed of Carboniferous sandstones, limestones and shales, was lifted with the Southern Appalachian Mountains as North America and Africa collided during the formation of Pangea, some 300 million years ago. While the Plateau's western edge has been obscured by glacial erosion in northeastern Ohio, it stands out as a prominent escarpment through the southern half of the State, rising 500 feet above the adjacent lowlands. The Central Lowlands within Ohio are comprised of four sub-provinces: the Lake Plain, the Glacial Till Plains, the Ohio Valley and a small segment of the Interior Low Plateaus; the latter, unglaciated province, characterized by glades and karst landscapes, extends from Adams County, in southwestern Ohio, southward and then westward through Kentucky, western Tennessee, southern Indiana and southern Illinois.
The Lake Plain of northern Ohio is a swath of flat terrain south of Lake Erie, representing the post-glacial extent of Lake Warren, Lake Erie's larger predecessor; it is underlain with Devonian sedimentary rocks which have since been covered by glacial till and sandy lake deposits (though these rocks are exposed along the Lake Erie shoreline, in major river valleys and on Ohio's Lake Erie islands). South of the Lake Plain, the gently rolling farmlands of central and west-central Ohio occupy the Till Plains, molded by a number of post-glacial streams that flow southward to the Ohio River; beneath the thick layer of till are Silurian (western Ohio) and Devonian (central Ohio) sedimentary rocks, deposited in shallow seas from 400-350 million years ago. Finally, in the southwest corner of Ohio, ancient Ordovician limestones and shales, 500 million years old, have been sculpted into the hilly terrain of Greater Cincinnati by the erosive force of glacial meltwater and the continued action of post-glacial streams; harboring fossils of trilobites, brachiopods and other early marine invertebrates, these are the oldest exposed rocks in the State.
Tuesday, March 13, 2012
Black Squirrels
Having lived among gray tree squirrels and golden-brown fox squirrels throughout my life, I am always caught off guard when I re-encounter the black squirrels of northeastern Ohio during visits to my wife's home town. These melanistic variants of eastern gray squirrels are not isolated mutants but, rather, represent the dominant phenotype of their species.
When European explorers and settlers first arrived in North America, almost all eastern gray squirrel populations were reported to be black in color. Thought to have evolved as camouflage from predators when these agile creatures inhabited the dark, mature forests of the eastern U.S. and eastern Canada, the coloration has shifted to gray or gray-brown in the open forests, woodlots and suburban areas that characterize most regions today. Nevertheless, the black race of eastern gray squirrels remains dominant in many areas of the Northeast, from southern Canada to northeastern Ohio and northern Pennsylvania and from Michigan to New England. In some areas, eastern gray squirrels may harbor a mixed coat of gray-brown, black and white.
In all other respects, these racial variants manifest the same behavior and arboreal lifestyle and, as members of the same species, they are able to interbreed; their variable coloration merely reflects the outward expression of their genome (as does the hair color and skin tone of humans). Sexual reproduction ensures a serial mixing of their genes and, over many generations, natural selection determines the physical appearance of regional squirrel populations, retaining traits that favor survival within each ecosystem.
When European explorers and settlers first arrived in North America, almost all eastern gray squirrel populations were reported to be black in color. Thought to have evolved as camouflage from predators when these agile creatures inhabited the dark, mature forests of the eastern U.S. and eastern Canada, the coloration has shifted to gray or gray-brown in the open forests, woodlots and suburban areas that characterize most regions today. Nevertheless, the black race of eastern gray squirrels remains dominant in many areas of the Northeast, from southern Canada to northeastern Ohio and northern Pennsylvania and from Michigan to New England. In some areas, eastern gray squirrels may harbor a mixed coat of gray-brown, black and white.
In all other respects, these racial variants manifest the same behavior and arboreal lifestyle and, as members of the same species, they are able to interbreed; their variable coloration merely reflects the outward expression of their genome (as does the hair color and skin tone of humans). Sexual reproduction ensures a serial mixing of their genes and, over many generations, natural selection determines the physical appearance of regional squirrel populations, retaining traits that favor survival within each ecosystem.
Saturday, March 10, 2012
Visiting the Past
This coming week, my wife and I will visit our home State of Ohio to see relatives and, perhaps, a friend or two. Having lived in other parts of the country for most of our careers, we try to make the pilgrimage at least twice each year.
Of course, most of our old friends have since left Ohio and the urban landscapes have changed dramatically, including the demolition of past apartments and sentimental college hangouts. Nevertheless, driving through old neighborhoods or walking across modern versions of our campuses will remind us of those we left in the past, those who often surface in our memories and, of course, those who still haunt our souls.
There is a great deal of truth to the observation that you can't go home again. But you can still touch base with the landscape of your formative years and, by doing so, come to better understand the person that you have become. Living in the past, with its embellished joy and buried pain, can only produce regret and self-delusion but the past must be acknowledged and appreciated; after all, it has a profound effect on our present and will continue to influence our future.
Of course, most of our old friends have since left Ohio and the urban landscapes have changed dramatically, including the demolition of past apartments and sentimental college hangouts. Nevertheless, driving through old neighborhoods or walking across modern versions of our campuses will remind us of those we left in the past, those who often surface in our memories and, of course, those who still haunt our souls.
There is a great deal of truth to the observation that you can't go home again. But you can still touch base with the landscape of your formative years and, by doing so, come to better understand the person that you have become. Living in the past, with its embellished joy and buried pain, can only produce regret and self-delusion but the past must be acknowledged and appreciated; after all, it has a profound effect on our present and will continue to influence our future.
Friday, March 9, 2012
Music of the Gods
While a minority of us enjoy a severe thunderstorm, the sound of distant thunder seems to comfort most humans. Like other universal emotional responses, I suspect that this reaction to thunder is inborn, buried in the collective soul of our species.
Though the distant rumble of thunder could be accepted as a warning, a signal to retreat from nature's fury, it also implies relief from the heat and the promise of rain for a parched earth. Considering the universal appeal of music, with its bass rhythm and percussion, early humans may have perceived thunder to be the music of the gods, a welcome sign of their providence.
For whatever reason, the sound of a thunderstorm has a soothing effect on most humans, yet more evidence that we are part of nature's domain; physically, mentally and emotionally attached to her web of life and death, we are ultimately dependent on her bounty, however fickle she may be in its delivery.
Though the distant rumble of thunder could be accepted as a warning, a signal to retreat from nature's fury, it also implies relief from the heat and the promise of rain for a parched earth. Considering the universal appeal of music, with its bass rhythm and percussion, early humans may have perceived thunder to be the music of the gods, a welcome sign of their providence.
For whatever reason, the sound of a thunderstorm has a soothing effect on most humans, yet more evidence that we are part of nature's domain; physically, mentally and emotionally attached to her web of life and death, we are ultimately dependent on her bounty, however fickle she may be in its delivery.
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