Friday, November 30, 2007

Solitary Hunter

As the cold, dark season envelops the land, hikers are more likely to encounter our resident carnivores; stirred by the cold and intent on survival, even nocturnal hunters may be active during the day. But only the most observant (and lucky) backcountry visitors will see a fisher, one of our more reclusive predators.

Limited to coniferous and mixed forests of Canada and the mountainous regions of North America, this mid-sized mustelid is solitary for most of its life. Identified by its long, stocky frame, dark brown body and light brown face, the fisher, like most mustelids, is a voracious hunter. Prey includes grouse, mice, hares, muskrat and beaver; fishers are well known for their prowess at killing porcupines and have been introduced in some areas to control this quilled herbivore. While primarily terrestrial, fishers, like their smaller cousins, the martens, are excellent climbers and may den in tree cavities. Mating occurs in late winter and an average of three kits are born in spring of the following year (implantation is delayed).

Like many reclusive animals, such as mountain lions, a loss of natural habitat is forcing this solitary hunter to adapt to human "development." Sightings have reportedly become more common in New England and, before long, they will be labeled a menace; how dare they invade our territory and kill our pets!

Thursday, November 29, 2007

Clouds and Heat

Clouds, as beautiful as they can be, are nothing more than water vapor suspended in the air. Their formation requires the presence of adequate humidity in air that is cooled to its dew point; further cooling leads to precipitation, in the form of rain or snow. When this process occurs near the ground, fog develops; when it occurs higher in the atmosphere, we see clouds.

Humid air is less dense than dry air and cannot get as hot or as cold. As a result, we find the highest and lowest temperatures in areas where the humidity is very low, i.e. deserts and the polar regions. Humidity thus moderates air temperature but clouds generally have different effects on our surface temperature in the summer and winter. During the warmer months, clouds reflect the sunlight, shade the ground and provide a cooling effect at ground level; if the humidity is very high, producing a high heat index, this cooling effect will be less noticeable. In contrast, clouds tend to warm the surface air during the winter, when the sun angle is low and the solar heating effect is reduced; in this case, clouds provide a blanket effect, reflecting radiant heat from the ground back toward the surface. Such cloud blankets are especially noticeable on cold, winter nights; in dry areas of the West, where clouds tend to dissipate through the evening, overnight lows often plummet into the teens and single digits.

This morning dawned clear as a bell, not a cloud in the sky. The temperature was 21 degrees!

Wednesday, November 28, 2007

The Pleiades

As earth hurtles through space, on its annual journey around the sun, we are treated to an ever-changing view of the night sky. For any given time of night, the frame shifts gradually from east to west and, due to the earth's rotation, the stars appear to move from east to west throughout the night.

One of the more striking features of the Northern Hemisphere's winter sky is the Pleiades cluster; also known as "The Seven Sisters," due to the prominant, hot blue stars within the group, this bright, compact cluster is "M45" to astronomers. Visible to the naked eye, the Pleiades begin to rise above the eastern horizon in late October and are now high in the eastern sky by 9PM. Viewed with binoculars, this cluster is seen to contain many more stars that the Seven Sisters and has a hazy, nebular appearance; this, in fact, is not a star factory but, rather, a hydrogen cloud through which the Pleiades are currently moving. The cluster is actually composed of nearly 1000 stars, many of which are brown dwarfs.

Perhaps the most interesting feature of the Pleiades cluster is its youth, having formed just 100 million years ago, during the reign of Tyrannosaurus rex! Currently some 440 light years from Earth, this brilliant star cluster is (from our perspective) moving toward the Orion constellation and will eventually be torn apart by gravitational forces. For now, unlike most of the star patterns that man has named, the Pleiades are truly grouped in space, not merely an optical illusion produced by earth-based viewing.

Tuesday, November 27, 2007

Below the Jet

On its annual push to the south, the jet stream has settled down across the northern States this week, guiding a series of Pacific storms across the country. Acting as a barrier, this steering current is also keeping the frigid, Arctic air to the north of its flow.

Here in Missouri, buffered from extreme cold, we are experiencing the ups and downs of each frontal passage. Ahead of the storms, southerly winds bring mild conditions, with highs in the fifties; behind the fronts, the wind shifts to the northwest, dropping overnight lows into the 20s and afternoon highs into the upper 30s. Since the storm centers are well to our north, most of the rain and snow will occur across the northern Rockies, the Dakotas and the Great Lake States, including lake-effect snows east of the Lakes.

Such roller coaster patterns are typical of early spring and late autumn, when the jet stream is caught between summer and winter. For now, we'll enjoy the brief, dying gasps of autumn, but our descent into the cold, dark season has begun.

Monday, November 26, 2007

Fear of Winter

Many humans despise winter, blaming the season for their blues and inactivity. But I suspect that a true "fear of winter" resides within the collective human psyche. Appropriately called the "Naked Ape" by Desmond Morris, man evolved in the Tropics and spread across the globe before his body changed in any significant way. Rather, the power of the human brain intervened, giving us the ability to fashion warm clothing long before any fur-bearing, northern subspecies evolved.

Humans are equipped with efficient cooling mechanisms (primarily through the skin and lungs) but our heat generating capacity is limited (via shivering, muscular activity and the metabolism of food and stored nutrients). Given adequate fluid and nutrition, a naked human is able to maintain his vital core temperature across a fairly broad environmental range (generally between 55 and 130 degrees F). Hypothermia is of no concern in the Tropics and a naked human could survive in the Temperate Zone for much of the year. But without adequate shelter and clothing, he would quickly succumb to winter conditions.

In this modern industrial and technological age, we seldom consider the limitations and environmental threats that our species once faced. But deep inside, we remember.

Sunday, November 25, 2007

The Katy Trail

One of the best Rail-to-Trail projects in the country, the 200-mile Katy Trail hugs the north edge of the Missouri River floodplain, from St. Louis to Boonville; there, it crosses the River and angles to the southwest, leading through the rolling farmlands of west-central Missouri. This wide, graveled path runs atop the old bed of the Missouri-Kansas-Texas Railroad, which ceased operations in 1986. Managed as a State Park, the Katy Trail and its immediate surroundings attract hikers, trail bikers, joggers, fishermen and naturalists throughout the year; however, trail use diminishes significantly throughout the colder months and those who enjoy solitude will find this route an appealing destination for winter nature hikes.

On its route along the floodplain, the Katy Trail winds through swamp forest, crosses wooded meadows and fords numerous streams and wetlands. Birders should see an excellent variety of bottomland residents, including wood ducks, belted kingfishers, red-headed woodpeckers, barred owls, red-shouldered hawks, winter wrens, song sparrows and American tree sparrows. Turkey vultures often soar above the limestone cliffs while bald eagles, ring-billed gulls and a variety of waterfowl are common along the river. Floodplain mam-mals include white-tailed deer, beaver, muskrat, mink, raccoons, opossum, skunk, red fox and coyotes.

The historic town of Rocheport, Missouri, reached via Exit 115 from I-70, is one of the more appealing access points along the Katy Trail. Ample parking is provided and the hike southward is especially scenic, characterized by towering cliffs, river views and floodplain wetlands.

Saturday, November 24, 2007

Santa Ana Winds

The Santa Ana Winds are scouring Southern California once again and destructive wildfires have reignited. These hot, dry, powerful winds typically occur during the fall and winter months, as periods of high pressure develop across the Great Basin. Like a giant piston, this high pressure zone creates sinking air over the high deserts of the Basin; in concert, winds flow clockwise around the center of this pressurized air mass and are directed into the mountain ranges of Southern California. Much of this flow is forced to rise over the mountains while some is funneled through the major passes (espe-cially Cajon Pass, between the San Gabriel and San Bernardino Mountains).

As the pressured air descends from the high desert and mountains into the Los Angeles Basin, it compresses, dries out and heats up, often bringing the highest temperatures of the year to the coastal cities. The speed of the wind is augmented in canyons of the Transverse and Peninsular Ranges, sometimes reaching 100 mph or more; while the power of these winds is destructive in itself, the winds also fan the flames of any wildfires that develop, making efforts to control them nearly impossible.

Once the high pressure in the Great Basin moves on to the east, the winds subside and "onshore westerlies" bring cooler, more humid air in from the ocean. Of course, Southern California residents hope that this marine flow will also bring rain to the valleys and foothills, nourishing and restoring the vegetation before the next round of Santa Ana winds.

Friday, November 23, 2007

The Common Stranger

Suburban residents are generally familiar with most of our common bird species. They know cardinals, blue jays, chickadees, robins, mourning doves, crows and goldfinches, among others. But one of our more common and conspicuous neighbors, the tufted titmouse, is known only to those who actively feed and observe our avian visitors.

A bit larger and heavier than a chickadee, this species is easily identified by its tufted crown, gray head and back and its white abdomen with buff-colored sides. Its ringing call, usually described as "peter, peter, peter," is commonly heard in residential areas and is especially noticeable in winter, when other birdsong is subdued. Like chickadees, titmice feed on insects and seeds, often scouring bark and twigs for insect eggs or hibernating larvae; they are also common at feeders and seem to have a special fondness for safflower seed. Ranging throughout the central and eastern U.S., tufted titmice are replaced by plain and bridled titmice in the Southwest.

Tufted titmice are among our permanent residents that move about in loose flocks, often in the company of chickadees, nuthatches and downy woodpeckers. Walking a woodland trail, the birder may see or hear little activity before coming upon these "feeding groups." It often appears to me that there is more to these mobile gatherings than a cooperative effort to find prey; rather, they seem to enjoy each other's company!

Thursday, November 22, 2007

Thanks to Gramps

All of us who are fascinated by nature have someone in our past who instilled and fostered that enthusiasm. For me, it was Gilbert Siegel, my maternal grandfather. Always introducing me to the plants and animals in his suburban, Cincinnati yard, he had a special fondness for birds and squirrels, some of which fed directly from his hand. On one occasion, he took me to visit the farm of a friend and we toured the property on a tractor; for the first time in my life, I was immersed in the sights, sounds and smells of a rural landscape.

Though he died when I was twelve, I still think of him often and have long recognized the major influence that he had on my life. So today, on this annual Day of Thanksgiving, I want to publicly thank my grandfather for his love, his time and his inspiration. Thanks, Gramps!

Wednesday, November 21, 2007

Feeding the Birds

As cold weather grips the country, many Americans will begin filling their backyard feeders. Some will perform this ritual purely out of concern for their feathered friends, worried that they may otherwise succumb to the cold and snow. Most just enjoy watching the birds, though many know them only by their shapes and colors. And then there are the avid birders who know that feeders are the best way to attract rare, unusual or vagrant species to their yard.

Regardless of your motive, remember that birds would get by just fine without our assistance; of course, some would perish in the harsh winter conditions but, then again, that's nature's way. And, if you do feed the birds, know that simple, home-made feeders are just as acceptable to them as the high-tech, expensive models. Fill them primarily with black sunflower seed, a low cost brand (especially when purchased in bulk) that attracts the widest variety of birds; adding a source of fresh water, a hanging block of suet and, perhaps, a tube of Niger (thistle) for the finches, will augment the diversity of visitors.

Our well-intended generosity can have negative consequences. Unnatural crowding of birds around feeders increases the risk of disease transmission and backyard feeding stations concentrate the targets of predators such as sharp-shinned hawks and domestic cats.

Tuesday, November 20, 2007

The Tularosa Basin

Looking at a satellite map of New Mexico, one is struck by two prominent features in the south-central part of the State. The first is a narrow, elongated swath of black, resembling spilled ink; this, in fact, is a basaltic lava flow. South of this flow is a blotch of white, representing extensive dunes of gypsum, the famous White Sands of New Mexico. Both of these geographic features are within the Tularosa Basin, which is flanked by the San Andres Mountains, to the west, and the Sacramento Mountains, to the east. The valley itself has an average elevation of 4000 feet.

During the Permian Period, some 250 million years ago, this portion of North America was invaded by shallow seas. Sedimentary rocks from these seas were uplifted as the Rocky Mountains formed, 70 million years ago. Then, about 30 million years ago, tectonic forces began to pull this region apart; the crust began to thin, upwellings of magma developed and the Permian Uplift was split in two. Today, the San Andres and Sacramento Mountains are remnants of that Uplift and are separated by the Tularosa Basin, the northernmost extension of the Chihuahuan Desert.

Throughout the wet climate of the Pleistocene, rain and snow eroded these mountains, sending mineral-laden waters into the enclosed Basin; with no outlet to the sea, Lake Lucero formed, covering the western half of the valley. As the climate began to dry, at the end of the Pleistocene, the Lake gradually retreated, leaving extensive, gypsum-covered playas in its wake. Southwesterly winds began to create the dunes of white, gypsum sand about 7000 years ago; the process continues today and the dune field now covers more than 275 square miles (half of which is protected within the White Sands National Monument).

Partly stabilized by drought tolerant plants such as dropseed, sandhill muhly, gyp gramma and soaptree yucca, the gypsum dunes are home to a fascinating variety of wildlife; some species, including the bleached earless lizard, Cowles prairie lizard and Apache pocket mouse, have evolved a white coloration, camouflaging them against the white sands. Other residents include kit fox, pallid bats, kangaroo rats, bobcats, western coachwhips, Sonoran gophers, western diamondback rattlesnakes and Texas horned lizards; orynx, an African antelope, have also been introduced to the area, threatening the fragile environment (they are fenced out of the National Monument).

Formation of the Tularosa Basin occurred in concert with regional volcanism; several Tertiary volcanoes dot the northern section of the Sacramento Mountains and are responsible for the formation of their higher summits (including Sierra Blanca). A smaller volcano, now represented by the Little Black cinder cone, west of Carrizozo, released the basaltic lava flow north of the White Sands; this flow occurred about 5000 years ago and lasted 30 years or more. Known as the Malpais (Badlands), the Carrizozo basalt flow is 40 miles long and up to 60 feet thick. The Valley of Fires Recreation Area, on the east side of the lava flow, is accessed by U.S. 380.

Monday, November 19, 2007

Warm before the Storm

Strong southerly winds are pushing temperatures into the mid seventies across the Plains and Central Midwest today. When such unusually mild conditions develop during the colder months, one can generally assume that a Pacific or Arctic Front is approaching and, as suspected, that's the case this week.

A strong cold front is moving across the northern and central Rockies today, bringing heavy snow to the mountainous areas of Montana, Idaho and Wyoming. This frigid air mass will push on to the south and east over the next few days, igniting thunderstorms and heavy rain along its leading edge (and snow behind the front). Meanwhile, ahead of the storm, a southerly flow is producing high temperatures some 15-20 degrees above the mid November average.

Hopefully, the storm will retain its power and draw plenty of Gulf moisture into the drought-plagued Southeast. If so, Thursday will be a true day of Thanksgiving for those folks!

Sunday, November 18, 2007

Saved by Wildlife

Long drives can be tedious, especially when they cover familiar terrain. On my frequent, I-70 treks, between Missouri and Colorado, I rely on music and wildlife watching to quell my boredom.

Leaving our Littleton farm early this morning, I noticed our resident fox sitting next to the barn, as if to bid a farewell. Accepting this as a good omen, I put in a Neil Young CD and headed out of Denver. East of the city, several groups of mule deer browsed in the predawn light, the young bucks clearly agitated by the rut. Further along, on the prairie north of Limon, scattered herds of pronghorn moved among the cattle and, near the Kansas line, a rough-legged hawk perched on a fencepost.

Meadowlarks and horned larks were fairly common across the Plains, though significantly outnumbered by starlings and pigeons. Near Quinter, a red-tailed hawk rose from the crop stuble, lunch in his talons, and, just west of WaKeeney, a northern harrier flapped low across a hay field; both of these hawk species became far more common as I continued to the east. Surprisingly, a Swainson's hawk soared above the highway in central Kansas, apparently late for his trip to Argentina.

East of Junction City, a lone coyote roamed the Flint Hills and, as woodlands thickened in eastern Kansas, wild turkey appeared on the meadows. Dusk descended as I crossed into Missouri, bringing squadrons of ducks and V's of Canada geese across my path; hoping to spot a migrant flock of snow geese which, in my opinion, is one of the most stirring sights (and sounds) in nature, I scanned the darkening sky. Alas, the snows were not to be found and I completed my trip in the dark, watching for deer in the headlights.

Saturday, November 17, 2007

Waterton Canyon

Waterton Canyon, southwest of Denver, represents the South Platte's final journey through the Rockies before rumbling onto the Colorado Piedmont. Accessed by a six-mile, gravel roadway that parallels the River, the Canyon is a popular destination for hikers, fishermen, bikers and naturalists.

Towering walls of rock, foothill shrublands, pine-fir forest and the winding, vibrant River attract a wide variety of wildlife. Golden eagles, canyon wrens, dippers, scrub jays, belted kingfishers, Steller's jays and black-billed magpies are among the permanent residents; during the warmer months, they are joined by lesser goldfinches, rock wrens, black-headed grosbeaks, rufous-sided and green-tailed towhees, white-throated swifts and violet-green swallows. Resident mammals include mule deer, bighorn sheep, rock squirrels, yellow-bellied marmots, golden-mantled ground squirrels, Colorado chipmunks, coyotes and the occasional mountain lion. The bighorn sheep are usually found on the sun-scorched, south-facing slopes of the canyon; since their breeding season begins in November, this is a good time to see the head-butting duels of the adult rams.

The popularity of Waterton Canyon often leads to congestion on warm weather weekends; I recommend an off-season and/or weekday visit if possible. To protect the resident wildlife, dogs are not permitted in the Canyon.

Friday, November 16, 2007

Earth's Brown Cloud

After a day in the clean, clear air of the Front Range mountains, I returned yesterday afternoon to find Denver enveloped in a brown haze. Many western cities, including Denver, Phoenix, Salt Lake City and Los Angeles, are known for their "brown clouds;" located in valleys or basins and fully or partly hemmed in by higher terrain, these cities experience frequent inversions, where a layer of cold air, trapped beneath warmer air, fills with pollutants. The brown haze is primarily due to particulates, which are a special problem in the dry, dusty West.

In reality, the western "brown cloud" cities are just poster children for a worldwide dilemma. All major cities are prone to air pollution and the "developing" regions, where industry is outpacing technology (and will power), the problem is especially severe; the upcoming Olympics in Beijing will surely highlight this issue. Yet, all of us are polluters; if we drive a car, heat our home or use electricity, we are complicit in this threat to the global environment. And who pollutes more: the country resident who commutes forty miles per day in his SUV or the urbanite who takes a bus, subway or bicycle to work?

We humans are multiplying at an unsustainable rate. Having no natural predators other than microbes, parasites and other humans, we seem to be unable or unwilling to control our own exponential growth. Technology, designed to minimize our impact on the environment, will never eliminate the need for human population control.

Thursday, November 15, 2007

North Fork Valley

Leading southwestward from Metro Denver, U.S. 285 climbs through Turkey Creek Canyon and then undulates across the foothills. After descending Crow Hill, this scenic roadway begins a westward run along the North Fork of the South Platte River; the imposing wall of the Platte River Mountains forms the south edge of the Valley while the Mt. Evans massif and Continental Divide loom to the north. Forty six miles from the edge of Denver, the highway crosses Kenosha Pass (elevation 10,000 feet) and drops into South Park; the pass, which represents the western end of the North Fork Valley, connects the Platte River Mountains with the Continental Divide.

Several trailheads along U.S. 285 provide access to the Platte River Mountains and three Forest Roads lead to campgrounds, jeep trails and hiking paths into the Mt. Evans Wilderness or onto the Continental Divide. One of these Forest Routes, the Guanella Pass Road, heads northward from Grant, crosses Guanella Pass (11,669 feet) and then descends to Georgetown, on I-70; this road is especially popular with birders since the Pass is one of the best spots in North America to find white-tailed ptarmigan.

Sunny, mild weather made my visit to the Valley especially pleasant today. Though the birding was average (dominated by ravens, Steller's jays and mountain chickadees), I did spot some bighorn sheep near Grant, found a few dippers along the North Fork and saw a large herd of elk in South Park. The view from Kenosha Pass was spectacular, with the snow-capped peaks of the Mosquito Range rising west of the broad grassland; to the southwest, a few of the rugged Sawatch Mountains completed the scene, poking into the clear, blue sky.

Wednesday, November 14, 2007

Vertical Migration

Almost everyone knows that birds fly south for the winter. Even those who have no interest in nature have heard of this phenomenon in songs, poems or common folklore. But few are familiar with the concept of vertical migration, the seasonal movement of birds and mammals in mountainous areas.

Rather than changing latitudes, many mountain residents adapt to the seasons by altering the elevation of their residence. Heavy snows and severe winter weather can impair the survival of mountain dwellers and they have thus developed the instinct to move on to lower terrain as the days shorten. Elk, mule deer and bighorn sheep adhere to this pattern, as do the carnivores (mountain lions, wolves and coyotes) that prey on them. The same is true for a number of mountain birds; an exception among Colorado birds is the blue grouse, which summers in the footills but winters in the higher mountain forests.

Contrary to popular perception, winters are relatively mild across the Front Range urban corridor. Though overnight lows often drop into the teens, January highs are usually in the low 40s (in contrast to the low 20s across the Upper Midwest); combined with abundant sunshine and modest winter snowfalls (the heaviest snows arrive in early spring), the region is downright balmy when compared to the mountain conditions. Our Littleton farm, which sits at 5400 feet, welcomes a number of mountain migrants each winter; among them are Townsend's solitaires, red-breasted nuthatches, dark-eyed juncos (gray-headed race), Cassin's finches, pine siskins, mountain chickadees, red crossbills, golden-crowned kinglets and yellow-rumped warblers.

Tuesday, November 13, 2007

River Walk

Though snowy peaks rose to the west, it was warm and sunny in the South Platte Valley this morning. The River, high for most of the spring and summer, had fallen to its typical flow but few waterfowl fed along its channel; once the Front Range lakes and ponds freeze over, their number and variety on the South Platte will increase significantly. There were a few mallards, gadwalls and common goldeneyes, joined by a lone female hooded merganser. And, of course, the ubiquitous Canada geese were there, flying overhead or grazing on the floodplain meadows.

The onset of the quiet season was surely evident as I strolled the riverside trail. Juncos and sparrows chirped from the thickets but, except for the gab of magpies and the occasional chatter of kingfishers, the rapids made most of the noise. Even the northern flickers were silent as they moved among the cottonwoods. Mammals were likewise quiet and, if you don't count the fox scat on the trail, were represented only by fox squirrels in the trees and a single muskrat on the riverbank.

You would think that such a beautiful morning would really bring out the wildlife. But they don't share our obsession with "nice days;" they know that every day brings its life and death struggles and they are better than we are at pacing themselves. Tomorrow morning is forecast to bring cold rain or wet snow; most of us will find something to do indoors but the wild creatures will be out there, perhaps in numbers greater than today. After all, they have to be!

Monday, November 12, 2007

The Highway Hawk

The most common and widespread buteo in North America, the red-tailed hawk is especially abundant on the farmlands of the Midwest. Favoring open country with nearby woodlands, these raptors often perch on limbs, fenceposts or phone poles along highways, scanning the roadside grassland for cottontails, mice and voles. Any heavy-bodied, white-breasted hawk perched along a U.S. interstate is a red-tailed hawk until proven otherwise; their pale, red tail becomes conspicuous when they soar above the pastures and cropfields.

Driving west on I-70 today, I saw at least 100 red-tails between Columbia, Missouri and Salina, Kansas. Further west, where few trees dot the High Plains, red-tails are much less common; this is the domain of Swainson's hawks (summer residents), ferruginous hawks, rough-legged hawks (winter) and prairie falcons. Red-tails become common once again across the Front Range urban corridor; here, woodlands line the South Platte River, Arkansas River and regional reservoirs, offering sites for roosting and nesting. Of course, these buteos also inhabit the many parklands of the Colorado Piedmont and Front Range foothills. Rather silent for much of the year, their piercing call is often heard in late winter as their breeding season begins.

Sunday, November 11, 2007

Crab Orchard Mountains

On my recent trip to Florida, our flight crossed Tennessee just west of Knoxville. From my east side window on that clear, sunny after-noon, I could easily see the broad swath of the Ridge and Valley Province in the distance. The rolling landscape of the Appalachian Plateau (known as the Cumberland Plateau in this region) lay beneath our path while the more rugged profile of the Smokies stretched across the southeastern horizon.

Nearing the Tennessee and Clinch River Valleys, I noticed a cluster of mountains northwest of Knoxville. Rising along the north edge of the Ridge and Valley swath, these peaks were clearly higher than the adjacent plateau and their topography was more typical of the Smoky Mountains to the south. Confused by what seemed to be an outlier of the Smokies on the north side of the Ridge and Valley, I began looking for an explanation over the following days. I soon learned that this rugged piece of terrain is known as the Crab Orchard Mountains and that it represents the southwestern end of the Cumberland Mountains.

The Cumberland Mountains stretch along the southeast edge of the Appalachian (Cumberland) Plateau; faulting and uplift along this margin, which coincides with the Kentucky-Virginia border and then penetrates central Tennessee, has produced the highest elevations of the Plateau and has given the terrain a rugged, mountainous character. The same is true along the eastern edge of the Appala-chian Plateau in Pennsylvania and West Virginia, where the "Allegheny Front" is typified by high, imposing terrain.

The Crab Orchards harbor fourteen peaks over 3000 feet, the highest landscape in the State outside of the Smoky Mountains. Like the adjacent Plateau, they are composed of Pennsylvanian sedimentary rock (in their case, a thick layer of reddish Crab Orchard Sandstone); by comparison, the core of the Smokies is composed of Precambrian igneous rock, which is at least 500 million years older. Though the age of their component rocks differ, the uplift of the Appalachian Plateau, Cumberland Mountains and Smoky Mountains occurred in concert, as North America collided with Africa, some 250 million years ago.

Friday, November 9, 2007

Hibernation

Mammals of the colder latitudes prepare for winter in a number of ways. Some, including whales, elk and caribou, migrate to wintering areas where food will be more available or where conditions will favor their survival. Others, such as chipmunks, pikas, tree squirrels and voles, store seeds, nuts or dried vegetation to get them through the winter. Many mammals remain active, putting on fat and a dense coat of fur through the autumn; while some den up during periods of intense cold or heavy snow, they will continue to forage and hunt through the winter months. Finally, there are the true hibernators: woodchucks, marmots, ground squirrels, some bears and most bats; they will spend the winter in caves or dens, surviving on a dense layer of brown fat.

Hibernation is a complex and risky adaptation to cold weather, used primarily by mammals of the Temperate Zone. Tropical mammals have no need to hibernate and few Arctic mammals attempt the feat (Arctic winters are too long and too severe to permit their survival). True hibernators eat voraciously during the late summer and autumn, putting on a layer of brown fat that will fuel their metabolism through the winter; at the same time, they gradually decrease their activity, helping to insure that their calorie storage will be sufficient.

Shortening daylight, periods of cold weather and diminishing food supplies are thought to trigger hibernation, which generally occurs after several false starts. Distinct from sleep, hibernation is an active process in which reduced respiration and heart rate precede a fall in core body temperature. At some point, the hibernating mammal enters a coma-like state and its metabolic rate falls to a level just adequate to support cellular metabolism; these mammals have an innate ability to tolerate hypothermia, hypoxemia and lactic acidosis. Should their energy supply be insufficient to fuel arousal in the spring, the animal will die.

Thursday, November 8, 2007

Climate Cycles

The Pleistocene "Ice Age," which began 2 million years ago and ended 10,000 years ago, was just the latest of at least six glacial epochs in the 4.6 billion year history of our planet. And if the Pleistocene was typical of the other ice ages, they were characterized by intermittent periods of glacial formation and glacial retreat, as the climate cooled and warmed. During the Pleistocene, there were four major episodes of glaciation, separated by warm, interglacial periods.

We live in the Holocene Period, which began 10,000 years ago. Most climatologists believe that this is just another interglacial period and that our climate will begin to cool in another 5-10,000 years. In fact, a brief period of cooling, often called the Little Ice Age, occurred from about 1300 to 1850 AD, when global temperatures dropped by 2-3 degrees C.; during this period, glaciers advanced, northern com-munities collapsed and crop failures were widespread. The cause for this brief ice age is uncertain but most evidence points toward decreased solar activity.

Today, as we hear several times each day, Earth's climate is warming. While man is certainly contributing with his indus-trial "greenhouse gases," other factors are surely at play. Most of the Pleistocene interglacials were much warmer than our present-day climate and climate cycles have occurred throughout Earth's history. Our focus on man's role, which began with the industrial revolution (120 years at most) is a reflection of our human-centered view of the Universe; we are, after all, "the culmination of God's creation." To think that our current global warming might be due to factors out of our control (like the solar activity level) is to question our own self-importance. And while we must try to minimize our impact on the ecosystems of our home planet, we cannot forget that nature's cycles developed long before we graced the scene.

Wednesday, November 7, 2007

The Mogollon Rim

The Mogollon Rim is a prominant escarpment that curves across Arizona from the western end of the Grand Canyon to southwest New Mexico. More than 200 miles long, this wall of late-Paleozoic sediments, broken by numerous canyons, represents the south-western edge of the Colorado Plateau. Its upper surface of Permian Coconino Sandstone rises 7000 to 9000 feet above sea level; the highest areas are near the Arizona-New Mexico border. Sedona and Payson sit near the base of the Mogollon escarpment while Williams, Flagstaff, Holbrook and Winslow are atop the plateau, some 6000 feet higher (and two life zones colder) than Phoenix.

South of this spectacular Rim, the land falls away as a network of mountain ranges and foothills, molded and drained by the Verde, Salt and Gila Rivers, which merge in the low desert of Greater Phoenix. The surface of the Colorado Plateau is covered with vast tracts of ponderosa pine, dotted with Tertiary volcanic peaks and incised by the deep canyons of the Colorado and Little Colorado Rivers. Forests of ponderosa pine cover higher elevations of the mountains south of the plateau while pinyon-pine woodlands adorn the lower slopes. At elevations near 3000 feet, saguaro cacti grace the scene, distinctive figures of the Sonoran Desert landscape.

Tuesday, November 6, 2007

North Winds

Yesterday dawned with sunny, mild conditions in Columbia. A gentle breeze from the south had pushed the temperature into the low 50s and there was no sign of coming change in the sky or on the radar. Then, about 11 AM, the winds shifted to the north and grew in strength throughout the day, dropping the temperature ten degrees by late afternoon. Our first freeze of the season occured overnight and we awoke to a clear sky and 31 degrees this morning.

The polar front that dropped through Missouri yesterday morning has moved on to the east and south, bringing the first taste of winter to the eastern U.S. While a lack of moisture prevented the development of showers (or even clouds) with the frontal passage in Missouri, the northwest winds and cold air produced lake-effect snows in the Upper Midwest and Northeast. And in the Southeast, where the humidity was higher, the front brought much-needed rains and thunderstorms in Tennessee and Mississippi.

Still early in the season, this polar outbreak will soon be replaced by a surge of warm air from the southwest. Eventually, as the Arctic cold deepens and solar heating diminishes, the jet stream will retreat to the south and these polar outbreaks will become more frequent, more intense and longer lasting. Winter will then grip the Heartland.

Monday, November 5, 2007

Winter Song

For the first time this season, the song of white-throated sparrows rang through the neighborhood as I walked to work this morning. Natives of the Canadian North Woods, they generally arrive with the first pulse of winter, content to vacation in the cold, gray Midwest.

These hardy sparrows spend most of their day scratching for food among shrubs and thickets, often gathering beneath feeders to feast on fallen seed. Along with northern cardinals, they are the last birds to return to their roost each evening, making the most of the short winter days. And their hearty song, "Oh my Canada, Canada, Canada," brightens the dark season for all of us.

As spring approaches, their chorus will intensify and, by mid April, they will return to their homeland. Until then, I thank them for their company.

Sunday, November 4, 2007

The Beloved Bluebird

One of the more beloved birds in North American, the eastern bluebird is common east of the Rocky Mountains and is the State Bird in both New York and Missouri. Bluebirds that inhabit Canada and the northern U.S. move south for the winter but those that reside throughout most the the central and southern States stay through the year.

While they feast primarily on insects during the warmer months, eastern bluebirds shift to a diet of berries from late fall through early spring; wild grapes, chokecherry, sumac, cedar and juniper berries are among their favored foods. And while they pair off in spring and early summer to raise their young, these sociable birds form loose flocks for much of the year and may roost together in tree cavities or nest boxes to conserve heat in winter.

Eastern bluebirds favor wooded meadows and farmlands and often gather on powerlines or fences. Come spring, potential parents look for nest cavities in trees, fence posts or man-made boxes; competition for these sites comes from tree swallows, starlings and house sparrows, posing a threat to the welfare of this attractive and beloved native.

Saturday, November 3, 2007

Tropical Storm to Nor'easter

After forming in the eastern Caribbean and bringing deadly rains to the Dominican Republic, Tropical Storm Noel crossed Cuba and lost some of its punch. Redeveloping over the Bahamas, it then lolled about for several days, lashing the coast of Florida with a steady east wind and eroding many of its beaches.

Yesterday, with little fanfare, the storm gained strength and developed into the fifth Atlantic hurricane of the season. With sustained winds of 80 miles an hour, Noel drifted northward and became "extratropical," no longer sustained by the heat engine of warm, tropical waters. Entering the temperate latitudes, it was now energized and steered by an approaching front.

This morning, Noel, centered off the mid-Atlantic coast, is lashing eastern Long Island, Martha's Vineyard and Nantucket with tropical force winds. The storm is expected to move rapidly to the northeast (along the approaching front), raking Cape Cod and the east coast of New England before making a direct hit on Nova Scotia.

Friday, November 2, 2007

Waterfowl Highway

Rising along the Continental Divide in southwestern Montana and northwestern Wyoming, the Missouri River exits the Rocky Mountains at Great Falls and then flows eastward across the Northern Plains. In eastern South Dakota it turns to the south, forming the common borders of Nebraska, Iowa, Kansas and Missouri; at Kansas City, it flows eastward once again, dipping through Missouri and merging with the Mississippi just north of St. Louis.

Before modern man dammed and channelized it, the Missouri was a wide, braided, meandering river as it crossed the vast, semiarid Northern Plains. Numerous oxbows and extensive wetlands bordered its channel, offering irresistable reststops for migrant waterfowl. As the only major river system in that part of the Continent, the Missouri became a natural highway for these migrants, guiding them from their arctic and prairie breeding grounds to wintering areas along the lower Mississippi Valley and Gulf Coast.

Though man has altered its flow and drained most of its wetlands, the Missouri remains the primary route for migrant waterfowl in the Central Flyway of North America. Numerous wildlife refuges line its corridor and November is one of the best months to visit these preserves. The DeSoto National Wildlife Refuge, on the Iowa-Nebraska line, and Squaw Creek National Wildlife Refuge, in northwest Missouri, are two of the best.

Thursday, November 1, 2007

The Nature of November

Were it not for Thanksgiving, November would not be welcomed by many Midwesterners. Usually depicted as a gray, windy month, it often brings the first significant cold wave of the season and heralds the onset of winter. And it doesn't help that November arrives on the heels of sunny, colorful October!

But November brings many natural highlights to the Heartland. Early in the month, when the weather is still relatively mild, the waterfowl migration is peaking and a wide variety of geese, ducks, grebes, loons and cormorants gather on our lakes and reservoirs. By the middle of November, huge flocks of snow geese are moving south along the Missouri and Mississippi valleys, stopping to rest and feed as they head for coastal marshes. In the woods and wetlands, resident mammals are increasingly active and visible as they engage in their annual rut or collect food for the lean months ahead.

November also brings a change in our regional bird population as visitors from the north (juncos, hermit thrushes, red-breasted nuthatches, winter sparrows) replace our summer songbirds. Finally, by the end of the month, as their mating season begins, our resident owls become more vocal and conspicuous, filling the night with their love calls.