Sunday, January 30, 2011

The Elusive Owl

Of the many bird species that are widely distributed in North America, the northern saw-whet owl is certainly the most elusive. This small, reddish-brown raptor breeds across southern Canada, the northen U.S. and down the mountain corridors of our country, wintering in these and most other regions, as far south as the Gulf Coast; nevertheless, due to its diminuitive size, retiring nature and strict, nocturnal habits, this owl is rarely encountered.

Northern saw-whet owls favor moist, coniferous woodlands, where they nest in tree cavities, often utilizing abandoned woodpecker holes. Feeding on mice, shrews, large insects and small songbirds, they roost in dense groves of conifers once the breeding season is over; during the day, they are generally quiet, immobile and rather tame, rarely flushing if humans approach.

Birders seek this prized addition to their life list by looking for tell-tale piles of regurgitated pellets, white-washed with excrement, beneath the saw-whet's roosting site. Some use recordings of their monotone whistle to draw them into the light or listen for the mobbing calls of chickadees and other small birds that are trying to dislodge the owl from their territory. Whatever method one might use, a great deal of luck will be the primary key to finding this elusive visitor.

Friday, January 28, 2011

The Sarah Palin Syndrome

American history is replete with individuals who came from modest backgrounds and, through talent and hard work, achieved international fame in their chosen career. This, after all, is the defining principle of the American dream, facilitated by the freedoms of our political and economic system.

In recent decades, however, a disturbing path to fame has emerged, driven by social networking, an explosion of cable channels and the rise of instant, digital communication. Individuals with a talent for self promotion have discovered opportunities for stardom via reality shows, online videos and the media's insatiable appetite for dysfunctional personalities. The more outrageous and bizarre the behaviour, the greater its value for mass exploitation.

The patron saint of this modern American trend is Sarah Palin. Rescued from a failing and scandal-plagued governorship by a desperate presidential candidate, Ms. Palin demonstrated little qualification as a running mate and insured his defeat. Nevertheless, thrown into the national spotllight, she had traits that the media adored and has since become an international celebrity. While deficient from an intellectual point of view, Ms. Palin has shown a talent for attacking the thoughtful work of others, opening up lucrative speaking engagements and spawning a series of philosophical tomes. Hesitant to criticize such a popular hero of the religious right, conservative politicians praise her virtues and, recognizing the value of controversy, the media giants are quick to publish her daily pronouncements. In America, it seems, entertainment has now become the primary road to success.

Thursday, January 27, 2011

The Uinta Mountains

Looking at a map of North America, one notices that the major mountain ranges trend north to south; this reflects the compressive, subduction and, in the case of fault-block ranges, stretching forces that produced the uplifts, which have generally come from an east-west direction. Two exceptions are the Transverse Range of Southern California, created by northward compression along the San Andreas Fault, and the Uinta Mountains of northeast Utah.

The Uintas, the highest range in the State, formed during the Laramide Orogeny (70-60 million years ago), which lifted the Rocky Mountain chain. Pressure within the North American craton, presumably secondary to the Farallon Plate subduction along the west coast, crumpled ancient Precambrian bedrock up through the overlying Paleozoic and Mesozoic sediments. Parallel faults in northeastern Utah, running west to east, dictated the unusual orientation of the Uinta uplift; furthermore, subsequent shifts in the crust forced the initial anticline northward atop the edge of the Green River basin, tilting the block. This latter movement, along a thrust fault, explains why the crest of the Uinta Range is much closer to its steep northern slope than to its more gradual southern slope. The uplift of this massive range also produced deep basins to its north, south and east, which held the Green River Lakes of the Eocene, among the largest freshwater lake systems in the history of our planet.

During the Pleistocene, glaciers scoured the summits of the range and produced broad, U-shaped valleys on its flanks, especially along the south side of the Uintas; this glaciation also created massive domes and flat expanses of tundra, with numerous glacial lakes, atop the range. Drainage along the south side of the Uintas is via streams that flow southeastward across the Uinta Basin to join the Green River, a major tributary of the Colorado; most streams on the north side also drain to this River though the western third of the north flank feeds the Bear River, which flows to the Great Salt Lake.

Wednesday, January 26, 2011

Hualapai Crossroads

Just southeast of Kingman, Arizona, the scenic Hualapai Mountains form a high wall above the east edge of the Colorado River Valley. Like most of the ranges in the Basin & Range Province, it is a fault-block uplift, aligned from north to south, the product of stretch and fracture within the Earth's crust.

The most interesting feature of the Hualapai Range, however, is its location at the crossroads of several geophysical provinces. To its east, beyond the Big Sandy River Valley, is the western wall of the Colorado Plateau, which extends across northern and eastern Arizona, southeastern Utah, northwest New Mexico and western Colorado. The Hualapai Mountains, themselves, lie within the southernmost extension of the Mojave Desert while, to their south and southwest, the terrain drops into the Sonoran Desert of southeast California, southern Arizona and northwest Mexico.

For now, the Hualapai Range towers above the stark, arid landscape of northwest Arizona, offering a cool escape for wildlife and humans alike. Eventually, as rifting continues across the Great Basin, the ocean will invade through the lower Colorado Valley and these mountains, like other ranges of the Intermountain West, will overlook a vast inland sea.

Monday, January 24, 2011

La Nina & the Australian Floods

The massive flooding across eastern Australia, which began in November, has been associated with the La Nina phenomenon, which tends to peak every 3 to 7 years. Produced by high pressure over the eastern Pacific and low pressure over the western Pacific, this weather pattern results in strong Pacific trade winds, which bring relatively warm ocean waters to the southeast coast of Asia and the northeast coast of Australia. This spawns strong cyclones and excessive rainfall in these areas, generally during an autumn to autumn cycle in the Southern Hemisphere.

Coinciding with a high Southern Oscillation Index, which measures the seasonal variance of sea surface pressure between Tahiti and Darwin, La Nina episodes trigger excessive precipitation across northern and eastern Australia. This year's flooding has been especially severe, disrupting transportation, stranding inland towns, inundating coal mines and wiping out much of the region's wheat crop. The Great Barrier Reef may also be affected, as plumes from the rivers of northeast Australia sweep particulates and pollutants toward that fragile ecosystem.

The current Australian flooding may prove to be the worst in recorded history. Unfortunately, some climatologists project that the La Nina and the opposite El Nino patterns will intensify with the advance of global warming. For eastern Australia, that could mean an alternating pattern of severe floods and prolonged drought.

Sunday, January 23, 2011

From Sand to Snow

Departing Tampa under sunny but chilly skies, our flight paralleled the west coast of Florida, crossing the numerous beaches, islets, sand spits, wetlands and meandering rivers that characterize the region. After passing Cedar Key and the Suwannee River delta, the north coast of the Gulf came into view, with St. Vincent, St. George and Dog Islands forming an archipelago just offshore.

As we passed east of Tallahassee, plumes of smoke appeared across the Coastal Plain, where farmers were torching their fields to prepare for the coming spring. Further north, we crossed the Walter F. George Reservoir, on the Chattahoochee River, and then passed the tortuous arms of Lake Martin, northeast of Montgomery, Alabama. Nearing Birmingham, the topography became more interesting, as a ridge and valley landscape marked the transition from the flat Coastal Plain to the south end of the Appalachian Plateau.

A bank of clouds, just north of Birmingham, was the leading edge of the latest cold front and the clouds continued to thicken for the rest of our journey. While, at 35,000 feet, the sunshine of the South remained with us, I knew that our next view of the ground would produce a jolt of reality. Sure enough, our descent through the clouds began ninety miles southeast of St. Louis and, when the Mississippi Valley finally emerged, it was quilted with snow-covered fields and shrouded by a gray winter sky. After all, it is January and we were back in the Heartland.

Saturday, January 22, 2011

Oscar Scherer State Park

Established in 1956 and expanded to 1381 acres in the 1980s, Oscar Scherer State Park, south of Sarasota, Florida, protects scrubby flatwoods, vital breeding habitat of the threatened Florida scrub jay. Dominated by scrub oaks, wax myrtle, cabbage palm and scattered groves of slash pine, this scenic preserve is accessed by fifteen miles of hiking trails and is maintained by prescribed burns; the flat, sandy terrain is drained by South Creek, which meanders southward and then westward, toward Dryman Bay.

A nature center introduces visitors to this unique ecosystem and to the varied wildlife that inhabit the Park. In addition to the Florida scrub jays, the latter include ospreys, bald eagles, gray fox, bobcats, gopher tortoises, indigo snakes, wild turkeys and white-tailed deer; Big Lake, at the southeast edge of the Park, attracts a wide variety of water birds and migrant waterfowl.

The entrance to Oscar Scherer State Park is on the east side of U.S. 41, approximately six miles south of Sarasota. The Park is open every day of the year, from 8AM to sunset; an entrance fee is charged. The preserve is also crossed by the Legacy Trail, a rails-trails bikeway that opened in March, 2008; ten miles in length, this path connects Sarasota and Venice.

Friday, January 21, 2011

Cape Cod, Florida

For residents of South Florida, the months of winter and early spring offer relief from the heat, humidity and tropical storms that characterize this region. However, those escaping the frigid weather of a northern winter are hoping to find the intense sunshine and sultry conditions that they associate with Florida and are not thrilled to encounter cool, breezy weather; this week, while pleasant, has certainly been far from balmy.

Walking Lido Beach this morning, we were enveloped in thick, cool fog; only the beach, the crashing waves and the first line of dunes were visible and all was silent except for the roar of the surf and the occasional shriek of a gull. If it were not for a mixed flock of royal and sandwich terns, resting on the beach, we could easily have been at Cape Cod on a summer morning; indeed, the Theme from Summer of 42 popped into my head as we strolled along.

Such weather is certainly not unusual for South Florida at this time of year. As experienced naturalists know, one cannot fully appreciate an ecosystem without visiting it during all seasons; a subtropical latitude does not guarantee the hot, humid weather that many snowbirds seek.

Thursday, January 20, 2011

Reddish Egrets

Mention egrets and most Americans will think of the white wading birds that are so common across our Southeastern States. Experienced birders know that these great, snowy and cattle egrets also migrate to northern regions of our country during the warmer months, following the shorelines or major inland rivers.

But one egret is neither white nor inclined to leave the Gulf Coast. The reddish egret (which actually does include a white race) is far less common than its cousins and is confined to Florida, the Gulf Coast and southern California. The plumage of its head and neck is a dark salmon color while its body and legs are bluish gray; in contrast to other egrets, it has a pink bill, tipped with black, and sports a shaggy crest of plumes atop its head.

Best found on tidal flats of coastal bays, reddish egrets are often first noticed due to their active feeding style, dancing about to snare small fish and invertebrates while holding their wings in an uplifted position. For some reason, I have seen more reddish egrets on this trip to Longboat Key than on past visits; pure luck, I would guess.

Wednesday, January 19, 2011

Shifting Sand

Barrier islands, perhaps the most transient landforms on Earth, are created, molded and destroyed by waves and ocean currents. Attracted to their scenic bays and seascapes, man has ignored the natural history of these islands, designing homes and buildings that, theoretically, are able to withstand tropical storms and hurricanes. But, while these structures might remain anchored in the bedrock of the continental shelf, the sand, roads and foliage that surround them may be swept out to sea.

Greer's Beach, on the north end of Longboat Key, has attracted naturalists, photographers and sun-bathers for decades. Its fabulous variety of shells reflects the divesity of its offshore marine life which, in turn, attracts a fascinating variety of birds, sea turtles and dolphins. Long a protected site for nesting colonies of least terns and black skimmers, this beach is regularly assaulted by storms and is especially vulnerable to changing currents since Longboat Pass is just to its north.

Significant loss of beach width has occured in recent years and the Longboat City Council is struggling with the restoration choices that they face, all of which are very expensive and none of which is likely to offer a permanent solution to the natural process of beach erosion. We humans like to think that, equipped with modern technology, we are able to control nature; but, when it comes to living on barrier islands, such conviction is pure folly.

Tuesday, January 18, 2011

A Day on the Bay

Awakening to the yodel of a common loon, I looked out to find Sarasota Bay shrouded in fog. The loon drifted on its surface, just off shore, and the distant silhouettes of herons and egrets, standing in the Bay, let me know that low tide was at hand. By mid morning, the fog began to lift and small flocks of ibis, wood storks and snowy egrets moved between the mangove islands. A lone dolphin plied the boat channel, a flotilla of white pelicans gathered in a nearby cove and, out on the calm waters, double-crested cormorants and red-breasted mergansers dove for their breakfast.

Clear, sunny skies illuminated the Bay by mid afternoon, drawing brown pelicans, belted kingfishers, ospreys and royal terns to the scene, circling above the water before diving to snare their prey. Along the sea wall, great blue and green-backed herons patrolled for insects, lizards and small fish while, near the entrance to our harbor, a large school of striped sheepheads drifted through the clear, sunlit water.

This evening, as a full moon rose above Sarasota Bay, squadrons of laughing gulls, white ibis, snowy egrets and royal terns headed for their nightly roosts. All was silent except for the intermittent splash of restless fish, seemingly glad to have survived another day amidst their numerous avian predators.

Monday, January 17, 2011

Fast Track to Spring

Ah, the joys of modern travel. One can depart the cold, gray, Midwestern winter and, within two hours, arrive in the mild, fragrant clime of South Florida. Thus was our experience today as we traded the snowy hills and fields of Missouri for the lush, subtropical landscape of Longboat Key, a barrier island off Sarasota.

Having climbed above the barren woods of St. Louis, we landed amidst the greenery of Greater Tampa, surrounded by pines, palms, live oaks and fig trees. While noisy flocks of Canada geese had plied the chilly morning fog of the Missouri River Valley, lines of brown pelicans now drifted through the balmy haze of Florida's coastal bays. Red tails that perched in the leafless trees along I-70 were replaced by ospreys here, resting on channel markers or rising from the open waters, juggling fish in their talons.

Our rendevous with spring will last but a week, since work and other duties beckon from the Heartland. We'll do our best to forget those obligations for now and turn our attention to the beaches, bays and mangrove islands of this fabulous coastal ecosystem. Details to follow.

Sunday, January 16, 2011

Human Society & Mental Illness

Throughout most of human history, mental illness remained a mysterious affliction, thought to represent the presence of evil spirits; for this reason, psychotic individuals were either confinded to asylums or put to death. Even today, some religious groups promote the concept that psychosis is the result of demonic possession.

While modern science has uncovered the pathophysiology of mental illness, this diagnosis retains its negative image and the families, friends and associates of afflicted individuals are loathe to acknowledge or discuss its effects. Even though drug companies have succeeded in turning some behavioral conditions, such as ADHD and Bipolar Disorder, into national fads, the diagnosis of a psychotic disorder, such as schizophrenia, is often kept under wraps.

The unwillingness or inability to deal directly with the consequences of psychoses extends beyond the immediate family to society as a whole. Insufficient funding is directed to inpatient and outreach facilities, responsible parties ignore the clinical signs of disease progression, laws prevent confinement of uncooperative patients and untreated psychotic individuals roam our communities. Squeamish about mental illness, human society looks the other way, setting the stage for the tragedies at Virginia Tech, Tucson and many future locations.

Saturday, January 15, 2011

Great Basin National Park

Just west of the Utah line, U.S. 50 crosses the Snake Range of east-central Nevada, among the highest mountain ranges in the Great Basin; indeed, Wheeler Peak, 13063 feet, which caps the southern portion of this Range, is the second highest summit in Nevada and the 12th most isolated peak in the U.S. (it is 232 miles to the closest higher summit). Like the other fault-block ranges of the Great Basin, the Snake Range is oriented north-south and formed along a fracture in the Earth's crust; the rise of the Sierra Nevada batholith, to the west, and the uplift of the Colorado Plateau and Rocky Mountain corridor, to the east, have stretched (and continue to stretch) the crust of this region.

Since 1986, Wheeler Peak has been the centerpiece of Great Basin National Park, which highlights the varied life zones of this stark landscape, from the high desert to the alpine tundra. Introduced at the Visitor Center, in Baker, Nevada, and accessed by the State's highest paved roadway (which ascends to 10,161 feet) the Park harbors a wide range of plant and animal life, drawn to the "sky islands" of this arid region. Among the Park residents are mountain lions, elk, mule deer, bighorn sheep, bobcats, porcupines and ring-tailed cats. Various bat species inhabit more than 40 caves in this scenic Park, the most famous of which are found in the Lehman Caves group, eroded from Cambrian limestone during the wet climate of the Pleistocene.

North of U.S. 50, which summits the Snake Range at Sacramento Pass (7154 feet), is the Mt. Moriah Wilderness Area. Harboring the same life zones and wildlife as the National Park, this region is reknowned for its massive alpine tableland, bordered by groves of bristlecone pine. The longest-lived trees on our planet, some of these pines germinated 5000 years ago.

Friday, January 14, 2011

Tree Weasels

American pine martens are mid-sized members of the mustelid (weasel) family that inhabit coniferous forests of North America; their range extends across Alaska, Canada, northern New England, the Upper Great Lakes and the major mountain chains of the western U.S. Equipped with a luxurient coat, broad, furred paws and retractable claws, martens are as comfortable in the trees as they are on the snow-packed ground.

Pine martens are omniverous and primarily nocturnal; while red squirrels and other small mammals are their favored prey, they also feed on fish, frogs, birds, carrion, eggs, berries and nuts. Solitary for most of the year, they mate in late summer and, following a period of delayed implantation and a two month gestation, the kits are born in March or April. Females and their young may den in tree cavities, hollow logs or rock piles while males roam larger territories and use a variety of temporary shelters.

Elusive and generally inactive during the day, martens are rarely encountered by those of us who venture into their domain. Nevertheless, their population was once decimated by the American fur trade and their welfare remains threatened by deforestation. Here's hoping that these attractive tree weasels haunt the Great Northwoods for generations to come.

Thursday, January 13, 2011

Heart of the Cold

The massive dome of cold air that brought snow and ice to much of the country is centered over Missouri this morning, giving us a morning low of minus 4 degrees F; it doesn't get much colder at this latitude of the American Midwest. Indeed, since we now sit beneath the heart of the dome, it is currently 15 degrees colder in Columbia than it is in northern North Dakota.

While it's still far to early to know, this may be the coldest morning of the winter. As the atmospheric dome drifts off to the east, our afternoon high will rebound into the mid twenties, a typical overnight low for this time of year; a return to more seasonable temperatures, later in the week, will feel like spring.

Mid January is often the most difficult time of year for humans in the Northern Hemisphere. Though we are a few weeks past the winter solstice, longer days will not become apparent until later in the month and the persistent darkness and cold begin to take a toll on our minds and bodies. Designed to function in the Tropics, we were coaxed into northern latitudes by our large brains and must now live with the consequences.

Tuesday, January 11, 2011

Relative Hardship

We humans are prone to self pity. This week, there is plenty of grumbling across the U.S. as snow and ice grip large segments of the country, snarling traffic, closing airports and triggering a wide range of accidents. Of course, when compared to our ancestors, who lived without heated homes, running water or even the hint of modern technology, our transient difficulties seem minor indeed.

And then there is Haiti. The citizens of that impoverished country may be immune to ice and snow but, one year after their devastating earthquake, much of the population still lives in tent cities. Despite the initial wave of attention and contributions and the continued efforts of public and private relief organizations, the suffering of Haitians has faded from our collective conciousness. The same, of course, is and has been true for other regions of the globe, where humans live on the edge of survival.

There is no doubt that many of us suffer from disaster fatigue, having contributed to a large number of relief funds and then left wondering what middle men and corrupt officials might benefit from our charity. But it is truly hard to justify the broad range of hardship that defines the human condition; a day or two in a U.S. airport is certainly less demanding than a year in a tent.

Sunday, January 9, 2011

Sociable Siskins

Yesterday afternoon, with bright sunshine streaming through the frigid air, a flock of songbirds alighted at our backyard feeder. Smaller and slimmer than sparrows, they were heavily streaked, like female house finches, but their markings were cleaner and darker. As they moved about the feeder, flashes of yellow appeared on their wings and at the base of their notched tails; combined with their thin bill and pale wing bars, the markings gave the impression that they might be yellow-rumped warblers.

In fact, these amiable birds were pine siskins, small members of the finch family. After breeding in the vast coniferous forests of Canada, New England and the western mountains, they roam about in large flocks during the colder months. An irruptive species, pine siskins are very erratic in their movements throughout the central and eastern U.S. and their numbers vary widely from winter to winter, depending on the seed crop in their home territory.

When they do appear, these gregarious birds are usually found in large flocks, often in the company of goldfinches, crossbills or redpolls. Their rising, wheezy call aids identification and their flight is equally distinctive; while siskin flocks undulate, in the manner of goldfinches, they also close in and spread out in rhythmic sequence, accentuating their cooperative spirit. Indeed, while many bird species congregate during the winter months, pine siskins tolerate one another during the breeding season as well, often placing their shallow, cup-shaped nests in close proximity. Just another species for humans to emulate.

Saturday, January 8, 2011

The Ice Belt

The development of an ice storm requires two primary ingredients: a shallow layer of cold air at the surface and a center of low pressure that sweeps warm, moist air above that colder layer. In this scenario, rain develops in the upper atmosphere and freezes within the cold zone (to produce sleet) or upon striking the frozen surface (freezing rain). Such conditions develop along the leading edge of a cold front, where frigid air is knifing in below warm, humid air.

A geographic belt of the Southern U.S., extending from the Carolinas to Oklahoma and North Texas, is especially prone to ice storms. Far enough south to avoid deep pockets of cold air and subject to incursions of warm, moist flow from the Gulf of Mexico, this region is regularly placed at risk as winter and early spring storms move eastward along the Gulf Coast. While most regions of the U.S. are subject to ice storms from time to time, this belt, caught between the warm Gulf waters to the south and the frigid snow belt to the north, gets more than its fair share of these deadly storms.

This weekend, the right conditions appear to be developing for another extensive ice storm across the Deep South. Time will tell where the clash zone sets up; further north, precipitation will fall as snow while, to the south, cold rain will develop. Either would be preferable to a crippling glaze of ice.

Friday, January 7, 2011

The Nature of Emotion

Despite the numerous problems facing this nation....the wars, health care, the deficit, a sluggish economy, political stalemate, etc., the media is mesmerized by John Boehner's tendency to cry in public. After all, America is a stoic country, proud of our military and economic power; we prefer a macho image: John Wayne, Dirty Harry and George Patton are the saints that we adore.

Nevertheless, humans are emotional creatures, a consequence of our large brains which provide the capacity to love, ponder, hope, remember, fear, regret, imagine and empathize. How we express these emotions is a product of our constitution and our childhood experience; our genetics, our family and our culture all influence this trait. Many of us are taught, sometimes admonished, to keep our emotions in check while others are encourged to be open and expressive, at times to excess.

One would hope that our opinion of others is based on their views and actions, not on their tendency or reluctance to show emotion. In the case of John Boehner, I am more concerned about his policies than his propensity to tear up in public. Indeed, I am less bothered by those who wear their emotions on their sleeves than by those who appear to be incapable of emotion, sensed or expressed.

Thursday, January 6, 2011

Snowshoe Hares

Common residents of boreal and mountain forests, snowshoe hares are found across the northern tier of North America, from Canada and Alaska to New England, the northern Great Lakes region and the Pacific Northwest; they also inhabit forests of the Appalachian mountains, south to Virginia, and the subalpine zone of the Rocky Mountains, down to northern New Mexico.

Possessing a rich brown coat in summer, these hares molt to white during the snowy months, prompting their other name: varying hare; the snowshoe title reflects their large hind feet which are furred on the soles, improving mobility in deep snow and increasing traction on icy surfaces. Snowshoes feed on a wide variety of plant greenery from spring to early fall, switching to a diet of twigs, buds and conifer needles in winter; they also gnaw on carrion throughout the colder months, including the dead of their own species. After spending the day in a hidden "form" or abandoned burrow, snowshoe hares become active at dusk and are primarily nocturnal; as in other prey species, this adaptation helps to protect them from predators, which include mountain lions, lynx, bobcats, coyotes, fox, weasels, fishers, owls, gyrfalcons and golden eagles.

Mating begins in late winter and females produce up to four litters from February through late summer. This high productivity leads to a population boom every decade, followed by a significant drop-off in their numbers; of the many species that prey on snowshoe hares, it is the lynx that is especially reliant on this food source and their population rises and falls in response to the snowshoe cycle.

Wednesday, January 5, 2011

The Permian Reef

During the Permian Period, about 260 million years ago, a shallow, tropical sea covered what is now southern New Mexico, West Texas and northern Mexico. A broad arm of this sea, known to geologists as the Delaware Basin, was rimmed by a massive reef, formed by the calcareous shells and body parts of marine organisms.

As Pangea broke apart, tectonic uplift cut off this sea's connection with the ocean and, over thousands of years, it evaporated, leaving the reef encased in halite, gypsum and other deposits. Additional layers of sediment and wind-blown deposits covered the region througout the Mesozoic Era and Tertiary Period, obscuring all evidence of the Permian reef. Then, during the Miocene-Pliocene Uplift, some 20-10 million years ago, the reef and its encasing sediments were raised and erosion gradually uncovered portions of the reef's Capitan limestone, with its cargo of marine fossils.

Today, much of the 400-mile long, U-shaped reef remains buried below the landscape of West Texas and southeastern New Mexico but its massive limestone formations are exposed as the Apache, Guadelupe and Glass Mountains. In addition, one section of the buried reef, in New Mexico, has been hollowed out by acidic groundwater, yielding Carlsbad Caverns, among the largest and most spectacular cave systems on our planet.

Tuesday, January 4, 2011

Prairie Falcons

More slender and lighter colored than their famous cousin, the peregrine, prairie falcons inhabit the semi-arid grasslands of the High Plains and Intermountain West, from southern Canada to Mexico. In summer, they are also found on the alpine tundra of western mountains and, in winter, some roam to eastern regions of the Great Plains.

Often seen perching on a fencepost in open country, this falcon is best identified when it streaks across your path and its black axillary plumage becomes evident. Matching the flight speed of peregrines, prairie falcons hunt low to the ground, racing along to snare unwary birds, ground squirrels, prairie dogs or pikas.

Like golden eagles, prairie falcons nest on the ledges of rock cliffs, often on the edge of mesas and buttes that rise above open terrain. Females lay 2-6 eggs on a mat of twigs and the young are fledged within a month of hatching, free to soar the Big Sky country of the American West.

Monday, January 3, 2011

Hooked on Relief

All regions of our magnificent planet harbor enough natural diversity to keep an avid naturalist engaged for a lifetime. Having had the opportunity to explore many of these areas myself, I must admit a preference for landscapes with vertical relief.

Perhaps my early discovery of a limestone gorge near our neighborhood (as described in my Wonderland blog) set the stage for this enthusiasm, which is now reflected by a keen interest in topographic maps. There is something about the raw manifestation of erosive power, so evident in mountain and canyon landscapes, that both invites exploration and ignites curiosity about the geophysical forces that produced the spectacular scenery.

As a naturalist, I am also drawn to the stacked life zones that characterize these vertical landscapes. The interplay of mean air temperature, sun exposure, precipitation, growing season and soil condition produces these vegetation zones, each of which attracts its unique cast of wild residents. Trails that lead upward or downward through vertical landscapes wind through a changing mix of flora and fauna and offer a series of unique perspectives on the regional environment. Finally, these geophysical barriers, by creating upslope precipitation, downslope warming, rain-shadow patterns and life-giving streams, have significant effects on surrounding ecosystems, further augmenting the natural diversity of the region.

Sunday, January 2, 2011

Wintering Cranes

Sandhill cranes breed across the Arctic tundra of North America and in scattered regions from the Upper Midwest to the Intermountain West; a separate population inhabits the dry prairie region of south-central Florida. Come fall, most of the northern flocks migrate to wetlands from the Texas Gulf Coast to Southern California and southward into Mexico.

A large percentage of these wintering cranes congregate at a chain of National Wildlife Refuges across West Texas and southern New Mexico; these include Muleshoe NWR, northwest of Lubbock, Bitter Lake NWR, northeast of Roswell and Bosque del Apache NWR, south of Socorro, New Mexico. Feeding in crop fields and boggy grasslands throughout the day, the cranes return to these refuges at sunset, roosting in broad, shallow lakes that offer protection from nocturnal hunters.

It is the opportunity to observe these large flocks of sandhills as they arrive at sunset or depart at sunrise that draws birders and naturalists to the Southern High Plains in the middle of winter. Of course, other wildlife can also be seen at these refuges, including snow geese, bald and golden eagles, prairie falcons, a large variety of waterfowl, roadrunners, longspurs and wintering bluebirds; mammals include coyotes, mule deer, pronghorns and, at Bosque del Apache, porcupines.

Saturday, January 1, 2011

The Human Year

For most human cultures and with the general consensus of others, today marks the beginning of a new year. Though long established by religious and political tradition, it is an arbitrary assignment, having no significance in the natural world. Indeed, since a year coincides with the length (in time) of Earth's orbit around the sun, the winter solstice marks the beginning of nature's year.

Whatever New Year's Day we might choose, the interval of a year is firmly ingrained in the human psyche, tied directly to the awareness of our own mortality. We measure our lives by this time period and know just how many years we might expect to live. Some years hold special significance in our memories, usually related to relationships and events, while others loom as mileposts of opportunity or demise in our future.

Taking us through the seasons, each year enriches our lives and provides 365 days to explore the rich diversity of our home planet, from natural ecosystems to the varied manifestations of human culture. We would do well to make the most of each day and become less focused on the larger divisions of our lives; for all we know, those years may be limited.