Nature's Advance Man

This morning, an eastern phoebe flitted across the restored prairie at Forum Nature Area, in Columbia. Moving through chilly, moist air under gray skies that might rain or snow, the flycatcher seemed out of place.

Yet, this is his annual calling card.  Nature's advance man often arrives by mid March, six weeks ahead of many northern flycatchers.  Among the earliest signs of spring, eastern phoebes are generally found alone, flicking and spreading their tail as they alight on a sapling or dead wildflower stalk.  Until the insect supply catches up with their energy needs, they feast on berries and soft seeds as well; once the weather is reliably warm and hordes of insects fill the air, eastern phoebes pair off, nesting on cliff ledges, beneath bridges or along the eves and beams of barns and other out-buildings.

The hardiness of this flycatcher is also apparent in the fall, when they stop to winter along the southern tier of the U.S., well north of their cousins that head for the balmy air of Central and South America.  Why a bird that feeds on flying insects would evolve this pattern of behavior, matched only by the tree swallow in North America, is somewhat of a mystery.  Despite their habit of arriving before the last winter freeze and wintering in areas prone to cold weather, eastern phoebes thrive;  indeed, their population is increasing, partly in response to the varied nest sites that we humans provide.

Denial in Boston

Devout Catholics, like almost everyone else, favor efforts to minimize the need for abortion; eliminating unwanted pregnancies offers the most direct route toward that goal.  One assumes that they also support the prevention of sexually transmitted diseases, such as  HIV, Hepatitis B, Hepatitis C, gonorrhea and chlamydia, among others.

Nevertheless, officials at Boston College, a Catholic institution, oppose a student program to improve access to condoms on campus.  Apparently convinced that this project will shed a negative light on their University and encourage premarital sex, they announced their intention to shut down the program; they softened their position by citing the availability of condoms at retail stores or through public health services.

This antiquated stance, surely taken to appease older alumni and donors, is just the latest attempt by conservative religious organizations to deny the nature of human sexuality.  Whether they admit it or not, sexual activity is widespread among college students, including those at Catholic institutions.  Improving access to condoms does not encourage sexual activity; rather, it serves to reduce the incidence of sexually transmitted diseases, unwanted pregnancies and abortion.  Though it has long been squeamish about dealing with human sexuality, including its own sexual scandals, one hopes that the Church will soon emerge from its state of denial and join the preventive healthcare movement.

Avian Drones

Driving back to spring, we left the wintery landscape of northeastern Ohio and headed WSW across the Glaciated Plain of the American Midwest.  While we enjoyed clear skies and mild weather, wildlife observations were rather limited.  Turkey vultures were the lone exception, soaring above the snow speckled farmlands from Ohio to Missouri.

These avian drones, unlike their military counterparts, are not predators; rather, they keep an eye (and, more importantly, a nose) on the rolling fields below, searching for carrion.  Roadkill is readily available along and near the highway and many small mammals, especially young cottontails, likely succumbed to our recent storm which left a heavy blanket of snow across the Heartland, now melting in the late March sun.

Terrestrial animals, including humans, tend to focus on the horizontal.  While we enjoy a colorful sunrise or sunset and glance at the night sky now and then, our daily chores keep us focused on our personal landscape; the heavens are reserved for pilots, meteorologists, astronomers and day-dreamers.  Prey animals, though subject to attack by raptors, must also concentrate on their ground-based habitat in order to find food, a potentially lethal distraction; even the terrestrial hunters, sniffing the air and scanning the horizon, pay little attention to the dome of sky.  Above us all, vultures survey the drama, gliding on thermals and waiting to feast on the leftovers.

The Seams of Life

Yesterday, facing another cold, gray, snowy day in northeastern Ohio, we opted for a visit to the Rock & Roll Hall of Fame, in Cleveland; it proved to be a very rewarding decision.  The Hall has created a fabulous review of rock history, from the late forties through the present, and the visit reinforced my view that music, more than any other human endeavor, keeps us tethered to the people, places and events of our life.

Music connects us with our past, with other persons of our generation, with those who influenced our lives and with world events that shaped our personal philosophy.  While many other factors are vital to our development as human beings, music is closely intertwined with memory, giving our life historical perspective.  Indeed, in the quilt of life, music provides the seams.

Some might argue that I am placing too much emphasis on the importance of music; after all, some cultures place strict limits on its use, concerned that its influence is too potent.  If anything, such fear reinforces the fact that music has always played a central, powerful role in human civilization, stirring our emotions, encouraging action and cementing relationships.  Our visit to the Rock & Roll Hall of Fame made all of this perfectly clear.

Horned Grebes

This morning, a pair of horned grebes rippled the calm, gray waters of Sandy Lake, southeast of Kent.  While the landscape of northeastern Ohio retains the look and feel of winter, these avian visitors were evidence that spring is gradually unfolding, however reluctant it may seem.

Indeed, horned grebes summer on freshwater streams, ponds and wetlands from southern Alaska to east-central Canada, including the northernmost tier of the American Great Plains.  Come fall, they head for saltwater bays and brackish rivers of the Pacific and Southeastern Coasts; a minority may also be encountered on southern freshwater lakes.  There and during their migrations, they are adorned in their black and white winter plumage, molting to their more colorful breeding plumage once back in their northern homeland.  Like pied-billed grebes but unlike western and eared grebes, horned grebes are rarely found in sizable flocks; rather, these small, stocky birds are usually seen alone, in pairs or in small groups.

Diving for small fish, aquatic invertebrates and insects, horned grebes are able to remain underwater for several minutes.  Floating nest platforms of dead vegetation are anchored to emergent marsh plants and 3-6 eggs are generally produced; both parents rear the youngsters which, like those of other grebe species, often ride on their backs until fledged.  Of special interest, horned grebes are known to consume some of their own feathers (and feed some to their young); ornithologists believe that this gastric plug retains small fish bones until they are more thoroughly digested.

Spring Postponed

A broad atmospheric trough, dipping through much of the U.S., has put spring on hold for the next few days.  Allowing cold Canadian air to plunge across the Great Plains and Midwest, this southern dip in the jet stream is steering the latest winter storm across central latitudes of North America, a region that is often well into spring by late March.

A swath of snow, from the Rockies to the Mid-Atlantic, now coats the early spring landscape, masking the greenery that began to spread over the past two weeks.  The cold air has also put a halt to the emergence of flowers and leaves across our woodlands, prolonging the barren look of winter.  Even the hardy tree frogs, which were calling from chilly pools and lakeshores have been silenced by this late blast from the north.

Visiting relatives in northeastern Ohio, we have escaped the heaviest snow but are left with the cold, gray shroud of a Great Lakes winter.  Five days into the astronomical spring, signs of the season are limited to longer days and snow-covered bulb plants; yet, birdsong is progressing on schedule and a hardy pair of Canada geese are incubating eggs at the edge of a marsh.  We humans may loathe this harsh, unseasonable weather but the wildlife, oblivious of calendars and devoid of expectations, are not burdened by impatience.  They do not share our disappointment; they know that spring has arrived.

Sports Heroes

In March, as coverage of the NCAA basketball tournament blankets the airwaves, we are reminded that, more than any other field of human endeavor, sports provides our heroes.  As early as grade school, star athletes emerge as our most admired peers and, by college, rabid fans wear the jersey of their favorite player, signaling both their infatuation with that athlete and their personal identification with his or her accomplishments.

Indeed, unlike members of other professions, athletes enjoy a fan base that is emotionally invested in their success or failure.  While the fans of musicians or actors may admire their work, extending both the gift and curse of celebrity, fans of athletes often sense a partnership with their heroes; in their minds, they are members of that player's team, sharing in the joy of victory and the agony of defeat.  Through their cheers, rituals and energy, fans actively participate in the contest and, as a consequence, become emotionally connected with the athletes.

This human tendency to anoint sports heroes, thereby basking in their glory, is fraught with danger for both the athlete and the fan.  Placed on a pedestal for their athletic talents, these heroes are almost certain to fail in some aspect of their life; they are, after all, humans, often having emerged from a disadvantaged childhood and ill-equipped to deal with their celebrity. In response, devoted fans feel betrayed and the blow to their self-esteem is redirected toward their fallen hero; his or her reputation, once embellished, now becomes a target of ridicule.

Dramatic Route to the Rockies

Back in the early 80s, when we lived in Arkansas, we usually took a southern route to the Rocky Mountains.  After following I-40 through Oklahoma and northern Texas, we would either head northwest, from Amarillo to Raton or, in a few cases, took a more dramatic route.

Leaving the Interstate at Tucumcari, New Mexico, we would follow New Mexico 104, passing or camping at Conchas Lake, on the Canadian River; the latter rises on the east slope of the Sangre de Cristo Range, in north-central New Mexico, and then angles SSE across the High Plains, carving a stark canyon through the Kiowa National Grassland before reaching Conchas Lake (elevation 4200 feet).  From the lake, Route 104 heads southwest and then northwest, passing a host of low mesas before reaching a prominent escarpment; climbing 1100 feet (from 5500 feet at its base to 6600 atop the cliffs), the traveler is suddenly treated to a spectacular view of the snow-capped Sangre de Cristo Range, from its southern end above Santa Fe to its Culebra segment, in southern Colorado.

Most visitors who drive to the Rockies from the central or eastern U.S. follow I-70 or I-80, both of which provide distant glimpses of the Front Range long before the grandeur of the mountains becomes evident.  While the southern route through Dalhart, Clayton and Raton is better, cutting through the scenic, volcanic terrain of northeast New Mexico, the route past Conchas Lake and on to Las Vegas, New Mexico, is, by far, the most dramatic.  For those who have never seen the Rockies, New Mexico 104 offers the most inspiring introduction.

The Maumee Torrent

Toward the end of the Pleistocene, a lobe of the Wisconsin Glacier pushed southwestward into northeast Indiana.  Its maximum extent was reached about 22,000 years ago and, as it retreated toward Ohio and Canada, it left a series of terminal moraines in its wake.  The last of these in Indiana was the Ft. Wayne Moraine, which curved through the present day city of Ft. Wayne, extending northward and southeastward from that site.

As the Ice Sheet melted from the region, Glacial Lake Maumee formed behind the Ft. Wayne Moraine. West of the Moraine, the ancestral St. Joseph and St. Marys Rivers merged to form the Little River, which flowed southwestward to join the Wabash just west of Huntington, Indiana.  Then, about 14,000 years ago, Lake Maumee breached the Ft. Wayne Moraine, sending a torrent of glacial meltwater through the Little River Valley and thence down the Wabash to the Ohio River.

As the Wisconsin Glacier continued to retreat into Canada and the St. Lawrence Seaway opened, the Great Lakes drained to the east; in concert, their surface areas decreased and the region began to rebound from the weight of the Ice Sheet.  A vast Lake Plain with extensive swamps and inland dunes developed across northwestern Ohio and the Maumee River cut its way upstream, capturing tributaries north and east of Ft. Wayne (including the St. Marys River).  Deprived of these headwater streams, flow through the Little River was greatly diminished and this stream now meanders through a broad floodplain of wetlands, the remnant path of the Maumee Torrent.

Cambrian Rock Exposures

Unlike strata from the other Paleozoic Periods, Cambrian rock exposures are relatively rare throughout the United States.  Deposited from 542 to 488 million years ago (MYA), when the variety of shelled and soft-bodied marine life was exploding on Planet Earth, Cambrian sediments lie deep beneath most regions of our country and are exposed primarily in association with ancient Precambrian basement rocks.

Where Precambrian domes or ridges have pushed up through overlying Paleozoic, Mesozoic and Tertiary strata, Cambrian sediments, usually metamorphosed by heat and pressure, may be found along the primary uplift.  Examples include Cambrian strata ringing the Black Hills, St. Francois Mountains (southeast Missouri) and Adirondack Mountains and seams of Cambrian deposits along the Blue Ridge of the Carolinas and northern Georgia; scattered Cambrian exposures are also found in the Rockies and throughout the Great Basin where fault blocks ranges brought deep basement rocks to the surface (e.g. in the Inyo and Nopah Ranges of southeastern California).  As one might expect, Cambrian rocks lie relatively close to the surface along the outer edge of some structural geologic basins; though often covered by younger sediments, they have been exposed by glacial erosion in Upper Michigan and eastern Wisconsin (along the northwest rim of the Michigan Basin).  Finally, Cambrian sediments are exposed deep in the Grand Canyon, lying just above the ancient Vishnu schist at the bottom of the chasm.

While Cambrian rock exposures are rather limited throughout most of North America, our Continent does harbor Earth's most famous Cambrian time capsule.  In the Canadian Rockies, west of Calgary, the Burgess Shale, deposited some 505 MYA, is renowned for its cargo of early marine fossils, including trilobites, brachiopods and soft-bodied organisms.

Pure March

Classic March weather has settled across the American Heartland this week.  Chilly, humid air, gray, breezy skies and intermittent rain, sometimes mixed with sleet or snow, envelop the landscape.  We humans, native to the tropics, retreat to our dry, heated homes while nature conducts her slow transition from winter to spring.

In the countryside, livestock plod through soggy fields, hawks patiently cling to damp, barren limbs, crows and starlings swarm across dreary farmlands and pickups leave muddy tracks on the graveled roadways; even our beloved bluebirds, perched on icy powerlines, reflect drab silhouettes in the filtered sunlight.

Yet, the fields and lawns are slowly greening, migrant waterfowl grace the ponds and lakes, the first dandelions glow along roadside sloughs and robins pick their way across the thawing soil.  Hyacinths, daffodils and early tulips brighten our flowerbeds and a purple haze of henbit will soon spread across the floodplains.  The dingy, wet, raw days of March are setting the stage for the glory of April and May, when a tide of fragrance and color will sweep across the Midwest.  We may not enjoy nature's preparations but the feast of spring will reward our patience.

Singles Day at Eagle Bluffs

Yesterday, enveloped in chilly air and shrouded by a low overcast, Eagle Bluffs Conservation Area, on the Missouri River floodplain, was loaded with ducks.  Mallards, gadwall, shovelers, coot and blue-winged teal filled the shallows while flocks of lesser scaup, ring-necked ducks and ruddy ducks gathered on the deeper pools.  They were joined by scattered pairs of Canada geese, a few pied-billed grebes and the occasional great blue heron, stalking the shorelines.

Of special interest were one snow goose, resting in a flooded woodland, a single white pelican, lounging on a mudflat and a lone trumpeter swan, feeding in a shallow channel.  All three of these species are generally found in sizable flocks and the combined presence of these solitary visitors was unusual, especially during the spring migration.

When a flocking species is found alone, it is often a sign that the bird is sick or injured.  If so, these white-feathered visitors, conspicuous in the brown, March landscape, will soon be culled by a coyote, a fox or a bald eagle.  Such is nature's way; spring may be the time of birth and renewal but death knows no season.  Then again, these loners may just relish their solitude and, once they tire of the hospitality at Eagle Bluffs, will join their cohorts to our north.

The Nature of Discrimination

This week, a Conservative U.S. Senator reversed his position on gay marriage.  The reason?  His son announced that he is gay.

The Senator's personal decision crystallizes the nature of human discrimination.  Planted in the minds of children and sustained by fear and ignorance, negative feelings toward persons of another race or culture persist.  So too do we learn to discriminate against those with physical or mental disabilities and those who manifest atypical behavior.  Homosexuality, derided as a mental illness or a sinful indulgence throughout human history, remains a target of discrimination, even in light of scientific evidence that sexual orientation is a genetic trait.

Once ingrained, intolerance of those unlike ourselves tends to persist until we are forced to confront those attitudes through personal experience or intimate relationships.  Those who remain sheltered from such interactions retain their zealous intolerance while those who develop a close association with past targets of discrimination come to respect those individuals and support their rights.  Education and social interaction are the keys to ending discrimination on a personal level; to eliminate intolerance on a broader scale, public pressure must weigh on those entrusted with writing and enforcing our laws (like Senators, for instance).

Detour to Wilson Lake

On my frequent trips between Colorado and Missouri, I often take short detours or side trips that offer relief from the monotony of the Interstate highway.  Yesterday, under warm, sunny skies dotted with flocks of migrating cranes, I opted for a visit to Wilson Lake, northeast of Russell, Kansas.

Created by damming the Saline River in 1964, Wilson Reservoir is renowned for its clear, blue water and good fishing.  Initially constructed for flood control, water supply and recreation, the lake's waters were found to be too salty for irrigation or home use and debate continues whether desalination or mixing in fresh aquifer water would be feasible; indeed, the use of this reservoir represents just one of many controversies regarding water rights throughout the Western U.S.  And, like many other water projects, its creation disrupted a natural river ecosystem to "produce wildlife habitat", a beautiful but unnatural oasis amidst a dry landscape.

Looking past these issues, Wilson Lake and its coves expose scenic bluffs of Cretaceous Dakota Sandstone which lie beneath the Cretaceous Greenhorn Formation; the top layer of the latter group is the Fencepost Limestone, long used to support barbed wire fencing throughout central Kansas.  Wilson Lake State Park, on the reservoir's southeast shoreline, was established in 1966; while interesting, it lies adjacent to a large residential development and naturalists should head to Lucas Park, north of the dam, which protects natural landscape along the lake's northwest shore.  Yesterday, large rafts of bay ducks (redheads, ring-necks, lesser scaup) drifted on the calm, blue waters, while horned grebes and buffleheads fed closer to shore.  Trumpeter swans winter along the inlets of Wilson Lake and, as I witnessed, large flocks of sandhill cranes circle overhead in March, their distinctive calls echoing through the valley.

Arctic Ice

As one might expect, the extent of ice cover on the Arctic Ocean waxes and wanes with the seasons, reaching its annual maximum in March.  Of course, as global warming progresses, the ice cover will continue to diminish and, by 2040, the Arctic Ocean is expected to be ice free during the summer months.  Indeed, as the Arctic ice gradually disappears, less solar radiation is reflected into the atmosphere, accelerating the rate of Arctic warming.

Following the breakup of Pangea and the opening of our "modern" oceans, the northern Continents had drifted into their current positions by the end of the Cretaceous Period, some 70 million years ago (MYA).  Since the global climate remained relatively warm through the early Tertiary Period, Arctic Ocean ice did not begin to form until the late Eocene (about 47 MYA), reaching its maximum extent during the glacial periods of the Pleistocene (2.2 MYA to 10,000 years ago); during warm interglacial periods of the Pleistocene, the Arctic ice may have nearly disappeared, especially through the summer months.

The reduction of Arctic sea ice, in both area and thickness, has accelerated over the past century, as has melting across the Greenland Ice Sheet and the Antarctic ice shelves.  Current scientific evidence indicates that human activity (superimposed on the warm interglacial period in which we live) is responsible for this acceleration, which is having a dramatic impact on polar ecosystems.  Of course, as the ice melts and sea levels rise, that impact will be transmitted to warmer latitudes as well.

The Uncompahgre Plateau

At the beginning of the Miocene Period, some 25 million years ago (MYA), the Colorado River and its tributaries were cutting their way through a layer cake of Tertiary and Cretaceous sediments (top to bottom) in western Colorado; colorful Jurassic and Triassic rocks lay beneath these sediments, not yet uncovered by the river.

Then, as the Miocene-Pliocene Uplift began, a block of Precambrian granite began to rise; 100 miles long (NW-SE) and 25 miles wide, this block caused the overlying Mesozoic and Tertiary sediments of western Colorado to warp across it, forming the Uncompahgre Plateau.  Eventually rising more than 6000 feet above the surrounding terrain, the plateau has also been whittled by erosion, removing its Tertiary veneer and exposing layers of Cretaceous, Jurassic, Triassic, and Precambrian Rock (top to bottom); all Paleozoic sediments had been eroded from the top of the Precambrian block during the Pennsylvanian and Permian Periods, some 300-225 MYA, producing the unconformity that we see today (i.e. Mesozoic sediments lying directly on Precambrian rock).

At the north end of the Uncompahgre Plateau, stream erosion has produced a scenic wonderland of Mesozoic redrocks, including massive walls of Wingate Sandstone (late Triassic-early Jurassic in age) and, higher up, pink cliffs of Jurassic Entrada Sandstone, separated by the Kayenta formation.  The Jurassic Morrison formation, famous for dinosaur fossils, lies above the Entrada Sandstone and, at the top, lies Cretaceous Dakota Sandstone.  Younger Mancos Shale, which surfaces throughout the Grand Valley, Mesaverde Sandstone, which forms the Book Cliffs north of Grand Junction, and Tertiary sediments that compose the bulk Grand Mesa and the Roan Plateau, have eroded from the northern end of the Uncompahgre Plateau.  Today, Colorado National Monument, west of Grand Junction, protects this spectacular product of deposition, uplift and erosion, allowing visitors to wind upward through the Mesozoic Era.  Stopping to gaze across the Grand Valley, one looks down at rocks that are younger than those on which they stand.

For more on the Uncompahgre Plateau, see:  Unaweep Canyon Mystery

The Desert Hawk

Zone-tailed hawks inhabit the Desert Southwest, from Southern California to southwest Texas, and range southward through Mexico, Central America and semiarid regions of South America; most of those that breed in the U.S. winter in Mexico.

A large but slender buteo, zone-tailed hawks resemble turkey vultures when in flight and often soar with flocks of those scavengers; indeed, some ornithologists believe that this behavior is an effort to deceive their prey (small mammals, birds and reptiles) that tend to ignore the harmless vultures.  Preferring desert and semiarid grasslands with nearby trees and cliffs, zone-tailed hawks are best found near desert ranges where they roost and nest in wooded canyons.  After engaging in spectacular mating flights, characterized by steep dives, these raptors construct a nest of sticks in a tree or on a rock ledge; two or three eggs are generally produced.

Easily identified by their black plumage, yellow legs, banded tail and vulture-like flight, zone-tailed hawks adapt well to dry habitats and their population appears to be increasing in the Desert Southwest.  Most return from Mexico by early spring and generally remain in the U.S. through mid autumn; a small number may be encountered in southern Arizona or New Mexico during the winter months.

The Nature of Comets

Comets are small astronomical bodies composed of rock, ice and frozen gases; they range in size from 1000 meters to 30 miles or more in diameter.  Almost 5000 comets are known to science though they likely represent a tiny fraction of the actual number.  Short period comets, defined as those with a period of less than 200 years, are thought to originate in the Kuiper Belt, beyond the orbit of Neptune, which contains countless icy objects and planetoids (including Pluto).  Long period comets, which have periods exceeding 200 years (up to many thousands of years) are assumed to arise from the Oort Cloud, at the outer edge of our solar system.

In either case, the comet is likely drawn from its original orbit by gravitational effects from the large gaseous planets, sending it toward the sun.  As it approaches the sun, ice, gases and dust from the comet are vaporized by the solar wind, producing a "coma" envelope around the rock nucleus and a tail that points away from the sun.  The rock surface of comets is known to have low reflectivity and the light that we see is solar reflection from the vaporized elements as well as ionization within the volatile gases (similar to what occurs in our aurora displays).  Over many periods, the volatile components are exhausted and the comet becomes an inert, invisible asteroid; in some cases, as we observed in 1994 when the fragmented Comet Shoemaker-Levy 9 collided with the surface of Jupiter, comets may break-up in response to gravitational effects from the Sun or from the large planets.  Finally, some comets are thought to become "hyperbolic," slung into space after they loop around the sun (never to return) while some long period comets are converted to short period comets by the gravitational effect of Jupiter.

Our best known comet, Halley's Comet, has a known period of just over 75 years; following its appearance in 1986,  it will next return in 2061.  Many of us also remember the spectacular Hale-Bopp Comet, which graced the night sky in 1997 and will return in about 4200 years.  This month, Comet Pan-STARRS appears low in the western sky just after sunset and, on March 12-13, will be found adjacent to the moon; this relatively faint comet is best viewed with binoculars, away from city lights.  In November, Comet ISON, discovered last year, is expected to provide a more spectacular display.

Upslope Slop in Colorado

As predicted, a typical upslope snowstorm is underway in Metro Denver.  Most common in March and April, these storms develop when the central low pressure of a Pacific system passes south and east of our region, sweeping Gulf moisture counterclockwise and "uphill" toward the Front Range.  As the air is forced to rise across the High Plains, Piedmont, foothills and mountains, it cools below its dew point and, depending upon the air temperature, precipitation falls as rain or snow.  The highest snow totals in Denver generally result from storms that move east along the Colorado-New Mexico line, producing an upslope flow from the northeast.

Today's storm is centered over western Kansas and our wind direction is more from the north, reducing the snow potential.  In addition, the air temperature is hovering in the low thirties (F),  producing a heavy, wet snow that is melting on our roadways (still warm from recent mild, sunny weather).  As a result, the storm has created a scenic but sloppy landscape; of the 8-10 inches that are predicted for Metro Denver, half will likely melt before colder air sweeps in overnight.

Then again, winds are expected to pick up this afternoon and blizzard conditions are likely to develop across the High Plains of northeastern Colorado and neighboring States as the system moves off to the east.  Its gift of copious moisture is surely welcome in this semi-arid environment, especially since we remain in a prolonged drought and sunny, warm weather is forecast for the coming week.  Such is the spring weather pattern along the Colorado Front Range: upslope snowstorms sandwiched between periods of mild, sunny weather.

March on the South Platte

Yesterday's sunny, mild weather sent me down to South Platte Park for a hike along the river.  Since the valley ponds and lakes are beginning to open, many of our wintering waterfowl have dispersed from the river but most species were still represented.  However, the large, mixed flocks have given way to scattered pairs, a sign that spring fever has taken hold; pairs of common goldeneyes, buffleheads and green-winged teal were encountered, joining pairs of our common, permanent residents.  The large flocks of wintering Canada geese have begun their journey to the north, leaving pairs and small, family groups scattered throughout the valley; nesting should commence within a week or two.

The distinctive calls of white-breasted nuthatches and the hysterical cries of northern flickers echoed through the cottonwood groves, where downy woodpeckers, chickadees, house finches, magpies and blue jays were all especially vocal.  In the riverside marshes, male red-winged blackbirds delivered their loud, monotonous tune while belted kingfishers perched above the river or chattered along the stream.

The sounds and feel of spring were certainly evident along the South Platte but, as Front Range residents know, the snowiest stretch of the year has just begun and our annual spring roller-coaster will persist through April (if not mid May).  Indeed, the next Pacific storm is spinning in the Desert Southwest and upslope snow is expected along the Front Range urban corridor by late tonight; the snowy landscape won't last long, however, as highs in the fifties and sixties (F) are forecast for early next week.

River Connections

Rivers connect us with distant ecosystems, sculpt our landscape and provide vital water and nutrients to areas far from their source.  In effect, rivers give us a sense of place while highlighting our dependence on the health of their entire watershed.

On my regular visits to the Missouri River, west of Columbia, I often ponder the varied sources of the water that passes through our region.  Much of the water is derived from snow that fell on the eastern flank of the Rocky Mountains while some was dropped by blizzards and thunderstorms across the Great Plains.  A small but significant percentage bubbled from hot springs at Yellowstone National Park or was squeezed from prairie air as it rose along the rugged slopes of the Black Hills.  In most cases, the water first flowed through tributaries of the Missouri, including the Milk, the North and South Platte Rivers, the Yellowstone and streams of the Great Plains, such as the Cheyenne, White, Niobrara, James, Big Sioux and Kansas Rivers.

We cannot adequately protect our local ecosystems without paying attention to the health of our rivers and, consequently, of all ecosystems that lie upstream.  When rivers are tainted by pollution (industrial, agricultural, urban), diverted for irrigation or dammed for flood control, water supply, recreation or hydroelectric power, the effects are carried downstream, impacting flora, fauna and human communities.  While they are natural lifelines, rivers are not immune to our carelessness or to our misguided attempts to control them; in the end, we humans are also victims of the riverine ecosystems that we destroy.

Australia's Largest River System

Most of Earth's Continents are known for their major river systems; there is the Amazon Basin of South America, the Mississippi Watershed of North America, the Nile and Congo systems of Africa, the Rhine of Europe and the Ganges-Brahmaputra and Yangtze of Asia, among many others.  When it comes to Australia, however, a nation Continent known for its vast desert landscapes and sunny climate, rivers do not immediately come to mind.

The Murray-Darling River System of southeast Australia is the largest on that Continent.  The Murray River, which rises on the western slope of the Great Dividing Range in New South Wales and Victoria, is Australia's longest river; flowing westward to form the border between those two States, it then angles to the southwest across the southeastern corner of South Australia, entering the Southern Ocean south of Adelaide to complete its 1476 mile course.  The major tributary of the Murray is the Darling River, which merges with the Murray in western New South Wales; the Darling rises as numerous tributaries along the western slope of the Great Dividing Range, from southeastern Queensland through much of New South Wales, and along the southern flank of the Expedition Range, northwest of Brisbane.  While the Darling itself is "only" 915 miles long, the area of its watershed is larger than that of the Murray above their junction.

Since the Great Dividing Range lies close to the eastern coast of Australia and since rain-producing weather systems arrive from the east, the Murray-Darling watershed drains the dry-side of those highlands; numerous coastal rivers, rising on the east slope of the Divide discharge far more water to the sea than does the massive Murray-Darling River System.  Finally, this system, like the Mississippi-Missouri network of North America, highlights the fact that our longest continuous waterways do not always correspond to the course of our "longest rivers."  The latter is determined by how we choose to name the segments of any given watershed; the longest waterway in North America begins at the uppermost headwaters of the Missouri River and ends at the tip of the Mississippi Delta while the longest waterway in the Murray-Darling System begins in the mountains of southeast Queensland and ends at the mouth of the Murray River, on the coast of South Australia.

Snow-stressed Snow Geese

Heading west this morning, I saw numerous flocks of snow geese between Columbia, Missouri, and Lawrence, Kansas; most were not heading north.  In fact, the flocks were moving in all directions, clearly looking for potential feeding sites amidst the snow-covered landscape.  In a few areas, I saw small groups that alighted on parcels of grassland cleared by wind or sun exposure but most flocks remained in flight, circling above the thick blanket of snow.

While Mississippi Flyway snow geese generally follow the Mississippi and Missouri Valleys, they rely on wetlands, grasslands and crop fields for nourishment on their "spring" journey to the Arctic.  Facing the widespread snow cover, they will likely congregate along the major rivers, where floodplain marshes, side channels and oxbow pools offer access to aquatic vegetation; the backwaters of large reservoirs, if not frozen, might also be utilized.

West of the Flint Hills, in eastern Kansas, I encountered several flocks that were more fortunate;  the fields from Junction City to Salina were dappled with snow but most of the grass and crop stubble was accessible to the vocal migrants.  Of course, my concern for the welfare of these hardy travelers is a bit misplaced (if not paternalistic); regularly moving through the Heartland in November-December and, again, in February-March, they are surely capable of dealing with snowstorms.

Sparrow Month in the Heartland

Like small sandpipers and Empidonax flycatchers, sparrows are often difficult to identify, especially for the beginning birdwatcher.  Across the American Heartland, March is the best month to compare our sparrow species since permanent, winter and summer residents may all be encountered.

Common permanent species include song, field and house sparrows (the latter are actually introduced weaver finches but tend to be grouped with native sparrows); vesper and savannah sparrows may also be encountered throughout the year.  Common winter residents, present throughout March, include white-throated, white-crowned, fox, swamp and American tree sparrows; they may be joined by rare winter residents such as Le Conte's, Harris' and Lincoln's sparrows.  By late in the month, summer residents, including Henslow's, chipping, lark and grasshopper sparrows begin to appear in the Heartland.

House (permanent), white-throated (winter) and chipping (summer) sparrows are common in residential areas but others may turn up at backyard feeders (especially fox, white-crowned and American tree sparrows).  As with most birds, the identification of sparrows is aided by the habitat in which they are found; fox, song, white-throated and Harris' sparrows favor thickets, chipping and American tree sparrows are best found in open woodlands, swamp, Lincoln's and Le Conte's sparrows inhabit wetlands and white-crowned, lark, field, grasshopper, vesper, savannah and Henslow's sparrows forage in open fields and meadows.  Of course, a good pair of binoculars and an illustrated field guide are essential to identifying these various species.

The Nature of Sinkholes

The unfolding tragedy in southwest Florida demonstrates the unpredictable nature of sinkholes, which can swallow roads and buildings as they suddenly form and expand.  These geophysical landforms develop in karst regions, where a layer of soluble bedrock (limestone or dolomite) lies near the surface.

Channelized by underground streams, the sheets of porous bedrock are penetrated by a network of tunnels and caverns which surface as springs.  Eventually, as a cave enlarges and its ceiling thins, it may collapse from the weight of the overlying soil, vegetation and/or structure, producing a sinkhole.  Depending upon the depth and width of the collapsing cavern or tunnel, the sinkhole may be small or massive and stress on the adjacent ceiling might produce an unstable collapse, prone to further expansion.

The Florida Platform, composed of limestone (deposited during periods of high sea level) overlying older basement rock, makes the Sunshine State especially prone to sinkhole development.  Other active karst regions (where a wet climate supports continued erosion of the limestone or dolomite bedrock) are concentrated in Kentucky, Tennessee and Missouri.  In fact, as I write this blog, I am sitting atop a thick slab of Mississippian Limestone which, this week, supports the additional weight of a foot or more of heavy, wet snow, some of which will feed a web of channels that run beneath our city; indeed, just south of town, Rock Bridge Memorial State Park harbors a fascinating collection of sinkholes, caverns, springs and underground streams.

March & Wednesday

Since many humans live for weekends, Wednesday, often referred to as hump day, represents the last hurdle before our downhill slide toward better days.  While it is welcomed as a sign that we have survived the first half of the work week, it is also a reminder that two more days of stress and tribulation stand between us and our weekend rewards.

March, the first calendar month of the northern spring, arrives before winter has thrown in the towel.  While the darkest and coldest months are behind us, the fickle weeks of March are not always as spring-like as we might prefer.  Indeed, in the American Heartland, this month is renowned for its raw weather, muddy landscape and all-too-slow progression.  The days may be longer and the greenery may be advancing but the glory of spring has yet to arrive.

March is a wonderful month for waterfowl watchers and college basketball fans but, for many in the Midwest, it is just a damp, gray, chilly interlude between the stark beauty of winter and the fragrant, colorful warmth of spring.  We are, after all, impatient, tropical creatures, inclined to dwell on the past but always rushing toward the future.  Focused on April, we slog through March in our parkas and boots, worried that global warming is but a myth.