Friday, May 31, 2013

Pushing Testosterone

After blanketing cable TV and the internet with ads for erectile dysfunction drugs over the past few years (see The E.D. Epidemic), the pharmaceutical industry is now pushing testosterone supplementation.  Like the E.D. campaign, the ads feature attractive, middle aged couples and offer a simple fix for relationship problems.  In reality, these drugs are likely targeted at aging baby boomers, especially those with young mistresses or young, second wives; of course, the testosterone supplements may also appeal to younger men intent on improving their athletic or sexual performance.

While the ads provide a litany of potential side effects from the use of testosterone, the visual effect of young, happy couples outweighs the more sober warnings of the narrator.  Physicians are well aware of the risks associated with hormone supplementation, including estrogen, testosterone and cortisone; yet, some will comply with their patient's request and the ads are designed to trigger that demand.  The ads also suggest that there is a clear-cut association between one's serum testosterone level and a variety of emotional or sexual problems; this message greatly oversimplifies the approach to such disorders and exaggerates the true incidence of clinically significant testosterone deficiency.

Most disconcerting is the fact that these pharmaceutical companies devote so many dollars to the production, promotion and distribution of these agents when far more common and serious medical conditions are not adequately addressed, when health care costs are out of control and when many Americans have inadequate access to quality health care.  Erectile dysfunction and testosterone deficiency, well down the list of pressing health care issues, are getting a large proportion of the exposure.

Thursday, May 30, 2013

Saved by Flooding Rains

Under a tornado watch for most of the day, central Missouri has escaped severe weather due to recurrent periods of torrential rain.  Developing by early afternoon along a cold front that stretched from Oklahoma to Wisconsin, these training storms cooled and stabilized the atmosphere, greatly reducing our risk of tornadoes.

Indeed, today's twisters formed along the southern and northern ends of the front, where daytime heating, in combination with the front and a potent jet stream, was sufficient to ignite relatively isolated, rotating storm cells.  Between these areas, the storms coalesced into a swath of heavy rain, studded with thunderstorms, dropping up to 5 inches of rain that produced widespread flooding.

Moving northeastward along the front, the thunderstorms that crossed Missouri dampened the potency of storms in their wake.  Tornadic supercells, like hurricanes, rely on an inflow of warm, humid air at the surface and may ignite other supercells along their outflow boundaries.  Once a supercell enters rain-cooled air, however, it begins to dissipate and the risk of a tornado falls in concert.

Wednesday, May 29, 2013

Cape Fear's Gift

Though I have been fascinated by nature as long as I can remember, my childhood explorations were limited to woods and fields near my Cincinnati home and beaches along Lake Erie and the Florida Gulf Coast where my family travelled for vacations.  I would not be fully immersed in a new environment until my wife and I moved to Wilmington, North Carolina, for our medical internship, in 1976.

It was there that I spent much of my free time along the shores and streams of Cape Fear, drawn by its diverse population of marine and wetland birds.  Purchasing my first field guide, I documented the majority of my initial lifetime sightings over the course of that year, exploring the varied ecosystems during each season.  As a beginning birder, transplanted to a new region of the country, every species seemed to be exotic; of course, as I gained experience, I learned that many of those birds could be found in or near my home town, far from the Atlantic Coast.

Many, if not most, naturalists and birders have had a similar experience.  Our fascination with nature receives a boost during a visit or a move to alien territory, unfamiliar landscape that opens our eyes to the diversity of life on this planet.  In concert, we learn about many species that we managed to ignore in our past and come to appreciate the interdependence of widely dispersed ecosystems.  My year on the Carolina coast ensured that a childhood interest in nature, awaiting nourishment for many years, blossomed into a passion that has greatly enriched the rest of my life.

Tuesday, May 28, 2013

Dark Days in the Heartland

For the past week, a stationary front has draped itself across the Midwest, separating warm, humid air to its south, from cool, dryer air to its north.  Pacific storm systems have moved along that front, unleashing torrents of rain and spreading a thick, gray cloud deck above the region.  Brief, sunny interludes have given way to the next system within a few hours, leaving us in dusk-like darkness much of the time.

Here in central Missouri, we have managed to dodge the severe weather, though, as I write this post, we have been placed under a tornado watch.  As they have over the past week, thunderstorms are moving in from the west, seemingly hitched to Interstate 70; these "training" storms have produced a soggy landscape with significant flooding in some areas.

On the heals of a severe drought, we are now looking for a few dry, sunny days to cut the grass or tend to the crops.  Both the drought and the deluge are/were products of stationary weather patterns that developed in response to the jet stream's course.  Throughout the drought, the jet arched far to our north, taking storm systems across southern Canada and the Northern Plains;  this spring, it has undulated across central latitudes of North America, sending storms through the Heartland and, in some cases, providing the upper level energy and wind shear that spawn supercells and tornadoes.

Monday, May 27, 2013

Jumping Spiders

For some reason, likely the cool, wet weather, a large number of jumping spiders have invaded our house this spring.  Found on all Continents except Antarctica and represented by more than 5000 species, they are the largest family of spiders on Earth.

Named for their means of pouncing on prey and escaping danger, jumping spiders are equipped with a hydraulic mechanism in their limbs that allow them to jump up to 50 times their body length.  Their hunting prowess is also aided by excellent, 360 degree vision via four eyes on their face and four smaller ones on the top of their head as well as a highly mobile anterior segment; scientific studies suggest that they also possess color vision.  Unlike many spiders, they do not use webs to catch their prey; rather, they stalk prey and then jump to attack the victim, using a single strand of silk as a safety line should they miss their target.  Primarily carnivorous, jumping spiders consume a wide variety of crawling and flying insects; some species also feed on nectar.

Small tents of silk are used for protection at night and during storms.  Females also wrap their eggs in a cocoon of silk and, in some species, she may remain with the eggs until they hatch.  Like most of their cousins, jumping spiders induce unreasonable fear in many humans but play a valuable service in the control of harmful insects.  Besides, their antics are fun to watch!

Sunday, May 26, 2013

China's Major Rivers

While a complete summary of China's Rivers is well beyond the scope of a blog post, there are four major river systems that cover the heavily populated, eastern half of the country; from north to south, they are the Amur, Yellow, Yangtze and Pearl Rivers.  The Amur River, rising in eastern Mongolia, runs along the China-Russia border for most of its course and eventually enters the Strait of Tartary, which connects the Sea of Okhotsk with the Sea of Japan; along its 1755 mile route, the Amur drops more than 6700 feet.

The Yellow (Huang He) River rises in the Bayan Har Mountains along the eastern edge of the Tibetan Plateau and flows almost 3400 miles to the Bohai Sea (southeast of Bejing); en route, it drops more than 15,700 feet and passes through the major cities of Lanzhou, Yinchuan, Wuhai, Baotou and Jinan, among others.  The Yangtze River, the longest in Asia and the third longest on Earth, also rises on the eastern edge of the Tibetan Plateau and flows 3915 miles to the East China Sea; from its source to the sea, the Yangtze drops more than 16,000 feet and passes through spectacular gorges.  About one third of China's population lives along this river, including the cities of Chongquing, Yichang, Wuhan, Nanjing and Shanghai.

The Pearl (Zhu Jiang) River drains an extensive watershed in southeastern China, just north of Vietnam.  Numerous tributaries feed the main channel of this system, which flows 1491 miles to the South China Sea at Hong Kong.  While it is the third longest river in China, the Pearl is second only to the Yangtze in its annual discharge volume, a fact that reflects its subtropical latitude.  Among the larger cities along its course are Wuzhou, Zhaoquing and Guangzhou.

Saturday, May 25, 2013

The Appalachian Warbler

During my medicine residency, in Morgantown, West Virginia, I would often go hiking and birding at a hemlock preserve, east of town.  It was during one of those excursions that I first encountered black-throated blue warblers and, since leaving that region of the country, I have not seen them again.

Indeed, black-throated blue warblers breed in dense forests along the Appalachian Chain, from north Georgia to New England; they also summer in northernmost Minnesota and Wisconsin, on the Upper Peninsula of Michigan and across southeastern Canada.  Adult males are unmistakeable with their striking slate-blue, black and white plumage; the dull olive-gray females, on the other hand, are nondescript in appearance and were once thought to represent another species.  Since these warblers favor deep woods with heavy undergrowth, logging by early settlers threatened their existence but conservation measures and the reforestation of old farmlands has since stabilized their population.

Best found along forest trails, black-throated blue warblers are rather tame and tend to remain in the thick undergrowth, feeding on insects and berries.  An open cup of bark, moss and spider web strands is placed in a shrub and 3-4 eggs are generally produced.  Come September, these small, reclusive songbirds head for the Greater Antilles where they spend the northern winter in dense, tropical forest.

Friday, May 24, 2013

The Missouri-Arkansas Divide

The Missouri and Arkansas River watersheds, spreading across more than 1 million square miles and 170,000 square miles, respectively, cover most of the American Great Plains.  The divide between these watersheds begins on the Continental Divide, just west of Hoosier Pass in central Colorado; from there it runs southward along the crest of the Mosquito Range which separates the upper Arkansas Valley, to its west, from the broad expanse of South Park, to its east, which is drained by the South Platte River (a tributary of the Missouri).

After crossing Trout Creek Pass, the Missouri-Arkansas Divide curves eastward along the southern rim of South Park, running atop the volcanic Thirty-nine Mile Range before snaking northeastward through the Front Range foothills.  Emerging onto the Colorado Piedmont, the divide follows the crest of the Palmer Divide, an erosional remnant of the High Plains that extends eastward from the foothills just north of Colorado Springs.  After crossing I-70 north of Limon, the divide curves to the southeast, crossing the highway once again at Genoa, Colorado; from there it swings southward and then eastward along the southern edge of the Republican River watershed, a tributary of the Missouri.

Entering Kansas, the Missouri-Arkansas Divide follows the southern edge of the Smoky Hill and Kansas River watersheds before reaching southwest Missouri.  There, this hydrologic barrier runs along the northern edge of the Neosho and White River watersheds (tributaries of the Arkansas), ending in the eastern Ozarks where short streams of southeastern Missouri and northeastern Arkansas empty directly into the Mississippi.

Thursday, May 23, 2013

The Politics of Disaster

Many politicians, especially Conservative Republicans, want to shrink the scope of the Federal Government; focused on the rights of States, they want policies and funding to be determined at the local level, free of Federal input or regulation.  Of course, should a natural disaster, such as a tornado or drought, affect their constituency, Federal assistance is sought and welcomed.

Unfortunately, while they recognize the hardships imposed by natural disasters, they seem oblivious to the trials and tribulations associated with poverty, unemployment and lack of access to medical care.  Often representing rural communities, which benefit from urban economies yet are sheltered from the difficulties that cities face, they minimize (if not completely ignore) the complex nature of human society.  To deny the Federal Government's essential role in the areas of social welfare, healthcare, education and environmental protection demonstrates a provincialism that, in turn, spawns an indifference to the challenges that confront many Americans.

The loss of one's home to a powerful storm is surely a terrifying and stressful experience.  Yet, it is no more devastating than the inability to house, feed and clothe one's children due to the ravages of poverty.  The victims of disaster, whether natural or man-made, need compassion and assistance, not political rhetoric and posturing.  Federal funding must extend beyond our bloated Defense Budget and the Farm Bill.

Wednesday, May 22, 2013

The Cost of Lawns

While I have written posts about the negative effects of residential lawns (Man and his Lawn, Lose some Lawn) the ecologic impact of these green carpets is even more dramatic along highways, around industrial parks and in the landscaping of commercial and residential developments.  This fact became especially evident on our recent road trip to and from Florida, when we passed numerous mower crews along the Interstates, cutting miles of grass that often extended fifty yards or more from the edge of the road.

In like manner, massive, weed-free lawns front corporate office buildings and buffer the parking lots of retail centers.  While pleasing to the eye for many humans, these manicured borders of grass consume large amounts of water, require regular mowing (including the fuel consumption and exhaust production that accompany that process) and involve the application of chemical fertilizers and herbicides to maintain the purity and luster of the lawn.

Lawns are not natural habitats.  They are human imposed landscapes that consume vast amounts of water and fuel and, in the course of their lifetime, transfer a variety of pollutants to the soil, streams and groundwater.  While the use of drought-tolerant lawns for parks and recreation fields is appropriate (assuming they are not doused with chemicals) the widespread use of these manicured carpets destroys natural habitat and pollutes the environment.  Except where needed to improve visibility and access, lawns should be replaced with naturalized borders of native plants.  

Tuesday, May 21, 2013

Survival on the Plains

The Great Plains of North America are the product of their geology and geography, further molded by wildfire, periodic drought, severe weather, relentless wind and, in the past, massive herds of bison.  Wildlife native to that physiographic region have managed to survive by utilizing underground burrows to escape wildfire or severe weather and by undertaking seasonal migrations to less hostile environments.

Native Americans and early European settlers lived in small, widely dispersed communities and, in contrast to modern Americans, were able to relocate or rapidly rebuild their primitive homes when natural disaster struck.  While some, like the wildlife, succumbed to storms, drought or severe winters, their personal skills and knowledge of the wilderness made them more resourceful than most modern humans, reliant as we are on the products of our industrial and technologic revolutions.

This week's tragedies in Oklahoma remind us that we remain at the mercy of natural forces and encourage us to learn from our wild neighbors.  While our tornado warning systems continue to improve, our means of escaping these deadly storms have not kept pace.  Indeed, according to a report on the Weather Channel website, most homes in Oklahoma are not equipped with basements (due to soil conditions and current building codes).  As our cities sprawl across the Plains (and as our climate continues to warm) we will become increasingly susceptible to episodes of mass destruction.  At the very least, we should make every effort to ensure that safe refuge is provided in homes, schools and workplaces; bathtubs and mattresses are not the solution.

Sunday, May 19, 2013

St. Marks NWR

Stretching along the Gulf Coast, 25 miles south of Tallahassee, Florida, St. Marks National Wildlife Refuge was established in 1931 to protect natural habitat for wintering birds.  Its vast realm of saltwater marshes, riverine woodlands, tidal creeks, pine flatwoods, swamp forest and man-made wetlands is fed by seven rivers, including the St. Marks River; this stream rises in eastern Leon County and is fed by discharge from Wakulla Springs on its journey to the Gulf of Mexico.  At the mouth of the river, on the north shore of Apalachee Bay, is the St. Marks Lighthouse; built in 1932, this structure is a National Historic Landmark.

On our visit to the Refuge this evening, we headed south on Lighthouse Road from U.S. 98 at Newport, Florida; within 3 miles, this road enters the refuge, passes its Visitor Center and winds for 7 miles through the heart of the preserve, providing access to a number of trails, boardwalks and viewing sites before ending at the lighthouse.  Passing both freshwater and saltwater wetlands, we saw a fabulous diversity of birdlife, including anhingas, great blue and little blue herons, common egrets, white ibis, black vultures, ospreys, brown pelicans, double-crested cormorants, least terns, laughing gulls, killdeer and belted kingfishers.  Other nesting species of note include least bitterns, bald eagles,  swallow-tailed and Mississippi kites, clapper rails, purple gallinules, American oystercatchers, black-necked stilts, common ground doves, barn owls, red-cockaded woodpeckers, gray kingbirds, fish crows, marsh wrens, prothonotary warblers, blue grosbeaks and both Bachman's and seaside sparrows.

To the delight of our grandson, we observed four large American alligators in the roadside wetlands.  Among the other non-avian residents at St. Marks NWR are white-tailed deer, river otters, black bear and a wide variety of reptiles and amphibians.  As at all nature preserves, wildlife viewing is most productive early and late in the day and this spectacular refuge is open from dawn to dusk; a modest entry fee is charged per vehicle.

Friday, May 17, 2013

Florida's Great Bend

While the majority of Florida's coast is renowned for its fabulous beaches, they are nearly absent from Tarpon Bay, on the west coast of the peninsula, to Ochlockonee Bay, along the eastern panhandle.  This Great Bend region is characterized by coastal marshes, swamp forest, pine flatwoods, meandering rivers and rich estuaries, all vital to the Gulf of Mexico ecosystem.

Home to black bear, American alligators, bald eagles, ospreys, a wide variety of waders (herons, egrets, spoonbills, ibis, limpkins) and a host of other birds, mammals, reptiles and amphibians, this vast coastal wetland is relatively inaccessible and generally ignored by most visitors to the Sunshine State; on the other hand, fishermen, birders and naturalists appreciate its natural diversity as did the first humans to colonize the region.

Last evening, standing on a small beach at Bald Point State Park (just south of Ochlockonee Bay), it was easy to appreciate the serenity that the Great Bend affords in an increasingly populated State.  As the sun set beyond the pines to our west, lines of brown pelicans cruised above Apalachee Bay, shorebirds foraged among the gentle waves, ghost crabs scurried across the darkening sand and evidence of human habitation was nowhere in sight.  Only the occasional deer fly disturbed the serenity.

Wednesday, May 15, 2013

The Southern Vulture

Driving southeastward from Missouri today, I encountered the first flock of black vultures in southern Kentucky.  Unlike their larger cousin, the turkey vulture, black vultures are primarily found across the southeastern quadrant of the U.S. and southward through Mexico, Central America and much of South America; in summer, they may be seen as far north as the Ohio Valley and Mid-Atlantic region.

Since they hold their broad wings in a horizontal position and take to the air with powerful wing beats, black vultures may initially be mistaken for eagles; their bare gray heads, black plumage and the prominent white patches beneath their wing tips aid identification.  Highly social, these scavengers soar above open woodlands to search for carrion; since their sense of smell is inferior to that of turkey vultures, they often join their larger, leaner cousins, sharing if not stealing the carcasses that they locate.  Black vultures may also scavenge at landfills and are commonly encountered at coastal ports where they dine on fish scraps.

Monogamous, black vultures may live for 25 years in the wild and tend to remain in family groups.  While they prefer to roost in trees, these vultures nest on the ground, often beneath the cover of dense foliage, a rock ledge, a cave entrance or an abandoned structure.  One to three chicks are generally produced each spring and are fed by both parents throughout their first summer.

Tuesday, May 14, 2013

First Wave of Summer

Two months into this cool, wet spring, the first wave of summer has pushed across the American Heartland.  Thanks to high pressure over the Southern Plains and a low pressure trough over the Northeast, southwesterly winds are raking the Great Plains and Midwest, producing clear skies and afternoon highs well above average.

This injection of heat should allow our vegetation to catch up with the season, combating the cool soil temperature that has slowed the growth of crops and the leafing of trees; indeed, the azaleas along the north side of our house are finally in bloom, a good month behind schedule.  Wild birds and mammals, governed by the daylight cycle rather than the weather, have gone about their business as usual but this wave of summer will surely invigorate the turtles, snakes, lizards and amphibians which, to date, have been relatively inactive.

Our summer interlude is forecast to continue for the next few days; by then, a Pacific storm front will invade the region and the emplaced heat will likely fuel severe thunderstorms.  In nature, the good and the bad are often linked; in this case, our dose of summer will prime the atmosphere for violent weather which, in turn, will bring welcome rains to the drought-ridden Plains.  We will escape that show, heading south for our son's medical school graduation; reports from the Gulf Coast in the coming days.

Monday, May 13, 2013

The Potomac River

The North Branch of the Potomac River rises on the Appalachian Plateau of West Virginia, within the boundaries of Fairfax Stone State Park.  Flowing northeastward, it forms the border between Maryland and West Virginia; about halfway to Cumberland, it was dammed to create Jennings Randolph Lake in 1981.  From Cumberland, the Potomac makes a broad dip to the south, where it is joined by its South Branch, and then continues northeastward to Hancock, Maryland, where it reaches its most northerly point.

From Hancock, the Potomac River flows southeastward and receives the waters of the Shenandoah at Harper's Ferry, West Virginia.  There it becomes the border between Maryland and Virginia, passing through a double water gap in the Blue Ridge Mountains and then angling more sharply to the SSE.  Fourteen miles north of Washington, D.C., the Potomac drops through its Great Falls, a point on the Fall Line of the American Southeast, marking the boundary between the resistant bedrock of the Piedmont and the softer sediments of the Coastal Plain.  The spectacular falls drop 76 feet through Mather Gorge, the major impetus for constructing the Chesapeake & Ohio Canal between Georgetown, D.C., and Cumberland, Maryland; used from 1831 to 1924, the canal and its corridor along the Potomac are now protected as a National Historic Park.

Beyond Washington, the Potomac River broadens into an ever-widening estuary, reaching a maximum width of 11 miles as it enters the Chesapeake Bay, more than 400 miles from its headwaters.  Before the end of the Pleistocene Ice Age, the Potomac was a tributary of the lower Susquehanna River, now flooded by rising seawater to form the broad, shallow Bay.

Sunday, May 12, 2013

The Choice of Motherhood

Women who choose the joys, trials and responsibilities of motherhood are, to say the least, vital to the welfare of human society; yet, the physical capacity to conceive should not be the sole factor in that decision.  Indeed, many women who are unable to bear children prove to be wonderful mothers via adoption or surrogate pregnancy while some endowed with fertility choose not to have children.

One would hope that all children are blessed with a loving mother who wants them and who has the intellectual capacity, emotional stability and economic means to care for them; unfortunately, that is not always the case.  Unwanted or unloved children and those raised by dysfunctional parents are prone to a wide range of mental, physical and behavioral disorders, stemming from neglect, malnutrition, lack of proper medical care or outright abuse.  Though many are rescued by social support networks, including orphanages, foster care, teen homes and adoption, the damage is done early in life.

For a variety of political and religious reasons, some want to deny the role that choice should play in motherhood; beyond sexual abstinence, they oppose any effort to prevent or abort pregnancy, even in cases of rape or mental incapacity.  Included in this group are those willing to produce numerous offspring while lacking the economic means to provide for them.  In the end, the children and the rest of human society must deal with the consequences of forbidden choice and misguided policies.

Saturday, May 11, 2013

The Sounds of May

We naturalists tend to associate certain natural sounds with specific times of the year.  For example, while the call of a white-breasted nuthatch is heard throughout the year, I associate that nasal yank with mid autumn, a time when fall colors paint the forest and when the cool, dry air is tinted with the scents of black walnuts and wood smoke.

There are several sounds that I have come to associate with the a Midwestern May.  One is the sharp "peent" of a common nighthawk in the evening sky, a welcome sign that he has safely returned from his winter home in South America.  Another is the loud "wrheep" of the great crested flycatcher, often delivered repeatedly from the top of a large shade tree.  A third is the "ker-plunk" of the male cowbird, a warning that he and his mate will soon parasitize the nest of a hapless songbird.  Finally, while the calls of peepers and chorus frogs peak in March and both the duck-like chortle of leopard frogs and the trill of American toads dominate April wetlands, the deep grumble of the bullfrog and the broken-banjo-string tune of the green frog serenade visitors to the marsh in May.

Though a Midwestern May is traditionally associated with colorful flowers, verdant foliage and severe thunderstorms (it is the peak month for tornadoes in the American Midwest), I often think of the above sounds when the month is mentioned.  Of course, in some years (as will occur in the Northeast this May), a brood of periodic cicadas commandeers the month , their shrill, deafening calls ringing through our parks and neighborhoods and their carcasses collecting on our roads, decks, cars and lawns; in those years, other sounds of the season are lost in the din of their frenzied orgy.

Friday, May 10, 2013

Spring Envelops Eagle Bluffs

Despite its slow and erratic progression, spring has finally taken control at Eagle Bluffs Conservation Area, southwest of Columbia.  Though the weather remained cool and cloudy this morning, the Missouri River floodplain is now adorned with the rich greenery of May and most summer residents have returned to nest in its woods and wetlands.

Shorebirds, on their way to breeding grounds across the Northern Plains and Arctic tundra, were especially abundant, represented by yellowlegs, stilt sandpipers, short-billed dowitchers, western sandpipers and Wilson's phalaropes, among other species.  Encouraged to leave their secluded haunts by the gray overcast, a group of soras foraged along a marsh-lined stream.  Out on the open pools, blue-winged teal, American coot and pied-billed grebes were found while Canada geese nested along the grassy shores and great-blue herons stalked the shallows.  Of special interest was a small flock of white-faced ibis, the first that I have ever encountered at Eagle Bluffs.

Checking the riparian woodlands along the Missouri River, I found indigo buntings, yellow and prothonotary warblers, common yellowthroats, American redstarts, northern orioles, house wrens and gray catbirds, joining mixed flocks of permanent residents.  Red-tailed hawks soared above the refuge, a variety of swallows strafed the open waters and turkey vultures lounged on the roadways, playing chicken as my pickup approached.  A few box turtles also took their chances on the graveled roads, attracted by their warmth on this cool spring morning.

Tuesday, May 7, 2013

The Blood of Life

Yesterday, my drive from Columbia to Cincinnati crossed soggy terrain.  Rivers and streams were out of their banks,  crop fields were muddy (if not swamped) and sloughs along the highway were filled to the brim.  Overhead, thick gray clouds, pregnant with moisture, dropped curtains of rain across the verdant landscape.  While the flooding is a bit late this year, spring is the season of rebirth and water is the blood of all life on Earth.

Indeed, life evolved in Earth's primordial seas some 3.6 billion years ago, nourished by the effluent of surface streams and deep hydrothermal vents.  Those initial cells and the cells of all bacteria, fungi, plants and animals throughout our plant's history have been dependent on the availability of water, a medium vital to the biochemical processes that sustain life.

Though water covers more than 70% of our planet's surface, only 3% of the water on Earth is freshwater; of that small amount, almost two-thirds is trapped within polar and mountain ice sheets and permanent snow fields (the great majority of which is on Antarctica).  About half of liquid freshwater is in the form of groundwater while the combined freshwater in lakes and rivers accounts for only 0.5% of the water on Earth.  While spring floods may be inconvenient and, in some cases, destructive, the above facts demonstrate how vital they are to the health of natural ecosystems and, by extension, to the welfare of human society.  We cannot afford to waste or pollute what little freshwater is available.

Monday, May 6, 2013

Sierra Grande

The Clayton-Raton Volcanic Field stretches across northeastern New Mexico, extending into southern Colorado and extreme western Oklahoma.  Produced by hotspot volcanism that began about 9 million years ago and ended just 40,000 years ago, the axis of the field is oriented NW-SE, extending from the vicinity of Trinidad, Colorado, to Clayton, New Mexico.

Among the many volcanic features that are scattered across the field, the largest is Sierra Grande, a massive shield volcano that rises to an elevation of 8720 feet, nearly 2000 feet above the surrounding High Plains.  Shield volcanoes are produced by repeated flows of low-viscosity lava, often yielding a broad, symmetrical cone; Sierra Grande is thought to have formed less than 3 million years ago.  Visible throughout northeastern New Mexico, this isolated mountain looms just SSW of Des Moines, where US 64/87 jogs past its northern and eastern flanks.

Though its summit is 4000 feet lower than the crest of the Sangre de Cristo Range, to its west, Sierra Grande's isolation, prominence and massive bulk endow this extinct volcano with a grandeur that range-bound peaks cannot match.  I certainly recall my first glimpse of its majestic cone following a long journey across the Great Plains, an awe-inspiring preview of the mountain landscapes that lay ahead.

Sunday, May 5, 2013

River Walk

Despite the cool, gray weather, birdlife was pleasingly varied along the Missouri River yesterday afternoon.  Hiking along the Katy Trail, west of Columbia, we found the cliffside forest and floodplain woodlands alive with the sight and sound of avian residents and visitors, some newly arrived from the south.

Lending color to the overcast afternoon were northern cardinals, blue jays, bright male goldfinches, indigo buntings, rufous-sided towhees, yellow and yellow-rumped warblers, blue-gray gnatcatchers and northern orioles.  Less colorful but equally conspicuous were eastern wood pewees, tufted titmice, black-capped chickadees, mourning doves, house wrens, American robins and a lone wood thrush.  The calls of red-bellied and downy woodpeckers, northern flickers, American crows and white-breasted nuthatches echoed through the woodlands, a great blue heron hunted in a shallow pool, squadrons of cliff swallows strafed the river and a flock of turkey vultures soared above the limestone bluffs.

Had it not been a spontaneous, mid-day stroll, devoid of binoculars, many more species could have been found along that scenic stretch of the Missouri.  After all, this is the peak of the spring warbler migration, an exciting and productive time for avid birdwatchers.

Saturday, May 4, 2013

March in May

Thanks to a deep atmospheric trough that has nosed its way from Canada to the Gulf Coast, we have experienced raw, March-like weather in Missouri over the past two days.  Low clouds, drizzle, intermittent cold rain and temperatures in the 30s and 40s F have set back the seasonal clock, temporarily denying us the annual rewards of early May.

Snow has fallen across western Missouri and northwest Arkansas and, this morning, heavy rains are pushing northward along the eastern edge of the trough.  Trapped within its chilly realm, those of us in central Missouri will endure another day of cool, cloudy weather with scattered showers; meanwhile, residents of northern Michigan, Upstate New York and Maine will enjoy a sunny May weekend, with highs in the seventies.

Such disparate conditions across our country, reversing the usual effect of latitude, illustrate the potent role of the jet stream as it undulates through the season.  Within its dips, cold, Canadian air pours southward while, within its northerly curves, warm air streams up from the south.  By June, the jet begins to settle down, leveling out across Canada and setting the stage for the relentless heat of an American summer; it is then that we long for another cool trough to invade the Heartland.

Thursday, May 2, 2013

Midwestern Mimics

In spring, when birdsong is most intense, even non-birders take note of the varied tunes offered by our mimic thrushes.  Composed of short, repeated phrases that mimic the calls or songs of other birds (or even the mechanical noises that arise from human habitation), the intense songs of these residents are hard to ignore.  All three Midwestern mimic thrushes usually forage on or close to the ground, where they consume a mixed diet of insects, nuts and berries.

Best known of this group is the northern mockingbird, a resident of suburbs, farmlands and wood margins.  Easily identified by his black and gray plumage and his prominent white wing patches and white outer tail feathers that appear in flight, this common and aggressive bird delivers each phrase several times and may sing day or night.  Our second mimic is the brown thrasher, sporting cinnamon plumage on his upper side and black streaks on his white chest and abdomen; the male prefers to sing from an exposed perch (often atop a tree) and generally repeats each phrase 2-3 times.  The third and least conspicuous of our Midwest mimic thrushes is the gray catbird, which usually skulks about in low shrubs and forest understory; dark gray in color with a black cap and tail (and a rusty patch on the underside of the tail base), its song is less strident than that of the mockingbird and thrasher and is interspersed with episodes of cat-like mewing.

Though not a mimic thrush, the yellow-breasted chat, a large warbler, is also known for his repetitious song, composed of various squeaks, trills, clucks and whistles.  This extrovert is inclined to sing from the top of a shrub or hedgerow and is easily identified by his white spectacles, his thick black bill and his bright yellow chest.

Wednesday, May 1, 2013

Fast Forward into Spring

Heading back to Missouri yesterday, I left Denver and drove eastward across the High Plains. There, thanks to a continued drought and a raw early spring, greenery was limited to scattered yuccas, juniper snow fences and the first shoots of winter wheat; it looked more like February than the last day of April.

By the time I reached central Kansas, a warm, south breeze was spinning the wind turbines near Ellsworth and a faint sheen of greenery was spreading through the canopy of riparian woodlands.  Blooming redbuds appeared in Junction City and, near Topeka, the leafing of many trees had begun in earnest.  Finally, from Kansas City to Columbia, the verdant spring caught up with the date, spurred on by recent heavy rains and mild, humid air.

Tuning into an agricultural radio program, as I often do on my journey across the Great Plains, I learned that farmers across the Central and Southern Plains are still dealing with drought conditions while those in the Midwest, their crops decimated by drought last year, are now facing extremely wet soil following excessive rain over the past two weeks.  As of yesterday, only 3% of the nation's corn crop had been planted, compared to an average of 33% by the end of April.  While most of us are occupied with the signs of spring, griping about its slow or uneven progress, farmers face the trials of this fickle season on a daily basis.