Saturday, June 30, 2007

Rain Train

For the past two weeks, upper level low pressure has settled over west Texas and western Oklahoma, pumping a steady stream of moisture northward from the Gulf of Mexico. To the east, a dome of high pressure has kept this stream along its outer edge, steering it over eastern Texas, eastern Oklahoma and southeastern Kansas. This persitent weather pattern has produced an unending chain of thunderstorms and heavy rains across that swath, leading to widespread, historic flooding.

In the past few days, a week cold front has pushed down from the northwest, stalling out along a line from New Mexico to northern Illinois. As a result, the stream of precipitation has been directed eastward, following the border of the stalled front. Looking at the weather radar, one sees an unbroken arc of rain and thunderstorms from Houston to Wichita to St. Louis. Here in Columbia, rain has been falling for three days, recharging our creeks and wetlands. Relief from the deluge is expected in the next couple of days as Canadian high pressure sinks across the region and shuts off the moisture flow; unfortunately, for those in eastern Texas, this front is expected to pass to their northeast and rains will likely continue.

Friday, June 29, 2007

Ohio's Black Hand Region

A thick bed of sandstone stretches through east-central and south-central Ohio. Deposited in shallow seas and along river deltas of the Mississippian Period, 330 million years ago, this multi-layered bedrock is named for a prehistoric pictograph found on one of its outcrops. While it was untouched by the Pleistocene glaciers, the Black Hand Sandstone was carved and molded by torrents of meltwater and by the heavy precipitation of that Epoch. Today, a landscape of rugged hills, deep gorges, rock bridges, waterfalls, recessed caves and glacial relict vegetation reflect the erosional forces and climatic conditions of that periglacial zone.

Northwest of Athens, a chain of parks and nature preserves protect a wonderland of sandtone formations. Most renowned is Hocking Hills State Park, home to Old Man's Cave, Cedar Falls and Ash Cave; the latter is the largest recessed cave in Ohio and its 90 foot cascade is the highest waterfall in the State. Just north of the State Park is Conkle's Hollow State Nature Preserve; protecting a scenic gorge with 200 foot cliffs and a periglacial, hemlock forest, this is, in my opinion, the most spectacular landscape in Ohio. West of Logan and north of Conkle's Hollow are the Cantwell Cliffs, part of the State Park; here, a rugged, multi-fingered gorge is accessed by a network of rimtop, cliffside and valley floor trails. Finally, northwest of Logan, the Rockbridge State Nature Preserve protects a span of Black Hand Sandstone, the largest natural bridge in Ohio.

Too often, Americans assume that the spectacular scenery of our country is limited to the mountainous States. The Black Hand region of Ohio proves otherwise.

Thursday, June 28, 2007

Two Hundred Years

From the perspective of our short life spans, we often assume that the assembly and formation of our continents and oceans were events of the past, preparing the world for human habitation.
But we need only look at the events of the past 200 years to realize that the landscape of this planet is still a work in progress and that we humans are not immune to those forces.

In 1811-1812, the New Madrid earthquakes shook the heart of North America and altered the course of the Mississippi River. Three years later, the eruption of Tambora, in Indonesia, killed over 100,000 people and triggered a volcanic winter. Krakatoa erupted in the Java Straits in 1883; its massive explosion and secondary tsunami killed 40,000. The great San Francisco earthquake of 1906, famous in the U.S., killed 3000 while a 1923 earthquake in Tokyo took 140,000 lives. The greatest death toll in recent history was caused by the 1976 Tangshan earthquake, in China/Tibet, which killed 500,000 people. More fresh in our minds, the tragic tsunami of 2004, triggered by an earthquake off Sumatra, took more than 200,000 lives.

Of course, there have been many other deadly natural disasters in the past 200 years, far too numerous to list here. Beyond the earthquakes, tsunamis and volcanoes, we watched fragments of a comet strike Jupiter in 1994 and are still dealing with the devastation wrought by Katrina in 2005. Who knows what tomorrow will bring?

Wednesday, June 27, 2007

Killer Heat

Now that the first heat wave of the summer is moving through the Northeast, we will soon be hearing about heat-related deaths in our major cities. Yet, since man evolved in the tropics, we are equipped with efficient mechanisms for heat dissipation, primarily through our skin and lungs. And, except for those who venture out unprepared, we rarely hear about heat-induced deaths in desert regions, where human and animal inhabitants have learned to retreat to caves, burrows, rock shelters and other oases during the heat of the day.

Indeed, heat-related deaths are far more common in our modern cities, where the brick and concrete radiate heat throughout the day and night and where numerous frail and elderly persons live in cramped, uncooled and poorly ventilated apartments. And then there are the macho deaths, generally induced by zealous drill sergeants and football coaches, who force their recruits to exercise in the mid-day sun.

Most of us can easily prevent heat-related illness by drinking plenty of water, avoiding excessive caffeine and alcohol, dressing in loose, light-colored clothing and limiting strenuous, outdoor activity to the early morning and evening hours. The elderly and those with chronic disease need to be especially cautious in hot weather; our body's cooling system, as efficient as it is, can place a significant strain on the heart.

Tuesday, June 26, 2007

Dog Day Cicadas

After several weeks of hot, humid weather, the annual cicadas are beginning to emerge in central Missouri. Unlike their periodic cousins, which appear in huge numbers during late spring, this species waits for the stifling conditions of mid summer and is thus called the Dog Day Cicada. And while their periodic counterparts remain underground for 13 or 17 years, the larvae of the annual cicadas are ready to emerge within two years; populations mature each year and, in contrast to the explosive arrival of periodic broods, their emergence is spread over 8 to 10 weeks.

Upon reaching the surface, the larva climbs onto a tree, fence or building to dry out and molt to the adult form. Its adult life, lasting but a week or two, is dedicated solely to breeding; the males attract mates with their high-pitched "song" (which tends to peak in the evenings) and the females lay their eggs on the tender vegetation of shrubs and trees. Though they don't eat during their brief life span, adult cicadas are prized snacks for crows, starlings, blue jays, raccoons and house cats.

Cicada eggs may remain on the plants through the winter, providing nourishment for chickadees, titmice, nuthatches and yellow-rumped warblers, or may hatch and drop to the ground. Once on terra firma, the larva burrows beneath the soil, attaches to the root of a shrub or tree and patiently waits for its 2-year confinement to end.

Monday, June 25, 2007

Settling Down

While humans evolved 125,000 years ago and had spread to six of the continents by 15-20,000 years ago, we did not establish towns and cities until the end of the Pleistocene Ice Age. Prior to that time, humans were nomadic, living in small clans and moving about in the pursuit of game and other food sources. Indeed, it was the hunting of migratory mammals such as bison and reindeer that primarily led man across the globe.

At the dawn of the Holocene, 10,000 years ago, man began to establish settlements in the Fertile Crescent of the Middle East; this cultural shift soon spread throughout the Mediterranean region and across the southern rim of Asia. Though dogs had been domesticated 2000 years earlier, goats were the first animals raised for food, milk and hides; this occured in the Middle East about 10,000 years ago while pigs and sheep were domesticated in Syria 1000 years later. Cattle were brought under human control 8000 years ago, in western Asia and northern Africa, and chickens were domesticated in Southeast Asia about the same time. Among the earliest crops were peas, barley and wheat, first cultivated in the Middle East 10,000 years ago. As these cultures fluorished and trade lines developed, man domesticated the horse (6000 years ago, in central Asia), the donkey and the camel; the latter two beasts of burden were domesticated in northern Africa and Arabia about 5500 years ago. Finally, ducks were domesticated in Southeast Asia, 5000 years ago.

The same advances were occuring in the Americas during this time. Squash was cultivated in Mexico 10,000 years ago, followed by maize, 6300 years ago, and sunflowers, 4500 years ago. Caral, Peru, established 4600 years ago, is the oldest known city in the Americas; residents of that region grew giant pumpkins and raised guinea pigs. It's truly amazing to realize how much change (good and bad) man has produced over the past 10,000 years, a mere instant in the course of Earth's history.

Sunday, June 24, 2007

Stranded

After several weeks of hot weather and little rainfall, the Forum Nature Area wetland, in southwest Columbia, is drying up. An expansive, shallow lake just a month ago, the central basin is now covered by grassy fields, mudflats and a few dwindling pools. On our visit this morning, killdeer and a pair of spotted sandpipers hunted across the muddy shores while a few mallards huddled in the shallows. Taking advantage of the concentrated prey, green-backed herons patrolled the waterline, patiently stalking insects and small amphibians.

But the spectacle of this morning was the large number of bullfrogs and green frogs that waded through the shrinking ponds. Normally hidden by marsh and lake waters, these hapless residents sat silently in the pools, seemingly stunned by their loss of habitat. Easy prey for snakes, mink, fox and great blue herons, stranded frogs must find a moist retreat or venture off to locate another pond. Whatever choice they make, the ongoing drought will surely decimate Forum's frog population; but then, nature is not sentimental.

Saturday, June 23, 2007

Life on the Wing

The magnificent frigatebird, also called the hurricane bird or the Man O' War bird, spends almost all of its life in the air. Landing in mangroves only to nest, this seabird is usually seen alone or in pairs, soaring offshore or drifting in to circle above the barrier islands of the Gulf Coast or Baja; during the breeding season, they gather in colonies on remote, mangrove keys. On occasion, they are seen inland, especially after tropical storms pass through the region.

Easily recognized by its long, thin wings (held in a bent position), long, hooked bill and long, forked tail, the frigatebird has the greatest wing span per body weight of any bird, including the albatross. Indeed, its 90 inch wing span is more than twice as long as its length from bill to tail. Males are solid black except for a red-orange throat pouch which expands during the mating season; females are also black but have a white chest.

Unable to take flight from the ground, frigatebirds must land on trees or cliffs which permit them to sail away and return to the air. Neither can they take off from the surface of the ocean; rather, they deftly pick fish and shrimp from the waves, catch flying fish in mid air or harass other seabirds until they release their catch (gulls, terns, pelicans, boobies and ospreys are all common robbery victims). More comfortable in the sky than anywhere else, frigate-birds are able to sleep as they soar above the ocean. Oh, to have that ability for a day!

Friday, June 22, 2007

Front Range Summer

As spring gives way to summer, the weather along Colorado's Front Range enters a predictable pattern. Daytime heating on the Piedmont causes warm air to rise along the mountain slopes and, by late morning, clouds boil up above the Continental Divide. Some of these will become thunderstorms and, as their tops enter the upper atmosphere, high level westerlies push them to the east. Dropping isolated sheets of rain along the way, they merge into monstrous thunderheads on the eastern plains of Colorado, often producing large hail and tornados.

As they move across the urban corridor, the thundershowers reward some neighborhoods with heavy downpours while leaving most high and dry. When showers are light, the thin, dry air of the Piedmont often causes the rain to evaporate before it hits the ground; called virga, such aborted showers are a common sight during the summer months. By evening, the skies are clearing along the foot of the mountains and Front Range residents are treated to dramatic lightening shows to the east. As the sun sets behind the mountains, the thin air and clear skies cause rapid "radiant cooling" and, reinforced by the drainage of cool air from the highlands, overnight temperatures usually fall into the fifties.

This pattern of hot, sunny days, hit and miss showers and cool, dry evenings will continue until the monsoons of August bring in clouds and moisture from the Southwest. Not a bad place to spend the summer!

Thursday, June 21, 2007

Summer Solstice

Today is the summer solstice, the first day of summer and the longest day of the year in the Northern Hemisphere. The changing seasons are a result of the Earth's tilt on its axis; as our planet makes its annual trip around the sun, our Hemisphere tilts toward the sun in the months surrounding June 21 and away from the sun in the months surrounding December 21 (of course, the opposite is true for the Southern Hemisphere). On this solstice, we are at our maximum tilt toward the sun and, from now until December 21, our days will gradually shorten.

While this is the longest day of the year, our warmest months lie ahead. This is due to the continued, gradual warming of the ground, lakes and ocean waters of the Northern Hemisphere, moderation of the Arctic conditions via the perpetual daylight of summer and a "high riding" jet stream, which blocks cool Canadian air from moving southward. We can't expect much relief from the hot, hazy days of summer until this pattern breaks, generally about mid September in the American Midwest.

Wednesday, June 20, 2007

The Okefenokee

The broad basin that now holds the Okefenokee Swamp, in southeast Georgia, was an arm of the Atlantic Ocean at the end of the Mesozoic Era. While the sea retreated millions of years ago, the basin's landscape has undergone a series of reincarnations, changing in concert with the regional climate. The current swamp ecosystem began to develop 7000 years ago, reflecting the onset of a warm, wet climate, averaging 55 inches of precipitation each year. Over this time, thick deposits of peat, formed by the decay of aquatic and semiaquatic vegetation, settled on the sandy basin floor, setting the stage for today's mosaic of ponds, wet prairies, drier scrub zones and tree islands; the latter, which include stands of blackgum, pond cypress, red bay, red maple and pine, are home to the endangered red-cockaded woodpecker.

The Okefenokee Swamp, covering 700 square miles, is drained primarily by the Suwannee River; the St. Mary's River drains the southeast corner of the refuge. Countless lakes, ponds and channels feed into these rivers and their vast shallows offer prime habitat for herons, egrets, ibis, bitterns, wood storks, gallinules, wood ducks, cottonmouths, snapping turtles and American alligators. River otters, black bear, beaver, mink, gray fox and marsh cottontails are among the resident mammals. More than 620 plant species inhabit the Swamp, including saw palmetto, sedges, water lilies and a fantastic variety of carnivorous plants (sundews, pitcher plants and butter-worts); in addition, coastal plants grow along Trail Ridge, the remnants of a sandy barrier island chain that runs along the eastern edge of the Swamp.

Though protected within the largest National Wildlife Refuge in the eastern U.S., the Okefenokee remains vulnerable to drought and wildfire, as we saw this spring. But these natural forces are vital to the health of this Wilderness, clearing excessive timber and opening new prairies. Without wildfire, this diverse wetland would gradually yield to the expanding forest, eventually becoming the Okefenokee Pinelands.

Tuesday, June 19, 2007

High, Dry and Fractured

The Great Basin of western North America stretches from the crest of the Sierra Nevada to the summit of the Wasatch Plateau and from southern Nevada to central Oregon; this vast, high desert covers western Utah, most of Nevada, eastern California, south-central Oregon, the southeastern rim of Idaho and extreme southwestern Wyoming. As its name implies, the rivers and streams of the Basin do not flow to the sea; rather, they empty into shallow, saline lakes that expand and contract with the seasons. The Great Salt Lake, a remnant of Pleistocene Lake Bonneville, is, of course, the largest of these basin lakes.

Cut off from precipitation by high mountains to its east and west, the Great Basin is North America's largest desert; sage grasslands and salt flats cover the majority of its surface with pine and juniper woodlands limited to the higher terrain of its stark ranges. During the Miocene-Pliocene Uplift, which began about 15 million years ago, the crust of the Great Basin began to stretch and numerous north-south fault lines developed; slippage along these faults has produced the linear, wave-like ranges that characterize the landscape. In fact, the Wasatch Front, on the east edge of Salt Lake City, is the easternmost of these fault-block ranges.

Assembled by the fusion of exotic terrains during the Mesozoic Era, the Great Basin has thus been pulling apart for the past 15 million years. With the accelerated rise of the Sierra Batholith, 4 million years ago (a process that continues today), the crust of the Basin continues to stretch and fracture. Eventually, the ocean will invade the Basin, likely opening northward from the Gulf of California.

Monday, June 18, 2007

Fireflies

Adult fireflies have reappeared in the dusk sky of mid Missouri this week. Members of the beetle family, over 2000 species inhabit our planet, 10% of which live in North America. During their brief lifespan (a few weeks to a couple of months), these fireflies attract mates with their unique pattern and color of flash; while most will enjoy a limited diet of small insects and nectar, some species are canni-balistic and will use their flash to attract meals.

Female fireflies lay their eggs in loose, moist soil where they will hatch into larvae in a week or two. Unlike the adults, firefly larvae are voracious predators, feeding on worms, slugs and snails. Come autumn, the larvae burrow into the soil or retreat beneath the leaf litter to spend the winter; if not consumed by moles, shrews or birds, they will emerge in the spring and, within a few weeks, molt to the adult form.

A welcome sign of summer and a joy for many children, fireflies produce their "lightning bug" flash via the process of biolumi-nescence, a chemical reaction that conserves more than 95% of its energy; only 2% of the flash is lost as heat. Fireflies are found throughout tropical and humid temperate regions of the globe, preferring moist, wooded areas; the suburbs of the eastern U.S. offer prime habitat.

Sunday, June 17, 2007

Fathers

In the great majority of animal species, the male parent's respon-sibilities end with fertilization; unfortunately, some human males adhere to that pattern. Mothers of "lower" animals such as fish, insects, amphibians and reptiles also have little, if any, interaction with their offspring but the maternal parent of birds and mammals takes an active role in nourishing, protecting and rearing their young. In fairness, most male birds, while monogamous for the breeding season only, do take part in nest building and feeding.

On the other hand, most mammal fathers are both polygamous and devoid of parenting skills. Some predators and most primates form family groups but these are generally short lived; only humans maintain a long term relationship with their offspring and it is only in the human species that the ongoing role of the father is critical. Throughout most of human history, the father has been the primary hunter, protector and enforcer; whether he is less skilled in nurturing than his female partner or just less inclined to do so is a debatable point. Certainly, that nine-month connection between mother and child can never be matched.

Yet, over the past 50 years, the distinction between paternal and maternal roles has become blurred; women have begun to assume traditional male careers and men have opted to remain at home with the kids. But the essential gifts that mothers and fathers extend to their children have not changed and the absence of a father, all too common in our society, often leads to emotional and behavioral problems in his offspring. Today, we honor those fathers who chose to stick around.

Saturday, June 16, 2007

The Great Dunes

The Great Sand Dunes of the San Luis Valley, now protected within a National Park, are a relatively new feature of Colorado's landscape. During the Pleistocene Ice Age, 2 million to 10 thousand years ago, mountain glaciers and heavy meltwater eroded the San Juan, La Garita and Sangre de Cristo ranges which flank the Valley; the Rio Grande River and its many tributaries spread a thick layer of this sandy debris across the basin. As the Pleistocene ended and the climate warmed, the San Luis Valley, cutoff from moisture by the surrounding mountains, became a high desert. Over the past 10,000 years, prevailing westerlies have carried the sand eastward and, funneled toward Medano and Mosca passes, dropped their cargo at the base of the Sangre de Cristos; this process continues today.

Rising 700 feet from the valley floor and covering 55 square miles, the Great Sand Dunes are the tallest sand dunes in North America; shimmering like a mirage and backed by the majestic Sangre de Cristo Mountains, they are a scenic and fascinating destination for any naturalist. This National Park, initially established as a National Monument in 1932, offers camping from April through October on a first-come, first-served basis; access to the Park is via Colorado 150, which heads north from U.S. 160, 18 miles east of Alamosa (or 5 miles west of Blanca). A nature center introduces visitors to the natural history and native flora/fauna of the dunes.

One would think that these vast, shifting dunes, themselves lying within a Valley that receives less than 10 inches of precipitation each year, would not harbor any vegetation. In fact, several plant species, including Indian ricegrass, blowout grass, scurf pea and prairie sunflowers are able to tap moisture and nutrients within the dunes. Kangaroo rats, able to metabolize their own water, inhabit the dunes which also harbor two endemic insects: the Great Sand Dunes tiger beetle and the giant sand treader camel cricket. Pinyon pine and ponderosa pine woodlands rise along the edge of the dunes and are home to black bear, mule deer, bobcats, porcupine and coyotes. Pinyon jays, Steller's jays, bushtits, mountain bluebirds, blue grouse, Townsend's solitaires and Lewis' woodpeckers are among the avian residents.

Friday, June 15, 2007

Wild Borders

Most of us have planted trees and shrubs to beautify our property, provide shade or attract wildlife; sometimes they thrive and sometimes they don't. The best way to bring a wide variety of native plants to your yard is to establish a natural border. In these areas, protected from lawn mowers and other human distrubance, an amazing diversity of flora will develop.

On our Colorado farm, we have established a natural border that is 200 feet long and 20 feet deep. Since we bought the property, in 1990, this area has filled in with mulberry, ash, Siberian elm, crabapple and black locust trees; wild cherry, chokecherry, sumac, honeysuckle and lilac cover most of the understory while pockets of current and various wildflowers line the margin. In Missouri, our natural border is much smaller but the higher humidity and greater precipitation produces a larger variety of plants; black walnut, mimosa, red oaks, black maple, boxelder, yellow poplar, redbud and redcedar rise above elderberry, yew, wild grape, privet, honeysuckle, American holly and Virginia creeper.

Naturalists know that such border zones, with their mix of shelter, nesting sites, seeds, berries and insects, attract the greatest variety of wildlife. Among these are cardinals, catbirds, yellow warblers, towhees, thrashers, chats, orioles, goldfinches, sparrows, tree frogs, toads, deer mice, opossums, skunk and raccoons. Unlike most humans, wild creatures prefer unmanicured habitat.

Thursday, June 14, 2007

Weather and Climate

The peak of the snowmelt season, a heavy mountain snowpack and an exceptionally wet spring have all combined to produce the highest flow in the South Platte River that Colorado has seen in many years while, across the Great Plains, deep winter snows and heavy spring rains have created an unusually verdant landscape. At the same time, severe drought persists in parts of the northern plains and southern California and Lake Superior is at its lowest level in decades, reflecting a regional dirth of rain and snow over the past few years. While Tropical Storm Barry brought some relief to the parched landscape of the Southeastern States, the region's annual precipitation remains well below normal.

Such regional, cyclic weather patterns are distinct from climate change. The latter is a slow, steady change in the weather of a region, continent or the planet as a whole, resulting from long term changes in ocean currents, atmospheric conditions or even the location of the continents; for example, parts of Antarctica enjoyed a tropical climate before it drifted to the South Pole. On a smaller scale, a changing ocean current may enhance or diminish the precipitation along a coastal region; over thousands of years, this could lead to the development of a rain forest or a treeless desert, respectively.

Encouraged by a zealous media, the public often associates our transient weather patterns with global warming, the hot topic of the decade. While there is no doubt that our global climate is warming (and that humans likely play a significant role in that process), regional weather aberrations are not related to that phenomenon. But the presumed association makes good headlines!

Tuesday, June 12, 2007

Flying Mammals

A pair of little brown bats zig-zagged above our farm last evening, feasting on mosquitos, moths and other flying insects. Locating their prey by high-frequency sonar (echolocation), bats capture small insects directly in their mouth but use their wing membranes to snare larger victims. Contrary to popular folklore, bats are also equipped with good visual acuity.

Bats evolved early in the Cenozoic Era, just after the demise of the dinosaurs. The forelimbs of their terrestrial ancestors developed into webbed digits and thence into membranous wings while the hindlegs retracted into short, clawed appendages. Today, more than 920 species of bat inhabit our planet, representing 20% of all mammals. Large, fruit eating bats, often called "flying foxes," are found throughout the tropics, as are the infamous vampires; most bat species are relatively small insectivores.

Bats of the Temperate Zone hibernate through the winter, using caves or attics. Though most of these species breed in the fall, fertilization is delayed until early spring and females gather in nurseries by May or June; the latter may be in caves, tree cavities or abandoned buildings. Males often remain solitary through the summer but may gather in small groups. Unreasonably feared, bats play an important part in the control of insect populations and are surely more welcome in the neighborhood than those noisy insect zappers; on the other hand, bats can carry rabies and should not be handled.

Sunday, June 10, 2007

Man and Religion

Ever since man spread through southern Africa and dispersed across the globe, he has had plenty to fear. Storms, wild animals and hostile tribes likely topped the list but natural events such as comets, earthquakes and volcanic eruptions also triggered fear and uncertainty. With the development of agriculture, some 10,000 years ago, he also learned to fear drought, floods and insect hordes. Of course, as the first animal capable of intellectual fear, he has long worried about injury, illness and death.

Throughout his history on Earth, man has associated various gods with the natural forces that either threaten or sustain him. He learned to thank gods that brought him rain, light, hunting success or a good harvest; he also learned to appease the gods that threatened him with storms, fire, flood or other natural disasters. Today, we enlightened humans look back on the "pagan" rituals and beliefs of these early humans with a sense of superiority; how silly and ignorant they were.

But modern religions, founded before the scientific era and professed to be grounded in love and charity, are still sustained by guilt and fear. History is repleat with religious leaders who have used threats and fear to retain power and to fend off the influence of science and spiritual philosophy. In reality, religions are just another means of dividing us; they have brought more suffering than peace and they have no dominion over morality.

Saturday, June 9, 2007

Brushpiles

One of the best ways to attract wildlife to your yard is to create a brushpile. We have several on our Littleton farm and they are often the focus of wildlife activity.

Decaying wood and its associated fungal growths attract a wide variety of small invertebrates, including worms, insects, spiders and slugs. In turn, these primary consumers are preyed on by dragonflies, mantids, toads, lizards, mice, shrews and birds; among the latter, wrens, thrashers, catbirds, towhees, sparrows and mourning doves are frequent patrons of brushpiles. Higher in the food chain, snakes, opossums and raccoons feed on many of the primary and secondary consumers but may, themselves, fall prey to hawks, owls and fox.

In a way, brushpiles are miniature wildlife areas. The life and death struggles that occur within and around their tangled architecture mirror the cycles of nature as a whole. After providing the basic structure, we need only observe and enjoy the many creatures that live and hunt in this backyard refuge for years to come.

Thursday, June 7, 2007

The Verdant Plains

Driving back to our Colorado farm, it soon became apparent how much last winter's heavy snows and this spring's ongoing rains have transformed the landscape of the Great Plains. Just west of Columbia, the Missouri River was still spilling onto its floodplain, taking in heavy drainage from Nebraska, Iowa and the Dakotas. In like manner, the swollen Kansas River flowed into Lawrence, swirling among trees that normally stand above its banks.

West of Topeka, the Flint Hills were emerald green and their stream beds, often just rock-lined crevices, were now washed by gurgling creeks. Near Salina, the Solomon and Saline Rivers had come down but shallow lakes still covered depressions in the Kansas crop fields. Even the High Plains of western Kansas and eastern Colorado were verdant; the sparse trees looked especially vigorous and the vast grasslands were thick and green. Farm ponds and marshes, nearly dry in recent years, were filled to the brim and reflected the deep blue western sky. It's amazing what a foot or so of precipitation can do!

Wednesday, June 6, 2007

The Toba Winter

The eruption of the Toba Volcano, 74,000 years ago, was the largest in the last 2 million years. This "supervolcanic eruption" ejected 2800 cubic km of ash into the atmosphere; by comparison, the 1980 eruption of Mt. St. Helens produced 1 cubic km of ash. Twenty foot layers of compacted Toba ash has been found in central India, 1900 miles from the volcano. Today, the remnant caldera of this violent explosion, located in northern Sumatra, is up to 60 miles in diameter; Lake Toba fills much of this basin and a new volcanic dome forms a large island near its western shore.

Climatologists believe that the Toba eruption produced a "volcanic winter" that lasted for several years, lowering worldwide temperatures by 5 degrees C or more. Furthermore, DNA studies indicate a significant reduction of the human population, perhaps to 10,000 individuals or less, that seems to coincide with this event. At the time of the Toba eruption, early man had spread out of Africa and was colonizing the southern rim of Asia. Ashfall from the volcano was most intense throughout this region and few humans likely survived. It is theorized that a small, residual population in southeast Africa kept the human species from becoming extinct.

Though better prepared with our modern technologies, we remain vulnerable to such a devastating, natural catastrophe. The Yellowstone Caldera, in northwest Wyoming, is the remnant of three eruptions over the past 2 million years; the first and largest of these was a supervolcanic eruption, only 10% smaller than the Toba event. The floor of the caldera has been gradually rising in recent decades and some volcanologists believe that another major eruption is just a matter of time.

Tuesday, June 5, 2007

Big Sky, Short Grass

West of the 100th Meridian, the Great Plains of North America become semiarid. The rain shadow of the Rocky Mountains, higher elevations and an increasing distance from the Gulf of Mexico combine to limit annual precipitation to 20 inches or less. Stretching from eastern Montana to West Texas and eastern New Mexico, this province is the domain of the Shortgrass Prairie; blue grama and buffalo grass dominate, with pockets of sand dropseed, three-awn, sideoats grama and western wheatgrass. Saltbush, chokecherry, winterfat and groves of cottonwood line the drainages while yucca, prairie sunflowers, prickly pear and Indian paintbrush add color to the landscape. Today, most of this province has become a mosaic of irrigated croplands and cattle ranches.

The Pawnee National Grasslands, in northeastern Colorado, is one of the better places to explore what remains of the shortgrass prairie. Stretching north of Colorado 14, between Ault and New Raymer, the Grasslands are accessed by a network of dirt-gravel roads. Early or late day visitors should see coyotes, mule deer, white-tailed deer and, if you're lucky, swift fox; other resident mammals include pronghorn, black-tailed prairie dogs, badgers, jackrabbits and thirteen-lined ground squirrels. Bull snakes and prairie rattlers are often seen along the roadways and cattle, surrogates for the great bison herds, roam the prairie from May through October.

McCown's and chestnut-collared longspurs, western meadowlarks, horned larks, lark buntings, killdeer, spotted sandpipers, long-billed curlews, avocets and mountain plovers characterize the bird population. Raptors include golden eagles, Swainson's hawks, prairie falcons, American kestrels, ferruginous hawks, great horned owls and burrowing owls; the latter nest in abandoned prairie dog burrows and feast on the numerous grasshoppers.

Monday, June 4, 2007

The Blue Bird

One of my earliest memories is of a bright blue bird in the shrubs behind our Cincinnati home. Five or six at the time, I remember wondering whether it was someone's pet bird, freed from its cage. Today, more than 50 years later, the image of that bird remains very clear in my mind and I recognize it as an indigo bunting.

Such childhood experiences, compounded over the years, awaken us to the natural diversity of this planet and set the stage for a commitment to conservation later in life. As parents and grandparents, we should do whatever we can to expose our young ones to the many fascinating creatures that share this planet. We and they will be enriched by the process and nature will be the ultimate beneficiary.

Sunday, June 3, 2007

Tropical Savior

Tropical Storm Barry was a godsend for Florida, southern Georgia and the Southeast Coast, bringing 2-10 inches of rain to the area and putting a large dent in the regional drought. Hopefully, a few more of these tropical systems will bring an end to the wildfires and water shortages.

Like all Tropical Cyclones, Barry began as a Tropical Disturbance; this meteorological term refers to a cluster of thunderstorms that persists for 24 hours or more and moves with no relation to a front. In Barry's case, this distrubance developed in the western Caribbean while, later in the hurricane season, many develop as tropical waves, moving west from Africa. Once an internal rotation develops and sustained winds reach 23 miles per hour, the system becomes a Tropical Depression; Tropical Storms (which are named) have winds between 39 and 73 miles per hour while Hurricanes have sustained winds of 74 mph or higher.

The development of tropical storms requires three conditions: a water surface temperature of 80 degrees F or above, high local humidity and a lack of shearing winds in the upper atmosphere. As the thunderstorm cluster becomes organized, warm, humid air is drawn up through the center of the system, reinforcing the central low pressure and drawing in warm, humid air from the periphery. Condensation occurs in the upper levels of the storm, releasing energy which moves outward, enhancing the circulation and releasing the precipitation, which falls in heavy bands. If conditions remain favorable, this cycle continues, the storm intensifies and prodigious amounts of moisture are drawn into the atmosphere. Since the air is relatively warm at all levels, tropical systems produce far more rain than their northern cousins, the nor'easters.

Saturday, June 2, 2007

Dragonflies

Part of our natural world for 300 million years, dragonflies patrolled the primordial swamps and coal forests of the Pennsylvanian Period. Today, much smaller than their prehistoric ancestors, dragonflies have diversified into more than 5000 species, almost 10% of which inhabit North America. Of course, most are found in tropical and subtropical regions but they have adapted to a wide range of habitats, including subalpine and subarctic zones.

Equipped with keen vision and superb flying skills, dragonflies feed on mosquitos and other flying insects. Their ability to hover and maneuver in all directions results from the independent motion of their two wing pairs. Dragonflies are larger and much bolder than their brightly colored, dainty cousins, the damselfies; in addition, dragonflies rest with their wings in a flat, horizontal position while damselfies fold their wings vertically.

After mating, the female dragonfly deposits her eggs on aquatic vegetation or directly in the water, often accompanied by her protective mate (he's actually protecting his own genes). Once hatched, the nymphs mature underwater for weeks to years, depending upon the life zone. During this time, they feed on other insects, mosquito larvae and each other and must avoid their own predators; the latter include fish, frogs, wading birds and diving ducks. Upon leaving the water, the nymphs dry out on vegetation and molt to the adult form. Adults spend their three month existence feeding and mating; if not killed by birds, frogs, toads or windshields, they will die off with the first hard freeze and their offspring will overwinter as eggs or nymphs.

Friday, June 1, 2007

Hurricane Stuntmen

Today is the first day of the Atlantic Hurricane Season, which extends into mid November. These will be cherished months for travelling weathermen and exposure-concious reporters as they fan out across the Southeastern and Gulf Coasts, ready to provide eye-witness accounts of these powerful storms. Their patron saint is none other than Dan Rather, who, in the 1960s, launched his career by reporting on a Texas hurricane while lashed to a tree.

Though equipped with high-tech, long-range cameras, these intrepid reporters prefer to stand in the wind and rain, all the while admonishing the locals to evacuate the area. The lucky ones, cloaked in their ponchos and goggles, will bring the full-force of the storm into our homes. Those who choose the wrong location must be content with shots of waving flags and roadside puddles.
Unfortunately, it will probably take a serious, on-air accident or death to bring an end to this folly.