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Showing posts from April, 2009

The Amazon Basin

During this season of rising temperatures, increasing humidity, heavy rain and swollen rivers, we get a small taste of the Amazon Basin. Covering almost 2.75 million square miles (nearly the size of our lower 48 States), this geophysical province is bordered by the Guiana Highlands on the north, the Andes of southern Colombia, Ecuador, Peru and northern Bolivia on the west and the Brazilian Plateau on the south. Its vast tropical rainforest, representing 60% of that ecosystem on Earth, has spread across the Basin since the mid Cretaceous, 100 million years ago.

The Amazon River, the largest (by volume) on our planet, winds for more than 4000 miles, taking in flow from countless tributaries; the most prominent of these are the Rio Negro of northern Brazil, the Rio Madiera, which flows northeastward from Bolivia, and the Rio Tapajos, draining the northern edge of the Brazilian Plateau. The vast watershed of the Amazon transports 20% of Earth's river water and, at its mouth, discha…

Trough Triple Play

Troughs are "U-shaped" dips in the jet stream; some are rather narrow and uniform while others are broad and uneven, often covering a large area of the country. Since the trough allows cool, dry air to spill through its interior, its leading edge is a cold front, igniting thunderstorms and heavy rain as it pushes into warm, moist air east of the trough. Over the past two days, such a cold front triggered severe storms and flooding rains from Texas to Michigan; here in central Missouri, we received 2-3 inches of rain.

As the trough moves eastward, areas within its "U" become cooler and drier, sheltered from the active borders. After a string of summer like days, we sit at 46 degrees F this morning and our afternoon high should remain in the sixties; such trough-related respites are always welcome during the hot, muggy days of July and August.

Finally, as the trough continues to move east, its back edge approaches as a warm front, ushering more seasonable temperatur…

Spring Heats Up

Returning from a week in Colorado, I found that mid Missouri has greened up significantly. Some of the trees, including our magnolias and tulip trees, have fully leafed out and others are close behind; only the mimosas, among the last trees to develop leaves, retain their winter appearance.

A week of warm, humid weather has given spring a boost. Toads are trilling a night, the azaleas are in bloom and dogwoods have unfurled their showy white brackets. Down at the Forum Nature Area, aquatic turtles were peering from the shallows and a host of summer birds moved among the greening trees and shrubs; these included orchard orioles, indigo buntings, eastern kingbirds and a large number of chipping sparrows. Despite the dramatic shift toward summer, a few white-throated sparrows still called from the thickets, a bit tardy for their trip to Canada.

In the Midwest, the final week of April and the first week of May usually encompass the most abrupt change in course of nature's year. Win…

Carbon from Kansas

Those concerned with global warming and greenhouse gas emissions tend to focus on our major urban areas, the location of most factories, power plants and congested highways. Few would even think about Kansas, with its rural economy, expansive landscapes and relentless wind. In fact, with its commitment to wind farms, the State has become increasingly involved in efforts to combat our dependence on fossil fuels.

But anyone who drives through Kansas during April might have second thoughts. Clouds of smoke and charred grasslands cover large portions of the State; the effect is even more overwhelming at night when scattered lines of fire produce an eerie, orange glow. This annual practice of burning fields, to control unwanted vegetation and to enrich the soil, must send tons of carbon into the atmosphere. Then there's the cattle industry, a major contributor to greenhouse gases (especially methane); should you doubt this fact, stop by one of the huge feedlots that dot the State. Final…

April at Chatfield

Constructed primarily for flood control and completed in 1976, Chatfield Reservoir has since become the centerpiece of a large State Park, in southwest Metro Denver. Characterized by extensive grasslands, the open lake, backwater wetlands, ponds and riparian woodlands, the Park is an excellent place to study the flora and fauna of Colorado's Piedmont ecosystem. On this warm, sunny morning, it seemed like the perfect destination.

Spring runoff, exacerbated by the recent heavy snowfall, had produced a high lake level and significant flooding along Plum Creek and the South Platte River. Coot, mallards, green-winged teal and wood ducks gathered on these backwater shallows, joined by several flocks of American white pelicans at the South Platte inlet; pairs of Canada geese were nesting along the marshy shores and the distinctive calls of red-winged blackbirds and chorus frogs echoed across the wetlands. Western and Clark's grebes fed on the deeper waters, which also attracted do…

Home Planet Day

On this 40th Earth Day, many casual environmentalists will express their support for recycling, clean energy and conservation. Unfortunately, most will take little interest in a global approach to the problems of pollution, habitat loss and overpopulation. They have no appreciation for the effects that policies in distant countries may have on their own lives or on the lives of their children and grandchildren.

But we all live on the same planet with its thin envelope of atmosphere, its fragile hydrology and its fickle, global climate. Indeed, air pollution in China, deforestation in Brazil and overfishing by Japan will, eventually, affect us all. Of course, under the Bush Administration, the U.S. essentially withdrew from any global approach to environmental problems but, with a new attitude in Washington, we may once again provide leadership on these critical issues.

On the other hand, some dedicated individuals, while providing active and financial support for national and intern…

The Nature of Guilt

More than any other emotion, guilt is a source of human unhappiness. Whether intentional or not, it is imposed by parents, families, spouses, friends, teachers, supervisors, preachers, politicians and everyday pundits. At its core, guilt makes us question our beliefs, our choices, our actions, our abilities and our relationships.

And while the guilty party suffers, the purveyor of guilt gains power and expects some capitulation by the victim, whether it be emotional, intellectual, physical or financial. In the case of religions, their entire existence relies on guilt-ridden subjects, eager to pay restitution via their active and financial support. Human cultures do much the same, imposing compliance through legal forms of discrimination.

There are, of course, perfectly acceptable reasons for imposing guilt, especially when it comes to criminal behavior. But there are plenty of law-abiding, honest, responsible people out there who live their lives in a cloud of guilt. If only they …

Flicker Days

Most Americans would likely choose the robin as our bird of spring, since he returns to our suburban lawns as the soil thaws and his favorite quarry (earthworms) move to the surface. Others might select the mourning dove, her melancholy tune wafting through our colorful spring neighborhoods. But I am inclined to nominate the northern flicker, whose wild, hysterical call and incessant drumming heralds our season of renewal.

This is especially true at our Littleton, Colorado, farm, where the flickers seem to be even more noisy and active. Adding to this impression is their fondness for our metal, kitchen vent, which vibrates with their drumming from dawn to dusk. All of this clatter is, of course, the male's way of asserting his territory and attracting a mate. By May, their frenzied behavior settles down and the flickers pair off to search for a nest cavity in which to raise their brood of 6-8 chicks.

Unlike most woodpeckers, northern flickers often feed on the ground, searching for …

Weather Rebound

The storm that dumped heavy snow on Colorado's Front Range, just a few days ago, was the result of a trough (a dip in the jet stream), which allowed cold air to spill southward and triggered a potent zone of low pressure; the latter, which moved from the Great Basin onto the High Plains, produced upslope flow across eastern Colorado and heavy, wet snow for most areas above 5000 feet.

Moving off to the east, where it ignited thunderstorms and heavy rains, the trough was replaced by an atmospheric ridge, a northward bowing of the jet stream. In contrast to the trough, the ridge permits warm air to push up from the Southwest; as it crosses the Rockies, this air is forced to sink, further compressing, heating and drying its mass. As a consequence, the recent snow has essentially disappeared from elevations below 6000 feet and, with sunny, warm conditions expected this week, the snowpack in the foothills and mountains is sure to follow.

Tributaries of the South Platte are already swollen…

Journey Through the Seasons

Heading back to our Colorado farm, I left Columbia in a balmy mist, with an early morning temperature of 55 (F), knowing that a potent spring storm lay in my path. Between Columbia and Kansas City, the massive storm produced several bands of torrential rain, slowing my progress substantially. Once in Kansas, the rain stopped but low, gray clouds did little to brighten the landscape; in fact, a strong northwest wind (I was clearly on the backside of the storm) raked the eastern third of the State, dropping wind chills into the thirties.

Further west, where spring has barely risen from the soil, the clouds diminished and the bright blue sky, dry, cool air and golden fields made it look and feel more like October than April. The fourth season arrived in easternmost Colorado where only scattered, puffy clouds dotted the sky and where the afternoon temperature was pushing seventy. Despite the mild conditions, residual pockets of snow appeared near Genoa (along the High Plains escarpment) an…

Songbird Season

In the American Midwest, the period between April 15 and May 15 covers the annual peak of bird watching activity. This is the spring songbird migration, encompassing the departure of winter residents, the arrival of summer residents and the appearance of numerous transients. The observation of these small, colorful birds is aided by longer, warmer days and relatively leafless trees (at least through much of April).

As juncos and winter sparrows depart for Canada in mid April, the summer residents are beginning to arrive from the south, joining tree swallows and eastern phoebes that turned up in late March. Among the first to arrive are chimney swifts, brown thrashers and house wrens, followed by indigo buntings, gray catbirds, barn swallows and early warblers. Orioles, hummingbirds, thrushes and tanagers appear late in April, joined by a variety of flycatchers. Warblers peak in number and variety by early May and common nighthawks appear in the evening sky soon thereafter.

Beginnin…

The Wisconsin Ozarks

The landscape of the Upper Midwest and Great Lakes region demonstrates the effects of Pleistocene glaciation: flattened terrain, glacial lakes and till enriched soil. But one area, in southwest Wisconsin defies this description; spilling into southeast Minnesota, northeast Iowa and extreme northwest Illinois, this swath is characterized by a heavily dissected plateau of ridges and valleys.

Known as the Driftless Area and often called the Paleozoic Plateau, this terrain escaped the last two glaciations of the Pleistocene, preserving its topography and keeping its soil devoid of glacial drift. The last glacier, the Wisconsin (70,000 to 10,000 years ago), was diverted by the resistant Baraboo Ridge, north of the Driftless Area and the ice moved to the east and west of the plateau, merging to its south. Surrounded by ice near the end of the Epoch, the area was spared glaciation as the climate warmed and the ice sheets retreated into Canada before spreading inward.

Like the Ozarks of Missour…

Escape to the Unknown

On this frosty morning in mid Missouri, the song of white-throated sparrows is especially intense. They sense a coming journey and, like other wintering songbirds, will depart for Canada in the coming days.

Their behavior is, of course, entirely instinctual. They have no knowledge of their destination and no conscious rationale for their migration. Traveling at night, they will be guided by star patterns and by the magnetic field of our planet. En route, they will not recognize cities or landscapes but will "know" when they reach their breeding grounds; there, they will be naturally equipped to sustain themselves and to raise their young. Come October, these birds will return to the same Midwestern neighborhoods but will have no conscious memory of past visits and no comprehension of the hot, humid summer that we endured in their absence.

We humans anticipate and plan for our travels and usually have a motivation for the journey. As a consequence, we must deal with sched…

Spring Break

Following a seasonable March, April has been exceptionally cool in Missouri, with frequent frost advisories and a dearth of warm, sunny days. While there has been a gradual greening of the landscape, it seems that spring has been on hold for several weeks.

But while the cold has slowed the life cycles of plants, reptiles, insects and amphibians, the birds and mammals proceed on schedule, responding primarily to the lengthening days. Tree swallows, cliff swallows and eastern phoebes have been back for most of the month and are surely struggling with the chill's suppressive effect on insects. Most of the other summer residents should arrive over the coming week and, fortunately, warmer conditions are forecast. Wild mammals, of course, equipped with protective coats and versatile in their diet, are little affected by our cold spell.

This break from "normal" temperatures is far from unusual. Indeed, in the American Midwest, April is second only to March in the fickle natu…

Deadbeat Parents

Yesterday, the distinctive, gurgling call of a male, brown-headed cowbird rang through our neighborhood. Soon, his first mate of the season will be checking out nests in the area, waiting for the opportunity to deposit one or two of her own eggs in another bird's clutch; when doing so, she often removes one of the adoptive parent's eggs. Since her eggs tend to be larger, the adoptive parent may discard or destroy them; if not, the cowbird's chicks usually hatch first and, aggressive by nature, get most of the food that the attentive parents bring to the nest. Meanwhile, the female cowbird is off looking for another nest to parasitize and may deposit up to forty eggs (fertilized by a number of males) in various nests over the course of spring and summer; studies have shown that less than 5% of these cowbird chicks will reach adulthood.

Native to the plains of North America, brown-headed cowbirds moved into the eastern States as forest was cleared for farming and suburban …

Dandelion Season

To the dismay of lawn masters, dandelions are popping up around Columbia, about two weeks later than usual. These common wildflowers, also known as weeds, are native to Europe and prefer cool, moist conditions. By mid summer, they will die back, returning again in September, when the intense heat subsides.

Prolific and colorful, dandelions adapt to a wide range of soils but favor sunny locations. Bees and a variety of other insects feed on their nectar while cottontails consume all parts of the plant. Humans have also discovered the culinary benefits of this wildflower, using its leafy foliage for salads and its yellow flowers to make dandelion wine.

Like many species in nature, this plant is welcomed by some and despised by others. Regardless of your point of view, the dandelion is here to stay and one must admire its tenacity. In this competitive world, governed by natural selection, dandelions are among the clear winners.

Tsunamis and Subduction Zones

Subduction zones occur where one tectonic plate is forced downward beneath another plate. Most of these zones are found along the edges of the Pacific Ocean but there are others scattered across the globe, including the eastern border of the Caribbean and the western edge of Indonesia.

The downward warping of the two plates creates an oceanic trench in these regions. While the subducting plate continues to move downward, eventually melted by the underlying mantle, the edge of the overlying plate is also bent downward, a result of friction between the two plates. Eventually (and intermittently), this potential energy is released and the plate edge rebounds upward, pushing the overlying ocean upward and triggering a tsunami.

Like the effect of a pebble dropped in a pool, the tsunami wave rushes off in all directions, reaching speeds of over 500 mph. Relatively modest in height in the open ocean, the wave builds as it enters shallower water along continental shelves; this is due to increas…

The Nature of Ritual

Early man faced many threats to his survival: wild predators, hostile tribes, storms, drought, floods and insect hordes, among others. In response, he imagined gods that exerted control over these natural forces and, through appeasement, would offer him protection. A variety of rituals, unique to each culture, were established to honor and thank these gods.

Modern religions, all of which developed prior to the scientific era, morphed from these earlier beliefs and rituals. Today, such celebrations and commemorations occur primarily in churches, synagogues, mosques and temples but spill into the public sector in the form of invocations and prayer. Despite our commitment to separate Church and State, we receive a steady stream of pronouncements from politicians and media celebrities that they will be praying for someone or something.

As with early man, such rituals profess a belief that God or gods micromanage our universe, responding to individual requests for favor or forgiveness. …

Denver's Upslope Snowstorms

While meteorologists are very knowledgeable about atmospheric conditions and storm dynamics, I have found that they sometimes overlook the effects of landscape topography when making their forecasts. Just over the past month, national weather forecasts were inaccurate on several occasions when it came to snowfall in Denver.

Metro Denver sits at the southwest end of the South Platte Valley and is surrounded by higher terrain to the west (the Front Range) and to the south and east (the Palmer Divide and associated High Plains); there is also a ridge of higher terrain just north of the city. As a result, winds blowing into the region are downsloping from all directions except the northeast; since air warms and dries as it sinks, this topography is responsible for Denver's mild, dry, sunny climate.

And, contrary to its perceived image as a winter ski resort, most of the city's snowfall occurs in March and April, when Pacific storms cross the Rockies, pull moisture from the Great P…

Italy's Earthquake

This week's tragic earthquake in Italy is just another reminder that Earth's evolution continues to unfold and that human populations, especially those near active plate margins, remain at risk. Our brief life span, but a fleeting moment in geologic time, often gives us the impression that this planet has settled into a stable, mature state; then, another natural catastrophe forces us to face reality.

When the Tethys Sea split Pangea, 200 million years ago, the land that is now Italy moved south as part of the African Plate. As the Sea closed, the African and Eurasian Plates began to collide and Italy became the leading edge of that collision. Forced against southern Europe like a giant wedge, the Italian terrain was reunited with Eurasia and the impact of that collision rippled up the Alps and adjacent ranges. Beginning 50 million years ago, the process continues today, producing a vast network of faults throughout the region, all of which are subject to the type of motion…

Palo Verde Trees

Native to the Sonoran desert, palo verde trees are easily recognized by the greenish bark of their secondary branches and twigs. Barren looking for much of the year, the trees produce brilliant yellow flowers in spring and small, compound leaves develop on the terminal branches from mid summer into mid autumn. Since the green branches and twigs are capable of photosynthesis, the leaves are often dropped early if prolonged drought occurs; in fact, these trees are also capable of shedding their terminal branches in order to conserve water. Palo verdes are also equipped with deep tap roots, which obtain water from below and serve as anchors during flash floods.

Two species of palo verde are found in the Sonoran. The blue palo verde, Arizona's State Tree, grows to forty feet; favoring lower terrain along washes, this species is commonly planted as an ornamental due to its showy flowers and attractive blue-green stems. The yellow palo verde, found in foothills to 4000 feet, is a shrubby…

A Country Drive

Over time, we come to recognize places and activities that are especially relaxing. For me, these prime stress reducers are solitude, music and nature. Off work for the day, I decided to combine these therapies on a morning trip through the rural areas that surround Columbia. Taking along my binos and a few CDs, I escaped to the country.

Despite the cold, gray conditions, there were plenty of birds along the route. Bluebirds, hawks and a lone loggerhead shrike highlighted the drive across farmlands east of town. In the hill country to our south, wild turkeys and a Cooper's hawk spiced up the usual mix of woodland residents while, on the Missouri floodplain, killdeer, horned larks and red-winged blackbirds dominated the scene. North of Columbia, on the rolling landscape of the till plain, white-crowned sparrows and meadowlarks graced the fields, kestrels swayed on powerlines and turkey vultures, like wayward kites, dipped and soared in the strong, north wind.

Of course, the bir…

From Desert to Wetland

After several days in the dry, warm Sonoran Desert, we have returned to Missouri, finding the State enveloped in a cool, moist air mass; showers are expected throughout the day, changing to snow overnight. Not unusual for early April, the weather seemed perfect for waterfowl and I headed down to Eagle Bluffs, the best wetland complex in our region.

As expected, there was a great deal of activity at the refuge, dominated by large flocks of coot, blue-winged teal and northern shovelers. Great blue herons, lesser yellowlegs and an occasional muskrat also stalked the shallows while squadrons of tree and cliff swallows skimmed the surface, feasting on insects. Northern harriers patrolled the fields, vultures tilted in the west wind and a lone bald eagle soared above the wetlands. Flooded woodlands along the Missouri were alive with the calls of chorus frogs and the drumming of flickers; wood ducks, cardinals, downy and red-bellied woodpeckers, song sparrows and yellow-rumped warblers we…

Mt. Lemmon

Yesterday morning, we drove eastward across the flat landscape of Tucson, which was ablaze with the brilliant gold flowers of paloverde trees. Picking up the Catalina Highway, we continued toward the massive ridge of the Santa Catalina Mountains and soon climbed into the Coronado National Forest on the Sky Island Scenic Byway. This toll road, currently $5 per vehicle, winds upward and northward for almost 28 miles, to the summit of Mt. Lemmon.

Leaving the desert plain, we soon entered a zone of saguaro cacti, which continued to dominate the spectacular scenery to an elevation of 4000 feet. This habitat gave way to mountain shrublands between 4000 and 6000 feet, highlighted by massive towers (hoodoos) of granite. A rich, pine forest appeared above 6500 feet and continued to the summit of Mt. Lemmon (over 9100 feet), where it was scarred by wildfires earlier this decade.

One of numerous "sky islands" across the Great Basin and Desert Southwest, the Mt. Lemmon massif supports ec…

Sabino Canyon

Sabino Canyon incises the Santa Catalina Mountains at the northeast edge of Tucson, Arizona. Protected within a National Recreation Area, this refuge harbors a spectacular diversity of plants and animals, all of which typify the Sonoran Desert of North America.

If one avoids the central roadway, with its throngs of visitors and guided shuttle tours, he/she can experience the beauty and serenity of this spectacular ecosystem, with its diverse cacti, broad views and appealing mix of birdlife. Fortunately, a number of well marked trails lead away from the congested areas and a two hour hike took us through the heart of the refuge. Ocotillo, prickly pear and barrel cacti were beginning to bloom and we encountered a wide diversity of desert birds; the latter included cactus wrens, phainopeplas, broad-billed hummingbirds, Gambel's quail, Gila woodpeckers, verdins, green-tailed towhees, black-throated sparrows and plain titmice, among many others.

One can certainly find more pristine, uncr…

A Sea of White

For the past few weeks, I had been looking forward to yesterday's flight to Phoenix. Long a geography buff, I knew our route would take us across the Great Plains, the Southern Rockies, the Colorado Plateau and the low desert of Arizona. And all seemed well as we climbed east out of St. Louis, circled over the city and followed the Missouri River toward the west.

Unfortunately, we encountered thick cloud cover before we reached Jefferson City and this sheet of white remained below us for the next three hours, offering no chance to view the varied geography from 30,000 feet. Like a mariner stranded on a white sea, I searched in vain for a glimpse of terra firma. Finally, twenty minutes shy of Phoenix, the cloud cover broke, we descended across the Mogollon Rim and cruised into the Valley of the Sun.

Those of us who enjoy excursions into the natural world know that nature does not always cooperate. She takes no heed of our presence and has no need for our admiration. And fair weather …

April in the Heartland

Every month has its natural highlights but April harbors more than its share. As the jet stream inches its way back to the north, warm, moist air pushes further into the Heartland, setting the stage for frequent showers and thunderstorms. This increasing moisture feeds the cycle of life and, through the month, greenery intensifies.

Before the forest canopy closes out the sun, woodland wildflowers reach their annual peak; this is the month to look for spring beauty, trillium, hepatica and other forest species. Out in the wetlands, the building heat and humidity trigger the year's first explosion of insects, greeted by an increasing variety of birds and amphibians. Snakes and aquatic turtles emerge from their winter retreats, just in time to feed on this bounty, while swallows and swifts, back from the south, swoop above the seasonal ponds, feasting on the growing hordes of insects. Watching all of this is the barred owl and its questioning call echoes through our spring marshlands.

I…