Posts

Showing posts from May, 2011

A Ridge of Summer

A northward shift of the jet stream has allowed a ridge of summer heat to invade the central and eastern U.S. over the past 24 hours and is expected to remain in place for Memorial Day. Blocking the invasion of Pacific fronts, this dome of high pressure is shunting storms along its outer rim and, at least for the Holiday weekend, the soggy and storm-ravaged Midwest will be spared another round of severe weather.

Ushering in the first major wave of summer, this atmospheric ridge should help to dry out the muddy fields that stretch across the till plains and, for now, will reduce flow into our swollen rivers and streams. As expected, the heat has energized the periodical cicadas here in Missouri and the sunny weather, arriving just in time for the traditional kickoff to summer, is especially welcome after a cool, rainy spring.

Of course, this respite will be brief. A deep trough across the West, bringing snow as far south as northern Arizona, will nudge eastward as the ridge begins t…

On the Safe Side

After raking the Plains, Midwest and Mississippi Valley with severe thunderstorms, deadly tornadoes and torrential rains for the past week, the potent storm system moved east of Missouri overnight and we are now on its safe side. While it will still unleash severe weather from the Gulf Coast to New England today, the system is expected to weaken significantly over the coming weekend.

Here in Missouri, wrap around showers and a north wind will produce a raw, chilly day but the threat of dangerous thunderstorms has passed, at least for now. As the storm system moves further to the east, heat and clearing skies will build in from the southwest, drying the soggy landscape but setting us up for the next round of spring storms when another Pacific front drops from the Rockies.

It has, indeed, been a cool, wet spring in the Heartland as the jet stream has guided storms across the Northern and Central Plains. While their trailing cold fronts have dipped into Oklahoma and North Texas, the d…

A Delayed Chorus

In light of an exceptionally large brood in 1998, this spring's emergence of 13-year periodical cicadas in central Missouri was forecast to be overwhelming. However, it appears that the excessive rain and cool temperatures have, at the very least, delayed the spectacle.

Unlike the annual dog-day cicadas, periodical cicadas emerge in massive numbers every 13 or 17 years. Following a prolonged stage as nymphs beneath the soil, they climb onto a tree or other structure and molt to the adult phase, which lasts only a month or so. As adults, these cicadas are focused purely on producing the next generation; the scratchy calls of the males create a deafening chorus from dawn to dusk which increases in concert with the daily temperature. Once mating has occurred, the female lays her eggs in furrows along the tender stems of shrubs and trees, causing significant damage when the cicada broods are massive. If not eaten by birds, the eggs hatch and the nymphs drop to the ground where th…

The End is Near

After wrongly predicting that human life would end this past weekend, an evangelical preacher has become the target of jokes by comedians and newsmen alike. But, from the perspective of natural history, his guess may not have been too far from the truth.

Some 13.7 billion years after the Big Bang and 4.6 billion years after the formation of our home planet, the human race is less than 150,000 years old but already facing our own extinction. The end will not likely come by time zone, as the preacher suggested, but it could unfold rather rapidly, the consequence of a major asteroid strike or supervolcano eruption. More likely, we will orchestrate our own demise, continuing to ravage the environment through excessive consumption, pollution and unbridled population growth.

While the preacher's forecast was delusional, based on religious conviction and self-importance, the assumption that man can continue to plunder the natural environment without consequence is equally short-sighte…

The Noise Industry

As a naturalist, I enjoy walking on the beach to the sound of crashing surf and frantic gulls. I relish tranquil bays, cathedral forests, the solitude of deserts and the quiet inspiration of mountain vistas. Unfortunately, there is a growing industry that often deprives us of such experiences.

Marketed as exciting ways to explore nature, jet skies, four-wheelers, dirt bikes and snowmobiles have invaded the landscape, polluting the environment with their noise and fumes. While essential vehicles for certain cultures and businesses, they have spawned a population of "nature lovers" who are more interested in speed and power than in the natural surroundings through which they race. Those of us who do not share their infatuation with combustion engines must, unfortunately, accept the side effects of their activity. National and State Parks, after all, are for the people, not so much for the environment.

Many who read this blog will perceive my views as just more selfish gib…

A Parade of Supercells

Heading east in central Kansas last evening, I witnessed a parade of supercells, spaced across the eastern horizon; each half-again as tall as Mt. Everest, they reflected the setting sun. As I grew closer to this spectacle, the gaps began to close with new thunderstorms as outflow from the parent cells created lift. Soon, a massive wall of chaos loomed across my path; fortunately, I had made plans to spend the night west of the storms.

Safely in my motel room, I tuned into the Weather Channel and found that an interrupted line of severe thunderstorms, some with tornadoes, stretched from East Texas to Minnesota. I was also entertained by two of the Channel's expert stuntmen, doing exactly what they tell us not to do: standing in the dark near intense storms, looking for tornadoes with the aid of limited radar and night-vision glasses. Fortunately, no on-air mishaps.

The culprit for the severe weather was a massive, upper level low, parked over the Northern Plains. Still in pla…

Colorado Mountain Goats

There are few better symbols of alpine wilderness than the mountain goat; besides, their kids are downright adorable. For these reasons, this sure-footed resident of the alpine tundra appears on Colorado travel brochures and his image is utilized by a wide range of companies and organizations that cater to Colorado nature enthusiasts. Unfortunately, unlike Rocky Mountain bighorn sheep, the official State mammal, mountain goats are not native to Colorado; their natural range extends from Alaska and Canada to the mountains of Washington, Idaho and Montana.

In 1947, prompted by hunting organizations, a herd of mountain goats was transplanted from Montana to Mt. Shavano, in the Collegiate Range of central Colorado. Over the next two decades, additional groups were introduced on Mt. Evans, west of Denver, and the Gore Range, east of Vail. Well adapted to survive in the harsh environment of alpine ecosystems, the goats thrived and have since spread to nearby ranges. Controversy arose a…

Formation of the Great Lakes

Looking at a map of North America, one's attention is immediately drawn to the Great Lakes, the most conspicuous geographic feature of the Continent. Yet, carved by the Pleistocene glaciers, they are also among the youngest landforms on the surface of our planet.

The Precambrian basement of our continents, like the visible topography of Earth, is a composite of ridges, basins and plains. One of these basins, centered over Lower Michigan, encompasses the Great Lakes region, having filled in with Paleozoic, Mesozoic and Tertiary sediments. Over the course of this deposition, a major river system developed within the Michigan Basin, likely draining toward the Atlantic. During the Pleistocene, which began 2 million years ago, four major continental glaciers plowed across that basin, altering the landscape and widening the river valleys; the last of these glaciers, the Wisconsin, began to form just 70,000 years ago and reached its peak advance about 18,000 years ago. As it began t…

Spring Snow

Along the Colorado Front Range, the mountains affect our weather in many ways and, at times, offer an escape from shallow upslope rain and fog. This morning, faced with low clouds and drizzle, I decided to head for the hills, hoping to get in some hiking and birding above the unpleasant conditions. Unfortunately, the cloud deck was thicker than I had anticipated and, after winding slowly through the dense fog, I encountered snow above 8000 feet; while the skies may have cleared higher in the mountains, I elected to play it safe and detoured into the North Fork Valley from Pine Junction.

Below the snow once again, I got in some exercise at Pine Valley Ranch Park, elevation 6900 feet, and then headed east along the scenic North Fork of the South Platte, where giant slump blocks, dippers and fly fishermen were spaced along the river. Curving north on Foxton Road, I climbed out of the valley along Kennedy Gulch and made a second stop at Reynolds Park, another good spot for foothill bir…

A Rare Visitor

Working on our Littleton, Colorado, farm this week, I have enjoyed the company of our usual avian neighbors, including house wrens, American and lesser goldfinches, northern orioles and western wood pewees, among the more common, permanent residents. Swainson's hawks, cormorants, great blue herons, white-faced ibis and American white pelicans passed overhead and a host of migrants, including white-crowned sparrows, broad-tailed hummingbirds and western tanagers stopped by on their way to the mountains. But one rare visitor, a male rose-breasted grosbeak, was a special guest and, in my experience, the first to grace our farm.

After wintering in Central America, the Caribbean or northern South America, rose-breasted grosbeaks return to breeding grounds across southern Canada, the American Midwest, New England and the Appalachian highlands. Favoring wood borders, orchards and second-growth forest, a ragged nest of sticks is placed in a tree or shrub and both parents share the duti…

The Falklands & South Africa

When geologists first explored the Falkland Islands, 250 miles off the coast of southern Argentina, they found rock strata that did not correlate with those found on the mainland. Composed of igneous, metamorphic and volcanic rocks ranging from the Precambrian to the Jurassic, the two primary islands and their archipelago of numerous islets, were noted to possess a geological structure very similar to that found in South Africa. The solution to that mystery remained elusive until the theory of plate tectonics was proposed in the 1960s and has since been confirmed by field work.

As Pangea began to break up, some 200 million years ago, the Falkland microplate rifted from the southeast coast of South Africa and was pushed westward by rotation of the Antarctic Plate; since Africa, Antarctica and South America were still in close formation (as components of Gondwana), the Farallon microplate moved off with South America as the Atlantic Ocean opened during the Jurassic, some 150 million y…

Spain's Earthquake

On May 11, a magnitude 5.2 earthquake struck southeastern Spain, near the town of Lorca, some 30 miles southwest of Murcia. Lying near the boundary of the African and Eurasian Plates, which runs through the Mediterranean Sea, this area is prone to quakes, most of which are relatively weak. Unfortunately, the epicenter of this earthquake was shallow (less than a mile deep), leading to significant structural damage and the death of at least ten citizens.

About 50 million years ago, the Tethys Sea began to close and the African Plate drifted northward, triggering a collision with the Eurasian Plate that is crumpling up the Alps and associated ranges of southern Europe. Within another ten million years, the East African Rift began to develop, the Red Sea opened and the northward movement of Africa shifted to a northwesterly direction relative to the Eurasian Plate. Today, along the southern coast of Spain, the African Plate is both colliding with and slipping past the Eurasian Plate, …

March in Mid May

I left Columbia this morning in a chilly mist; a steady northwest wind and low, gray clouds made the temperature feel even colder than the official report of 41 degrees F. Heading west on I-70, the drizzle resolved within thirty miles but cloudy skies, a north wind and cool temperatures persisted all the way to Denver. While the green landscape looked like mid May, it felt more like March.

The unseasonable chill seemed to have an effect on wildlife as well. The usual roadside insectivores, including kingbirds, barn swallows and scissor-tailed flycathers, often common along the highway, were rarely seen, having likely retreated to sheltered wetlands where the wind and cool air would have less impact on their prey. Only the hardy vultures and hawks were well represented, benefitting from plenty of roadkill and industrious rodents stirred by the chilly weather.

While the drizzle was a backside gift of the latest storm system, which is still creeping toward the East Coast, high pressu…

A Chilly Fetch

Thursday afternoon, low pressure sat over north-central Kansas and its associated cold front stretched from the Great Lakes to West Texas. Ahead of the front, warm, humid air was moving up from the south while, north and west of this boundary, that cargo of moisture was swept counterclockwise through the chilly air.

Looking at the radar, one could see a swath of precipitation stretching from Minneapolis to Denver, rotating to the west and then southwest around the central low. In Minnesota, afternoon temperatures were in the fifties (F); as the air followed a broad curve toward Denver, it encoutered gradually rising terrain and cooled at is progressed. In South Dakota, temperatures were in the mid forties, falling to near forty in western Nebraska and into the upper thirties along the Front Range. Finally, one found that the rain turned to sleet and snow along the foothills of the Rockies and atop the Palmer Divide, south of Denver. On the south side of the latter divide, the ai…

Our Conspicuous Kingfisher

While they have numerous cousins across the globe, belted kingfishers have laid claim to North America and anyone who visits our streams, lakes and coastal bays soon becomes aware of their presence. Easily identified by their large, crested head, heavy bill and characteristic plumage, these birds are usually first noticed due to their loud, rattling call.

Favoring clear waters, belted kingfishers hunt from an overhead limb or hover above their prey before diving to snare it from the surface; victims include fish, amphibians, various aquatic invertebrates and large insects. Monogamous and highly territorial, they dig nesting tunnels into stream banks or nearby road-cuts; the eggs (usually 5-8) are incubated by both parents for three weeks.

The breeding range of this conspicuous kingfisher stretches from southern Alaska through most of Canada and southward across the U.S. Most are permanent residents (if open water is available) but more northern breeders migrate south and wintering …

The Pine Ridge Escarpment

Curving through northwestern Nebraska and into the southwest corner of South Dakota, the Pine Ridge Escarpment, rising to 5000 feet, divides the watersheds of the White River, to its north, and the Niobrara River, to its south. Like the Gangplank, west of Cheyenne, and the Palmer Divide, between Denver and Colorado Springs, this ridge is an erosional remnant, molded from Tertiary sediments during the cool, wet climate of the Pleistocene.

Capped with Miocene sandstone of the Arikaree Group, the north-facing, 100 mile long escarpment represents the edge of the High Plains, which stretch away to the south. North of the ridge, the terrain drops into the Missouri Plateau, where the White River and its tributaries have produced badlands in the older sediments of the Oligocene (the White River Group). West of Pine Ridge, the Hat Creek Breaks represent similar geologic strata, rising between the watersheds of the Cheyenne and Upper Niobrara Rivers.

Named for the groves of ponderosa pine th…

An Inland Surge

The flow through Midwest rivers generally peaks in April as snowmelt from the Appalachian Plateau and northern States combines with the copious precipitation of early spring. In addition, the leafing of trees and shrubs is limited during that season, transpiration is reduced and runoff increases through the numerous tributaries.

This year, torrential rains were superimposed on this natural cycle as a stationary front brought a seemingly endless train of storms across the region. Beginning in mid April and persisting for several weeks, the rains fell on saturated ground and flash floods were common from eastern Oklahoma and Kansas to the Great Lakes and Appalachians. Eventually, all of this water drained into the Ohio and Mississippi Rivers, producing an inland surge that is now cresting at Memphis; over the next few weeks this surge will move further south, flooding the river towns of Louisiana and Mississippi.

Having channelized the rivers, destroyed the wetlands and developed the…

The Secretive Sora

Two days ago, on a summer-like evening, my wife and I visited the Forum Nature Area in Columbia. As expected, that wetland preserve was alive with the sights and sounds of the season, including a background din of cricket frogs, colorful summer songbirds and attentive Canada geese with their downy broods. But the highlight of our visit was witnessed for only a few seconds.

Approaching a marsh-lined pond, we accidentally flushed a sora; fluttering into the air, the small rail soon dropped into another patch of cattails and remained out of sight. Though a widespread summer resident in North America, breeding across southern Canada and the northern half of the U.S., from New England to the Great Basin, soras favor dense, freshwater marshlands, where they are fairly common but rarely encountered. Like other rails, they prefer to escape into the reeds when disturbed and are reluctant to take flight. Their descending whinny or sharp, two-note call usually announces their presence and t…

Homage to Mother Nature

On this day, when we honor our human mothers, it is appropriate to pay homage to Mother Nature as well. She, after all, gave birth to life itself.

While she nourishes both our bodies and our minds, Mother Nature is a fickle parent, prone to furious and destructive outbursts. She is neither sentimental nor judgmental, providing what we need but not caring whether we accept her gifts. At times seemingly cold and distant, she envelops us during every moment of our lives, a more intimate companion than human mothers could ever be.

We may blame Mother Nature for problems throughout our lives but we could not live without her. She is the essence of our being, the yearning in our heart and the inspiration in our soul.

Plate Accretion

The present geography of Planet Earth is just the latest snapshot in its 4.6 billion year evolution. The relative size and position of continents and oceans have undergone constant change; while this process continues today, we are only aware of the occasional earthquakes and volcanic eruptions that result from the underlying tectonic forces. Our life span is too short to appreciate any visible change in the surface geography; indeed, only subtle changes have occured since the birth of our species.

However, over the eons of geologic time, oceans have opened and closed and, in concert, land masses have rifted apart and cemented together. In areas where oceanic crust and continental crust collide, the more dense basalt of the oceanic crust dips (subducts) below the continental crust, disappearing into an ocean trench and recycled into Earth's mantle. As it decends, this ocean crust begins to melt and a chain of volcanoes, known as a volcanic island arc, develops along the outer …

River Otters

Before white settlers and trappers reached North American, river otters inhabited most of the Continent; only the High Arctic and Southwest deserts were devoid of these sociable mustelids. Prized for their dense and durable fur, they were extirpated from much of their native range by the 1930s, all but disappearing from the lower 48 States.

Reintroduction programs, many of which began in the 1980s and transplanted individuals from Alaska and Canada, have returned North American river otters to stream, lake and wetland habitats across the U.S.; indeed, some areas have liberalized trapping regulations in light of that success. Though widespread, these playful and agile creatures are primarily nocturnal and are rarely encountered by the casual hiker or naturalist. Never far from water, otters den in hollow logs or use the abandoned burrows of beaver, muskrats, nutria and woodchucks. Their diet includes fish, crayfish, turtles, amphibians, mollusks, aquatic birds and, occasionally, yo…

Sexual Reproduction & Evolution

Current scientific evidence suggests that life first appeared in Earth's oceans about 3.6 billion years ago. These initial organisms were unicellular, bacteria-like species that reproduced by simple division, leading to two identical individuals. Over time and countless generations, natural genetic mutations produced diversity and, about 2.5 years ago, intracellular organelles began to appear; these are thought to have developed when smaller cells and viral-like particles invaded larger cells. It is also believed that unicellular organisms began to exchange DNA-containing plasmids with one another, providing a means to repair lethal genetic mutations.

Nucleated cells (eukaryotes) were present by 1 billion years ago and multicellular organisms inhabited shallow seas near the end of the Precambrian, some 600-700 million years ago. It was also during this period that the process of meiosis became more widespread, resulting in cells with one half of the adult organism's geneti…

Appeasing the Masses

Throughout human history, kings, generals and religious leaders have attempted to appease the masses. Roman Emperors used the Coliseum to entertain their subjects while other rulers bestowed gifts of land, livestock or currency. But, when it comes to handing out human rights, these human gods have been a reluctant bunch.

Today, as revolution spreads throughout the Middle East, we bear witness to the tenacity with which dynasties cling to power. In a feeble attempt to stave off democracy, they offer a host of concessions and, in a few cases, have doled out cash. Even the Catholic monarchy, threatened by scandal and an increasingly educated populace, attempts to appease the faithful by offering sainthood to a once beloved Pope.

None of these rulers seem to understand that token gifts and rituals will have no effect on the undercurrent of distrust that flows through their kingdom or congregation. Once faith is lost and the fire of personal freedom ignites, any attempt to retain powe…

The Nature of Yard Work

Despised as just another chore during our teen years, yard work is a favorite activity for many adults. After all, it gets us outdoors, affords plenty of exercise, allows us to reconnect with nature and rewards us with garden foods and the beauty of flowering plants.

Of course, our definition of natural beauty varies and our individual preferences can lead to household conflicts. Some prefer manicured landscapes with broad, uniform lawns, evenly trimmed shrubs, neatly spaced plants and store-bought mulch. Others, myself included, favor limited lawn space, broad, naturalized borders and self-sustaining perennials. Perhaps the primary source of disagreement arises with the decision to use or ban fertilizers, herbicides, pesticides and other products that are marketed to yield pristine, weed-free, insect-controlled lawns and gardens. After all, one must compete with the neighbors.

If you, like most naturalists, want a property with a diverse population of wildlife, it's best to …

Death in the Spring

While we speak of spring as the season of renewal and rebirth, it, like all seasons, brings its share of death. Indeed, newborn animals are among the most fragile and vulnerable creatures on Earth and they succumb to a wide variety of natural and unnatural forces.

Many eggs, for example, never hatch, falling victim to accidents, cold weather, neglectful parents or predators such as crows, snakes and raccoons. Many, if not most, sea turtles never reach the ocean and the death rate among young cottontails is extremely high, thanks to lawnmowers, domestic cats and a host of native carnivores. Insects, emerging from their nymph stage in ponds or beneath the soil, are often snared by swallows and swifts during the first and only flight of their life; many nestlings, on the other hand, never fly, the victims of storms, inattentive parents, predators or even their own siblings. Young herbivores, still hampered by weak and wobbly legs, are common targets for coyotes, wolves and bears.

The…