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Exercise Canyon

Waterton Canyon, which incises the foothills southwest of Denver, represents the South Platte's final journey through the Rocky Mountains before it rumbles onto the Colorado Piedmont.  Harboring a wealth of scenic rock formations and home to a wide variety of Transition Zone flora and fauna, the canyon has long been a popular destination for hikers, birders, fishermen and naturalists.  Over the past decade or so, it has also become a mecca for bikers and joggers, now comprising at least 75% of the visitors.

While these trail athletes surely enjoy the pristine landscape, at least in a holistic sense, I doubt they pay much attention to the varied plants and animals, focused as they are on distance and time.  As they turdge along, gasping and spitting, or whiz by on their trail bikes, I often wonder if they could identify even a handful of species that inhabit the canyon.  They surely notice the bighorn sheep, for which this refuge is well known, but a fleeting glance is probably sufficient.

In this age of obesity, I certainly have no objection to aerobic exercise.  But I suspect these bikers and joggers choose Waterton Canyon for its graded climb and known distance (6 miles to the Strontia Springs Dam); of course, they also enjoy group exercise and avoid the heavy auto traffic that occurs in other foothill canyons.  Some might conclude that I envy the youth and vitality of these athletes (which is surely true to some extent) but I am more inclined to pity their lack of interest in nature's bounty.  Dogs are not permitted in Waterton Canyon in order to protect the bighorn sheep; perhaps we should limit its use as an athletic training site in order to protect the natural milieu.

The Kaibab-Coconino Plateau

As the Paleozoic Era gave way to the Mesozoic, some 225 million years ago (MYA), an ovoid upwarping of Earth's crust developed in what is now northern Arizona.  Reinforced during the Laramide Orogeny (the formation of the Rockies, 70 MYA), this broad ridge was eventually covered by layers of Mesozoic and Tertiary sediments (both erosional and volcanic).  Late in the Tertiary Period, the Miocene-Pliocene Uplift (stretching from about 15-5 MYA) lifted the entire Colorado Plateau and its rim of mountain ranges another 5000 feet, increasing stream erosion across the Province.  Rising on the west side of the Continental Divide, the Colorado River flowed westward and gradually southward to enter the Sea of Cortez; en route, it crossed northern Arizona, entrenched in the younger sediments that covered the Kaibab-Coconino ridge.  As the Colorado Plateau rose beneath it, the river was forced to cut down through this ridge of Paleozoic rock (and the upper layer of the ancient Precambrian basement that lies beneath it).  Augmented by the wet climate of the Pleistocene (2 to 0.01 MYA), the Colorado thereby sculpted the Grand Canyon, the most spectacular chasm on our planet.

The ridge itself, oriented NNW to SSE, has since been uncovered by erosion.  Streams from its eastern edge drain directly into the Colorado (or into the Little Colorado south of the Grand Canyon), while its northwest flank drains to the Colorado via Kaibab Creek and its southwest flank feeds the Cataract River, another tributary of the Colorado.  The exposed ridge is composed primarily of Kaibab limestone overlying Coconino sandstone; that portion north of the Grand Canyon is known as the Kaibab Plateau while its segment south of the Canyon is referred to as the Coconino Plateau.  The rock strata of the plateau, deposited during the Permian Period, form the upper layers of the Grand Canyon

The Kaibab Plateau rises to elevations that exceed 9200 feet, supporting a rich forest of fir, spruce and aspen, giving way to ponderosa pine and then pinon-juniper woodlands at lower elevations.  The Coconino Plateau is 7400 feet above sea level at the south rim of the Grand Canyon and gradually lowers toward the west, south and east; it is covered primarily by ponderosa pine parklands.  South of the Coconino Plateau, the landscape is dominated by the high peaks and scattered cones of the San Francisco Volcanic Field, including Humphreys Peak (12,633 feet), the highest point in Arizona.

Prairie Racerunners

Closely related to the six-lined racerunner of the Mid-Atlantic and Southeastern U.S., the prairie racerunner is found from northwestern Indiana and southern Wisconsin, westward to southern Wyoming and southward to Arkansas, West Texas and New Mexico.  Favoring dry, sandy soil and hot weather, these lizards inhabit prairie grasslands, abandoned farms, glades and rocky hillsides; attracted to disturbed areas, they are known to spread along power line swaths and railroad lines.  Here in Colorado, prairie racerunners are abundant from the High Plains to the shrub zone of the lower Front Range foothills.

Emerging from hibernation in late April or May, prairie racerunners are best observed during the morning and early afternoon hours of June and July, dashing across trails or clearings and disappearing into clumps of vegetation to snare prey or to avoid predators.  Their long tail, twice the length of their body, is thought to serve as a counter-balance as they zig-zag at speeds up to 18 miles per hour.  Mating occurs by late spring and five eggs are generally produced; as with most lizards, the hatchlings are miniature replicas of the adults and must fend for themselves.  While a second brood may be produced within a few weeks, adult prairie racerunners begin to hibernate by late August or early September; the young, needing more time to generate fat stores, wait until late September or October to settle in their winter burrows (depending on their home latitude).

Feasting on a wide variety of insects and other invertebrates during their brief season of activity, prairie racerunners may fall victim to grassland hawks, prairie falcons, burrowing owls, fox, coyotes, roadrunners, magpies and a variety of snakes.  Using shallow burrows during the warmer months, they dig a deeper channel with a terminal chamber for their prolonged hibernation; during that time, in sharp contrast to their frenzied life above ground, their metabolic rate falls dramatically and they rely on fat deposits to fuel their survival.  If they make it through their first winter, adult prairie racerunners are thought to have a natural life span of 4-5 years.

Front Range Oasis

While those of us who live along the Colorado Front Range enjoy abundant sunshine and a mild, semiarid climate, there is plenty of aquatic habitat along the urban corridor.  One of the best places to observe water-loving birds and mammals is South Platte Park, which stretches across the river's floodplain from the northern edge of Chatfield Reservoir State Park to the outskirts of downtown Littleton.  A mosaic of ponds, lakes, wetlands, meadows and riparian woodlands, the Park is accessed by a paved bikeway, its parallel walking path and a number of adjoining trail loops.  An Interpretive Center, west of Santa Fe Drive and north of Mineral, introduces visitors to the varied fauna and flora of the Park.

On this mild, clear morning, the refuge was teeming with birds, including many that non-Coloradans might not associate with our State.  A dozen American white pelicans moved among the lakes or fished in the shallows, joined by a large number of double-crested cormorants, scattered great blue herons, a pair of snowy egrets, a flotilla of common mergansers, noisy flocks of Canada geese and a varied assortment of ducks (primarily mallards, gadwall and wood ducks).  Tree and barn swallows swooped above the ponds, a Swainson's hawk circled overhead, belted kingfishers chattered along the river and a wide assortment of songbirds moved among the trees and cattails; these included yellow warblers, common yellowthroats, American and lesser goldfinches, western wood pewees, northern orioles, house wrens, northern flickers, downy woodpeckers and those ever-vocal red-winged blackbirds.  A lone black-crowned night heron, spooked from his shadowy haunt, was my final sighting of the morning.

Though represented only by fox squirrels, cottontails and black-tailed prairie dogs this morning, a variety of mammals also inhabit the Park and are best seen at dawn or dusk.  Among these residents are mule and white-tailed deer, red fox, coyotes, beaver, muskrats, raccoons, striped skunks,  meadow voles and deer mice; mountain lions and black bear are potential visitors but are rarely encountered.

Monsoon Relief

Returning to our Littleton, Colorado, farm today, I found that early monsoon rains have revitalized the landscape.  Indeed, over the past few days, heavy rains have moved northward across the Front Range, bringing much needed rain to the tinder-dry mountain forests and welcome moisture to the urban corridor.  While some flooding, mudslides and sinkholes developed, the storms have reduced the wildfire risk to some degree and, so far, have not ignited any new fires.

The annual monsoon rains of the American Southwest result from a southerly flow that brings in moisture from both the Gulf of California and the Gulf of Mexico.  The engine for this wind pattern is high pressure over the Southern Plains that generally develops by early July and persists through much of August; winds move clockwise around that atmospheric ridge, sweeping moisture northward along its western rim.  Showers and thunderstorms are usually confined to the Desert Southwest and Four Corners Region early in the season, reaching the Colorado Front Range by late July and August.  Thanks to the dome of drought that has plagued the south-central and southeastern U.S. for several weeks, the Monsoon got an early start and Colorado, caught in its own drought after a mild, snow-starved winter and a warm, dry spring, has received an early and very welcome gift.

Unfortunately, the monsoon flow will be shut off for the rest of this week as high pressure builds in from the West, bringing another round of hot, dry weather to the State and blocking the southerly stream of moisture.  When the Southwest Monsoon might generate more relief is anyone's guess but its typical arrival date is still a week or two away.

Colorado's Black Canyon

Near the end of the Mesozoic Era, as the Cretaceous Sea retreated to the southeast, Colorado was a relatively flat landscape of wetlands, sandhills and primitive forest.  Then, about 70 million years ago (MYA), pressure within the North American craton crumpled up the Rocky Mountains, pushing ancient Precambrian rock up through the overlying Paleozoic and Mesozoic sediments.

As soon as they formed, the forces of erosion began to act on these new mountains, filling the intervening valleys with debris.  About 35 MYA, volcanism developed in central and southwestern Colorado, lifting the West Elk and San Juan Mountains; the copious ash, pumice and lava from these eruptions also coated the valleys and basins of that region.  By 10 MYA, the Gunnison River had formed; rising on the west side of the Continental Divide, in the Sawatch Range, and receiving large tributaries from the West Elk Mountains, to its north, and the San Juans, to its south, this river flowed west to join the Colorado.  Entrenched within the erosional and volcanic debris that had settled across the broad, intervening basin, the Gunnison was forced to cut into a ridge of Precambrian gneiss and schist, east of present day Montrose, that was buried within the sediments.  Since that time, the river has sculpted the Black Canyon of the Gunnison from that ancient rock, a process that was augmented during the cooler, wetter climate of the Pleistocene.

Almost 50 miles in length, the Black Canyon is up to 2720 feet deep and 1100 feet across at its rim; at river level, it is much narrower, only 40 feet wide in one area.  The Painted Wall, on the north flank of Black Canyon, is named for the light-colored lava rock that laces its surface and is the tallest cliff in Colorado, dropping 2250 feet.  Within the canyon, the Gunnison River drops 43 feet per mile, a grade that is almost six times steeper than the Colorado River's course within the Grand Canyon.  Named for its shaded walls, hidden from the sun by its deep and narrow topography, the Black Canyon of the Gunnison is protected within a National Park that stretches along its middle (and most spectacular) 14 miles.  Farther west, the Gunnison is thought to have carved Unaweep Canyon through the Uncompahgre Plateau, later diverted northward by a landslide to join the Colorado west of Grand Junction (see my blog on 12-27-10).

Looking at the Invisible

This week at CERN, the Organization for European Nuclear Research, near Geneva, Switzerland, nuclear physicists may have discovered the Higgs boson, first theorized to exist back in 1964.  Using the Large Hadron Collider, in operation for just two years, they smashed protons together at high velocity and found a particle that had never been observed with past forms of technology.  Based on their initial calculations, it is thought to be a transient manifestation of the cosmic soup that gives mass to the elementary particles.

If confirmed, this discovery will herald a new era in our understanding of the Universe, focusing on the dark energy and dark matter that, combined, make up over 95% of its content.  Indeed, the visible stars, planets, comets, asteroids and interstellar dust make up less than 1% of the Universe, with intergalactic gas accounting for 3.5% or so.  This week, we caught our first glimpse of the dark side and took our first step toward understanding the dark energy that is causing the Universe to expand at an increasing rate.

For most of us, the details of the Higgs boson discovery are difficult to understand.  Those who prefer to concentrate on the simplistic dogma of their chosen religion will dismiss the news as scientific heresay; after all, bosons are not mentioned in the Bible.  But for those hungry to understand the complex nature of our Universe, this discovery promises a new world of adventure.

A Stubborn Ridge

The dome of high pressure that has parked itself over the Heartland for the past two weeks shows no sign of abating.  Rather than drifting off to the east, it has backed into the Southern Plains; unfortunately, those of us in the lower Missouri and Mississippi Valleys remain within its grip.

Beneath this atmospheric ridge, the air is sinking and drying out, producing excessive heat and retarding cloud formation.  Storm systems are shunted along its outer rim, exacerbating drought within the dome while fueling violent weather at its periphery (as we saw in the Upper Midwest and Mid-Atlantic region last week).  On the positive side, this stubborn ridge may ignite the Monoon Season across the American Southwest, pulling in moisture from both the Gulf of California and the Gulf of Mexico as clockwise winds stream along its western rim.

Those of us caught within its boundaries can expect another week of hot, dry weather, with afternoon highs near 100 degrees F.  Beyond prolonging our personal discomfort, this dome of drought is taking a toll on forests and crop fields across the Heartland, stressing natural ecosystems and posing a serious challenge for farmers and ranchers.  Unless relief arrives in the form of a potent Canadian front, it may take a hurricane to dislodge this ridge.

The Heart of Champions

As the Olympic Trials wind down and national teams prepare for London, it is clear that there is something special about Olympic athletes.  Like others in their respective sport, they are talented and hard-working individuals who enjoy a good deal of support from family, friends and colleagues.  Yet, these Olympians seem to harbor traits that set them apart.

Despite their success and self-confidence, few (if any) are arrogant or egotistical.  Rather, their achievement reflects their competitive spirit, their courage in the face of adversity and, perhaps most importantly, an unwillingness to concede defeat.  This latter trait, which might be defined as heart, is found in all champions, from race horses to long-distance runners to heavyweight boxers.  When the margin of victory is razor thin or when endurance plays a major role, heart is especially vital.

Of course, this trait is not confined to sports.  While some owe their success to good fortune, most champions of human society possess this same competitive spirit; facing obstacles that discourage their rivals, they have the heart to persevere.  Heart is, indeed, a human trait which seems to require a delicate mix of genetic, familial and cultural factors.  Alas, in most individuals, it never reaches full expression. 

The Season of Insanity

Humans, tropical creatures that we are, have a healthy respect for winter,  Not naturally equipped to survive its wrath, we take shelter from winter's storms and tend to hibernate for much of its course.  While the cold, dark season may be depressing for some and does induce its fair share of injuries, winter keeps us on our guard and, for the most part, out of trouble.

Summer, on the other hand, that carefree season of vacations, picnics and outdoor recreation, is welcomed by most humans and its dangers are too often ignored.  But, contrary to what many believe, the summer heat causes far more deaths than does the winter chill.  The elderly, stressed by excessive heat and too often housed in poorly ventilated apartments, are the primary victims; ironically, young, healthy athletes are the other group at risk.  Driven on by macho coaches and drill sergeants or by their own sense of immortality, they work out or engage in sports on summer afternoons and, as we observe every year, some fall victim to heat stroke..  There is a popular misconception that exercising in the heat, drenched in sweat, is a more effective way to lose weight or to get in shape than is exercising during cooler parts of the day.  This, of course, is false and such behavior invites disaster.

Despite these admonitions, repeated throughout the summer by news and weather reporters, many will ignore the warnings and our current heat wave will be the last for some young athletes.  We may be designed for the tropics but there are limits to our capacity to dissipate heat.  Staying well hydrated is important but common sense is our best means of protection.

Life in the Universe

Current scientific evidence indicates that the Universe is 13.7 billion years old and that the galaxies formed 12 billion years ago.  Yet, our home star, the sun, is less than 5 billion years old, the Earth  formed just 4.6 billion years ago, unicellular life did not evolve on our planet until 3.6 billion years ago and we humans did not appear until 130,000 years ago.  Countless suns, their solar systems and the life that inhabited their planets likely evolved and disappeared long before our own sun and planet came into existence.

Among the 100 billion galaxies and trillions of stars that stretch across the ever-expanding Universe, there are surely millions of other planets that sustain life which, in many if not most cases, has progressed farther along the evolutionary tree than has life here on Earth.  In other words, it is almost a certainty that many human-like civilizations inhabit this Universe, most of which are more advanced than our own.

It is understandable that religious persons might find these rational facts too threatening to contemplate but it is disconcerting to hear scientists and scientific journalists question whether life exists elsewhere in the Universe.  Sitting here on our smallish planet that circles a modest-sized star on an outer band of a massive galaxy, it is absurd to suggest that we might be the only intelligent beings that inhabit the billions of galaxies.  The Universe surely teems with life and it is only our irrational self-importance that keeps us from embracing that fact.

Desert Heat in the Midwest

Records are falling across the American Midwest this week as the first major heat wave of the season invades our region.  High pressure over the Southern Plains, combined with a high pressure dome over the Southeast, has ushered in the hot, dry air; afternoon highs should top 100 degrees F in most areas.

In part, the extreme heat reflects the dryness of the air, as Gulf of Mexico moisture is kept at bay by the blocking high across the Southeast.  Dry air is more dense than humid air and is thus capable of reaching higher temperatures.  Indeed, winds are from the west-southwest and it feels more like Phoenix than Miami across the Heartland.

This heat wave will be slow to break as cloudless skies permit the intense sunshine to heat up the roofs and roadways in our towns and cities; this heat radiates into the air overnight, keeping the morning low well above average.  In addition, it will likely take a strong cold front to displace this high pressure ridge and none are forecast over the coming week.  For now, we'll confine our outdoor activities to the early morning and evening hours, hide from the afternoon sun and dream of October.

Industrial Obesity

Not long ago, we humans could not help but get plenty of exercise.  We had to hunt and spend long hours in the fields to obtain our food.  We had to chop wood to heat our homes and carry fresh water from the well or the river.  Travel was by foot or horseback and almost any task involved physical labor.  Perhaps most significant, we did not have televisions or computers to keep us inactive and entertained for hours at a time.

While many studies have demonstrated a higher rate of obesity in westernized countries, much of the focus has been on the dietary changes associated with our mechanized cultures.  But, while the excessive intake of sodas and cheeseburgers and donuts should raise concerns about our nutrition, it is, in my opinion, a less significant factor in the modern scourge of obesity than is our sedentary lifestyle.

Today, almost every technological advancement is designed to make our lives easier.  We may take our morning or evening stroll to get some exercise but most of our day is spent in cars, elevators and desk chairs.  Even farmers and construction workers have a wide range of machinery and tools that limit their physical labor.  Then, at the end of the day, exhausted and stressed, we plop in front of the television for several hours of mindless entertainment, getting up for a snack during commercial breaks.

The Nature of Volcanism

Volcanoes develop in areas where the heat from Earth's mantle melts the overlying crust.  This occurs along subduction zones, where one of the tectonic plates is dipping toward the mantle, in rift zones, where the crust is thinning (allowing the mantle to move upward) and at hotspots, where a mantle plume is rising into the crust.

Subduction volcanoes are the most widespread form of volcanism on Earth and are concentrated along the Pacific Rim where the Pacific Plate and its associated oceanic plates are dipping beneath the South American, North American, Eurasian and Australian Plates.  The Andes, the volcanoes of western Central America and Mexico, the Cascades, the Aleutians and the volcanoes along the western edge of the Pacific (Japan, Taiwan, Philippines, New Zealand) result from this process.  Other subduction volcanoes include those along the western and southern edge of Indonesia, the volcanic islands of the eastern Caribbean and Mt. Etna, on Sicily, one of the most active volcanoes on our planet.

Rift volcanoes include those above mid-oceanic ridges and those developing along rift valleys in continental crust.  Most oceanic ridge volcanoes are well below the surface of the sea and thus not readily observed; the major exception is the island nation of Iceland, which formed (and continues to form) above the mid-Atlantic ridge.  Continental rift volcanoes are seen along and within the East African Rift and the Rio Grande Rift of the American Southwest; they are also scattered throughout the Great Basin of the U.S. where the crust is being stretched (and thinned).  Hotspot volcanism occurs across the globe, along the ocean floor and beneath/within continental crust; the Hawaiian Islands, the Galapagos Islands, the Canary Islands, Yellowstone, the San Francisco Peaks of northern Arizona and the volcanic field of northeastern New Mexico are but a few examples.

The Lena River Delta

On satellite imagery, the Lena River Delta on the northern coast of Siberia gives the appearance of a fan coral, its braided channels and numerous lakes forming an intricate pattern across the Arctic tundra.  It is this landscape of countless pools and waterways that attracts huge congregations of loons, grebes, shorebirds and waterfowl to this 11,600 square mile wetland to nest and raise their young during the brief Arctic summer.

The Lena River, the second largest stream in Siberia, rises a few miles west of Lake Baikal, flowing northward and gradually eastward for 2700 miles to its delta on the Laptev Sea.  There it delivers tons of sediment each year, gradually enlarging and enriching the delta which is also an important spawining area for Arctic fish.  Nesting birds of note include red-necked grebes, four species of loon, whooper and tundra swans, bean geese, black brant, king and Steller's eiders, long-tailed ducks, Ross's and Sabine's gulls and numerous shorebird species.  Of course, willow grouse, rock ptarmigan, snowy owls, peregrine falcons and a wide variety of Arctic songbirds also inhabit the delta.  Resident mammals include gray wolves, Arctic fox, wolverines, least weasels, stoats, lemmings, tundra voles and reindeer; beluga whales, walruses and a variety of seals often visit the area.

Fortunately, most of this vast tundra wetland is protected within the Lena River Delta Nature Reserve, the largest nature preserve in Russia.  Visited only by the most adventurous naturalists, this spectacular but remote site is relatively free of human disturbance; nevertheless, the Lena, like all rivers on our planet, is tainted by pollutants from agriculture, mining, industry and sewage and their long term effects on the delta ecosystem is yet to be determined.

Dubious Debby

After forming in the eastern Gulf of Mexico over the past 48 hours, Tropical Storm Debby is going nowhere fast.  Parked west of Tampa and south of Panama City, she seems to be teasing the National Hurricane Center with her uncertain intentions.

The question is whether a weak cold front dropping through the Southeast will pick up the storm and shunt it northeastward, across Florida, or whether Debby will drift westward, gathering strength over the warm waters of the Gulf before impacting Texas.  Other computer models suggest that the storm might exit to the north, crossing Louisiana, Alabama or Mississippi.

Currently raking the western edge of Florida with heavy rains and high surf, Debby is a lopsided Tropical Storm, its center of circulation west of the rain bands.  This reflects the presence of upper level winds, crossing the storm from southwest to northeast and keeping the thunderstorms along its eastern and northern rim.  Should the storm remain in the Gulf and drift westward, it may escape this wind shear, allowing a closed system to develop (with thunderstorm bands circling the center of low pressure).  Such architecture is essential to the formation of hurricanes and it remains possible that this tropical storm could become Hurricane Debby in the western Gulf.  Time will tell but, for now, she has the forecasters baffled.

Avalonia

There are few terranes that illustrate the science of plate tectonics and continental drift better than Avalonia.  This micro-continent formed as a volcanic island arc along a subduction zone off the African Coast; at that time, late in the Precambrian Era, Africa was attached to the other southern continents to form Gondwana, which stretched across the South Pole.  During the Cambrian Period, some 530 million years ago (MYA), as shelled marine life was exploding in diversity, Avalonia rifted from the African Plate and drifted northward ahead of the Rheic Ocean, which opened between it and Gondwana.

Late in the Ordovician Period, some 450 MYA, Avalonia docked with Baltica, the craton that now underlies Scandinavia, Eastern Europe and western Russia.  This combined continental mass then collided with Laurentia (proto-North America) during the Silurian Period (440 MYA) as plants and animals were first colonizing the land; the collision forced up the Northern Appalachians, an event known as the Acadian Orogeny.  When the Earth's land masses merged into Pangea during the Permian Period, about 270 MYA, Avalonia was caught in the middle, compressed between the northern and southern continents.

As the Tethys Sea opened east to west, some 200 MYA,  Avalonia remained with Laurasia (the combined northern continents).  During the Jurassic (150 MYA), the Atlantic Ocean began to open, splitting Avalonia as it divided the North American and Eurasian Plates.  Today, fragments of Avalonia form coastal New England, Nova Scotia and the Avalon Peninsula of Newfoundland on the North American Continent; across the Atlantic, it is represented by Wales, England and the northern portion of Western Europe.  Small fragments of Avalonia have also been identified in South Carolina and along the western rim of the Iberian Peninsula.

Australia's Great Basin

The Lake Eyre Basin of east-central Australia is a vast topographic bowl within which streams drain toward the lowest part of the basin, never reaching the sea.  Covering 440,000 square miles from southwestern Queensland to South Australia and from the southeastern corner of the Northern Territory to the northwestern edge of New South Wales, most of it is dry, desert landscape through which ephemeral streams lead to Lake Eyre, in the southwest corner of the Basin.  Nearly dry and coated with salt flats most of the time, the lake fills only twice each Century (on average); composed of a large northern basin connected to a smaller southern basin by the Goyder Channel, Lake Eyre covers 3700 square miles and has an average depth of less than 10 feet (when full)  The lowest point of the lake basin, in Belt Bay of the northern portion, is 50 feet below sea level while the rim of the lake is 30 feet below the level of the sea.

The Lake Eyre Basin began to form about 200 million years ago, when Australia was part of Gondwanaland.  Tectonic forces caused the crust of this region to subside and, within another 100 million years, an arm of the sea invaded the basin; when uplift occurred along the northern and eastern margins of the basin, the sea drained away and rivers flowed across the region, depositing sediments on their way to the ocean.  During the middle of the Pleistocene, about 1 million years ago, uplift along the southern rim closed off the basin and all streams fed Lake Diers, the much larger predecessor of Lake Eyre (as Lake Bonneville preceded the Great Salt Lake in the U.S.).  As the climate became warmer and drier late in the Pleistocene and into the Holocene, the flow through the rivers diminished and eventually became sporadic.  Today, what little water reaches the lake is via three primary river systems: the Georgina River from the north, the Diamantia River from the northeast and Cooper Creek from the east.  Most streams from the west and northwest dry up before reaching Lake Eyre.

During those rare periods when monsoon rains or tropical storms fill Lake Eyre, this remote oasis attracts huge flocks of shorebirds, terns and Australian Pelicans that nest on the islands and feed in the shallows; how these birds know that the distant lake is full remains a mystery.  Lake Eyre National Park stretches along the east shore of the northern lake, just a short 435 mile drive north from Adelaide.  Major towns within the Lake Eyre Basin include Alice Springs, Mt. Isa, Longreach and Broken Hill.

Racing Past the Solstice

Last evening, the Northern Hemisphere crossed the summer solstice, its annual maximum tilt toward the sun.  Over the next six months, the sun will gradually retreat to the south and, in concert, our hours of sunlight will steadily diminish until we reach the winter solstice, on or about December 20.

It will take several weeks before we notice much change in the sunlight and several months before the longer nights take a toll on the summer heat.  Of course, the rate of change will be far more dramatic in the Arctic, sending shorebirds south by August and waterfowl in their wake.

Those of us who are not fond of hot, humid weather look forward to the cool, crisp weather of autumn and would like to accelerate the sun's retreat.  But it is the Earth's journey that governs our seasons, revolving around our home star on a tilted axis, steadily changing the angle of solar radiation that we receive.  Since we are already moving at 66,000 miles per hour to cover the 300 million miles between summer and winter solstices, a bit of patience seems to be in order.

Colorado's Beetles & Wildfires

After dealing with an overwhelming pine beetle blight for the past few years, Colorado residents now face what, so far, is a devastating fire season.  A modest winter snowpack, combined with a dry spring, has set the stage for lightening and human-induced forest fires.  In addition, the presence of so many dead pine trees will surely exacerbate that threat.

Our human-centric view of nature often leads to false conclusions about man's role in the occurrence of "natural disasters."  Many are quick to blame fire-suppression policies for both the beetle blight and the wildfires while others see the hand of God, a biblical punishment for the ills of human society .  But natural wildfires play a vital role in the maintenance of forest ecosystems, clearing out dead wood, opening the canopy and allowing the seeds of certain trees (lodgepole pines, for example) to germinate.  In like manner, pine bark beetles attack stressed or diseased trees and their massive infestations, which probably occur every century or so, restore forests with a diverse assembly of young, healthy trees.  While it is an unwelcome sight for residents and tourists, the remnant landscape of dead or burned trees is a necessary stage in the life of a forest; unfortunately, when viewed from the perspective of our brief human life span, it appears all too permanent.

Aspen trees, which spread by suckering and take advantage of clearings in the coniferous forests, will likely be the primary beneficiaries of these "disasters" in the short run.  Humans who chose to reside in western forests are among the primary victims, losing pristine scenery if not their homes.  Like those who live on barrier islands or along river floodplains, they were taking a chance; most will be philosophical, acknowledging the risk that comes with living in the Colorado mountains and respecting the natural forces that, over the centuries, mold our landscape.

The Congo River

Almost 3000 miles long and second only to the Amazon in its annual flow volume, the Congo River curves counterclockwise through the Democratic Repbulic of the Congo, taking in tributaries from a watershed that exceeds 1.5 million square miles.  The Upper Congo, known as the Lualaba River, receives the Luvua River from Lake Mweru, on the Zambian border, and flows northward, gathering the waters of other streams from Lake Tanganyika, to its east.  Alternately placid and turbulent, the Lualaba reaches Kisangani following a sixty mile course of rapids known as Boyoma Falls (formerly Stanley Falls).

From Kisangani to Kinshasa, at the west end of the Malebo Pool, the 1000 mile stretch of the Middle Congo is wide and navigable, receiving large tributaries such as the Lomami, from the south, the Aruwimi, from the east, and the Ubangi, from the northeast; just upstream from the calm, deep Malebo Pool, the Kasai River enters from the southeast.  Below Kinshasa, Livingston Falls, 90 miles of rapids and cataracts, make the Congo unpassable once again; to bypass this stretch, the Matadi-Kinshasa Railway was constructed in the 1890s.  From Matadi to the Atlantic Ocean, the river is broad and navigable and its braided delta begins just west of Boma; the Congo's total elevation drop, from Lake Mweru to this delta, is just over 3000 feet.

Crossing the equator twice and winding through the second largest tropical rainforest on our planet, the Congo evokes a sense of adventure, mystery and hidden danger.  Long before humans tainted its name with the atrocities of colonialism and slavery, this mighty river nourished and cleansed the Heart of Africa, connecting its lush savannas and dense forests to the distant sea; that role will surely continue long after we have plundered the natural bounty of our native Continent.

Missisquoi NWR

As heat and humidity grip much of the country over the next few months, those of us in the Midwest and Southeast will look for escapes to cooler, northern climes.  For naturalists, one option is a visit to Missisquoi National Wildlife Refuge, in northwest Vermont.

The Missisquoi River rises in the uplands of northeast Vermont, loops westward through southern Canada and then returns to Vermont to enter Lake Champlain along its northeastern shore.  There it has created a delta of marshlands, channels, mudflats and islets, providing ideal nesting and feeding grounds for migrant and resident waterfowl, shorebirds, waders, rails and wetland songbirds.  Established in 1943, the Missisquoi NWR now protects the delta, the adjacent Big Marsh Slough and parcels of northern forest.  At least 300 species of birds visit the refuge throughout the year and nesting species include ospreys, great blue herons, least bitterns, black terns, common goldeneyes, soras and Virginia rails, among many others.

Missisquoi NWR is located NNW of Swanton, Vermont, which is just west of I-89 (Exit 21).  Like most of our National Wildlife Refuges, it is accessible from dawn to dusk every day of the year; the refuge Visitor Center is open M-F and most Saturdays from mid May through October.  Adventurous visitors might want to rent a canoe in Swanton and explore the refuge marshlands from the cool waters of Lake Champlain.

Glacial Lake Souris

Near the end of the Pleistocene, 10-15,000 years ago, large meltwater lakes formed along the retreating edge of the Continental Ice Sheet. One of these, Lake Souris, extended from north-central North Dakota into Manitoba, intermittently connecting with Glacial Lake Agassiz, to its east.

All of these lakes expanded and contracted depending upon their interconnections, the regional climate and the rate of meltwater production. Dammed by tongues of ice or moraines of glacial debris, some would occasionally break through their retaining wall, sending a torrent of water across the flat landscape of the Northern Plains. One such event involved Glacial Lake Regina of southern Saskatchewan, which flooded southeastward into Lake Souris; the broad, shallow channels of this flood remain evident today and are partly occupied by the Upper Souris River and its major tributary, the Des Lacs River.

East of Minot, the Souris River now enters the former lake bed of Glacial Lake Souris, following it north and gradually eastward to merge with the Assiniboine River of southern Manitoba; Lake Souris, itself, eventually drained into Lake Agassiz, which contracted into Lake Winnepeg after drainage opened to the north. National Wildlife Refuges now line the Des Lacs and Souris Rivers which, as we saw last summer, may still flood across the Pleistocene channels and lake beds when a deep winter snowpack is followed by heavy spring rains.

The Flathead River

The Flathead River of northwest Montana rises via three primary forks. The North Fork heads in the mountains of southeast British Columbia and then flows south along the western edge of Glacier National Park. The Middle Fork rises in the Rocky Mountains, northwest of Great Falls, winding northwest and then westward to join the North Fork. The South Fork also rises in the Rockies, more directly west of Great Falls, and flows NNW, where it enters Hungry Horse Reservoir before merging with the combined North and Middle Forks. The primary channel of the Flathead River then enters the Rocky Mountain Trench, a broad valley formed by downwarping of the crust as mountains rose to its east and later occupied by Pleistocene glaciers. Flowing southwestward and then southward, the river passes Kalispell, Montana, and enters Flathead Lake; the Stillwater, Whitefish and Swan Rivers also feed the lake.

The largest natural freshwater lake (by area) in the western Lower 48, Flathead Lake initially formed from glacial meltwater behind a terminal moraine that was deposited late in the Pleistocene; the lake valley was also inundated by Glacial Lake Missoula as it expanded and retreated 30-15,000 years ago (see my blog on 4-2-12). Exiting the southwest corner of its lake, the Flathead River snakes southward across a landscape of plateaus and ridges before flowing westward through a rugged canyon to join the Clark Fork River.

The upper forks of the Flathead have all been designated National Wild & Scenic Rivers and are among the most remote and least disturbed streams in our country. Nevertheless, the North Fork faced possible contamination from proposed coal mining and gas production in southeastern British Columbia over the past few decades; fortunately, an agreement between the U.S. and Canada has, for now, blocked that "development."

Mt. Washington, NH

When I climbed Mt. Washington with a group of friends, in 1974, it was my first experience with mountain hiking. Standing atop the treeless summit, raked by a cold wind and looking out over the surrounding landscape of peaks and valleys, I enjoyed both a sense of accomplishment and the reward of magnificent vistas. We had ascended from Pinkham Notch, east of Mt. Washington, camping below Tuckerman Ravine for the night before a boulder-climbing assault on the summit the following day.

Anchoring the Presidential Range of northern New Hampshire's White Mountains, Mt. Washington tops out at 6288 feet, the highest summit in the northeastern U.S. The Presidential Range, trending southwest to northeast, catches both Canadian storm fronts and nor'easters from the Atlantic Seaboard, bringing copious precipitation to this high wall of Precambrian rock; Mt. Washington receives over 100 inches of precipitation each year, most of which arrives as snowfall (usually exceeding 300 inches). North and northeastward from Mt. Washington are, in sequence, Mt. Clay, Mt. Jefferson, Mt. Adams and Mt. Madison while, to its southwest, are Mounts Monroe, Franklin, Eisenhower, Pierce and Jackson. While the terrain climbs gradually across the western flank of the Range, Pleistocene glaciers carved steep cliffs and ravines along its eastern side; the Grand Gulf curves northeastward from Mt. Washington, Huntington Ravine drops across its eastern flank and Tuckerman Ravine forms a steep wall on its southeast edge.

The alpine summit and its Weather Observatory, which still holds the world record for a human-recorded surface wind speed of 231 mph in 1934 (eclipsed by an automated measurement of 253 mph from Cyclone Olivia, in Australia, 1996) can also be reached via a cog railway or via an auto road that winds up from Pinkham Notch. Whether visitors hike or ride to the summit, they are treated to spectacular mountain scenery and have a chance to observe a wide variety of Northwoods wildlife, including black bears, moose, white-tailed deer and a host of north country birds.

High Deserts

To most of us, deserts are landscapes of dryness, sparse vegetation and perpetual heat. But, in high deserts, the interplay of elevation and dry air produces wide temperature variations from day to night and from one season to another. Examples within the U.S. include the Great Basin Desert, with floor elevations from 5000 to 6000 feet, the Red Desert of southern Wyoming, ranging from 6000 to 8500 feet, and the San Luis Valley of Colorado, with an average elevation of 7600 feet. In all of these deserts, hemmed in by mountain ranges, the annual total precipitation is below 10 inches and surface temperatures may vary by as much as 70-80 degrees F between night and day.

However, the high deserts of the U.S. pale in comparison to the extreme conditions found in other regions of our globe. The Gobi Desert of Mongolia and the varied Patagonian Desert of Argentina are somewhat comparable with regard to elevation but are far larger and are affected by the extreme conditions of neighboring ecosystems. The Atacama Desert of Peru and Chile, the driest on Earth, stretches from the sea to the foot of the Andes and thus harbors varied life zones from zero to 11,000 feet or more. Among the highest deserts in the Western Hemisphere are the Bolivian Salt Flats (12,000 feet) and the Salinas Grandes of Argentina, 12,500 feet above sea level.

But the most impressive high deserts on our planet are the Tibetan Plateau, north of the Himalayas, averaging 14,500 feet in elevation, and the Antarctic Plateau of east-central Antarctica, with a mean elevation of 9800 feet. Despite the fact that its ice and snow harbor over 70% of the fresh water on Earth, Antarctica is our driest Continent, with most of its precipitation falling along the coastal shelves; ascending toward the great plateau, the dry polar air cools further, dropping its meager cargo of moisture on lower terrain.

House Wren Mystery

Having spent a great deal of time in central Missouri over the past 15 years, I have become accustomed to the arrival of house wrens in late April, their loud song and buzzy chatter echoing through the neighborhood. By early summer, the parents are usually escorting their brood through the trees and shrubs, appeasing them with a smorgasbord of insects.

But this year, despite actively searching for these tiny songsters, I have not encountered a single house wren on our property and cannot recall seeing any on my walks to and from the University. I initially blamed their absence on landscaping activity in our backyard but that ended long ago and, still, no house wrens to brighten my evenings; frankly, I feel a bit betrayed. A few visits to our Colorado farm have turned up the usual number of house wrens along the Front Range, adding to the mystery here in Missouri.

Perhaps I am becoming less perceptive with advancing age or have been too busy this spring to give sufficient attention to our wild neighbors. I have even thought to blame the unusually warm spring and early leafing of our shade trees, which might have encouraged the wrens to move farther north before settling down. Then again, the populations of most other summer residents seem to be unaffected. This apparent dearth of house wrens may be just an illusion but, in some 40 years of birding, I can't recall anything quite so mystifying.

Siberian North America

Contrary to a popular assumption, the major tectonic plates of Planet Earth do not correspond directly to the contour of the continents and oceans for which they are named. The North American Plate, for example, extends westward from the mid-Atlantic Ridge, thereby including the western half of Iceland, the western half of the Atlantic Ocean, Greenland, Canada, the Continental U.S., Cuba, the Bahamas, the Gulf of Mexico, the northern Caribbean and the country of Mexico. Its western edge generally follows the west coast of Mexico, the U.S. and Canada (excluding the Baja and Southern California, which are on the Pacific Plate), curving westward below Alaska and its Aleutian Chain and then dipping southward to take in the northern islands of Japan; from there, the western edge of the North American Plate angles NNW, cutting across eastern Siberia.

The Chersky Range of eastern Siberia, trending NW to SE, is a swath of parallel ridges and deep gorges; geologically, these mountains represent a compression zone between the North American and Eurasian Plates and are thus prone to frequent earthquakes. Extending northwestward from the Chersky Range is the Laptev Sea Rift, cutting through the Laptev Shelf on the northern coast of Siberia; this rift is a continental extension of the Gakkel Ridge, the spreading zone of the Arctic Ocean which, across the globe, is continuous with the Mid-Atlantic Ridge. The North American and Eurasian Plates are thus diverging along the Mid-Atlantic/Gakkel Ridge and colliding at the Chersky Range.

Of more significance to politically-minded, nationalistic humans, eastern Siberia, including the Kamchatka Peninsula, is on the North American Plate while Southern California and Hawaii are on the Pacific Plate, tied tectonically to Tahiti, the Soloman Islands and Southern New Zealand. Perhaps, if we paid more attention to the geology of our planet and less to our cultural differences, we might be more devoted to our common welfare.

The Rise of Independence

A recent poll of Americans, reported on the PBS News Hour, revealed that 38% of us identify ourselves as being politically independent; some 32% expressed an affiliation with the Democratic Party while only 24% claimed to be Republicans. I suppose the other 6% are simply apathetic.

In light of ongoing stagnation within the U.S. Congress, it is no wonder that more Americans prefer to be identified as an Independent than to be associated with one of our traditional political parties. But one can hope that this move toward independence also reflects a broader degree of human enlightenment. While our species has a long history of tribalism, first adopted for self defense and later usurped to achieve and maintain power, this trait continues to be a source of discrimination, divisiveness and intolerance. In the spirit of John Lennon's immortal song, imagine a world without countries or religions.

Oppression, after all, has many faces. Its enforcement is not limited to dictators; rather, our freedom is often curtailed by the power of organized religions and entrenched political parties. The rise of independence will, over time, shatter their grip on the soul of humanity.

Dry Rivers on the High Plains

Most of the rivers that cross the High Plains of the American West would hardly be recognized as creeks farther to the east. While the primary rivers that rise in the mountains, including the Missouri, Yellowstone, Platte and Arkansas Rivers deserve their title, many of the smaller rivers, heading on the High Plains Province itself, are dry for much of the year, transmitting water only after episodes of torrential rain or rapid snowmelt. Among these sandy channels are the upper tributaries of the Niobrara, Republican and Smokey Hill watersheds.

Cut off from Pacific moisture by the Continental Divide and located far from the Gulf of Mexico, the High Plains only receive copious precipitation when powerful storms draw in moisture laden air from the east, events that most often occur from February through June; indeed, this geophysical province receives less than 20 inches of precipitation each year. Yet, if we study the High Plains topography, we find that these meager conduits have managed to carve ridges, hills and valleys from the otherwise level plain, suggesting that they were more substantial streams in the past. In fact, during the Pleistocene Epoch (2 million to 10 thousand years ago) the regional climate was much cooler and wetter, giving rise to rivers that, in today's climate, have withered to channels of sand, prairie grass and scattered stands of cottonwood trees.

As with other ecosystems across our globe, it is impossible to understand the current geography without an appreciation for natural history and the region's underlying geology. In the case of the American High Plains, Pleistocene rivers sculpted the Tertiary deposits and underlying Cretaceous Sea sediments into the landscape that we find today; feeble and intermittent streams now occupy the valleys that those rivers left behind.

Rock Squirrels on the Piedmont

Rock squirrels have long been common residents of canyons throughout central and western Colorado and of the varied rock formations that rise along the base of the Front Range foothills. Our largest ground squirrel is easily recognized by his attractive salt-and-pepper coat and his large bushy tail. Most often seen lounging on rocks early or late in the day, these omnivores consume a wide variety of plant materials (nuts, fruits, vegetation) in addition to insects, carrion, bird eggs and even small mammals on occasion. Two litters are produced each year (mid spring and late summer) and, though they retire to their dens for most of the winter, they store food and are not true hibernators, becoming active during periods of mild weather.

Over the past few decades, rock squirrels have ventured onto the Colorado Piedmont and High Plains, following river channels from their original homeland in the foothills and lower mountains. Their expansion has been well documented along the Cache la Poudre River, in northern Colorado, and along the Arkansas River, from Pueblo all the way to the Kansas border. In all of my years hiking along the South Platte, I had not encountered rock squirrels until this week, when I saw a pair at the major rapids area in South Platte Park (just east of the golf course).

Though I am not familiar with scientific studies regarding their dispersal, I suspect that rock squirrels are spreading eastward due to both opportunism and human encroachment on their native habitat. Suburbs have increasingly pushed into the areas just west of the Dakota Hogback as well as along the primary canyons that incise the foothills. In addition, we humans have lined our river channels with rocky embankments, protecting our homes while producing new living quarters for the rock squirrels. Of course, over time, their presence becomes a nuisance as their digging and foraging creates havoc for human engineers and gardeners; once viewed as fascinating residents of our foothill parks, they are now despised as invasive varmints to be trapped or killed.

Denver's Monster Storm

Late yesterday afternoon, a line of thunderstorms developed across northeastern Colorado, a typical occurrence in early summer. One of these was a tornadic monster that stretched from Castle Rock to the area just east of Denver International Airport.

While such storms usually move rapidly off to the east, this storm, unaffected by steering winds, sat in place throughout the evening, dropping torrential rain, producing large hail and spawning several tornados. In fact, by 10 PM, the massive thunderstorm began to drift southwest and then northwest, eventually stretching along the foothills west of Denver. Though radiation cooling generally causes Front Range storms to dissipate after sunset, this one continued to intensify and, by midnight, was illuminating the sky with incessant cloud-to-cloud and cloud-to-ground lightening.

Its final push across Metro Denver triggered severe thunderstorm and flash flood warnings from the National Weather Service. Here in Littleton, we received heavy rain and an inch or two of pea-sized hail; some areas reported golf ball sized hail and the region south and east of Denver, impacted twice by the same storm, received up to five inches of rain. Exiting the Front Range by 2 AM, the massive storm had put a significant dent in our drought and had produced the most spectacular light show that I have ever witnessed. Of course, for those impacted by large hail, flooding and tornados, the memories of this unusual weather event will be less positive.

A Morning Chat

On this bright, cool morning, we opted for a hike through the South Platte Valley, looping past several lakes that border the river channel. In one area, the trail crosses a brushy ridge with scattered groves of cottonwoods and it was there that I heard the unmistakable "song" of a yellow breasted chat, more like a loud, rambling conversation. Indeed, though classified as a warbler (our largest), the chat acts more like a thrasher or a catbird, skulking in the shrubbery and delivering its litany of seemingly unrelated calls and noises.

Solitary for most of the year, yellow breasted chats summer across the Lower 48, preferring riparian woods and brushy hillsides. Nests are placed in low shrubs and these common birds would probably go unnoticed were it not for the male's tendency to sing from an exposed perch, his bright yellow chest and abdomen glowing in the early summer sun. Here in Colorado, chats are especially common along streams of the lower foothills where they feast on insects and berries. While some winter along the East Coast of the U.S., most yellow breasted chats head to Mexico or Central America for the colder months.

This morning, our songster was accompanied by house wrens, lesser goldfinches, yellow warblers, song sparrows, black-billed magpies, broad-tailed hummingbirds, a Say's phoebe, northern flickers and those ubiquitous robins and house finches. Double-crested cormorants moved among the lakes, fishing for their breakfast, while great blue herons, a black-crowned night heron, flocks of Canada geese and squadrons of ducks passed overhead. But it was the chat that made our morning, delivering his strident lecture to all who cared to listen.

Front Range Drought

Following a lackluster snow season and spotty rain throughout the spring, Colorado's Front Range is tinder dry and wildfires have become a significant problem, especially for residents of foothill communities. Over the past two days, the fire risk has increased dramatically as hot, dry, southeast winds have raked the area; while the humidity has increased a bit with this upsloping wind flow, little precipitation has developed and "dry thunderstorms" threaten to ignite more fires.

Along the urban corridor, the winds are producing a welcome "wind-chill," making the mid afternoon heat feel less intense than it might on a calm day. A stroll along the South Platte revealed water levels lower than I have encountered in many years; with much of its flow diverted for irrigation and water supply, the shallow river attests to the ongoing drought in much of the State. On the positive side, the sluggish stream attracted a variety of birds from the parched fields and woodlands, including yellow warblers, belted kingfishers, spotted sandpipers, killdeer, swallows, great blue herons and mother ducks (mallards and wood ducks) with their broods in tow.

There is some hope that the gusty, upsloping winds will produce showers and thunderstorms overnight but, even if they do, a widespread, soaking rain is not expected. As often occurs along the Front Range, the precipitation will be spotty in nature, with some areas enjoying a cloudburst and others left in the windblown dust. In reality, a significant break from our ongoing drought will probably not occur until the late summer Monsoon pumps moisture up from the Desert Southwest. Let's hope that annual relief arrives early, rescuing the Front Range from what appears to be a destructive wildfire season.

High Plains Thunderstorms

Our trip from Missouri to Colorado today was almost entirely under sunny skies, with afternoon temperatures near 90 degrees F. The one, significant exception was an imposing wall of dark clouds, lightening and intense rain along the Kansas-Colorado border. Though our journey through the storms was brief and, thankfully, unaccompanied by large hail, the thunderstorms were training over Kit Carson County, including the city of Burlington, triggering a flash flood warning from the National Weather Service.

Encounters with severe weather can be unsettling in any location but they are especially terrifying on the Plains or on open water. In these areas, one gets both a broad view of the storm's size and ferocity and plenty of time to observe the approaching monster, wondering what it might do to your vehicle or boat. In addition, if caught in an open landscape, one experiences a sense of hopelessness, finding no means to escape the looming threat.

While some make their living chasing and photographing storms on the Great Plains, the rest of us are well advised to check weather forecasts prior to our journey and be willing to stop at a safe location if unexpected storms develop. Today's storms seemed to blow up before our eyes and we had no recourse but to slow down and hope for the best; fortunately, the major storms were well away from the highway as we passed through and we had only to contend with torrential rain and gusty wind. Once we were through this swath of fury, the clouds dispersed and we crossed dry, sun-drenched terrain all the way to Denver.

American Creationists

This week, CNN reported on a recent survey of American adults that revealed almost half of us reject the concept of human evolution and believe that humans were created by God within the past 10,000 years; among Republicans, 60% hold this view. This large contingent of creationists is, to say the least, disturbing to those of us who accept the scientific method as the only legitimate means for solving the mysteries of the Universe and for defining our place within its vast realm.

The results of the survey suggest that two factors are at play. First, scientific education within the U.S. is woefully deficient, even among college-educated adults. Second, the influence of organized religion in America remains very powerful and, despite the copious scientific evidence that supports human evolution, many religious persons either choose to ignore that data or find the ancient, pre-scientific writings of early prophets more convincing. There is little doubt that religious beliefs, ingrained in childhood and sustained by fear and guilt, fuel distrust of science, as they have since the earliest days of human civilization.

The fact that we live on a small planet near the outer edge of a massive galaxy that is one of billions of galaxies in our Universe seems to have no bearing on their belief; neither does the evidence that the Universe is 13.7 billion years old, that Earth is 4.6 billion years old and that life has colonized our planet for 3.6 billion years. If the creationists are correct, God is a very patient deity indeed.

The Birding Doldroms

For the amateur, summer is a good season to engage in birdwatching; a wide variety of species are present and the weather is conducive to both field study and patient observation. But, for veteran birders, June and July are probably the least interesting months of the year.

By June, the spring migration has ended and a population of well-known, frequently-observed summer residents has settled in our parks and neighborhoods. Early summer is an unlikely time to find rare vagrants, the cherished quarry of avid birders; rather, such wanderers are far more common in late summer, during the spring and fall migrations or throughout the lean months of winter.

Of course, travelling to other regions of the country or planet is the best cure for the birding blues, but, for many (if not most) of us, such a remedy is not feasible. Those who cannot travel must wait for shorebirds to start dribbling south in mid summer or be satisfied with visits by our less common summer residents. During these birding doldroms, I suggest that birders broaden their horizon, taking an interest in the wide variety of plants, insects, reptiles and other creatures that share our home ecosystem; by doing so, we also develop a better appreciation of the environment in which our resident and migrant birds obtain the essential elements of their survival.

A Breath of Spring

After weeks of summerlike heat, cool, Canadian air has dropped into the Heartland. The jet stream is ushering in this fresh breath of spring, dipping east of the Rockies, across the Southern Plains and then northeastward above the Mississippi and Ohio Valleys.

Here in mid Missouri, we awoke to clear, dry air and a temperature of 48 degrees F, twenty degrees cooler than recent overnight lows. Our high is forecast to peak near 70 degrees this afternoon, a pleasant change from the oppressive air that enveloped our region through most of May. Indeed, on this first calendar day of summer, we will enjoy our first spring-like day in many weeks.

Of course, nature pays no heed to the human calendar and her unpredictable style demands our attention. While we are grateful for her refreshing gift today, the next round of heat and humidity sits on our doorstep and a long, hot summer may soon take hold. Hopefully, she'll appease us with occasional waves of cool, northern air until the invigorating chill of autumn invades the Midwest.

A Natural Break

Most evenings, if daylight permits, I head out back for thirty minutes of natural solitude. While mowers may hum in the distance or trucks may rumble on a nearby road, I try to focus on the sights, sounds and fragrance through which I stroll. I also try to ignore problems that may have occupied my day or that await my attention tomorrow.

This natural form of stress reduction has become a vital part of my life and, though I make no attempt to search for any particular plants or animals, I generally encounter something unexpected or see it in a different light. More than anything else, these breaks from human responsibilities make me appreciate the calm patience that typifies the lives of wild creatures and, on most evenings, I seem to absorb some of that serenity.

I could be getting some bills paid or subjecting myself to the endless parade of reality shows on cable TV but those thirty minutes are a cherished part of my day. While these outdoor rambles often provide fodder for future blogs, I seek only the company of our wild neighbors and a chance to enter their world, however brief that visit might be.

Italy, Earthquakes & Human Nature

After enduring two tragic earthquakes within a span of nine days, residents of northeastern Italy are both distraught and mystified. As emphasized in news reports, that region had not experienced a significant earthquake for hundreds of years. Yet, this industrial valley stretches between the Apennines and the Alps, mountain ranges that owe their very existence to the collision of the African and Eurasian Plates.

This tectonic collision, though too gradual to witness during our brief life span, has been going on for at least 40 million years, producing the varied landscape of southern Europe. A quiescent period of seismic activity in any given area, even lasting hundreds or thousands of years, is to be expected as pressure along the collision zone shifts from one region to another. While we may understand the geologic cause for the earthquakes, our inability to accurately predict the timing of such events has become all too clear over the past few decades; nevertheless, scientists in Italy are facing manslaughter charges for their failure to predict the 2009 quake in the Apennines, east of Rome, which killed more than 300 citizens.

We humans have a tendency to blame others for the misfortunes that we endure, even when they arise from the uncontrollable and, to date, unpredictable natural forces that mold our planet. We also tend to interpret our Universe, distant galaxies or local geography, from the narrow perspective of our human life span. Anyone who resides along the active plate margins of Planet Earth cannot afford to ignore the realities of its past and ongoing geologic evolution, however remote the risk of catastrophe might seem at the present time. After all, the Africa-Eurasian collision has been underway for 40 million years, 400 times longer than our own species has walked the planet.

The Arctic Fox

Mention Arctic land mammals and the image of large, well-insulated creatures comes to mind: polar bears, musk ox, caribou and the extinct woolly mammoth, to name a few. But the small Arctic fox, the most northern-living canine on our planet, has managed to thrive on the harsh, treeless tundra of the Arctic biome. Equipped with a compact body habitus, thick, dense fur, furred paws and changing coloration to blend with its environment, this hardy fox also has an exquisite sense of hearing for prey location, adapts well to an omniverous diet and produces large litters to sustain its population.

After breeding in late winter or early spring, the monogamous pair uses a large den network in which to raise its litter of 6 to 15 or more kits; the newborn fox will remain with their mother through the summer and, as with some other wild canines, a few yearlings often stay behind to assist with feeding and protecting their younger siblings. The diet of the Arctic fox is dominated by lemmings and other small mammals (including seal pups) but also includes berries, vegetation, carrion, birds, fish and the eggs of seabirds and waterfowl. When food is abundant, they will bury eggs or meat in the Arctic permafrost for consumption during the harsh months of winter.

Circumpolar in their distribution, the populations of Arctic fox are stable in most areas though they are endangered in Scandinavia due to overhunting. Having evolved late in the Pleistocene, about 250,000 years ago, they spread across northern oceans on the vast ice shelves of that Period and are the only mammal native to Iceland. Today, like many polar species, Arctic fox are threatened by global warming that is changing their habitat, altering their food supply and allowing dominant predators (such as red fox and gray wolves) to invade their territory.

Faith & Suffering

It seems very likely that religious beliefs first arose in early human clans (some 130,000 years ago) when gods were invoked to counter fear and suffering. After all, our distant ancestors were traumatized by natural catastrophes, brutal weather, predators, mysterious diseases, fatal injuries, famine and tribal warfare on a regular, if not daily, basis.

At some point during our evolution, certainly by three to four thousand years ago, suffering had become more than the impetus for religious ritual; it had become ingrained in the rites themselves. We humans had come to imagine that our gods are appeased by suffering; as a result, human sacrifice, self-inflicted pain and self denial became an essential part of religious ceremony. Even today, despite our advanced scientific knowledge, such attitudes persist, represented by a wide range of beliefs and rituals, from giving up desserts during Lent to volunteering as a suicide bomber. Orders of monks and nuns retreat to lives of fasting and prayer, Catholic priests take vows of celibacy, devout believers lash themselves with reeds or whips and many (if not most) of the faithful view their earthly suffering as a ticket to heavenly rewards.

Of course, if this delusional, suffering-based faith only affected those who practice it, the rest of us would be free to focus on the enlightenment of human culture. Unfortunately, their beliefs permeate human society, stifling education, fomenting warfare, fostering intolerance and instilling fear in younger generations. Worse yet, those who view suffering as a means to salvation are more willing to inflict its scourge on the innocent. One hopes that we will eventually evolve beyond these primitive delusions but our zealous, god-fearing brethren, obsessed with their image of a vindictive deity, are not likely to fade from the scene anytime soon.

An Early July

On this Memorial Day weekend, July has made an early appearance in the Heartland. With afternoon highs in the 90s (F) and overnight lows in the 70s, it feels like mid summer; were it not for the plentiful moisture still in the soil, the vegetation would be wilting in the intense heat, but, in this case, the verdant face of May persists.

This early heat wave is courtesy of a high pressure ridge over the southeastern U.S.; beneath this dome, air is sinking and heating up, retarding cloud formation, while, along its outer edge, thunderstorms will ignite across the Upper Midwest. One crop of storms, off the coast of South Carolina, has developed into Tropical Storm Beryl, which will move WSW along the rim of the dome over the next 24 hours, bringing heavy, much-needed rain to southern Georgia and northern Florida.

The high pressure ridge should stay in place through the holiday weekend and will then drift to the east, allowing cooler and drier air to filter in from the northwest. Until then, we'll endure heat and humidity more typical of July and the Southeastern Coast will receive an early taste of the hurricane season (which officially begins on June 1). Here's hoping that a premature summer ushers in an early autumn!

Midwest Mountain Lions

Having once inhabited most of the United States, mountains lions were extirpated from eastern and central portions of our country by the early 20th Century; an exception was the Florida panther, which managed to survive in the dense vegetation of the Everglades and adjacent cypress swamps. Throughout most of the 1900s, the easternmost populations of cougars (other than the Florida panther) were in West Texas and in the Black Hills of western South Dakota.

However, over the past decade, sightings of mountains lions have increased signficantly across the American Midwest. Almost all of the confirmed cases have been males, presumably banished from their home range by other dominant males; indeed, cougars are territorial and field studies have revealed that the home range of adult males is in the neighborhood of 100-300 square miles. While 5 mountain lions inhabited the Pine Ridge Escarpment of western Nebraska in 2004, 30 were documented by 2011, including females and cubs. Sightings in Kansas, Missouri, Iowa, Minnesota and Wisconsin have involved male cougars that are thought to have wandered eastward from South Dakota and western Nebraska (though some may have arrived from Colorado via the Arkansas River corridor). One famous case involved a male that wandered through Minnesota and Wisconsin in 2009-2010 and ended up getting killed in Connecticut in 2011. Here in Missouri, there have been at least 29 cougar sightings since 1994, though, in some cases, multiple sightings of the same cat may have occurred. Since mountain lions are secretive and primarily nocturnal, an accurate estimate of Midwest wanderers is very difficult to obtain and it is likely that more pass through this region than some human residents might care to imagine; on the other hand, livestock loss to cougars has been minimal since these travelers seem to favor small mammals and the occasional deer.

Of course, unless females begin to follow the nomadic males from mountainous areas of the West, breeding populations will not become established in the Heartland. The increasingly common sightings in recent decades surely reflects the growth of human populations throughout the Mountain West, depriving these predators of their natural habitat and forcing males to head east, following river channels across the Great Plains. Any excitement associated with the opportunity to observe these magnificent cats in the Midwest is tempered by the knowledge that we have driven them from their modern homeland and that they are returning to an ancient homeland that has forever changed. Whether they will be welcomed or persecuted remains to be seen.

The Treetop Vocalist

Over the past month, loud vreeeps have echoed through our neighborhood on my morning walks to work. Their source is always difficult to locate but these clear, ascending calls seem to arise from the treetops, where the vocalists remain hidden amidst the dense foliage of late spring.

In fact, they are the distinctive calls of great crested flycatchers, colorful insectivores that prefer to hunt in the upper canopy of open, deciduous woodlands; suburbs of the central and eastern U.S. thus appeal to these summer residents. Nesting in tree cavities, great crested flycatchers utilize a wide variety of nesting materials, including human trash and discarded snakeskins; it is only during the collection of these items that they are likely to be seen on the ground and, even then, they fly from site to site, not hopping or walking like most songbirds. The great majority of their time is spent in the trees, snaring insects from leaves and stems or catching them in mid air.

By late summer, great crested flycatchers begin to migrate toward their wintering grounds in the Caribbean, Central America and northern South America. There they feast on insects in the canopy of rain forests and, unlike most migrant songbirds, remain vocal throughout the year.

Sediments, Fossils & Time

Amateur naturalists are often confused by the distribution of fossils across our globe, wondering why certain fossils (of dinosaurs, for example) are plentiful in some areas but absent in others. In general, the fossils of plants and animals result from their remains having been trapped within sediment (lake deposits, ocean floor sediment, river mud, volcanic debris, etc.) that, over millions of years, hardened into sandstone, mudstone, limestone or some other sedimentary rock. Of course, most animals and plants die under circumstances in which their remains are consumed, undergo decay or are scattered by predators and natural forces before such fossilization can occur.

The type of fossils present in any region of our planet depends upon the age of the exposed sedimentary rocks in that area; rocks that formed from sediments that accumulated during any given geologic era will harbor fossils of life from that era. The exposure of these sedimentary rocks is a product of regional uplift, erosion and the deposition of overlying sediments (not necessarily occuring in that order). For example, Jurassic sedimentary rock, which accumulated during the Age of Dinosaurs, may have been lifted to the surface (as in large parts of the American West), may be buried deep beneath younger sediments or may have long-since eroded from the surface due to action of streams or glaciers; in other areas, these sediments may have never accumulated in the first place due to regional topography throughout the Jurassic Period.

Millions of years from now, Holocene sedimentary rocks will be explored by our super-human decendants or, perhaps, by visitors from other solar systems. Encased in those rocks will be the fossils of human civilization, including our domestic livestock, our cultivated plants, our pet poodles and the plants and animals that comprise our natural ecosystems. These Holocene sediments may be found deep in canyons, atop mountain ranges or outcropping from desert plains; in many areas they will lie deep beneath the fossilized remnants of younger civilizations while, in others, they will have already washed away to the sea.

River Relief

Those of us who frequently travel across the Great Plains or the Glaciated Plain of the Upper Midwest are usually glad to encounter river valleys, which break the monotony of the flat terrain. In these areas, the primary channel and its tributaries have carved a mosaic of hills, ridges and valleys from the plain, necessitating dips and curves in the route of our journey.

Beyond the topographic relief, these river valleys harbor rich, moist soil, supporting a wide variety of vegetation, offering a sharp contrast from the cropfields, grasslands and sparse woodlands of the adjacent plains. Visually appealing to human travelers, these corridors also attract regional wildlife that utilize them to nest, roost, feed or to escape the harsh conditions on the plain. Indeed, naturalists know that wildlife viewing is significantly more productive along these ribbons of life than it is on the flat terrain that surrounds them; even open-country species tend to congregate near river valleys, a vital source of water and cover.

Of course, river corridors also appeal to those of us who take an interest in regional topography, providing insight into the evolution of Earth's landscape. Unless one is a robotic traveler, oblivious to the environment through which they move, rivers, like mountain ranges and lakes, give us a sense of place and direction, a natural perspective by which to gauge our progress.

Vulture Heaven at Eagle Bluffs

As a consequence of the lowest water levels that I have ever encountered at Eagle Bluffs Conservation Area, dead carp lined the central channel, providing a feast for numerous turkey vultures. Usually seen soaring above the countryside, these large scavengers had gathered on the mudflats and levees to partake in the bounty of rotting fish.

Of course, the low water was also beneficial to great blue herons, great egrets and green-backed herons, concentrating their prey in the shallow pools. Other highlights included a large number of wood ducks, the attentive females ushering their broods across the calm waters, and an unusual abundance of migrant shorebirds for late May. Cormorants and diving ducks were noticeably absent but small groups of coot, blue-winged teal and mallards plied the shallows or huddled on the shorelines. Throughout the evening, a steady background chorus was provided by bullfrogs, green frogs, cricket frogs, killdeer and indigo buntings as white-tailed deer emerged from the woods to browse the marshlands and crop fields.

Since the Missouri River is still fairly high, I suspect that the low water at Eagle Bluffs reflects an artificial drawdown, often utilized to mimic natural fluctuations that foster the welfare of native floodplain vegetation while discouraging the invasion of alien species. Whatever the cause, the drought-like conditions surely favor the hunters and scavengers; for the time being, it's vulture heaven at Eagle Bluffs.

The Perspective of Geese

During our travels along the spectacular coast of Lake Superior this week, we encountered a pair of Canada geese, ushering their brood across the unusually calm waters of the lake. West of the roadway was a pristine wetland, stretching out from the mouth of a rushing river; we naturally assumed that the pair had nested within that scenic marsh. Such encounters often make human envious of wildlife, recognizing both their freedom and their capacity to live in beautiful natural landscapes, unencumbered by the responsibilities of the human lifestyle.

On the following day, I saw another pair of geese with their young offspring, resting along a muddy pond in the industrial port of Superior, Wisconsin. Close to a wealth of pristine habitat, far more appealing to the human eye, they had chosen to nest along this unattractive pool, bordered by a litter-strewn lawn. Perhaps, once the goslings fledge, they will move on to a more pristine location but, for now, they appeared to be perfectly comfortable at their ugly urban site.

Unlike most humans, wild creatures focus primarily on their basic needs, not on the physical beauty of their surroundings. While they are far better equipped to wander off to spectacular landscapes that we can only hope to visit, they do not share our obsession with picturesque settings. Of course, neither do they worry about the effects that pollution might have on the welfare of their family; in that respect, they unknowingly depend on the wisdom and commitment of their human neighbors.

Superior's Northwest Coast

Just north of downtown Duluth, Interstate 35 ends and becomes Minnesota Route 61 that hugs the northwest coast of Lake Superior, all the way to the Canadian border. Providing spectacular and ever-changing views of the lake, this road also yields access to a chain of State Parks, most of which surround rivers that rise in the hill country to the west and rumble down to Lake Superior.

A few of these Parks deserve special mention. Gooseberry River State Park, a few miles north of Two Harbors, is accessed by an excellent network of trails that lead past a series of beautiful waterfalls, lead out to cliff-top views of the lake and river valley or take the visitor down to the rocky shore. Temperance River State Park, just north of Taconic Harbor, provides spectacular evidence of the erosive force of moving water; this turbulent stream has cut a deep, rugged gorge through the Precambrian volcanic bedrock, producing waterfalls, whirlpools and polished rock formations. Just shy of the Canadian border, Grand Portage State Park, stretching along the Pigeon River, provides access to Pigeon River Falls, the highest waterfall in Minnesota (120 feet). Finally, a scenic rest-stop, a few miles north of the town of Grand Portage, offers an awe-inspiring view of Lake Superior, its coastal hills, the offshore Susie Islands and the distant silhouette of Isle Royale, stretching across the northeastern horizon.

While towns, marinas, resorts and industrial ports are also spaced along Superior's Northwest Coast, they do not begin to detract from its fabulous natural landscape and the abundance of State Parks, State Forests and dedicated Wilderness could keep any naturalist entertained for months, if not years. Our only regret is that we had too little time to explore that scenic wonderland.

Western Lake Superior

Facing an off-week and yearning to get back to the North Country after our memorable journey across the Upper Peninsula of Michigan, last September, my wife and I decided to head for western Lake Superior. We left Columbia yesterday afternoon, driving north across the Glaciated Plain of northern Missouri and eastern Iowa, stopping for the night in Iowa City. This morning, we resumed our journey, dropping into the Mississippi Valley at Marquette, Iowa, and then paralleling the broad river and its wooded islands along the Wisconsin (eastern) shore. Scenic bluffs rise along both sides of the Mississippi Valley in this "Driftless Area" of the Upper Midwest, which was spared the erosive force of Pleistocene Glaciers.

Protected within the Upper Mississippi National Wildlife Refuge, access to the Mississippi and its varied riparian habitats is rather limited (except for boaters). However, Goose Island County Park, just south of La Crosse, Wisconsin, provided an excellent opportunity to study the floodplain wetlands, backwater bays and eastern channel of the river; birding was excellent at the Park. North of La Crosse, we cut away from the Mississippi for a more direct route to Duluth, Minnesota, where we are spending the night on that city's restored waterfront.

In the coming days, we plan to explore the northwest coast of Lake Superior and the Apostle Islands region of northern Wisconsin. So far, wildlife encounters have been limited to bald eagles, sandhill cranes, common loons, gulls, aquatic turtles and a host of waterfowl and songbird species. But we are now in wolf and moose country and I look forward to the possibility of seeing (or hearing) those North Country residents amidst the spectacular landscape that adjoins America's grandest Lake.

Miracle Drugs

Ever since early man discovered natural herbs and resins that seemed to ease his common maladies, we humans have been hooked on drugs. In the modern world, these heavily marketed agents are used to counteract the effects of our sedentary lifestyle or to rescue us from poor choices when it comes to our diet and recreational activities.

Of course, some pharmaceutical products have had a major impact on the health and longevity of the human species: vaccines, antibiotics and chemotherapeutic agents for some cancers (especially childhood leukemias) come immediately to mind. But many of our prescription drugs would not be necessary if we engaged in a healthy lifestyle and they often impose new health problems related to their side effects. Statins, the classic miracle drugs of the past decade or so, have been touted as the ultimate answer to preventing cardiovascular disease and are heavily advertised on American television; yet, within the past few months, evidence has surfaced that associates higher doses of some statins with an increased risk of developing diabetes. And just this week, studies were released that question the long term use of bisphosphonates, drugs used to combat osteoporosis; also heavily marketed on TV, these agents prevent reabsorption of bone, a natural process in the regular remodeling of our skeleton. The new studies reveal that, despite their remarkable effects in the first few years, these agents may be associated with long term effects that could actually increase the risk of future fractures.

These ongoing revelations regarding the long term effects of unnatural chemical agents are hardly a surprise to those of us in the medical profession. We regularly encounter patients who are taking twenty or more drugs, prescribed to combat maladies that are often secondary to inactivity, obesity, tobacco use or the excessive consumption of alcohol. The prevention of disease, including cardiovascular disease and osteoporosis, is best addressed through regular exercise, a healthy, balanced diet and the choice to forgo smoking and other self-inflicted risks. While the use of some medications may become necessary, there is no such thing as a miracle drug.

The Eurasian Mountain Arc

Looking at a map of Earth, one sees a complex of mountain ranges from Southeast Asia to Spain. Almost all of these ranges are relatively young, having crumpled skyward throughout the Tertiary Period; in fact, all are still rising today, a fact made evident by frequent earthquakes across this swath of landscape.

About 55 million years ago (MYA), soon after the Rocky Mountains formed in North America, the Indian Subcontinent began to collide with southern Asia, forcing up the Himalayas and its associated ranges, from southern China to Afghanistan. By 40 MYA, the Red Sea and Gulf of Aden began to open, splitting the Arabian Plate from Africa and pushing it northward into southwestern Asia; this compressed the crust of that region, lifting the ranges of Iran, eastern Turkey and the Middle East. About the same time, as the Tethys Sea was closing, Africa drifted northward to collide with southern Europe; this has crumpled up the Alps and its associated ranges, from western Turkey and Greece to the Pyrenees of Spain. In concert, regional subduction of the African Plate beneath the Eurasian Plate has produced a chain of volcanos along the western edge of Italy.

In some areas, such as the Pyrenees, older mountain ranges, having eroded to low hills, were renewed by these Tertiary orogenies. Today, as these tectonic forces persist and the "new" mountains continue to rise, the agents of erosion combat their uplift; molded by glaciers and incised by streams, their rock dust is carried off to the sea where, millions of years in the future, it may resurface as the core of another mountain range.

The Mackenzie River

Rising at the west end of Great Slave Lake in Canada's Northwest Territories, the Mackenzie River flows northwestward for almost 1100 miles to the Beaufort Sea. Un-dammed and winding through Subarctic and Arctic wilderness, its wide, braided channel is just the final conduit of a massive watershed that covers 20% of Canada, extending from northeast British Columbia, northern Alberta, northwest Saskatchewan and the western Yukon to the massive Mackenzie River Delta, the 12th largest on our planet. If one includes its most distant tributaries, this river system exceeds 2600 miles in length (the longest in Canada) and drains a watershed of almost 700,000 square miles.

To the southwest, the Peace and Athabaska Rivers rise on the east side of the Continental Divide in the northern Canadian Rockies; these large streams merge to form a large inland delta along Lake Athabaska, which drains to Great Slave Lake via the Slave River. Leaving Great Slave Lake, the Mackenzie River picks up meltwaters from the Mackenzie Mountains (to its west) via the Liard River system and then receives flow from Great Bear Lake, to its east, the largest lake in Canada. At its braided delta, just east of the Richardson Mountains, the Mackenzie discharges copious amounts of relatively warm, fresh, nutrient-rich water into the Arctic Ocean; this annual discharge, the 14th largest on Earth, dramatically affects the regional ecosystem, allowing boreal woodlands to extend well north of their usual range and increasing the diversity of plants and animals across the ever-changing delta. Beluga whales gather here in spring to molt in the mild river current and the countless, shallow lakes provide ideal breeding habitat for shorebirds, tundra swans and snow geese. Resident mammals include black bears, barren ground grizzlies, Arctic fox, Arctic wolves, caribou, moose, musk ox and a massive number of muskrats.

However, all is not well in this seemingly pristine wilderness. Dams on tributaries of the Mackenzie have reduced flow through its primary channel and are diminishing the annual floods that are crucial to the welfare of its delta ecosystem. In addition, worrisome levels of mercury have been found in the river over the past few years, the product of mining and power plant effluent across the watershed. Of course, as with other Arctic ecosystems, global warming may dramatically affect the natural diversity of this magnificent yet fragile landscape.

From Tropical Heat to Upslope Chill

After wilting in central Missouri over the last two days, enveloped in tropical heat and humidity, I arrived along the Colorado Front Range late this afternoon under low clouds and scattered showers; the temperature was 45 degrees F. These two weather extremes were produced by the same Pacific storm system; ahead of the front, muggy air was pumped into the Midwest from the Gulf of Mexico while, behind it, a plume of moisture was swept westward through the cool air. Since this flow is counterclockwise around the storm's central low, the moisture arrived from the northeast, the classic upslope direction for Metro Denver. Cooling and condensing as it rose across the western landscape, the plume dumped its cargo of moisture across northeastern Colorado.

Over the past 24 hours, Metro Denver received a half inch of rain in most areas while higher elevations to the west and south collected .75 inch or more, a welcome respite from the recent drought. Checking the foothills as I arrived from the east, it was obvious that the upslope shroud was beginning to lift though jet traffic was still landing to the north and likely offering a bumpy descent through the showers and virga. Our Littleton farm clearly benefited from the moisture, having taken on the untidy overgrowth that promises plenty of yard work this week.

As the system continues to move eastward, the muggy air and thunderstorms will be confined to the Eastern Seaboard and high pressure will reclaim the Heartland, bestowing warmth and sunshine for the days ahead. Here along the Front Range, the wind will shift to the south-southwest, a downsloping direction for Metro Denver; we expect sunshine, mild temperatures and a chance to dry out.

Southern Soup

Hot, humid air has been flowing into Missouri for the past two days and will continue for at least another 24 hours. This muggy, southern soup is courtesy of both a broad high pressure ridge over the eastern half of the U.S. and a slowly approaching Pacific front that should ignite thunderstorms by tomorrow afternoon.

Riding this river of subtropical air, the first wave of common nighthawks appeared in our skies yesterday evening. Among the last migrants of spring, they are more cautious than swallows and swifts, waiting until plenty of insects are reliably available for their late-day feasts. They'll be with us until late summer and, perhaps, as late as early October, departing for the tropics before autumn's chill annihilates their prey.

Meanwhile, here in the Midwest, this summer-like heat in early May is not welcomed by those of us who prefer cool weather. Fortunately, a milder and drier air mass is expected to move in by early next week, bringing spring conditions back to the Heartland. By then, I'll be heading to our Colorado farm, guaranteed to escape the heat and humidity that common nighthawks relish.