Showing posts from April, 2013

Late April at Mt. Falcon

Late April is a great time to visit the Transition Zone forest of the Colorado Front Range foothills.  Also known as the Montane or Yellow Pine Zone, this forest of open ponderosa pine woodlands (on south facing slopes) and dense Douglas fir forest (on shaded hillsides) stretches between elevations of 7000 and 9000 feet.  One of the better locations to explore this life zone is Mt. Falcon Park, in Jefferson County, just west of Metro Denver.

Yesterday morning, the woodlands of that Park were alive with the sound of ravens, Steller's jays, gray-headed juncos, mountain chickadees, hairy woodpeckers and all three nuthatches (white-throated, red-breasted and pygmy).  Mountain and western bluebirds hunted on the meadows, joined by Townsend's solitaires, robins, black-billed magpies and chipping sparrows.  White-throated swifts zoomed along the canyon walls, not yet joined by violet-green swallows; other summer residents yet to arrive include western tanagers, MacGillivray's war…

Earth's Evolving Landscape

From the moment of its formation, 4.6 billion years ago, Planet Earth's surface has been continuously molded by natural forces.  Plate tectonics has opened and closed oceans, lifted mountain ranges, torn continents apart and produced a wide variety of volcanic terrain.  At the same time, streams, rivers, wind, waves and glaciers have been eroding the landforms, leveling highlands, sculpting rock formations, opening caves, carving canyons and revising shorelines.  Finally, the interplay of climate, latitude, soil condition, wildfire, precipitation and other factors determine the changing mosaic of surface vegetation which, in turn, governs regional fauna populations.

During our brief lifespans we barely notice significant changes in Earth's landscape except for features that we, as a species, have produced: reservoirs, canals, man-made canyons, tunnels, agricultural fields and construction related to our towns and cities.  Active volcanic eruptions, earthquakes, floods, rockfal…

Front Range Waders

As the days lengthen and the weather warms, some birds return to the Colorado Front Range that may seem out of place in a State known for prairie, mountains and canyons.  Nevertheless, herons, egrets and ibis have long been residents of this region and man-made reservoirs have significantly increased their population along the South Platte and Arkansas River Valleys.

Great blue herons and a small number of black-crowned night herons are year-round residents of the Front Range urban corridor.  The population of the latter increases dramatically during the warmer months when they are joined by snowy egrets, green-backed herons, American bitterns and white-faced ibis.  Cattle egrets are also summer residents along the Front Range, attracted to the region by the combination of cattle ranches and reservoirs.  In late summer, great egrets and yellow-crowned night herons may also wander into the State and occasionally turn up along the Front Range.

The presence of these waders, generally ass…

Spring Arrives at Chatfield

Though it's a month late, spring has finally taken charge at Chatfield State Park, southwest of Denver.  On my visit this morning, I focused (as usual) on the backwater areas of the reservoir and along the ponds, wetlands and riparian woods that flank the South Platte River, south of the lake.

Scattered flocks of American white pelicans and western grebes graced the open waters, joined by double-crested cormorants, common mergansers and wood ducks.  Several ospreys perched above the shoreline or fished on the reservoir while lesser yellowlegs and spotted sandpipers foraged along the sandy rim and mudflats; in the shallows, chorus frogs, having recovered from our wintery setback, delivered their rising calls.  Though the cottonwood groves and willow thickets remain devoid of leaves, they were filled with songbirds and woodpeckers, including northern flickers, downy woodpeckers, house wrens, magpies, house finches and an abundance of yellow-rumped warblers; northern orioles and othe…

A Welcome Thrush

No sooner had the recent blanket of snow melted from our Littleton, Colorado, farm than a Swainson's thrush appeared, foraging in a flower bed.  Common migrants along the Front Range urban corridor, especially in spring, this spotted thrush breeds in coniferous forests of southern Alaska, Canada and the mountain ranges of the Western U.S.

Distinguished from other spotted thrushes by its dull, brown-olive back, its faded breast spots and its buff-colored eye ring, Swainson's thrush also delivers a unique, rising song.  Like its close cousins, it feeds primarily on the ground, consuming both insects and berries; unlike the others, it also feeds in the lower branches of trees and, at times, engages in fly-catching behavior.  Nests are placed in the understory shrubs of coniferous woodlands and 3 to 4 eggs are generally produced.  Come fall, Swainson's thrushes head to Mexico, Central America or South America for the northern winter.

Our visitor last evening was a welcome sig…

The Cost of Extravagance

While human society seems to value some professions with little attention to their social importance, we cannot deny anyone the income that his/her talent and hard work may produce within a free and open market.  How that money is spent, on the other hand, has a significant impact on the welfare of society as a whole.

Though legal restrictions on the various forms of consumption would be inappropriate, one hopes that those with high incomes have a social conscience.  After all, the willingness of many wealthy individuals to support education, creative arts, community recreation, social services and environmental programs has long been vital to the welfare of urban and rural communities.

Yet, extravagance persists.  Massive homes, luxury-focused lifestyles, excessive personal consumption, outrageous galas and preferential treatment by both the political and private sectors have a negative impact on the welfare of human society and on the health of natural ecosystems.  Indeed, the great…

Recovery in Sight

As light snow continues to fall along the Colorado Front Range and overnight lows dip near twenty degrees F, the signs of spring are few and far between.  During our brief warm interludes, the lawns and pastures harbor the greenery of the season but the shrubs and deciduous trees remain barren.  By now, the pears, wild plums and crab apples should be in full bloom but flowering is limited to the grape hyacinths, dandelions and purple mustard.

Some summer birds, including cormorants, western grebes, bluebirds and tree swallows grace the Front Range but seem out of place in the snowy landscape; other summer songbirds have likely been stopped in their tracks or turned back by the wintery weather.  While April snowstorms are common in this region, the intense cold, courtesy of recurrent atmospheric troughs across the Intermountain West, has essentially put spring on hold; unfortunately, for areas to our east, these same troughs have directed severe thunderstorms and flooding rains across …

Bluebirds in Colorado

During the warmer months, generally from April through early October, Colorado hosts all three species of North American bluebirds.  Arriving in early-mid spring, they inhabit wooded meadows and ranchlands, nesting in tree cavities or man-made nest boxes.  Primarily insectivorous in spring and summer, they also consume berries, especially during the fall and winter months.

Western bluebirds are found from the Front Range urban corridor to the western canyonlands of Colorado, favoring open woodlands of the foothills and mountain parklands.  Mountain bluebirds, sky blue in color, inhabit the upper foothills and mountains and are often seen above timberline.  Eastern bluebirds, recent immigrants to Colorado are primarily found along the eastern edge of the State; however, they seem to be expanding that range along the South Platte and Arkansas River corridors and small numbers have turned up in Front Range towns and suburbs.

Eastern bluebirds that summer in Colorado winter across the Cen…

South Platte Crossroads

Granted a reprieve from our wintery spring weather, I decided to visit South Platte Park, a greenbelt of ponds, meadows and riparian woodlands along the South Platte River.  Like our weather over the past week, a mix of winter and spring was evident across that riverside preserve.

Many winter ducks, including buffleheads, lesser scaup and green-winged teal had yet to depart for the north, joining permanent residents such as mallards, gadwall, shovelers, common mergansers and wood ducks on the river and ponds.  They were also accompanied by a number of summer residents that now grace the valley; among this group were double-crested cormorants, western grebes, cinnamon teal and tree swallows.  Lesser yellowlegs, common migrants in Colorado, were also seen, feeding along the sandy shores.

As in most parts of our country, mid-April is a time of transition, when the signs of winter fade from the landscape and the greenery of spring begins to accelerate.  Unfortunately, due to our recent co…

Australia's Great Central Ranges

While the Great Dividing Range runs up the east edge of Australia and various highlands are scattered along its periphery, the Continent is dominated by flat terrain; there are certainly no ranges comparable to the Andes, the Rockies, the Alps or the Himalayas in Australia.  However, that has not always been the case.

Back in the Precambrian Era, about 1 billion years ago, a massive, snow-capped range was lifted across the center of Australia, stretching east to west; while erosion began to demolish this lofty range as soon as it formed, subsequent uplifts occurred 500 million years ago (MYA) and 300 MYA.  Today, the remnants of those orogenies, known as the MacDonnell Ranges, are a swath of relatively low ridges and hills (with maximum elevations below 5000 feet) that stretch for 400 miles across the southern edge of the Northern Territory, just north of Alice Springs.  Another great mountain range, the Petermann Ranges, crumpled skyward about 600 MYA and its residual swath of hills …

The Spanish Peaks

In southern Colorado, southwest of Walsenburg, two prominent cone-shaped peaks rise east of the Sangre de Cristo Range.  In light of other volcanic features throughout southern Colorado and northern New Mexico, one might think that these large mountains are extinct volcanoes.

In fact, the West and East Spanish Peaks were intruded as magma beneath the surface during the late Oligocene Period, some 25 million years ago.  Encased within Cretaceous and early Tertiary sediments, the massive plutons and their lateral dikes of cooled magma rose during the Miocene-Pliocene Uplift and have since been uncovered by the forces of erosion.  Similar Tertiary laccolithic mountains include the La Sal, Abajo and Henry Mountains of southeastern Utah.

The higher elevations of both mountains are now protected within the Spanish Peaks Wilderness Area; East Spanish Peak rises to almost 12,700 feet while the summit of West Spanish Peak is just over 13,600 feet.  Visible from great distances throughout south…

Iran's Subduction Earthquake

Yesterday's magnitude 7.8 earthquake in southeastern Iran, the most powerful in that country in more than 50 years, occurred near the Pakistan border in a region of complex plate tectonics.  Caught between the Arabian Plate, which is moving northward to collide with the Eurasian Plate, and the Indian Plate, which has been colliding with the Eurasian Plate for at least 55 million years, a fragment of oceanic crust, known as the Makran Wedge, is forced to subduct beneath the Iran-Pakistan border region.

The opening of  the Red Sea, which began about 40 million years ago, split the Arabian Plate from the African Plate.  This rifting extended eastward, forming the Gulf of Aden, about 20 million years ago, and southward through Africa to produce the East African Rift, which will eventually split that continent.  As the Red Sea and Gulf of Aden continue to open, the Arabian Plate is forced northward, closing both the Persian Gulf and the Gulf of Oman.  Caught between the Arabian and Ind…

Our Response to Terror

Following episodes of terrorism, as occurred at the Boston Marathon yesterday, we immediately empathize with those caught up in the tragedy.  In an effort to allay our own fear, we seek every detail of the event, glued to television and online reports, hoping to somehow understand the reason for the act and to learn that progress is being made toward arresting those responsible for the tragedy.

Our first instinct is to blame groups known to employ terrorism in order to advance their agendas.  As a result, we are quick to focus on individuals who, based on their race or nationality, invite suspicion.  In addition, we look for others to blame, including public officials who, in our minds, might have done more to prevent the tragedy.  While, in a free society, absolute protection from determined terrorists is impossible, we want to know that security failures somehow enabled the horrendous act.

Finally, and most tragic of all, we begin to accept limitations on our freedom that might prev…

Drought Tolerant Shrubs

In our effort to reduce water consumption, it is important to landscape our property with plants that do not require irrigation (i.e. plants that thrive with their natural allotment of rain and snow).  Plants native to one's home environment are thus the ideal candidates.

Here along the Front Range urban corridor, shrubs native to the Piedmont and lower foothills are used for natural landscaping; these include rabbitbrush, sand willow, chokecherry, serviceberry, sumac, Gambel oak, wild cherry, mountain mahogany, potentilla, junipers and others.  On our Littleton farm, we also have a wide variety of non-native, drought-tolerant shrubs; lilacs, wild plum, Oregon grape, spirea, Hibiscus syriacus (Rose of Sharon), cacti and a variety of roses thrive in the dry, sunny climate of Colorado.

In addition to their role in saving water, the above shrubs provide a diversity of color and attract a wide variety of wildlife.  By expanding shrub borders and using native grasses for limited lawn s…

Water & the Southwest

Faced with a persistent drought and a below-average snowpack, superimposed on our arid climate, those of us who live in the American Southwest need to develop a more realistic approach to our worsening water shortage; indeed, global warming is expected to dramatically accelerate the problem.

This year, Metro Denver has imposed water restrictions, limiting the irrigation of lawns to two days each week.  Yet, one wonders why we need to be watering lawns, parks, golf courses and sports fields at all.  None of these grassy oases are natural and none are vital to the welfare of human society.  While there has been a movement to plant drought tolerant grasses, shrubs and trees, there is no reason to permit unnatural watering of our landscapes; after all, we chose to live in this sunny, dry climate and we should be willing to accept the natural features of our arid ecosystem.

Beyond limited water use and conservation measures, attention must be paid to expanded housing, industrial developmen…

The Shrike and I

Earlier this week,  a spring snowstorm expected to arrive on the following day, I opted for a drive into the mountains west of Denver.  With no particular destination in mind, I ended up at Geneva Park, a subalpine parkland between the Mt Evans Massif and the Continental Divide.

Parking along a graveled road, I got out of my pickup to enjoy the magnificent scenery, the cool, fresh air and the sights and sounds of the high country.  Puffy clouds raced eastward against a clear, blue sky and faint showers of snow, blowing down from the Divide, swirled across the meadow.  Except for wind in the trees, an occasional jet drifting toward DIA and the distant calls of ravens, all was quiet in that remote valley.  Scanning the willows and forest edge with my binoculars, I soon discovered a northern shrike, perched atop a barren aspen tree.  Though surely an illusion, we seemed to be the only creatures within that vast mountain landscape.

Visiting balmy Colorado for the winter, he would soon ret…

Fossils & Catastrophe

While the fossils of aquatic plants and animals are often preserved at the bottom of lakes and oceans during the natural process of sedimentation, the fossils of terrestrial plants and animals often reflect the occurrence of a natural catastrophe.

Were it not for sudden events that rapidly bury the remains of terrestrial plants and animals, their components would be consumed by predators and scavengers, degraded by natural decomposition and scattered by the forces of wind and water.  The best fossils are thus found where catastrophe rapidly entombed the victim, whether dead or alive as that process unfolded.  Examples include flash floods, mudslides, avalanches, sandstorms or volcanic eruptions that encased the plants or animals in debris before predation or decomposition occurred.  Some of the most complete anatomic preservations were produced when an animal (mammoth, human) was suddenly enveloped in ice or snow, having succumbed to a blizzard or having fallen into a glacial crevasse…

Eolian Jurassic Sandstones

Three eolian (wind-deposited) Jurassic sandstones make a major contribution to the spectacular scenery of the Colorado Plateau.  These strata, initially emplaced as dune fields, have compacted into unique sedimentary rocks, cemented by heat and pressure over more than 150 million years.

The oldest of these is the Wingate Sandstone, deposited at the dawn of the Jurassic (about 200 million years ago); in most areas, it sits atop late Triassic redbeds of the Chinle formation.  The Wingate forms massive red cliffs with vertical striations, often giving it a curtain-like appearance.  Atop the Wingate, the Kayenta formation of horizontal siltstones, conglomerates and sandstone separates it from the second major eolian sandstone of the Jurassic, the Navaho Sandstone.  White to pale pink in color, the Navaho has horizontal striations and also forms prominent cliffs; however, it erodes into rounded domes, wavy ledges and curved slickrock formations, many of which are honeycombed and pock-marke…

Close but no Blizzard

As one who practiced inexact science for more than 36 years, I am always hesitant to criticize meteorologists when their forecast is less than completely accurate.  After all, there are many factors involved in making such forecasts and modern computer models, while steadily improving, are not infallible.  So, when, after days of warnings that Denver would be buried under a foot or more of snow and be faced with a raging blizzard, Winter Storm Walda passed through our region without the expected armageddon, I was not overly surprised.

The first clue that our official forecast might not be accurate occurred yesterday afternoon as severe thunderstorms, some tornadic, ignited in northeastern Colorado.  Pacific storms that generate heavy upslope snows in Metro Denver generally move eastward along the Colorado-New Mexico line and the brunt of their severe weather develops across the Southern Plains.  The central low of Walda and its associated energy was moving further to the north, taking…

The Mt. Evans Massif

Mt. Evans, 14,264 feet, the prominent mountain WSW of Denver, is actually the high point and centerpiece of a dissected mountain ridge that stretches north to south between the Clear Creek and North Fork Valleys.  This massif is connected to the Continental Divide by a high alpine ridge to its west, crossed by the Guanella Pass Road; the latter connects Georgetown, on I-70, with Grant, on US 285, and may be inaccessible in winter or after heavy snowstorms (Guanella Pass has an elevation of 11,669 feet).

Most of the Mt. Evans massif is protected within the Mt. Evans Wilderness Area.  During the summer months, the central peak and its fascinating alpine ecosystem can be accessed with the family car by taking Colorado 103 south and upward from Idaho Springs (on I-70) and then switching to the Mt. Evans Highway (Colorado 5), a toll road, at Echo Lake.  More adventurous visitors can hike into the wilderness from a large number of trailheads; the most popular begin at the Mt. Evans State Wi…

Front Range Cormorants

Double-crested cormorants have returned to Front Range lakes and reservoirs over the past week, among the earliest summer residents to arrive from their wintering grounds.  These large, dark-colored, aquatic birds may be seen alone when fishing but are generally encountered in flocks, especially at their roost and nesting sites.

Indeed, this most common and widespread cormorant in North America nests in colonies, usually placing their bulky nests in a grove of trees but sometimes directly on the ground.  They prefer islands or narrow peninsulas along lakes where, over the years, their copious guano kills the trees; once this occurs, the flock will choose another site or simply nest on the ground.  Feeding primarily on fish, cormorants are superb divers, equipped with heavy bones and reduced oil on their feathers; due to the latter trait, their plumage gets wet and they often perch on logs, islands, tree limbs or man-made structures with their wings spread to dry.

The interior populati…

The Nature of Coaching

Regardless of the sport, a successful coach is characterized by two essential traits.  The first is the knowledge to teach the fundamental skills and strategies that will lead to effective competition.  The second is the ability to prepare his or her players both physically and mentally for the challenges of their contest; the latter includes their vital role of instilling confidence in those they coach.

The abusive coaching tactics uncovered at Rutgers University were thus both inappropriate and counterproductive, a fact evident in that coach's won-loss record.  Unfortunately, as occurred at Penn State, administrators were reluctant to intervene, devoted more to the reputation of their institution and to the financial windfall of major sports than to the victims of abusive behavior; in both cases, this misguided approach magnified their losses.  Of course, if the abusive coaching behavior had been associated with a minor, non-lucrative sport, the coach would have been fired long …

The Hartville Uplift

Wyoming is a spectacular landscape of mountain ranges separated by broad basins.  While most of the uplifts, including the Laramie, Medicine Bow, Wind River, Owl Creek, Bighorn, Absaroka and Teton Ranges, are well known to travelers, skiers, hikers and naturalists, a less obvious geologic uplift stretches across eastern Wyoming.

Known as the Hartville Uplift, this geologic arch connects the Laramie Range with the southwestern edge of the Black Hills, in South Dakota.  Separating the structural Powder River Basin, to its north, from the Denver Basin, to its south, this subsurface ridge of Precambrian basement rock formed during the Laramide Orogeny, some 65 million years ago, when the Rocky Mountains crumpled skyward.  Paleozoic and Mesozoic sediments lying above the arch were lifted as well, producing a broad ridge which has since been dissected by streams and buried by erosional debris from the mountains.

Today, evidence of the Hartville Uplift is provided by outcrops of Pennsylvania…

Plant Behavior

Last evening, an episode of Nature on PBS purported to demonstrate that plants, like animals, exhibit behavior.  A range of examples included chemical communication between plants, chemical signaling between plants and their pollinators, chemical defenses used by plants, competition between plants for nutrients, sunlight and space, the symbiotic relationship between fungi and plants and the sharing of nutrients between various plants within an ecosystem.

For students of biology, the show was interesting but none of the data was surprising or  game-changing.  Whether plants manifest behavior depends on how we define that trait.  In many ways, plants communicate and compete at a level that compares with lower forms of animal life; though immobile, plants manage to locate food, defend themselves from predators, communicate stress and cooperate with other plants.  In neither case (plant or lower animal) are these forms of "behavior" conscious; rather, they demonstrate reflexive …

An Upslope Stream

For the past 24 hours, cool air, low clouds and light drizzle have enveloped Metro Denver.  These classic upslope conditions have resulted from cold high pressure to our northeast and an upper level low over the Southern Plains.

The latter has been pumping Gulf moisture northward and its counterclockwise winds have been directing this flow northwestward across the Great Plains.  In concert, a high pressure dome over southern Canada and the Dakotas has blocked the moisture flow into that region and its outer clockwise winds have been pushing it toward the Front Range.  As this atmospheric stream was forced to rise by the terrain of the High Plains and Rocky Mountains, it cooled further and condensed, producing the low clouds and steady drizzle in Denver and light snow in the foothills west of the city.

Consulting the radar, one could see this rather narrow band of moisture, moving northward across Oklahoma City and Wichita and then making a broad curve across central Kansas, southweste…

The Adaptable Bobcat

Native to North America, the bobcat evolved during the Pleistocene Ice Age and ranges from southern Canada to central Mexico; though extirpated from some regions of the U.S., they have since recolonized most States, adapting to human presence and to a wide variety of habitat.  The most abundant and widespread wild feline on our Continent, bobcats are found from forested areas to grasslands and deserts but prefer wooded areas with rock outcrops in which to den.

Solitary for most of their life, which averages 6-8 years in the wild, bobcats are highly territorial.  Their diet consists primarily of rabbits and hares but may include mice, game birds, squirrels, skunks, fox and small deer; they may also consume insects, amphibians and reptiles and are known to attack small livestock on occasion.  Mating generally occurs in late winter and the kittens (usually 2-4) are born in mid spring; as with most mammals (including some humans), the father is not involved with the young once fertilizati…

The Nature of Influence

From the moment of our birth, we are influenced by other humans.  During our first few years, that influence comes primarily from family and caretakers but, as we age, friends, teachers, cohorts, supervisors, advertisers, lovers, spouses, writers, speakers, mentors and, in some cases, strangers have a significant impact on our personal philosophy and behavior.

The tools of influence are highly varied but generally fall into the categories of reason, modeled behavior, reward and punishment.  Young children learn by mimicking their parents and siblings and readily respond to any praise that they receive.  By their teen years, reasoned discussion becomes much more important; if mutual trust, honesty and respect are part of the equation, influence is maintained.  By contrast, attempts to exert influence via threats or by imposing personal, unsubstantiated dogma are unlikely to be effective and will diminish one's opportunity to influence behavior.  Education broadens our exposure to f…