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Showing posts from June, 2013

Early Summer at Eagle Bluffs

Early to mid summer is often the least interesting time of year to visit Eagle Bluffs Conservation Area, southwest of Columbia.  The migrant flocks have moved on, the spring frenzy is beginning to fade and oppressive heat suppresses the daytime activity of its wild residents.  Nevertheless, this Missouri River floodplain refuge offers something of interest in any season.

Yesterday, we were greeted by a scissor-tailed flycatcher along the entry road, where mixed flocks of swallows, dickcissels and mourning doves perched on the powerlines.  Noisy killdeer families gathered on the drying fields while flocks of turkey vultures lounged on the levees, awaiting the late morning thermals.  Great blue herons and great egrets foraged in the shallows and a group of double-crested fished on one of the few deep pools.  Belted kingfishers, yellow-billed and black-billed cuckoos, northern harriers and wood ducks flew overhead as we drove through the refuge, which was adorned with the blooms of mulle…

Aggressive Young Men

We encounter them on a regular basis, especially on our highways.  They race up from behind, riding our bumper and flashing their lights, demanding that we move from their path.  Others weave among the traffic or speed along on their motorcycle, sans helmet.  Some appease their aggression by signing up with the military, by joining gangs or by participating in violent sports.  Unfortunately, many end up in prison, in brain injury centers or in our cemeteries.

Aggression in young males is a natural trait, reflecting the testosterone-fueled conflicts in our hominid ancestors. Driven away by their father (nature's effort to discourage inbreeding), young males had to fight for their own territories and assemble their own clans.  Those unable or unwilling to engage in confrontation were marginalized and their genes did not contribute to the tide of human evolution.

To succeed in the modern world, however, young men must keep their physical aggression in check.  Mentorship from fathers …

East to the Trees

Except for desert species, which are equipped with a deep tap root, a widely radiating root system, small transient leaves and twigs capable of photosynthesis (among other adaptations), deciduous trees generally need at least 20 inches of precipitation per year and grow in soil that is capable of absorbing and retaining that moisture.

Heading back to Missouri, yesterday, we first crossed the High Plains of eastern Colorado and western Kansas, where trees (mostly cottonwoods) are confined to the primary steam channels.  Lying within the rain shadow of the Rocky Mountains and located far from the Gulf of Mexico, the streams of the High Plains are often dry, running only after thunderstorm downpours or during the rapid melt of a heavy snowpack.  East of Wakeeney, Kansas, trees become more numerous, covering the main stream valleys and stretching up along the tributaries.  Further east, near Ellsworth, Kansas, forests begin to cloak the shaded, north-facing hillsides, where soil moisture …

The Evolution of Science & Religion

In order to survive, early man had to learn a great deal about his natural environment.  At the same time, his complex brain led him to imagine gods who protected him from the many dangers that he faced (storms, predators, drought, hostile clans) and who provided the means for his survival.  For most of human history (which covers 130,000 years), factual knowledge and religious mysticism were intertwined and both evolved in concert; indeed, ritual became an important element of human culture, a means to appease the gods that ensured our welfare.

The relationship between our factual knowledge of nature and our religious beliefs would remain unchanged until a scientific revolution spread through human civilization, some 500 years ago; this offered the means (the scientific method) to scrutinize the assumptions that governed our view of this planet, its life forms and the celestial bodies that fill its skies.  As the advance of science began to conflict with religious doctrine (especiall…

Brushpile Assassins

A pair of eight-spotted skimmers have been hunting at our brushpile over the past week.  Skimmers are a family of dragonflies and the eight-spotted species is native to western North America, from the High Plains to the Pacific Coast.

Like other dragonflies, eight-spotted skimmers are voracious killers, feasting on a wide variety of flying insects, including mosquitoes, flies, beetles, moths and butterflies.  They generally hunt from a perch, attacking prey as they pass overhead.  Nymphs, called naiads, crawl from ponds in late May or early June and molt to the adult form; the latter are active from June through mid August.  After mating in flight, the female releases her eggs into a pond, attaching them to submerged vegetation; once hatched, the nymphs, as voracious as their parents, feast on insect larvae, tadpoles and small fish.

Eight-spotted skimmers, like all dragonflies, play an important role in the control of harmful insect populations (especially mosquitoes).  While they may…

A Thistle Garden

In the wild corner of our Littleton, Colorado, farm is a swath of bull thistles.  Just common weeds to most suburbanites, worthy of immediate eradication with a sickle and/or herbicides, thistles are among our more successful immigrant plants, found from coast to coast.  Admittedly, their purple-pink flowers are not terribly showy and, in most species, their foliage is festooned with spines.

We naturalists, on the other hand, tend to view weeds as non-native wildflowers.  Thistles attract a wide variety of pollinators that feast on their nectar and goldfinches that favor their seeds and down, using the latter to line their nests; indeed, since both the seeds and the down are most abundant in mid-late summer, goldfinches nest much later than other songbirds.  This afternoon, a squadron of metallic green bees moved among the flower heads and a variety of beetles cruised along their stems, potential prey for the garter snakes that patrol our wild corner.  In recent years, lesser goldfinc…

Natural History of Sea Turtles

Turtles evolved in the Triassic Period of the Mesozoic Era, some 200 million years ago, a time when small dinosaurs and the first, shrew-like mammals also appeared.  It would not be until the Cretaceous Period (during the reign of T. rex), about 120 million years ago, that sea turtles evolved from their terrestrial ancestors.

Initially represented by four families, seven species of sea turtles survive today; all but one (leatherbacks) are in the same family.  Most are omnivorous but the green sea turtle is herbivorous, feeding on sargassum and sea grasses.  Among the others, some have unique dietary preferences; leatherbacks feed primarily on jellyfish while hawksbill sea turtles favor sea sponges.  All sea turtles, should they survive their gauntlet from the nest to the sea, do not become sexually mature for several decades; from that point on, females breed every 2-4 years, depositing 100 eggs or more in a beach sand nest.

Sea turtles are threatened by a wide range of natural and hu…

Stoking the Social Divide

Wealthy Americans have always enjoyed the benefits of their money (however acquired): expensive homes and cars, fine clothes and jewelry, gated communities and country club memberships have defined their lifestyle.  And few of us would deny their right to personal extravagance.

However, a variety of public agencies have recently expanded the benefits of wealth and, in the process, have stoked the social divide that defines American society.  Money now ensures reserved parking at mass transit stations, access to express lanes on urban highways and the opportunity to bypass crowds at airport security checkpoints; these are but a few of the social perks granted to wealthy citizens.

Mayors and other city administrators will argue that this convenience tax helps to fund a variety of urban projects.  While this may be true, it also highlights the fact that, even at the level of public services, social class has an impact.  When a small segment of society is able to bypass the trials of dail…

Summer Smoke

I awoke last night to the scent of wood smoke.  While that smell is inviting and nostalgic during the colder months, its presence on a mid June night is generally a cause for concern, especially in the arid environment of the American West.

Indeed, the source of the smoke was the Lime Gulch wildfire in the Front Range foothills, southwest of Denver.  Local authorities report that the fire was ignited by a lightening strike on Tuesday evening and spread yesterday in response to gusty winds from other storms in the area.  As is typical in summer along the Front Range, these thunderstorms produced copious wind and lightening but little rain.  Last night, a southwest breeze carried smoke from the wildfire onto the Colorado Piedmont.

This year's wildfire season has, to date, been especially severe in Colorado.  While arson may have played a role in the largest and most destructive fire (in the Black Forest), dry vegetation, hot weather and windy conditions have set the stage for more d…

The Bushtit's Cowbird

Over the past several days, I have observed an amusing yet disturbing relationship on our Littleton, Colorado, farm.  A tiny bushtit "parent" has been tirelessly racing among the shrubs and trees, followed by its demanding and much larger "offspring."

The bushtit, usually observed with its true relatives in active, twittering flocks, has been the victim of brood parasitism by a brown-headed cowbird.  The latter species, common throughout southern Canada and the contiguous 48 States, lays its eggs in the nests of other songbirds, relieving the cowbird parents of incubation and feeding duties and allowing them to produce multiple clutches of eggs throughout the breeding season.  This behavior gives them a significant competitive advantage and is obviously detrimental to the foster parent songbirds. Indeed, the aggressive cowbird nestlings, often larger than their nest mates, end up receiving most of the food delivered by the host parents and may actually kill the gen…

Lake Lahontan

During the Wisconsin Glaciation, the last glacial period of the Pleistocene Epoch, a large lake covered most of northwest Nevada, extending into southwestern Oregon and northeastern California.  Fed by the Truckee, Walker, Carson and Humboldt Rivers (in addition to numerous smaller streams), this pluvial lake, known to geologists as Lake Lahontan, covered 8500 square miles and had a maximum depth of 900 feet; only the mountain ranges of that region rose above the surface of the vast Pleistocene Lake.

The lake owed its existence to the cool, wet climate of the Pleistocene, when mountain glacial meltwaters increased dramatically and when evaporation was reduced by humid air and cloudy skies.  The extent of Lake Lahontan reached its maximum at the peak of the Wisconsin glacial melting, some 12,700 years ago, its former boundaries now marked by tufa limestone formations that were deposited in its shallows; then, as the climate began to warm, the lake began to shrink, eventually separating…

The Kuskokwim River

Second only to the Yukon among Alaska's Rivers, the Kuskokwim (which means slow-flowing) drains the remote southwest region of the State's mainland, far from the tourist sites and most populated areas.  Its North Fork rises along the northwest flank of the Alaska Range before angling southwestward to flow between that range and the Kuskokwim Mountains, to its north; the latter range angles northeast to southwest and has summits that are generally below 4000 feet.

After merging with its East and South Forks and several other tributaries, the Kuskokwim angles northwest to slice through the Kuskokwim Mountains, and then meanders across Alaska's vast Coastal Plain, coming within 50 miles of the Yukon River, to its north.  Resuming its southwestward journey, the Kuskokwim passes Bethel, the largest town along its course, and eventually empties into the Bering Sea within the Yukon Delta National Wildlife Refuge.

The primary channel of the Kuskokwim is 724 miles long while the No…

The Human Calendar

Humans evolved in East Africa about 130,000 years ago (almost 13.7 billion years after the Big Bang).  If we condense the history of our species into one calendar year, each month represents approximately 10,800 years and each day covers about 360 years.

With that calendar in mind, humans remained on the African Continent through early May; by the middle of that month, adventurous clans began to leave Africa, moving westward along the edge of the Red Sea and, perhaps, directly across its shallows when sea levels fell during the last Pleistocene glaciation.  By mid June, humans had reached Southeast Asia and, by mid July, some had crossed to Australia.  During August, our ancestors spread northward through the Middle East and also colonized Japan which, at that time, was a peninsula along the east coast of Asia.  Humans likely entered Europe by early September and had completely displaced Neanderthals in that region by early October.  Having spread into eastern Siberia by late October,…

Waxwings in the Mulberries

For the past few days, a flock of cedar waxwings has visited our Littleton farm, heading straight for the mulberry trees.  We have four white mulberry trees and one weeping mulberry; all produce copious fruit and thrive in the semiarid environment of the Front Range (since moving to the farm in 1990, I have never watered those trees).

The presence of the waxwings, as usual, was indicated by their soft, high-pitched whistles (as well as by the squabbling of robins that resented their competition).  While the truculent robins did their best to discourage the waxwings, the beautiful and tranquil visitors awaited their opportunity in nearby trees, dropping in to ingest a few berries when the robins were preoccupied.  At times, they would turn to flycatching from other trees on our property, returning to the mulberries when the robins moved on.  Indeed, while cedar waxwings prefer fruit, they supplement that diet with insects and flower petals during the warmer months.

Highly social, waxwi…

The Season of Needless Death

As the first major heat wave of the summer sweeps across the nation, we are beginning to hear about heat-related deaths, the great majority of which are preventable.  Unlike forecasts of winter storms, hurricanes and severe thunderstorms, which are taken seriously by the general public, warnings regarding excessive heat are, for some reason, largely ignored.

Young children and pets are left in closed vehicles, hikers head into desert canyons with insufficient water, public ceremonies or parades are scheduled in the heat of the afternoon, drill sergeants and football coaches downplay the risk of heatstroke and young athletes, convinced of their immortality, exercise in the mid day sun.  Despite the advice of physicians, meteorologists and other professionals, such behavior is repeated year after year and needless deaths occur.

After all, common sense is a common deficiency in human beings and our personal interests trump attention to preventive health recommendations.  Though our bodie…

A Distant Fire

Yesterday afternoon, Metro Denver baked under a relentless sun and clear blue skies.  The air temperature was 99 degrees F, the humidity was 4% and a gusty west wind produced the feel of a blast furnace.

I was thus surprised to see an apparent thunderstorm boiling up to our SSE, offering hope that our intense heat might soon be squelched by a line of storms.  Tuning into the Weather Channel to check the regional radar, the cause for the "storm clouds" was soon apparent; they were reporting on a large wildfire in the Black Forest, northeast of Colorado Springs, and footage from a news chopper showed a dozen homes engulfed in flames.  The Black Forest, named for the dark appearance of its ponderosa pines from the adjacent plains, owes its existence to its location on the Palmer Divide ridge (elevation 7500 feet), which receives upslope moisture from both the north and the south; an impermeable layer of sandstone, several feet below the surface also creates a reservoir effect, …

Blue Grosbeaks

Though rather uncommon in most areas, blue grosbeaks breed across the southern half of the U.S. and northward along the Atlantic Coast, through the Great Plains (including eastern Colorado) and across the Intermountain West.  They favor brushy fields, especially near riparian woodlands, where they feed on insects, seeds and berries; grasshoppers are among their favored prey.

Adult males, similar to but larger than male indigo buntings, are identified by their royal-blue plumage, heavy bill and chestnut colored wingbars; they often sing from fenceposts or the top of saplings, wagging and spreading their tail in the process.  Females are rather nondescript, brownish birds but have pale blue feathers at the base of their tail; yearling males sport a mix of blue and brown plumage.

The nests of blue grosbeaks, frequently parasitized by brown cowbirds, are generally placed in shrubs or small trees and are lined with a variety of vegetation, human trash and snake skins.  Despite cowbird para…

New Mexico's Bootheel

While avid American travelers are familiar with many regions of our country, few have likely been to the Bootheel of New Mexico.  Part of a mountainous swath between the Chihuahuan Desert, to the east, and the Sonoran Desert, to the west, this remote, southwest appendage of the State consists of three north-south trending mountain ranges, separated by valleys of desert grassland.

The easternmost of the three ranges consists of the Little and Big Hatchet Mountains; the latter forms the southern end of the range and contains the higher summits (including Big Hatchet Peak, 8356 feet).  West of the Hatchets is the Playas Valley traversed by Highway 81; the valley floor has an elevation of 4200 feet.  Running down the center of the Bootheel, on the west edge of the Playas Valley, are the Animas Mountains, representing the southernmost leg of the Continental Divide in the United States; Animas Peak, the summit of this range, has an elevation of 8565 feet.  West of the Animas Mountains is An…

South Platte Summer

Summer now envelops South Platte Park, in Littleton, Colorado.  While most of the activity was concentrated along the River and its floodplain lakes during the colder months, winter flocks have departed for the north and the riparian woodlands have come alive with the color and sound of our fair weather songbirds.

The ponds and lakes now attract double-crested cormorants, pied-billed grebes and permanent waterfowl such as mallards, gadwalls, common and hooded mergansers, wood ducks and Canada geese.  Non-breeding white pelicans and western grebes also grace the pools and stragglers, including shorebirds and white-faced ibis, still visit the Park.  Killdeer and spotted sandpipers feed along the mudflats while beaver and muskrats ply the open waters or mend their homes.

The woodlands and meadows harbor a mix of noisy and colorful summer birds, including yellow warblers, yellow-breasted chats, common yellowthroats, house wrens, gray catbirds, western wood pewees, northern orioles, easter…

The Rivers of Yellowstone

Yellowstone National Park covers a massive volcanic plateau in northwestern Wyoming; slivers of the Park also extend into southern Montana and eastern Idaho.  This plateau, which has an average elevation of 8000 feet, is sculpted by a vast network of streams which, ultimately, feed two of North America's largest watersheds.

The Yellowstone River, a major tributary of the Missouri, rises in the Absaroka Mountains near the southeast corner of the Park.  Flowing NNW, it enters Yellowstone Lake and then drains that large body of water, dropping through its Upper and Lower falls and carving spectacular canyons before reaching southwestern Montana.  The Lamar River drains the northeastern corner of Yellowstone, rising in the Absarokas and flowing westward to merge with the Yellowstone River near the northern boundary of the Park.  The Gallatin and Madison Rivers rise in their respective ranges in the northwestern corner of Yellowstone, flowing northwest into Montana where they join the …

Front Range Storm Watching

As debates rage over the benefits and risks of storm chasing, whether for science, business or personal excitement, most of us prefer to observe severe weather from a safe distance.  Our Littleton, Colorado, farm sits on the west wall of the South Platte Valley and offers a broad view to the southeast, a great vantage point for watching the massive thunderstorms that roam the High Plains.

From late May through August, afternoon thunderstorms build above the Front Range and, by late in the day, drift eastward across the urban corridor and onto the plains.  While they may drop brief heavy rain and hail on the Piedmont, they are not generally severe close to the mountains.  Rather, they begin to grow east of the Front Range cities, drawing in heat from the surrounding plains; their pearly white thunderheads, towering 50,000 feet or more, reflect the sun as it drops behind the Rockies.  As the skies darken, spectacular lightening displays flash along the eastern horizon, many generated hu…

A Dry Upslope in Colorado

It was chilly and overcast across eastern Colorado yesterday.  Checking the weather satellite, one saw that the eastern half of our State was cloud covered while the western half basked in sunshine.  Yet, no rain was falling beneath those clouds.

The reason for the dryness was evident on the water vapor imagery which demonstrated a lack of moisture across the High Plains.  The upslope, produced by high pressure to our north (creating clockwise winds) and low pressure to our south (producing counterclockwise winds), pushed the relatively dry air toward the Front Range.  As it rose, the air cooled and the moisture condensed as a cloud layer; while fog and drizzle likely developed in the upper foothills and lower mountains, the Piedmont and High Plains remained dry.

On the satellite image, one could see a dramatic demarcation where the Front Range blocked any further westward advance of the upslope-induced clouds.  While the upslope flow dropped afternoon temperatures into the fifties (F…

The Crazy Mountains

Endowed with one of the more colorful names in the North American landscape, the Crazy Mountains are one of the isolated ranges that rise in western Montana, north of Yellowstone National Park and east of the Continental Divide; in combination with the Absaroka Mountains, to their south, and several other ranges to their north, the Crazies are part of "Montana's Front Range", rising above the Great Plains to their east.

Known for their rugged beauty, scenic glacial valleys and numerous alpine lakes, the Crazy Mountains rise NNE of Livingston, between the Musselshell (to their north) and Yellowstone (to their south) River Valleys.  Geologically, the Crazies are a cluster of igneous intrusions that pushed into older sediments about 50 million years ago (15 million years after the Laramide Orogeny, the formation of the primary Rocky Mountain Chain); the encasing sediments have since eroded away and Pleistocene mountain glaciers sculpted the spectacular peaks and valleys.  T…

Love & Fear

It seems to me that humans are primarily motivated by two emotions: love and fear.  As young children, before we ponder such things, we love those who provided what we need and fear separation from their comfort and attention.  By our turbulent teens, we strive to impress those we love and, while we pretend to shun their advice, we fear that we will not meet their expectations.

As young adults, romantic love often impacts our life though the fear of failure, of not achieving the goals that we and others have set for ourself, balances the reckless nature of romance.  Come middle age, as love of family and devotion to career complicate our lives, an increasing awareness of our own mortality instills pragmatism, demanding close attention to matters of health and finance.  Finally, in the last stage of life, we gain perspective and, if we have the mental capacity to do so, are apt to ponder how love and fear governed our life.

Many of us will have to admit that fear had too much influence…

Kites over Central Kansas

On my journey across the Great Plains yesterday, I encountered a pair of Mississippi kites, cavorting above a field near the Solomon River, in central Kansas.  While I had never seen these raptors so far north, they have been expanding their range across the Southern and Central Plains and individual wanderers have been documented across the northern U.S. and southeastern Canada.

The breeding range of the Mississippi kite extends from Kansas and southeastern Colorado southward to northern Texas and Oklahoma; they also breed across the Coastal Plain from southeastern Missouri to east Texas and eastward to the Carolinas.  Though not generally found on the southern peninsula of Florida, isolated colonies of Mississippi kites have been discovered in the Desert Southwest.  All spend the northern winter in central South America and they may be seen in large flocks during migrations.

Unlike most raptors, Mississippi kites feed exclusively on flying insects, such as dragonflies and cicadas. …

Into Drier Country

Heading back to Colorado this morning, I left Columbia under a gray overcast and drove west through a verdant but soggy landscape.  Floodwaters stretched across the Missouri River valley and several of its tributaries (especially the Lamine River and Davis Creek) enveloped their floodplains as well.  Following two weeks of intermittent, heavy rain, I was more than ready for the dry, sunny weather of the American West.

The overcast began to break up near Lawrence, Kansas, and, west of Junction City there was more blue sky than cloud cover.  As in western Missouri, the foliage of eastern Kansas was thick and green and its rivers and farm ponds were bank-full.  West of Salina, however, the greenery began to fade and, on the sun-drenched High Plains, the smaller rivers and farm ponds remained dry; indeed, the recent storms that produced flooding across the Southern Plains and Midwest bypassed the High Plains and drought persists in that region.

Of course, the High Plains, far from Gulf of…