Saturday, June 29, 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 mullein and showy milkweed.  Highlights included a group of red-headed woodpeckers in a drowned grove of trees and a lone black-necked stilt that flushed from a roadside marsh.

Some might ignore nature preserves during "non-productive off-seasons," confining their visits to the spring and fall migrations.  But naturalists know that we cannot truly appreciate natural ecosystems unless we visit them throughout the year, witnessing the complex cycle of life that they harbor and protect.

Friday, June 28, 2013

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 (or their male surrogates) is vital in this regard and those deprived of their discipline and influence are more likely to suffer the consequences of aggressive behavior.  With all due respect to, and admiration for, single mothers (victims, themselves, of irresponsible males), highly involved fathers play an essential role in the development of young men.

Thursday, June 27, 2013

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 is protected from solar evaporation; by the time one reaches the longitude of Junction City, now well within the Gulf of Mexico moisture plume, woodlands grow on south-facing slopes as well.

The thin, rocky soil of the Flint Hills, between Junction City and Topeka, discourages tree growth; prairie grasslands cover the ridges and riparian woodlands are confined to the stream valleys but the topography of these Hills, in comparison to the flat terrain of the High Plains, attests to the greater annual precipitation in this region.  Finally, in eastern Kansas and throughout Missouri, forests dominate the landscape, broken primarily by human environments (urban/suburban developments and cleared agricultural fields); thanks to Gulf of Mexico moisture, pumped northward ahead of advancing storm fronts, the southern Midwest receives about 35 inches of precipitation each year (compared to 10-12 inches across the High Plains).

Tuesday, June 25, 2013

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 (especially in the fields of astronomy, geology and evolutionary biology), the gap widened and powerful religious organizations launched efforts to derail scientific progress.  Despite their attempts, our scientific knowledge has continued to advance while religious doctrine stopped evolving centuries ago.

Yet, the war between science and religion persists and scientific education is threatened, especially at the grade school and high school levels.  Many humans gladly accept the benefits of modern science (especially in the fields of medicine and technology) while retaining religious beliefs that offer a simplified version of natural history and of our place in the Universe.  Whether humans evolve beyond our need for religion remains to be seen; for now, fear, guilt, ignorance and political pressure ensure its potent role in human society.  

Monday, June 24, 2013

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 provoke fear in children and hysterical adults, these assassins pose no danger to humans and should be welcomed at our gardens, brushpiles and ponds.

Sunday, June 23, 2013

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 goldfinches, common residents of foothill canyons, have been nesting on our property; no doubt, our substantial thistle crop encourages their annual return.

While invasive, non-native plants can have a negative impact on natural ecosystems, most common thistle species do not warrant eradication.  Besides, the herbicides used to control such "weeds" generally do more harm than the plants themselves.  We intend to keep our thistle garden, which thrives in the semiarid climate of the Front Range urban corridor.

Saturday, June 22, 2013

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 human-induced factors, including loss of nesting habitat, predation, pollution and collisions with boats.  Most hatchlings never reach the sea; eggs are consumed by humans, raccoons and coyotes and the young are picked off by vultures, mammalian predators and a variety of sea birds.  Once in the sea, others are consumed by sharks or large fish; while adult sea turtles have long been hunted by humans, that practice has decreased due to modern conservation programs.  Yet, the adults remain threatened by chemical pollution of our oceans and by the trash (especially plastic) that is dumped from ships or swept from our coastal towns and cities.  On land, adult females may also be killed by humans or other large predators (primarily dogs, coyotes and jaguars).

Friday, June 21, 2013

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 daily life, they lose empathy for the problems faced by the middle and lower classes and are less likely to support policies or legislation designed to deal with those problems.  In my opinion, the benefits of wealth should not extend to the public sector.

Thursday, June 20, 2013

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 devastation.  As vital as wildfire may be to the welfare of forest and grassland ecosystems, human habitation of those regions comes with the risk of tragedy, especially during periods of drought.  For their sake, let's hope that the summer monsoon and the autumn snows arrive early this year.

Tuesday, June 18, 2013

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 genetic offspring (actively or passively) in the process.  The populations of some native songbirds have been significantly threatened by cowbird parasitism; while some species recognize the cowbird eggs and either discard them or abandon the nest, female cowbirds are capable of laying up to forty eggs per season.

As a naturalist, I accept the fact that the doting bushtit and the aggressive cowbird fledging are merely responding to their natural instincts.  Indeed, evolution has been driven by competition and natural selection; nature neither displays favoritism nor rescues the victims of her complex web of life.  Still, I must admit feeling sorry for the bushtit and know that, if she survives her ordeal, she will be relieved when the cowbird departs to join its true relatives.

Monday, June 17, 2013

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 into a maze of smaller basin lakes.  Today, most of those lakes have dried up, leaving playas or "sinks," where their feeder streams disappear into the Great Basin desert; Pyramid Lake and Walker Lake are now the only remnants of Lake Lahontan.  Pyramid Lake, fed by the Truckee River (which flows down from Lake Tahoe), was the deepest segment of Lake Lahontan.  Recently, this lake, NNE of Reno, was found to harbor a remnant population of Lahontan cutthroat trout; thought to have become extinct, it is the largest species of trout native to North America.

While Lake Lahontan, like Lake Bonneville in Utah, formed during the Wisconsin Glaciation, there were predecessors of these vast meltwater lakes during earlier glacial periods of the Pleistocene.  Assuming that the current Holocene Epoch is just another warm interglacial period of the Quaternary, the glaciers and the Great Basin lakes will, from the perspective of geologic time, soon return.

Sunday, June 16, 2013

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 North Fork, its longest tributary, is 250 miles long; together, they represent the longest free-flowing river in the United States.  While secondary and tertiary tributaries rise in high terrain, the entire course of the Kuskokwim and its North Fork runs below an elevation of 1600 feet.  Renowned for its fishing, this wide, braided river, like the Yukon, connects the varied ecosystems of Alaska, home to a fabulous diversity of wildlife.

Saturday, June 15, 2013

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, humans crossed the Bering land bridge in early November, entering North America; by late November, they had colonized South America as well.

As December dawned, most humans were giving up their nomadic lifestyle and began to establish permanent settlements; we had just domesticated the dog, which offered companionship, protection and assistance with hunting.  Within the first week of December, we also domesticated goats, sheep, cattle and pigs; the domestication of horses, donkeys and camels would occur during the second week of that month (see Domestication of Animals).  The ancient Egyptian Civilization arose sometime on December 17, the first Chinese Dynasty began on December 20, Polynesian exploration of the South Pacific got underway on December 21, Ancient Greek Culture took shape on December 23 and the Roman Empire arose on December 25.  Polynesians reached New Zealand sometime on December 28, European Colonialism commenced on December 30 and both the American Revolution and European colonization of Australia would occur on the last day of our calendar year.

Friday, June 14, 2013

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, waxwings move about in flocks, turning up to feast on berry crops when the fruit becomes available; though the mulberries are not yet ripe enough for my taste, the robins and waxwings don't seem to mind.  Cedar waxwings breed across southern Canada and the northern half of the U.S., shifting southward in winter when they roam across the U.S. and Mexico.  Reflecting their sociable nature, these mild-mannered birds generally nest in colonies; unlike many songbirds, they are relatively immune to cowbird parasitism since the cowbird nestlings cannot survive on the high fruit diet that the waxwings feed to their young.

Thursday, June 13, 2013

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 bodies, which evolved in the tropics, are designed to dissipate heat, there is a limit to that capacity and prolonged exposure to or physical exertion in severe heat can be fatal, especially when shade and water are in short supply.  It is ironic that the most intelligent species on planet Earth is the one most likely to die from heat exposure; less intelligent animals know better.

Wednesday, June 12, 2013

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, retaining soil moisture that is sufficient to support the pine forest.

Unfortunately, due to the prolonged drought in southeastern Colorado, the Black Forest has been ripe for a wildfire and this week's hot, dry, windy weather only aggravated the conditions.  While the cause of the fire, some 60 miles SSE of our Littleton farm, remains uncertain, there were no thunderstorms along the Front Range at the time of its development; indeed, the massive plume from the wildfire produced the only image on the radar.  Wildfires, destructive as they may be, play an important role in the health of many natural ecosystems; however, when they are man-induced, their effects are especially tragic.  As of this morning, 60 homes have been lost.

Tuesday, June 11, 2013

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 parasitization, the population of blue grosbeaks appears to be stable in most regions and, as noted above, their summer range continues to expand northward.  Come September, these open country residents head for Mexico, Central America and the Caribbean.

Monday, June 10, 2013

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 Animas Valley, traversed by Route 338 and having a floor elevation of 5000 feet.  On the west edge of this valley are the Peloncillo Mountains that run along the New Mexico-Arizona line; this range has relatively low relief, reaching a maximum elevation of 6928 feet at Gray Mountain.  The Animas and Peloncillo Ranges continue into northern Mexico, eventually merging with the Sierra Madre Occidental.

All three of the New Mexico Bootheel ranges have complex geology, composed of both fault blocks and volcanic deposits.  The fault blocks, produced by regional stretching of the crust, contain Precambrian, Paleozoic and Mesozoic strata; these blocks and the associated volcanism developed during the Oligocene and Miocene Periods (30-20 million years ago).  The valleys, which warped downward as the mountains rose, held lakes during the cool, wet Pleistocene but are now crossed by seasonal streams, fed primarily by mountain springs and monsoon rains.  The higher summits of the ranges (especially in the Animas and Big Hatchet Mountains) act as sky-islands, home to a surprising diversity of flora and fauna, including many Mexican bird species during the warmer months.

Sunday, June 9, 2013

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, eastern and western kingbirds, blue-gray gnatcatchers, broad-tailed hummingbirds and lesser goldfinches, joining the permanent residents.  Red-winged blackbirds call from the cattails, tree and barn swallows strafe the ponds, great blue herons and snowy egrets stalk the shallows and a variety of raptors, including red-tailed hawks, Swainson's hawks, Cooper's hawks, great horned owls, American kestrels and an occasional bald eagle, patrol the refuge.  At dawn or dusk, visitors may also encounter mule deer, red fox and coyotes at South Platte Park.

Saturday, June 8, 2013

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 Jefferson River to form the Missouri.  Finally, the southwestern region of the Park is drained by the Upper Snake River and its tributaries; the latter include the Lewis River, which connects Shoshone and Lewis Lakes before continuing southward to the Snake and the Heart River, which leaves Heart Lake and flows southwestward to the Upper Snake River.  The Continental Divide winds through Yellowstone, separating the rivers that flow into the Missouri River Watershed (the Yellowstone, Lamar, Gallatin and Madison Rivers) from the Snake River tributaries which are part of the Columbia River Watershed of the Pacific Northwest.

While these rivers are vital to the ecology of Yellowstone National Park, they also serve as important migration corridors for resident herbivores and the predators that follow those herds.  As winter sets in, herds of bison, elk, mule deer and pronghorn leave the high plateau, traveling through the river valleys on their way to lower, more sheltered grasslands; come spring, their trek through these natural corridors is reversed as the herds take advantage of the short but verdant summer atop the Yellowstone Plateau.

Friday, June 7, 2013

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 hundreds of miles away.

While the incidence of tornadoes across the Southern Plains and Midwest peaks in May, tornadic thunderstorms are most common in June across northeastern Colorado; Weld County seems to be their favored target.  Safely ensconced near the mountain barrier, those of us in the Front Range cities can enjoy the beauty and power of these summer storms while, in most cases, avoiding the damage that they produce.

Thursday, June 6, 2013

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) across Metro Denver, the humidity in that air was too low to trigger precipitation.  Given the fact that the cloud deck was at least 2000 feet above the city, one can assume that the dew point was in the forties, at most.  By evening, as the upslope began to dissipate, clearing developed to our west and the loss of cloud cover overnight enhanced radiative cooling, dropping our morning low into the forties.  As winds shift from the northwest (downsloping across the urban corridor), warm and sunny conditions will prevail today.

Wednesday, June 5, 2013

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.  The volcanic Absaroka Range forms a high wall to their south, topped by Granite Peak (12,804 feet, the highest point in Montana).  Crazy Peak, 11,214 feet, forms the summit of the Crazy Mountains, which are easily viewed from I-90 (south of the Crazies), from US 191 (to their east) and from US 89 (to their west).

While conservationists have pushed for establishing a Wilderness Area in the Crazy Mountains, most of their lower slopes are privately owned and public access is relatively limited; three National Forest campgrounds serve as the primary trailheads.  Among the varied alpine wildlife are mountain goats, introduced to the Crazies in the 1940s; black bear inhabit the range but there is no known resident population of grizzlies in this isolated cluster of jagged peaks.

Tuesday, June 4, 2013

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.  We will acknowledge that our risk tolerance was deficient, that, at times, we were afraid to live, foregoing opportunities, adventures and relationships that may have enriched our life.  Better that we allow love to take control: love of self, love of those close to us and love of life itself.

Monday, June 3, 2013

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.  Agile in flight, they resemble falcons and, like the latter, often make high-speed dives in pursuit of their prey.  While they hunt in open country, these colonial birds nest in riparian woodlands, building a shallow bowl of sticks; two eggs are usually produced and both parents share incubation and feeding duties.  Like common nighthawks, Mississippi kites depart early in the fall, generally heading for South America by mid September.

Sunday, June 2, 2013

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 Mexico moisture and lying in the rain shadow of the Rocky Mountains are always relatively dry.  That semi-arid ecosystem, heavily utilized for cattle ranching, does not receive adequate annual precipitation for crop production; the latter is dependent on the use of irrigation systems, drawing water from the underlying Ogallala Aquifer or from reservoirs along major rivers.  While acknowledging the hardships produced by the ongoing drought, the sunny skies and dry air were certainly welcome today; to borrow a phrase from America's 1972 hit, "it felt good to be out of the rain."