Wednesday, April 1, 2015

A Failure to Evolve

We humans have inhabited Earth for at least 130,000 years.  In the course of our history we have spread across the planet, established vibrant cities, developed effective means of global transportation, created technologies to advance communication, healthcare and agriculture, harnessed energy from wind, sun, rivers, uranium and fossil fuels, explored near space and sent probes toward distant planets and galaxies.  While much of our activity has threatened the welfare of Earth's natural ecosystems, we have, in many cases, been able to utilize the same scientific discipline to repair the damage.

Unfortunately, while most humans benefit from the achievements of mankind, only a small minority understand the science that underlies that progress.  Worse yet, the great majority of humans retain mythologic belief systems that cause them to question the validity of science; furthermore, those beliefs tend to foster zealotry and tribalism which impede cooperation and incite conflict.

As a result, most of the resources that might be devoted to cultural development, education and scientific research are directed to politics, intelligence services, military programs and other non-progressive endeavors.  The hope that we might evolve into a more enlightened species, not subject to intolerance, discrimination and warfare, is all but dashed by persistent mythologies that first took root in the creative but science-naive minds of our distant ancestors.  When a species fails to evolve, it is on the road to extinction and we humans are not immune to that reality.

Monday, March 30, 2015

Grasshoppers in March

We generally associate the presence of Orthopterans (grasshoppers, crickets, katydids) with hot summer days and balmy August nights.  However, some species may be encountered in early spring, especially during periods of warm weather.

Following a week of summer-like conditions along the Colorado Front Range, small grasshoppers are abundant on our Littleton farm.  While most species overwinter as eggs and do not emerge until late spring or early summer, some species winter as nymphs, one of several intermediate stages between the egg and adult forms.  Unlike many insects, Orthopterans mature through incomplete metamorphosis; during the nymph stages they have the appearance of miniature adults and molt as they grow.

Grasshoppers encountered in early spring are those species that winter as nymphs, sheltered from the cold in leaf litter or other plant debris.  Fortunately, these species, while providing an important source of food for a variety of birds and mammals, do not damage cultivated plants and crops.

Sunday, March 29, 2015

First Swallows

Tree swallows spend the winter along the Gulf Coast, across Florida or in Mexico, much farther north than their cousins (barn, cliff, bank, violet-green and rough-winged swallows).  As a result, they arrive on their summer breeding grounds much earlier, generally by mid-late March.

Yesterday, I observed a small flock of tree swallows at South Platte Park in Littleton, Colorado, the first I have seen this season.  Strafing clouds of midges that hovered above the ponds, the swallows had likely hitched a ride on recent southerly winds that brought summer-like weather to the Front Range.  Soon they will pair off and locate a cavity (in a tree or nest box) in which the female will build a nest of dried vegetation.

Arriving in Colorado well before the end of our snow and ice season, tree swallows risk annihilation of their primary food source.  Fortunately, these aerial insectivores can expand their diet to include other invertebrates or plant material if necessary.  Nevertheless, one must admire their courage and optimism, even if it is instinctual.

Saturday, March 28, 2015

Mental Illness & Public Safety

This week's air tragedy in France was apparently the result of an unrecognized or unreported mental illness in one of the pilots; that failure led to the death of the afflicted individual and 149 other passengers and crew members.  While the perpetrator had sought medical attention for his condition, its ramifications were clearly not dealt with in an open, thoughtful and honest manner; initial reports suggest that airline executives were unaware of his diagnosis.

Similar tragic episodes have occurred in the military, in other industries and in society as a whole.  Due to our inability to accept the nature of mental illness, on a par with heart disease, diabetes and other human maladies, we are less willing to openly discuss its varied presentations or report our observations to mental health professionals.  We don't want to stigmatize relatives or friends with such a diagnosis and suspect that it might jeopardize their career;  unfortunately, this fear is too often confirmed by the actions of employers.  Finally, patient privacy laws may get in the way of effective communication; too often, public safety is ignored.

Mental illness is a biochemical, neuropsychiatric disorder; it is not a personal weakness, a demonic possession or the manifestation of mythological forces and, in most cases, it can be effectively treated with a combination of medications and psychotherapy.  Yet, if not recognized or properly addressed it may lead to tragic consequences for the patient and others.  As a society, we must commit ourselves to dealing with mental illness in a humane, thoughtful and effective manner without jeopardizing the safety of family, friends and the public at large.  (see also Human Society & Mental Illness)

Friday, March 27, 2015

Reading Outside

I often read outside, especially on calm, mild, sunny days.  Sometimes I take a nature magazine or a medical journal but it's usually the latest novel or collection of short stories recommended by my wife or a friend.  However, though my intentions are sincere, I generally end up behaving like an unfocused schoolboy, easily distracted by the natural surroundings.

Yesterday afternoon, I made it through two short chapters before a Townsend's solitaire began calling from the top of a juniper.  Then it was a spotted towhee scratching beneath the pinyon pines and the noisy flocks of Canada geese that circled overhead.  Setting my book aside, I got up to ramble through the farm,  taking notice of the early spring color provided by wild cherry shrubs, dandelions, grape hyacinths, periwinkle, clumps of blue scilla and the expanding greenery itself.  Cottontails darted across the pastures, robins hunted worms and insects on our patches of "lawn," the Mesozoic form a a great blue heron flapped overhead and northern flickers hammered away on dead limbs or belted out their hysterical calls.

Once again, the joy of outside reading proved to arise more from the location than the activity.  I'm sure I'll keep trying but late evening, indoor efforts will surely be far more productive (not that my time was wasted!).

Thursday, March 26, 2015

A Brief Intense Upslope

After a warm, sunny week, yesterday dawned cool and cloudy along the Colorado Front Range; periods of light drizzle moistened the pavement and the temperature hovered in the mid thirties (F).

Then, about 10 AM, flurries appeared in the air and, within15 minutes, intense snowfall enveloped our farm; two inches fell over the next 90 minutes, coating the trees, shrubs and grass but melting on the warm pavement.  By noon, the show was over and patches of blue appeared in the overcast.

Such brief periods of intense snow are not unusual along the Front Range urban corridor, especially in March and April.  As an unruly jet stream steers cold fronts down from the northwest, northeast winds just behind the front shove moisture from the Great Plains toward the Continental Divide.  Rising with the landscape, the air cools and condensation occurs, often producing bands of intense snow comparable to lake effect snows of the Great Lakes region; as the cold front moves off to the east, the upslope band shifts southward, eventually dissipating along the Palmer Divide beyond which the air flow is forced to descend, warm up and dry out.

Wednesday, March 25, 2015

Our Fickle Bushtits

The bird population on our Littleton, Colorado, farm is typical of other properties in the Temperate Zone of Western North America.  We host permanent residents, summer and winter residents, seasonal migrants and intermittent visitors such as Canada geese and cedar waxwings.  But one species is especially fickle, inhabiting the farm for extended periods of time and then disappearing for weeks or even months.

Common bushtits are small, long-tailed, highly social insectivores of the Western U.S. which prefer wooded scrublands, pinyon pine woodlands and suburban parks; they have cousins in Eurasia but are the only member of their family in North America. Twittering as they comb trees and shrubs for active or hibernating insects and spiders, bushtits often forage with chickadees and nuthatches.  Should one pair build their sock-like nest and deposit eggs, the entire flock joins in the incubation process, huddling together through the chilly western nights.

The flocks on our farm vary from a half dozen to fifteen or more individuals and may appear during any season of the year; they generally move in for a few weeks and, unless nesting has occurred, depart for a variable period of time.  I hesitate to call them visitors; rather, our farm seems to serve as their second home, one they utilize on no particular schedule.

Tuesday, March 24, 2015

The Sixth Mass Extinction

Those who study the natural history of our planet have identified five mass extinctions since the dawn of the Paleozoic Era (see Earth's Mass Extinctions).  Worldwide fossil records confirm these events, all of which reset the structure of life's evolutionary tree.

More controversial is the conviction of many biologists that we have entered the Sixth Mass Extinction on Planet Earth, one triggered by the activities of humans.  While life has colonized our planet for 3.6 billion years, humans (Homo sapiens) have roamed its surface for less than 140,000 years; for almost half that time, our species was confined to the African Continent and, for more than 95% of our history, we had little impact on the natural ecosystems of Earth.

Within the last 10,000 years, however, urbanization, cultivation, domestication, exploration and industrialization have had dramatic effects on our home planet and on the other life forms that inhabit its varied marine and terrestrial landscapes.  Spurred on by our uncontrolled population growth, we have destroyed natural habitats, polluted land, air and water, extirpated species via overhunting and overfishing and have significantly augmented global warming with all of its potential ramifications.  Of course, unlike other species, we also threaten our planet and our own welfare with global pandemics and nuclear conflict.  While we have the means to derail the Sixth Mass Extinction, one wonders if we humans, fueled by tribalism, greed and religious zealotry have the will to do so.

Monday, March 23, 2015

Cabbage Whites

Looking across our Littleton, Colorado, farm yesterday afternoon, a dozen or more cabbage whites fluttered amidst the greening landscape.  Generally the first butterflies to appear each spring and among the last to be seen in autumn, these small butterflies may be observed as early as February if warm spells envelop the Front Range.

Cabbage whites are off-white to pale yellow in color and bear black spots on their wings; females have two spots while males have one.  Emerging from cocoons in spring, the adults soon mate and females lay eggs on plants of the mustard family (including wild mustard, cabbage and radishes); the eggs hatch to release voracious caterpillars which later pupate to yield the next generation of adults.  In addition to their parenthood role, adults feed on nectar and pollinate a wide variety of wildflowers.

Natives of the Old World (Eurasia and Africa), cabbage whites were introduced in Quebec, Canada, in the late 19th Century and have since spread across most of North America, becoming one of our most abundant butterflies.  Their long period of activity (February to November in some years) and the abundance of their food crops account for their rapid dispersal across the Continent despite predation by bats, toads and a host of avian insectivores/omnivores (especially jays, bluebirds, mockingbirds and house sparrows).

Sunday, March 22, 2015

The Casiquiare Connection

We humans have long dug canals to connect watersheds, thereby improving irrigation or shortening navigation routes.  Examples range from small regional projects to the construction of massive channels that require locks and dams to permit river transport.

While natural connections between watersheds are relatively rare, the Casiquiare Canal in southern Venezuela offers a spectacular example.  Bifurcating from the Upper Orinoco River, this waterway snakes southwestward for over 140 miles, dropping 100 feet en route; at its southern end, the canal enters the Rio Negro River, a major tributary of the Amazon.  In effect, the Casiquiare Canal shunts water between two major watersheds, the largest river known to do so on Planet Earth.

How did this river come to cross a natural divide?  It appears likely that the Casiquiare, initially an upper tributary of the Rio Negro, cut its way upstream, eventually capturing flow from the Orinoco.  While the initial connection may have been rather meager, repeated flood events along the Upper Orinoco gradually widened and deepened the canal.  Today, unlike many human-made canals, the Casquiare is far from a sluggish, seasonal channel; rather, it is characterized by a strong and steady flow  between two of South America's largest river systems.

Saturday, March 21, 2015

Duck Count Doldrums

Despite the warm, sunny weather (or perhaps because of it) the March waterfowl count at South Platte Park was rather dull this morning.  The recent summer-like conditions have totally opened the ponds, lakes and wetlands throughout the Valley and the ducks (migrants, winter visitors and permanent residents) are widely dispersed.

Our group saw a fair number of common goldeneyes, buffleheads, mallards, shovelers, gadwall and coot; a few common and hooded mergansers were also observed.  As usual, Canada geese were common on the refuge though their massive wintering flocks have moved off to the north.  A lone double-crested cormorant was seen but no grebes or white pelicans made an appearance.

Migrants should pick up in the coming weeks and summer residents (including pelicans, western grebes, cinnamon and blue-winged teal) generally arrive by mid April.  The summer-like weather, on the other hand, will surely not last; upslope snowstorms are especially common in March and April along the Colorado Front Range.

Friday, March 20, 2015

The Nature of Fjords

Fjords are steep-walled, U-shaped, glacial-carved coastal valleys.  Especially common along the rocky coasts of Norway, Iceland, Greenland, Canada, Alaska and Russia, they are also found in New Zealand and southernmost South America.  Eroded by mountain glaciers as they flowed toward the sea, the cliff-lined channels now admit ocean waters; since sea levels were much lower during the Pleistocene, the floor of many fjords is hundreds if not thousands of feet below the water surface (and generally deepest inland).  Furthermore, since the glacial tongues left terminal moraines beyond the rocky headlands, those underwater ridges now produce upwelling and strong currents near the mouth of many fjords.

Among the more famous fjords is Sognefjord, in southwestern Norway.  More than 125 miles long and over 4200 feet deep, this scenic, branching channel is the longest fjord in Europe and is second only to Greenland's Scoresby Sund in depth; its majestic cliffs rise 3300 feet above the water line.  Long a natural waterway for explorers, settlers, fishermen and traders, Sognefjord is now traversed by pleasure boats and cruise ships.

Of course, fjords also offer prime nesting habitat for seabirds such as puffins, murres and kittiwakes and hunting grounds for whales, dolphins and seals;  cold water reefs have been found in some fjords (especially those of Norway and New Zealand) and most harbor rich fisheries for salmon and other marine species.  How global warming is effecting the ecology of these spectacular waterways is the subject of intense study.

Thursday, March 19, 2015

Two Seasons in One

Over the past few years, especially during the past two winters, weather conditions have been dramatically different in western and eastern regions of North America.  While California endured another warm, dry winter and southeastern Alaska received very little snow, the American Midwest was raked by frigid Canadian fronts and New England was buried by record-breaking snowfalls.

More than an inconvenience for humans and fodder for cable news programs, this stagnant weather pattern (an atmospheric ridge in the west and an atmospheric trough in the east) has caused significant ecological impacts.  A severe, four-year drought persists in the California, threatening water supplies and fueling massive wildfires.  Warm waters along the West Coast have diminished food supplies for many predators, altering their migrations and hunting patterns; stranded by parents who must feed well offshore, young sea lions have turned up on the beaches of California, exhausted, hypothermic and malnourished.  In the East, of course, the record snowpacks have set the stage for regional flooding and stream erosion.

While global warming is surely playing some role in altering the jet stream pattern, such stagnant weather patterns have occurred throughout the evolution of our Continent and will surely redevelop in the future.  Indeed, periods of drought and deluge have played a significant role in the dispersal and behavior of species throughout natural history, including the migration and settlement patterns of humans.

Wednesday, March 18, 2015

Zealandia

Zealandia is a long, relatively narrow fragment of continental crust that split from Antarctica early in the Cretaceous Period (about 120 million years ago) and from Australia toward the end of the Cretaceous (about 80 million years ago as the Tasman Sea opened).  This continent, 93% of which is submerged beneath the sea, has since drifted northeastward and now stretches NW to SE, from the tropics, north of New Caledonia, to the sub-Arctic zone, southeast of New Zealand; while most of Zealandia is hidden by ocean waters, it covers an area half the size of Australia.

Northern Zealandia, which is composed of two parallel ridges separated by a long, narrow graben, lies on the Australian Plate while Southern Zealandia (from New Zealand's southern island southward) lies on the Pacific Plate; compression between these plates forced up the Alps on New Zealand's southern island and subduction of the Pacific Plate beneath the Australian Plate produced the volcanoes on New Zealand's northern island.  New Caledonia, New Zealand and numerous small islands are the only segments of Zealandia that currently poke above the southwestern Pacific.

Since rifting from Australia and Antarctica, the portion of Zealandia visible above the ocean has expanded and contracted as sea levels have fallen and risen, respectively.  As one might expect, marine sediments are thus found on New Caledonia and New Zealand while fossils of Mesozoic plants and animals from Australia and Antarctica have been discovered on those land masses, attesting to the origin of Zealandia.

Tuesday, March 17, 2015

Geology of Vanuatu Archipelago

This past week, the Vanuatu Archipelago of the southwestern Pacific Ocean has been in the news due to massive destruction wrought by Typhoon Pam.  The volcanic island chain consists of more than 80 islands and islets, stretching 720 miles (NNW to SSE) along the edge of the Pacific Plate, northeast of New Caledonia.

Part of a long volcanic arc that includes the Solomon Islands to their north, the islands of Vanuatu began to form during the Miocene Period (some 20 million years ago) as the northeastern edge of the Australian Plate dipped beneath the Pacific Plate; this subduction process continues today, manifest by earthquakes and volcanic eruptions.  Indeed, most of the archipelago has surfaced since the late Pleistocene (within the last 200,000 years).

Of course, this ongoing volcanism and land formation is partially balanced by the erosive force of tropical storms and rising sea levels related to global warming.  On the other hand, the rugged volcanic landscape has served to protect the rich tropical forests of Vanuatu and the archipelago is renowned for its biodiversity.

Saturday, March 14, 2015

Reunion on the Platte

By mid February, migrant sandhill cranes begin to gather along an 80-mile stretch of the Platte River, in south-central Nebraska.  They are traveling northward from wintering grounds in West Texas, Mexico and eastern New Mexico, headed for northern Canada, Alaska and Siberia.

Their number will peak in late March, when 600,000 cranes stop to rest and feed along the Platte, and most will depart by mid April.  This reunion of sandhill cranes attracts hordes of humans as well and the annual Audubon Crane Festival is held in Kearney in late March.  Those unable to visit Nebraska are advised to check out the Rowe Sanctuary's Crane Cam, which gives one a feel for the sights and sounds of the rendezvous site (including the intense winds that frequently rake the Great Plains); my thanks again to Chuck Robertson, from Huntsville, Alabama, who brought the cam to my attention.

Cam viewing is best in the late daylight hours and during the hours just after sunrise, when the cranes move to and from their sandbar roosts; they spend the night on the broad, shallow Platte, which offers protection from coyotes and other predators.  During the day, the sandhill cranes spread out across regional crop fields, wetlands and grasslands to feed on waste grain, tubers and a variety of invertebrates.

Friday, March 13, 2015

Wildlife in the Mist

Low clouds, patchy fog and a cool mist enveloped central Missouri this morning and, as I reached Eagle Bluffs Conservation Area, a barred owl perched like a sentry along the entrance road.  Flocks of ducks, mourning doves and red-winged blackbirds pierced the humid air but my attention was soon drawn to a massive flock of geese on a flooded field.

Composed of snow geese and greater white-fronted geese, the restless and vocal flock was constantly in flux as some groups moved off to the north while others arrived from the south, circling above the field before choosing a site to land.  Smaller flocks of Canada geese fed in the adjacent stubble while mallards and blue-winged teal (the first I have seen this spring) speckled the deeper pools.  Other sightings on this cool, damp morning included bald eagles, common mergansers, killdeer, belted kingfishers, great blue herons, wood ducks and lesser scaup; an island of white pelicans was spotted on a distant lake, chorus frogs called from shallow sloughs and herds of white-tailed deer raced across the soggy floodplain.

While many birders and naturalists avoid field trips on such dreary mornings, the relative darkness often brings out reclusive and nocturnal creatures (e.g. owls, rails, beaver, mink, deer) and the damp chill invigorates diurnal species, making them more active and conspicuous.  Besides, at a refuge like Eagle Bluffs, one need not even leave their vehicle to see a spectacular variety of wildlife.

Thursday, March 12, 2015

Beyond the Mud

Across the American Heartland, March is known for its muddy landscapes, cold rain, wet snow and raw, windy days.  But, to the naturalist, March has far more to offer than ugly weather and sloppy terrain.

After all, the month generally brings the first flowers of spring, including crocuses, hyacinths, snowdrops, early tulips, dandelions and the flowers of red maples and forsythia.  Greenery appears on our lawns, first as clumps of wild onion and then spreading to the grass itself.  As the soil thaws and the earthworms rise, American robins stalk those suburban carpets and, by the end of the month, the first young cottontails scurry between the shrub lines.  Out in the wetlands, waterfowl migrations are peaking and the first summer residents, tree swallows and eastern phoebes, make their appearance, serenaded by chorus frogs and spring peepers.  The hysterical calls of flickers echo from the woodlands where the drumming of their red-bellied, downy, hairy and pileated cousins has intensified.  Birdsong is also growing in intensity, lead by northern cardinals, mourning doves, Carolina wrens, robins and homesick white-throated sparrows.

We may have to slog through the mud to witness some of the gifts of March but the effort is always worthwhile.  Besides, the intense heat of summer will be here soon enough; by then, the chill of March will be but a pleasant memory.  

Wednesday, March 11, 2015

Speed Birding

Most of our National Wildlife Refuges, Conservation Areas and large nature preserves are accessed by a network of graveled roads which permit close observation of the component habitats and their wild residents.  This provides an excellent opportunity for wildlife study and photography and experienced birders know that, by using their vehicle as a blind, they can observe and identify species at close range without spooking their quarry.

The roads also permit speed birding, a style utilized by those individuals more concerned with finding rare species than immersing themselves in the ecosystem.  Racing through the preserve, these veteran birders quickly identify birds by their silhouettes, plumage or behavior; ignoring the common species, they slow down only to check out unusual or unexpected birds, perhaps taking a photo for documentation.  After completing their tour, many contact their local birding society to report on rare species; for them, birding is a sport and keeping their names on the register is a means of scoring points.

Fortunately, most birders actually enjoy watching the birds and some of us are more fascinated by their roles in the ecosystem than by their individual presence.  With all due respect to the speed birders, those who take an interest in the landscape, plants, mammals, reptiles, amphibians and insects as well are, in my opinion, more likely to devote themselves to protecting our natural ecosystems.  After all, birding without experiencing the sounds, smells and feel of the birds' home environment is a rather sterile endeavor.

Tuesday, March 10, 2015

The Chad Basin

The Chad Basin is both a topographic and a geologic sedimentary basin that covers nearly 8% of the African Continent, stretching from southeastern Algeria to the northwestern Central African Republic and from central Niger to western Sudan; most of Chad, northern Cameroon and northeastern Nigeria also lie within the basin.  Lake Chad (elevation about 920 feet) lies at the center of the basin (though it is not the basin's lowest point).

Geologically, the Chad Basin is a broad depression of the Precambrian Shield upon which nearly 12,000 feet of Paleozoic, Mesozoic and Tertiary sediments have accumulated, deposited by inland seas or eroded from highlands that rim the basin.  Mega-Chad Lake, the precursor of Lake Chad, covered a large portion of the basin from about 40,000 to 3,000 years ago, draining to the Atlantic via the Benue and Niger Rivers; as the lake level fell, this outlet was lost and Lake Chad became a true basin lake, expanding and contracting with the regional climate.

Since the 1960s, Lake Chad has lost more than 90% of its volume, the result of dams on basin rivers, deforestation, overgrazing, increased water use for irrigation and global warming; desert and semiarid grasslands now cloak most of its floodplain, less than half of which is covered by open water (with an average depth of only 5 feet).  Almost all of the inflow now reaches Lake Chad via the Chari-Logone River system, rising in the Central African Republic.  While the Lake Chad Basin Commission was established to address this ecologic, economic and societal catastrophe, regional politics have, to date, derailed any significant progress.

Monday, March 9, 2015

First Wave of Pelicans

Light, patchy fog enveloped the Missouri River Valley just after dawn this morning.  At the Eagle Bluffs Conservation Area, flocks of geese and ducks wheeled above the refuge while groups of bald eagles (mostly immature) perched in the scattered trees.

In the southwest corner of the preserve, another mixed flock of snow geese and greater white fronted geese fed in the corn stubble, soon to depart for the next rest stop on their journey to the Arctic.  Among the ducks, lesser scaup and common mergansers were notably abundant though most migrant and wintering species were represented.  But the celebrities this morning were American white pelicans; two flocks, totaling 36 individuals by my count, were the first I have encountered this season.

Having wintered along the Gulf Coast, the pelicans are on their way to breeding lakes across the Northern Plains and Intermountain West.  They are common migrants through the Missouri River Valley, sometimes observed as early as February and generally seen through April; non-breeding birds may be encountered throughout the warmer months.  Their autumn migration generally begins by mid September, peaks in October and may persist into early November, especially if the weather is mild.  Huddled on sandbars or scooping up fish in the shallows, American white pelicans are always a welcome sight at Eagle Bluffs.