Thursday, September 26, 2013

Our Neighborhood Watch

It's been a busy week for our neighborhood watch.  Every morning, about ten o'clock or so, an intruder has invaded our Littleton, Colorado, farm and, within seconds, one of the security guards, adorned in his blue uniform, sounds the alarm.

Soon, the entire squadron is shrieking from adjacent trees and, once he's had enough, the intruder flees the scene; on most days it has been a sharp-shinned hawk but yesterday a large red-tail had settled in one of our elms.  The blue jays, self-appointed guardians of our three acre plot, fall silent once the danger has passed.

Aggressive, attentive and fearless, our resident jays are happy to provide the security service and ask for little in return; pinon nuts, berries, insects and feeder handouts keep them around and seem to be adequate payment for the protection.  Of course, other birds, mice and cottontails benefit from their behavior (except when the jays consume their offspring) and, as an avid birder, I appreciate knowing when raptors are paying a visit.  Blue jays may be bullies at feeders but their truculence has its rewards.

Wednesday, September 25, 2013

An Invasion of Clubtails

Clubtails seem to be everywhere on our Littleton farm this week.  These dragonflies, members of the family Gomphidae, are named for the bulge at the end on their long, narrow abdomen; in most species, the club is more prominent in males.  Clubtails are also identified by their clear wings and widely spaced eyes; the latter trait, combined with their thin torso, makes them resemble damselflies.

More than 900 species of clubtails have been identified worldwide and about 90 species are found in North America.  Most live along rivers and near ponds, where their nymphs burrow into the gravel or sediment of the stream floor or lake bottom; there they feed on the larvae of other aquatic insects and, in some species, may remain in the larval state for three years.  Molting to adults during the warmer months, clubtails are not strong fliers; rather, they flit from one perch to the next, snaring small insects en route.  Eggs are generally laid on aquatic vegetation but, in some species, may be deposited in mulch or leaf litter; in the latter case, the species may overwinter in the egg stage or the larvae may burrow into the rotting vegetation until they molt to adults in late spring or summer.

Our current invasion of clubtails will likely be short-lived.  The first freeze in Metro Denver generally occurs during the first week of October, putting an end to the lives of most adult insects; of course, exceptions do occur (honeybees, ladybird beetles and cave crickets are but a few examples).

Tuesday, September 24, 2013

Health Insurance & Young Adults

Among the groups that oppose the Affordable Care Act are young adults who resent the health insurance mandate.  They argue that their participation merely funds healthcare for the elderly since they, themselves, do not need expensive screening or medical therapies.

Unfortunately, that assumption is not always accurate.  Having practiced hospital medicine for most of my career, I cared for a large number of young adults who needed costly inpatient treatment.  In the majority of cases, their expensive hospitalization was related to accidents, malignancy or acute infections such as complicated pneumonia, meningitis and pyelonephritis.  Then there are medical problems that often present in early adulthood, such as type 1 diabetes, asthma, inflammatory bowel disease, lupus and schizophrenia, to name but a few.

To forego health insurance because one is "young and healthy" is to ignore the risk of a catastrophic injury or illness that may lead to financial disaster.  In many cases, such debt places the individual's family at risk as well; parents may exhaust their savings to provide assistance and the patient's spouse and children may become impoverished by the expenses of repeated hospitalizations, chemotherapy, rehabilitation and other treatments.  Indeed, financial planning must begin with the independence of early adulthood and obtaining health insurance should, in my opinion, take precedence over the purchase of a house and other investments.

Monday, September 23, 2013

Colorado's First Snow

While light snows may dust the higher peaks of Colorado during any month of the year, the latest cold front, which moved through the State over the past 24 hours, brought the first significant accumulations  to mountain areas above 11,000 feet.  In most locations, the snowfall was less than six inches and, as warmer temperatures return, much of that snow will melt or evaporate; nevertheless, on shaded, north-facing slopes and in protected cirques, this storm laid the foundation for the annual snowpack, which will build to a peak in early March.

The same storm brought a steady, light rain and scattered thunderstorms to the Front Range urban corridor, welcome precipitation in the southern parts of Metro Denver but unwelcome in the flooded areas north of the city.  According the NOAA, the average date for Denver's first snowfall is October 19 though, in my own experience, it may occur by early September; since moving to Colorado in 1982, I have also witnessed snow in the Metro area as late as early June.  Denver's heaviest snowstorms often occur in March and April, when Pacific storms move east across southern Colorado, sweeping Gulf of Mexico moisture toward the Front Range.

Here's hoping that the first mountain snows will usher in a heavy snowpack for the coming season and that gradual spring melting will fill our rivers and reservoirs without the specter of additional flooding;  nature, oblivious to our hopes and fears, will keep us guessing.  It is best that we make no assumptions, conserve her precious water and prepare for a wide range of possibilities.

Sunday, September 22, 2013

The Nature of Democracy

Democracy, which protects the power of the individual, relies on a spirit of cooperation and compromise in order to thrive.  While various parties may disagree on a wide range of issues, their willingness to consider and respect one another's views is essential.  So too is a commitment to ensuring that all citizens have a voice in the policies and laws that are enacted.

As we have seen with the Arab Spring, democracy cannot take hold in regions where factions or sects hate one another and choose to settle differences or exact revenge by violent attacks.  Neither can democracy flourish in countries where a dictator, a military junta or a ruling class determines the rights of individuals.

The United States, the paragon of democracy, was once nearly torn apart by civil war.  Having survived that threat and its aftermath, we now face a political movement that refuses to compromise with other segments of our population; demonstrating a profound degree of disrespect, they are willing to disrupt the stability of our country to achieve their narrow-minded goals.  Intolerant of other views while offering no constructive solutions for the problems that we face, they imperil our democracy in pursuit of their own agenda.  Hopefully, democracy will prevail and their radical, self-righteous obstructionism will fade from the political landscape.

Saturday, September 21, 2013

Eleven Mile Reservoir

Created by a dam on the South Platte River in 1932, Eleven Mile Reservoir lies in the southeast corner of Colorado's South Park.  Renowned for its fishing, most of the lake and the surrounding State Park stretch across flat, semiarid terrain while the reservoir's eastern end is lined by scenic granite outcrops at the base of the Puma Hills; indeed, some of the outcrops form islands in the reservoir.

Yesterday, my wife and I hiked the trail loops that run above the east shore of the lake, crossing Coyote Ridge and then winding through the hike-in campground on a peninsula of pine-fir-aspen woodlands and rock-walled coves.  It was there that we enjoyed a picnic lunch, looking north across the reservoir which is backed (east to west) by the distant walls of the Tarryall Mountains, the Continental Divide, the southern end of the Tenmile Range, the Mosquito Range and, west of the Arkansas Valley, the high spine of the Collegiate Range; to our southwest, the massive bulk of Thirtynine Mile Mountain rose above the lake.

While boats may crowd the reservoir during the summer months, only the occasional fishing craft distrurbed the natural chorus of grasshoppers, golden-mantled ground squirrels, magpies, Steller's jays, mountain chickadees and western grebes; the latter, lounging on the calm blue waters, were joined by ring-billed gulls and small groups of common mergansers.  The campgrounds, surely congested during the warmer months, were nearly empty as we hiked across the peninsula, reinforcing our conviction that off-season months are the best time to visit our National and State Parks.  Blue skies, cool air and an early hint of aspen gold made our visit even more enjoyable.

Friday, September 20, 2013

Memories of Canada

In September of 1973, I joined a group of friends for a canoe trip in Algonquin Provincial Park, in Ontario, Canada.  That was my first excursion to a wilderness area and my first trip to any region not on my family's limited vacation list (Lake Erie, the Smokies and the Gulf Coast of Florida).  After a week touring remote streams and lakes in the Park, a friend (see George) and I returned to Cincinnati via a long, scenic route, following the northern coast of Lake Huron, the southern coast of Lake Superior and the western coast of Lake Michigan.  En route, I was exposed to a spectacular diversity of landscape and wildlife and there is no doubt that the entire experience played a significant role in my development as a naturalist.

So too did our stop in Sudbury, where nickel mining had created a moonscape amidst the forests and lakes of Canada; never before had I encountered man's impact on natural ecosystems in such a striking and unsettling manner.  To this day, though the city has been recognized by conservation organizations for its effort to reclaim the landscape, that image of Sudbury comes to mind whenever the subject of human-induced habitat destruction is raised.

Indeed, a commitment to conservation generally arises from positive and negative experiences in our lives.  The exposure to pristine wilderness and scenic landscapes prompts our desire to protect those areas while the sight of polluted rivers, clear-cut forests and industrial carnage fuel our support for environmental regulations.  My trip to Canada, at the age of 23, did both.

Thursday, September 19, 2013

The Camargue

The Rhone River of Western Europe rises at the base of the Rhone Glacier in the Swiss Alps; flowing westward, it passes through Lake Geneva and then angles southwestward to Lyon, France.  There it merges with the Saone River and turns southward; at Arles, the Rhone splits into the Grand Rhone, to the east, and the Petit Rhone, to the west.  Both of these rivers empty into the Mediterranean Sea, west of Marseille, and the triangular delta between them is known as the Camargue.

Characterized by shallow brine lagoons (known as etangs), brackish marshes, grasslands and cultivated fields (primarily devoted to rice production), the Camargue is famous for its light-gray horses and its black bulls (bred for non-lethal bullfights).  To naturalists, however, this vast delta is best known for its diverse avian population (400 species either reside within or visit the Camargue in the course of a year).  Greater flamingos summer on the delta and large flocks of waterfowl, shorebirds and common cranes stop to rest and refuel on their long migrations between Africa and the Arctic.

The Camargue, a third of which is protected within a French Provincial Park, is the product of climate change near the end of the Pleistocene, some 12,000 years ago.  Glacial meltwaters, loaded with sediment, fed the Rhone and its tributaries, producing the vast delta; in concert, sea levels rose, causing the Mediterranean to spill across this low country.  As Earth's climate continues to warm, the Camargue will become a bay on the northern coast of the Mediterranean Sea.

Wednesday, September 18, 2013

An Explosion of Fungi

Following the recent heavy rains and cool weather along the Front Range, our Littleton farm is greener than it has been all year.  In concert, a wide variety of fungi adorn the property, concentrated at wood piles, mulched beds and wood borders.

Hidden within soil and decaying wood for most of the year, fungi produce their reproductive structures (which we know as mushrooms, puffballs, bracket fungi, etc.) when conditions favor germination of their spores; indeed, some species "bloom" in the spring while others appear in late summer or autumn.

One need not be an expert on fungi to enjoy their wide variety of colors and shapes (I certainly don't pretend to qualify); on the other hand, only experts should determine which species are edible since a large percentage of mushrooms are poisonous.  Most of us prefer to enjoy them with our eyes, knowing that these seasonal growths are components of far larger organisms that play a vital role in recycling the chemicals of life.

Tuesday, September 17, 2013

The Mental Illness Taboo

Once again, a mass shooting has been perpetrated by a man with an apparent history of mental illness.  As in most previous cases, the killer at the Navy Yard, in Washington, D.C., had demonstrated signs of paranoia and disordered thinking which were not adequately addressed.

Most humans are uncomfortable with mental illness and, though it has lost some of its stigma over the years, they are reluctant to intervene when they observe its signs in their friends or relatives.  As in the current case, even law enforcement officials are sometimes inclined to ignore evidence of mental illness if there is no immediate danger to the individual or to others.  There is even significant disagreement among mental health professionals with regard to the degree of intervention that is appropriate; some are opposed to the use of hospitalization altogether while others are hesitant to saddle the individual with a diagnosis that might limit his or her career opportunities and personal freedoms (including, of course, the right to purchase firearms).

Thus we continue to deal with the consequences of mental illness that is either ignored or inadequately treated.  A concerted effort to address this issue will require a unified commitment by all segments of human society and, to be clear, a significant increase in State and Federal funding.  Unfortunately, those who oppose reasonable gun control also oppose taxation; their answer is to arm everyone and to deal with mental illness via lethal force.

Monday, September 16, 2013

Lessons from Boulder

The tragedy unfolding in Boulder and nearby cities reminds us that the scenic foothill canyons were not carved by the beautiful whitewater streams that draw fly fishermen, kayakers, rock climbers and hikers to the Colorado Front Range.  Rather, these steep, narrow gorges were incised primarily by glacial meltwater torrents during the Pleistocene and have since been molded by periodic floods, unleashed by intense thunderstorms and deep snow packs.  The sheer rock walls, though permanent in appearance, are just the modern borders of these canyons; their predecessors gave way to rock falls and mudslides, the products of freeze-thaw fracturing and torrents of water.

Those who live in Front Range canyons enjoy spectacular scenery and a fascinating diversity of wildlife.  However, they, like those humans who live on barrier islands, on lowland floodplains, along fault lines and amidst the stark beauty of volcanic landscapes, accept the risk of "natural disasters" that continue to mold our planet; indeed, the residents of Western canyons also face the possibility of destructive yet vital wildfires.  Most will report that the rewards outweigh the risks and some will rebuild once the immediate danger has passed.

Of course, some will see God's hand in the disaster and a few conservative Congressmen will find a way to link Obama's policies to the tragedy.  But nature gives us plenty of warning; if we take the time to study her landscapes and her history, we can prepare for the floods, wildfires, hurricanes and earthquakes that produced our chosen habitat and that, sooner or later, will return.  Building codes and warning systems may reduce the impact of these natural events but, in the end, nature's power cannot be controlled.

Sunday, September 15, 2013

Into the Plume

Driving back to Colorado today, we traveled just south of a cold front that was pushing south across the Great Plains.  As a result, intermittent showers developed throughout most of Kansas though winds were light and afternoon highs hovered in the seventies.

Once we reached Goodland, however, we crossed the arc of the front and a northeast, upsloping wind, produced a layer of low, gray clouds.  The upslope intensified in eastern Colorado, leading to a persistent drizzle and banks of pea soup fog.  Finally, nearing Metro Denver, heavier downpours raked the highway, fed by monsoon moisture from the south; by the time we reached our Littleton farm, the temperature had dropped into the lower fifties and a chilly rain was falling.

Fortunately, the monsoon rains are expected to diminish over the next 24 hours and a warm, sunny week should dry out much of the Metro Area.  On the other hand, the extensive flooding across Boulder and Larimer Counties will take much longer to subside and the floodwaters will move down the South Platte Valley, inundating other areas of northeast Colorado and possibly extending into Nebraska.

Friday, September 13, 2013

Voyager 1 & Politics

Though not officially acknowledged by NASA until yesterday, Voyager 1, launched in September of 1977, likely reached interstellar space late last summer after sending back volumes of data from the outer reaches of our solar system.  Whenever that monumental event occurred, it was a testimonial to the potential achievements of humanity, even with the limited technology that was available 36 years ago.

One wonders if the cooperative spirit that fostered the American space program will resurface in our future.  For now, a small but significant segment of our society opposes any federal funding for science and education, let alone healthcare and social welfare programs.  Focused on their personal needs and freedoms, they demonstrate little if any support for scientific research; indeed, they exude distrust of all academic endeavors, viewing them as threats to their rigid and provincial belief systems.  Compromise is their enemy; intolerance is their mode of operation.

As Voyager 1 and its twin, Voyager 2, hurtle through space they carry the message of human good will to other civilizations; unfortunately, those sentiments are under attack within our own society.  Hopefully, by the time we receive the final transmissions from the Voyager probes, the political climate in America will once again embrace the value of scientific exploration.

Thursday, September 12, 2013

Front Range Deluge

Heavy rains along the Colorado Front Range over the past three days have produced flooding from Colorado Springs to Ft. Collins; the worst of the flooding has been in and near Boulder where some foothill locations have received a foot of precipitation and where several canyon streams cut across the city.

This deluge is the product of three atmospheric factors: an upper level low over the Great Basin, high pressure over the Southern Plains and a cold front that dropped south across the High Plains.  Behind the latter, an easterly, upslope flow is pushing moisture toward the Front Range; in addition, monsoon moisture is flowing northward across eastern Colorado, pumped from the Gulf of Mexico and the Sea of Cortez by the combined effects of the Great Basin low and the Southern Plains high.  In the Northern Hemisphere, winds move counterclockwise around low pressure zones and clockwise around high pressure domes; in this case, those wind patterns are merging to sweep abundant moisture toward the north.  As that warm, moisture-laden air encounters the cold front, it rises and condenses, adding copious precipitation to the upslope flow behind the front.

Twelve days into September, Boulder has already set a precipitation record for any given month (exceeding the previous record of 9.6 inches in May, 1995).  Since periods of heavy rain are expected to continue over the next few days, that previous record will be shattered and the risk of flash flooding and mudslides will persist.

Giant Sequoias & Wildfire

During this active wildfire season in California, concerns have been raised about the possibility of damage to giant sequoia groves.  These trees, the largest (though not tallest) in the world, are native to the western slope of the Sierra Nevada Range and are found primarily in 68 groves, all at elevations above 4500 feet.  Giant sequoias may exceed 300 feet in height and 50 feet in diameter though most never reach those extremes.

Despite public concerns, these giants, which can live for more than 3000 years, have long relied on wildfires for their survival.  Each mature tree harbors thousands of green cones which contribute to photosynthesis for up to 20 years or more before drying out and releasing their seeds; heat from wildfires is the primary trigger that opens the cones though beetles and Douglas squirrels also play a role.  Fibrous bark, up to three feet thick, protects the lower trunk of giant sequoias and wildfires may damage but rarely kill these trees; the risk of damage rises when fires are fueled by large amounts of dead wood, the result of repeated fire suppression.  Wildfire, which clears the understory and enriches the soil, is also vital to the germination and growth of sequoia seedlings.

Indeed, the primary threat to giant sequoias is regional human habitation which fuels a policy of fire suppression.  Fortunately, many of the largest groves are protected within National Parks and Monuments where natural wildfires and prescribed burns foster conditions that favor the survival of these majestic trees.

Wednesday, September 11, 2013

The Complex Anadarko Basin

A classic structural geologic basin, such as the Michigan Basin, is essentially a bowl within the deep, Precambrian basement rock into which younger layers of sediment have accumulated.  In that case, the deepest portion of the basin is near its center and, as layers of deposits fill the bowl over the eons, the youngest surface sediments end up above the center as well.

The Anadarko Basin, which covers 50,000 square miles of western Oklahoma, the northern Texas Panhandle and portions of southwestern Kansas and southeastern Colorado, is not your typical structural basin.  This basin initially formed above an aborted Precambrian rift and began to fill with Paleozoic sediments from the Cambrian into the Mississippian Periods (from 550 to 350 million years ago).  Compression of that region during the Pennsylvanian Period (about 300 MYA), in concert with the uplift of the Ouachita Mountains (a westward extension of the Southern Appalachians), deformed the basin by producing a shallower segment on its northern and western flanks.  Throughout the rest of the Pennsylvanian Period and into the Permian (250 MYA), the Anadarko Basin filled to its brim.  Today, the basin has an irregular topography, with a relatively shallow platform (2000 feet deep) on its western and northern rim and a very deep section along its southern edge; the latter, the deepest structural basin in North America, dips 40,000 feet below the rim of the basin.

The major source of natural gas in the United States and a significant source of oil as well, the Anadarko Basin poses a challenge for energy geologists.  Its irregular floor and steeply dipping layers of sediment make locations of oil and gas relatively hard to predict.  The Woodford Shale, for example, late Devonian to early Mississippian in age, is one of the primary sources of fossil fuel within the basin but has an average thickness of only 125 feet.  As one might expect, there is a great deal of controversy regarding future drilling opportunities within the Anadarko Basin but new technologies, including fracking, have significantly increased the prospects of success.  Of course, for those of us who support a shift toward clean, renewable sources of energy, this is not necessarily good news.

Tuesday, September 10, 2013

Late Summer Heat

After a relatively mild summer across the American Midwest, excessive heat has settled in over the past two weeks.  And, like an unwelcome houseguest, the late summer heat seems reluctant to leave.

High pressure, currently centered over Missouri, is responsible for the unseasonable temperatures, deflecting Pacific storm systems to the north and allowing intense sunshine to bake the region; afternoon highs have been in the mid to upper 90s (F), more than 15 degrees above average.  While precipitation was excessive in late spring and early summer, drought has returned to the Heartland and both crops and woodlands are wilting in the oven-like heat.

Fortunately, a pair of cold fronts are poised to drop southeastward from the Canadian prairies and cooler temperatures are expected by the end of the week.  Until then, we are reminded that the astronomical summer has not yet run its course and the season seems intent on dominating the region until the fall equinox (if not beyond).  On the positive side, the dry, sunny weather may intensify the autumn colors in October, that glorious month which always rewards our patience; in addition, for those in the Mountain West, the persistent high pressure dome over the central U.S. has prolonged the monsoon moisture flow from the Gulf of Mexico and Sea of Cortez.

Monday, September 9, 2013

Katydid Season

Reading next to a picture window last evening, I was startled several times by a thud against the glass.  In each case, a large katydid, attracted by the lamp, had jumped to the window from an adjacent shrub or tree.

Commonly known as bush crickets or long-horned grasshoppers, this diverse family of insects (numbering some 6500 species worldwide) is represented by more than 200 species in North America.  More closely related to crickets than grasshoppers, most are medium to large sized orthopterans and, in most species, the female is significantly larger than the male.  Most are green in color, blending with the vegetation on which they feed; remaining inactive for much of the day, their loud, scratchy fiddling begins at dusk and they spend the night feasting on leaves and flowers (some species also consume small insects).  Katydids move about by jumping and climbing and are best observed on window panes or on vegetation lit by outdoor floodlights.

Female katydids lay their eggs directly on leaves or within the soil.  Adults and juveniles succumb to the first hard freeze while the eggs overwinter in soil or leaf litter; those not consumed by birds, mice or shrews hatch into nymphs the following spring.  Following several molts throughout the spring and summer, juveniles that avoid predation by birds, snakes, mantids and toads reach adult size by August; it is then that their annual season of fiddling and mating begins, peaking in September and dying out as autumn chill sweeps across the Heartland.

Saturday, September 7, 2013

E.D. & World Hunger

When I posted The E.D. Epidemic in January, 2009, I expressed my conviction that drug companies were flooding the airwaves to cash in on the plight of aging males with young mistresses or second wives.  Little did I know that, more than four years later, the frequency of those advertisements would be undiminished (as if we have not memorized their content by now); one can only begin to imagine the cost of that campaign and, in my opinion, it is outrageous that remedies for erectile dysfunction have garnered so much funding by companies purportedly devoted to human health.

Meanwhile, children across this country and throughout the world are going hungry for lack of adequate resources.  While politics, war and corruption significantly exacerbate that problem, the maldistribution of wealth within and between human societies is shameful, to say the least.

There must be some way to balance the positive aspects of capitalism and socialism without stifling entrepreneurship and competition; we should be able to reward creativity and productivity without ignoring the needs of society as a whole.  Addressing the massive income disparity is an important first step, a goal that could be accomplished without reducing profits.  Whether we will ever value companies by measures more substantial than the bottom line (i.e. by their contributions to human society) seems unlikely at present but we must develop policies which encourage that transition.

Friday, September 6, 2013

Male & Female Healthcare

Ask any adult (or child for that matter) to enumerate differences between males and females and they would have little trouble coming up with a sizable list.  Of course, most of those differences would be superficial, relating to anatomy, clothing, behavior and other socially-evident traits.

In fact, the differences between men and women extend to the level of cellular functioning.  Yesterday, I attended a conference that focused on microvascular differences between males and females, including the reactivity and permeability of small blood vessels in response to various agents.  As it turns out, a significant difference exists in many cases and does not always relate to the presence or absence of sex hormones (testosterone and estrogen); indeed, some cellular functioning appears to be influenced by the genome itself, which affects the level and or sensitivity of various chemical mediators.  To further complicate the picture, these gender differences are often organ specific; for example, a difference may occur in the kidneys but not in the heart muscle (or vice versa).

These facts might be dismissed as scientific mumbo-jumbo by the general public but they are highly significant when it comes to healthcare.  Since most studies on the benefits and side-effects of medications are conducted on male populations (prisoners or impoverished young males, for example), the conclusions drawn may not apply to the female population.  Yet, an assumption is often made that males and females respond to a certain drug in the same manner and that the pathophysiology of a given disease is independent of gender.  As modern research is beginning to reveal, that is often not the case and gender specific therapies may be indicated.  Whether fiscally-minded governments and profit-focused drug companies acknowledge the need for such research remains to be seen.

Thursday, September 5, 2013

The Stable Continent

Though it appears static during our brief human life spans, Earth's surface is continually molded by natural forces and many of these ongoing events place the lives of humans at risk.  Those who live in geologically active regions are at most risk; such areas include subduction zones, continental collision zones, rift valleys, transverse faults and active volcanic hotspots.

Most of the Continents harbor a number of these high risk areas.  Subduction zones (where oceanic plates dip beneath the Continents), which produce earthquakes, tsunamis and volcanism, line the Pacific rim, including the west coasts of North and South America and the eastern edge of Asia; they are also found along the southeast coast of Asia and in isolated areas of southern Europe and southwest Asia.  Collision zones are prominent across southern Asia (at the northern edge of the Indian Subcontinent), across the Middle East, through the Alps of southern Europe and in eastern Siberia.  Rift Valleys, sites of earthquakes and volcanism, are found in East Africa, in the Rio Grande Valley of the American Southwest and across Iceland.  Transverse faults, where one tectonic plate is scraping past another, include the San Andreas Fault of southern California and faults along the east and west sides of the Arabian Plate.  Potentially catastrophic volcanic hotspots are found in North America (Yellowstone) and Indonesia.

Though it is subject to floods, droughts, tropical storms and wildfires, Australia, which sits near the center of its tectonic plate (far from active margins), is relatively immune from earthquakes and volcanism; in that respect, it might be considered the most stable Continent on which to live (excluding Antarctica which, at least for now, does not invite human habitation).  On the other hand, old suture lines, potential sources for earthquakes, criss-cross the bedrock of all continents, new volcanic hotspots (resulting from mantle plumes) may develop almost anywhere and no place on Earth is immune from cosmic collisions with asteroids.

Wednesday, September 4, 2013

Communal Bird Roosts

Last evening, waves of starlings passed over our yard in Columbia, Missouri, moving toward a roost site somewhere northwest of our neighborhood.  Though not native to North America, these maligned immigrants are among the most numerous and widespread of our avian species and are infamous for their massive communal roosts.

Most blackbird species, including grackles, red-winged blackbirds and starlings, utilize communal roosts, as do pigeons, robins, swallows, many wading birds, vultures and some waterfowl.  The reasons for this behavior remain uncertain though most ornithologists believe it diminishes the risk of predation and improves foraging success; indeed, birds that forage in large flocks are more likely to roost in colonies than are those that feed alone or in small groups.  While heat conservation has been suggested as a possible benefit of communal roosting, the above birding groups retain this behavior in warm southern latitudes.

 Some birds that use communal roosts also nest in colonies (e.g. waders, swallows) but most abandon the practice during the breeding season, when territorial instincts take control.  By late summer, as winter flocks reform, communal roost sites are established once again, not to be abandoned until the lengthening days of spring (or until angry humans, tired of the noise, smell and droppings, intervene).

Tuesday, September 3, 2013

September Mornings

Though warm (or even hot) days may lie ahead, the longer nights of September bring cool mornings across the American Heartland, generally free of the haze and heavy dew of July and August.  It will now take more time for the annual cicadas to strike up their late summer din and turkey vultures must wait until mid morning for thermals to develop.

Autumn color is spreading through the stands of sumac and patches of yellow and rust dot the forest.  Snakes and box turtles appear on our trails and roadways, soaking in heat after the long, cool nights and the morning songbird chorus has regained its vigor as the heat and humidity of summer slowly fade to the south; among our more vocal residents are Carolina wrens and white-breasted nuthatches, species that, like many humans, seem to relish the crisp weather to come.

Free of both oppressive August heat and numbing October chill, September mornings are among the more pleasant periods of the entire year.  Rarely blemished by severe weather, they rescue us from the inertia of summer and lead toward the glorious days of autumn.  And, for many parents, having endured a long stretch of domestic chaos, September mornings seem to be especially peaceful.  

Sunday, September 1, 2013

Brain Trauma Season

It's that time of year when I look forward to the start of college football season but must acknowledge that I am a reluctant fan.  Just days after the NFL reached a financial settlement with victims of football related brain injuries, young, healthy college kids are risking serious injury to raise millions of dollars for their universities, hoping to reap their own fortune as professional players after (or before) graduation.

Recent scientific evidence leaves no doubt that repeated head injuries (even mild concussions) can lead to both structural and functional changes in the brain, sometimes resulting in early dementia or other neurologic disorders.  Of course, this is above and beyond the acute injuries that, in some cases, lead to paralysis or even death.

While football is just one of many sports in which participants wear helmets, most of the others (with the possible exception of hockey) require them in case head impacts occur; in football, helmets are worn because repeated head impacts are expected.  As we intoxicate ourselves with food, drink and football fever, standing to cheer the team and to join in our college fight song, we must acknowledge the price that many of the young athletes will pay for our entertainment.  This is one American tradition that should be relegated to history but its financial benefits to universities, networks, sports equipment companies and the NFL will surely prevent that from happening.  Highly paid professional gladiators may choose to assume the risk but encouraging high school and college students to do the same is not in their best interest; to date, preventive measures have been limited and, without significant changes in the nature of the game, they will never be adequate.