Saturday, August 31, 2013

Amphibious Armies

Following two weeks of hot, dry weather, the seasonal lake at the Forum Nature Area, in Columbia, Missouri, is rapidly shrinking.  Broad mudflats now border the lake and even the deepest pools hold less than a foot of water.

This morning, thousands of froglets crowded the shallows, peering from the surface or basking on the muddy shoreline.  Having recently morphed from tadpoles, they seemed to relish their amphibious talents, hopping in and out of the water, oblivious to the dangers that lurked nearby; indeed, great blue herons, green herons, snapping turtles and northern water snakes are common residents of that wetland and all dine on amphibians.

For now, the legions of froglets would overwhelm any predator and their first (and perhaps only) season in the sun is reason enough to throw caution to the wind.  Within six weeks or so, an autumn chill will descend on this floodplain refuge and those that have escaped predation will retreat to a mud-caked tomb, there to await the warm rains of spring.

Friday, August 30, 2013

Sunflowers on a Sea Bed

Leaving for Missouri this morning, we headed east across the vast bed of a Cretaceous Sea, which stretched from Texas to British Columbia, some 100 million years ago.  Along the base of the Front Range and out across the High Plains, the ancient bed is covered by a veneer of younger, Tertiary sediments, eroded from the Rockies as they pushed skyward.  However, Cretaceous Pierre shale is exposed along the South Platte Valley, where the river has removed the overlying deposits; it is this marine sediment that enriches the soil and supports agriculture across the Colorado Piedmont.

Further east, in central Kansas, the Cretaceous sea deposits become more evident.  There, throughout the post rock country from Hays to Russell, marine limestone lies near the surface, outcropping at road cuts and widely used to construct farm houses and to support barbed wire fencing.

By late summer, as the intense sun takes a toll on the Great Plains greenery, prairie sunflowers adorn the landscape.  Rising in scraggly clumps across the High Plains, these wildflowers become more abundant on the lower, wetter terrain of central Kansas, where they blanket fallow fields and sprawl along stream valleys.  More than offering welcome color to the drying plains, prairie sunflowers provide food for a wide range of grassland mammals, game birds and open country songbirds.  For those of us driving across the semiarid landscape of the Great Plains, once occupied by a Cretaceous Sea, the bright yellow sunflowers are food for the soul as well.

Thursday, August 29, 2013

The Atlantic Hurricane Drought

Tropical depression is setting in at the Weather Channel.  Despite early forecasts for a reasonably active hurricane season, none of the named storms have met hurricane criteria and none are expected to develop over the next week.

While tropical waves continue to move westward off the African coast, they have been dissipating amidst a flow of dry air from the Saharan Desert.  Those that have managed to avoid annihilation in the central Atlantic have encountered unfavorable winds over the Caribbean, dismantling their structure and sending their remnants out to sea.

As a result, the hourly tropical updates on the Weather Channel have morphed into repetitious explanations of why nothing is happening.  Though conditions may change in September, the annual peak of the hurricane season, it appears very unlikely that their revised forecast of eight hurricanes will be anywhere close to accurate.  And while the TV meteorologists, like the rest of us, do not want to see any destructive storms, their disappointment is obvious; after all, they live to explain the dynamics of hurricanes, to keep us tuned in for the latest path projections and to report from the scene of a landfall, standing in the wind and rain like human weather vanes.

Wednesday, August 28, 2013

Combating Genocide

When a dictator and his regime embark on a course of genocide, as appears to be happening in Syria, the civilized world must intervene.  The question is always how that should be done.

Military strikes or shipping arms to the insurgents, which may soothe our sense of impotence, only worsen the situation for innocents who are caught in the struggle.  Rather, it seems to me, our focus should be on providing safe zones, funding refugee shelters and arranging emigration opportunities for those under siege and on doing whatever we can to cut off the economic and military resources that fuel the regime.  Whatever actions might be required in reaching those goals must be coordinated with as many allies as possible; that coalition (the U.N., NATO or other alliances) must be willing to put economic and political pressure on countries that support the genocidal regime; to do so, we must be willing to accept whatever economic consequences might result from that policy.

Some opine that America and other wealthy countries cannot police the globe and should only act if it is in our nation's interest.  In my opinion, the welfare of humanity as a whole is directly tied to our willingness to combat genocidal forces wherever they may arise.  Economic, not military, war is the answer; while military hawks (many of whom have never experienced combat) want to send our youth to war, it is better that we all participate by living with higher fuel prices, by accepting a drop in the value of our stocks, by welcoming refugees into our countries and by donating to the legitimate relief organizations that serve the innocent victims.  Of course, the arrest, trial and punishment of the dictator and his generals will follow in due time.  

Sunday, August 25, 2013

Southwest Flooding

Tropical moisture, swept into the Desert Southwest by Tropical Depression Ivo (now off the Baja Peninsula), has been caught in the Southwest Monsoon flow.  As a result, heavy rains are falling from southeastern California and western Arizona, northward and northeastward across the Great Basin and Colorado Plateau.  Precipitation is expected to reach 2-3 inches in many areas and flash flooding is likely, especially in desert canyons and across mountainous terrain.

Checking the radar this evening, the moisture plume extends from the Sea of Cortez to southeastern Wyoming; while the heaviest rains will fall west of the Continental Divide, a few thundershowers have dropped across the Colorado Front Range, bringing more rain to our Littleton farm.

High pressure over the Southern Plains, a vital component of the monsoon flow, produced clear skies over southeastern Colorado today, pushing afternoon highs near 100 degrees F.  Over the next few days, that high pressure dome is forecast to shift westward; in turn, the monsoon flow (which parallels its western rim) will shift westward as well, leaving the Front Range urban corridor with sunny, dry weather.  After four days of welcome precipitation, we have little reason to complain.

Saturday, August 24, 2013

Nighthawk Exodus

As the first hint of autumn penetrates the heat of summer, common nighthawks prepare for their long journey to South America.  Dedicated insectivores, they are early fall and late spring migrants, taking no chance that a sudden blast of winter will annihilate their prey.

By late August, their numbers increase in the evening sky, circling southward before summer fades from temperate latitudes.  Their exodus will gain momentum through mid September as their annual parade extends across the southern U.S., Mexico and Central America, bound for the tropics.  If conditions permit, a few stragglers may linger into early October, snaring prey over sports stadiums where moths and other insects are drawn to the lights.

After a winter in the balmy rainforests of South America, the nighthawks will begin to head north in April, reversing their autumn journey and reaching the American Heartland by early May.  Nesting on the ground in open woodlands or on flat roofs in urban areas, they will raise their young just in time to take them on a great adventure to distant landscapes.

Friday, August 23, 2013

Monsoon Reprieve

After more than a week of hot, dry weather, monsoon rains swept across the Front Range over the past two days and, last evening, our Littleton farm received its due.  Torrential rain, accompanied by light hail and spectacular lightening, arrived about 5:30 PM and lasted for more than an hour.

Our parched "lawns" and pastures should green up quickly as sunny, warm weather resumes, complemented by cool, late summer evenings.  While the monsoon pattern will soon shut down, milder conditions generally follow in September, when the first snows dust the higher peaks and the annual aspen display begins to unfold.

Indeed, once the heat and monsoon rains of August have dissipated, the Front Range urban corridor enjoys its best weather of the year.  Though snow showers may arrive in September, they generally hold off until October, when autumn colors adorn the Piedmont under crisp, blue skies.  Yesterday's rain will hopefully mark the turning point from the intense heat of summer to the invigorating splendor of fall.

Wednesday, August 21, 2013

The Greenland Ice Sheet

Greenland's massive ice sheet covers 80% of the island and sits in a topographic basin surrounded by highlands.  Over 1500 miles long (north to south) and nearly 700 miles across at its widest point, the ice sheet has an average thickness of 1 mile; its maximum thickness is almost 2 miles at a point where the ice surface is more than 10,000 feet above sea level.

Greenland's ice sheet began to form by the Miocene Period, about 15 million years ago; since that time, its thickness and surface area has waxed and waned in concert with Earth's climate.  Composed of compressed snow that, until the end of the Pleistocene, had been accumulating for about 100,000 years, the weight of the ice sheet has depressed the rock floor of its basin, which now sits below sea level at its center.  Along its rim, the ice sheet breaks through the highland barrier, forming stark canyons and feeding outlet glaciers which calve icebergs.  Meltwater also pours out through these canyons while, far from the edge, massive pools of meltwater develop atop and beneath the ice sheet; some geologists believe that melting on the underside of the ice sheet is due to heat radiating from Earth's mantle, conducted through Greenland's relatively thin crust.

Now in full retreat due to global warming, hydrologists and glaciologists are working to determine both the process and rate of melting and what effects that will have on sea levels, ocean currents and weather patterns across the globe.  It has been calculated that there is enough water within Greenland's Ice Sheet (8% of the freshwater on Earth) to raise sea level almost 24 feet.   Should that occur, a process that, depending on the rate of global warming, may take 2000 years, Greenland would become an oblong archipelago, formed by the mountains that now surround the ice sheet; eventually, the basin floor would rebound upward, reconnecting the islands.  Of course, the major question today is how rapidly and to what degree that scenario will unfold.

Tuesday, August 20, 2013

Endorsing Pseudoscience

Over the past few decades, there has been an explosion of books and programs that, while based on a kernel of scientific data, embellish the benefits of certain supplements, exercise routines and other therapeutic practices.  Often established or endorsed by physicians and other healthcare professionals who discovered a more lucrative use for their professional degree, the programs are generally directed toward management of common human maladies, especially those encountered by middle aged individuals; prostatism, bowel disorders, sexual dysfunction, depression, obesity and memory loss are among the common targets.

Long confined to infomercials, some of these "experts" are now turning up on educational channels, a careless endorsement of programs that have not been validated by scientific trials.  Misleading information is delivered to a receptive audience while potential side effects are either minimized or not mentioned at all.

Since programming executives seem to be failing in their due diligence, it is essential that the public learn to recognize the signs of pseudoscience.  If the health expert is offering a product or program that is guaranteed to cure a given problem, be suspicious.  If the expert's program comes with a book and/or set of DVDs, keep your hard-earned money.  If the expert implies that his product is free of side effects, be highly suspicious; man has yet to produce a medication or supplement that does not carry some risk of negative effects.  In the end, it is best to obtain medical advice from your healthcare provider and from science-based literature or programming.

Monday, August 19, 2013

Northern Cardinals in Colorado

As I discussed in a post back in February, 2007 (see Settlers and Cardinals), northern cardinals were limited to the southern tier of States until white settlers colonized the Continent.  Clearing forest for lumber and agriculture, humans enticed cardinals northward since they favor brushy woodland borders; today, these colorful birds inhabit the eastern and central portions of North America, from southern Canada to Mexico, and have spread through the Desert Southwest into California.

Here in Colorado, northern cardinals began to turn up along the South Platte, Republican and Arkansas Rivers over the past fifteen years or so, moving up these riparian corridors from the Great Plains.  In recent years, small populations have become established in towns along those river valleys and an increasing number of individuals and pairs have been making an appearance along the base of the Front Range.  Clearly, northern cardinals, currently classified as uncommon local residents in Colorado, are here to stay and, within a few more decades, will likely be common residents across the Front Range urban corridor.

Ever since our earliest ancestors left the African forests to inhabit open grasslands, humans have had a significant impact on other species.  In many cases, we have threatened species via overhunting or by destroying their natural habitat while, in others, we have favored their dispersal by creating habitat (e.g. farms, suburbs, skyscrapers) that serve their needs.  In the case of northern cardinals, human activity has greatly expanded their range.

Sunday, August 18, 2013

Oil & Wilderness

Yasuni National Park, in eastern Ecuador, lies on the eastern slope of the Andes in the upper Amazon Basin.  It protects one of the most biologically diverse tropical rain forests on our planet, home to more species of bats, birds, insects and frogs than any other site on Earth; more than 20 threatened mammals inhabit the refuge and biologists know that many species of plants and animals have yet to be discovered.

Yet, for the past decade, this spectacular wilderness, like many others across our globe, has been caught in a struggle between political, economic and environmental interests, triggered by a pool of oil beneath its pristine tropical ecosystem.  Ecuador's president has proposed that countries and organizations dedicated to conservation and concerned about global warming commit 3.6 billion dollars to cover half the economic loss of leaving the oil in place.  Lauded as a farsighted approach by some and as blatant blackmail by others, the proposal has never gained traction and oil development in Yasuni National Park has gradually progressed.  Of course, the oil companies claim that drilling can be accomplished safely and responsibly in Yasuni but history suggests otherwise.

It is a sad commentary on human civilization that even the most vital ecosystems on our planet are not immune to our never-ending quest for oil.  While we profess our commitment to renewable sources of energy to reduce pollution and combat global warming, we cannot muster the collective political will to accelerate our transition from fossil fuels and to, once and for all, eliminate threats to develop what little wilderness remains on this planet.

Saturday, August 17, 2013

Little Brown Bats

For most of us who live in North America, the small bats that flutter overhead on summer evenings are little brown bats.  Residents of the Temperate Zone, from southern Alaska to the Canadian Maritimes and southward through all but the southernmost regions of the U.S., these common mammals are most active at dawn and dusk, strafing the treetops for a wide variety of flying insects.

In spring, pregnant females gather at large nursery roosts, usually located in abandoned buildings.  After giving birth to a single pup (twins are rare), the mother nurses her newborn for several weeks; by one month of age, the young bat is self sufficient and female pups may mate by the coming fall.  During the warmer months, little brown bats roost in attics, barns, tree cavities and man-made bat houses (among  other sites), leaving to hunt at dusk and during the predawn hours; they are active only 4-5 hours each day.  Promiscuous breeding occurs in late summer and early autumn but the sperm is stored and fertilization does not occur until the following spring; births peak in late May to early June (depending on latitude).

As their prey dies off with the autumn chill, little brown bats gather in hibernation caves or abandoned mines for the winter; those that summer in northern latitudes usually migrate to more southern areas for hibernation.  Throughout the winter, the bats stir during periods of mild weather (and may be seen flying about) but generally do not feed; indeed, like all true hibernators, they depend on stored brown fat to fuel their survival, an adaptation that may prove fatal in years when winter conditions extend well into spring.

Friday, August 16, 2013

Black-headed Grosbeaks

Summer residents of western North America, from the High Plains to the Pacific Coast and from southwestern Canada to northern Mexico, black-headed grosbeaks favor riparian woodlands where they feed on a wide variety of insects, seeds and berries.  Despite their thick, conical bills and bulky stature, they are known for their melodious song, which is delivered by adult males and females.

Along the Colorado Front Range, black-headed grosbeaks are best found across the lower foothills, generally between elevations of 6000 and 8000 feet.  They are easily attracted to backyard feeders in that life zone and may wander onto the Piedmont for handouts as well.  In all parts of their range, nests are placed in dense vegetation near streams and both parents participate in incubation and childcare duties.  Both parents also vigorously defend their nest site from potential predators such as jays, crows and magpies.

By late summer, black-headed grosbeaks head for Mexico, sometimes traveling in sizable flocks.  There they spend the winter, adding monarch butterflies to their omnivorous diet (one of the few species unaffected by the protective toxins within those colorful insects).

Wednesday, August 14, 2013

Cottontail Comeback

Soon after we purchased our Littleton, Colorado, farm, cottontails disappeared from the property, extirpated by red fox that established a den beneath the barn.  After almost twenty years of residence, the fox were, in turn, killed off by coyotes that denned here for a year or two before I, in concert with neighbors (who began to lose pets) managed to discourage their presence.

This week, I have seen cottontails on the farm for the first time since the early 1990s.  Given their reproductive rate, I anticipate a healthy population in the near future, controlled by owls, hawks, snakes and visiting fox; should red fox move back to our farm, the cottontail recovery will be short lived.  Such is the beauty of natural ecosystems in which prey (cottontails, mice, voles, etc.) combat predation with evasive behavior and prolific reproduction; indeed, female cottontails give birth to four litters or more in the course of a year and females born in the early spring often breed by late summer.

In Colorado, there are two species of cottontail east of the Front Range foothills.  Desert cottontails inhabit the dry grasslands of the High Plains while eastern cottontails are found in riparian corridors of the Piedmont; it is the latter species that has taken advantage of suburban lawns and farmlands near the major cities.  A third species, Nuttall's cottontail (also known as the mountain cottontail) inhabits mountain parklands, mountain meadows and wooded canyonlands.

Tuesday, August 13, 2013

The Nature of Aging

Having punched the annual time clock of life three days ago, I, like most human males, am not modest about my age (63 journeys around the sun for me).  Yet, many humans of both genders tend to be uncomfortable with the process of aging, becoming depressed as their bodies change and their minds gradually fade to black (or at least gray).

Of course, age is relative to one's fitness, health and attitude and some persons in their eighties are more active than most humans are in their forties.  And current evidence suggests that the more active we remain (both physically and mentally), the healthier we tend to be at any given age.  Then again, longevity is most closely related to one's genetics, a factor over which we have no personal control (not yet, anyway).

Persons who become depressed about their age have likely been spared the early death of friends or family members during their life.  Those of us who have had such experiences feel fortunate to have survived another year and tend to appreciate the extended reprieve.  Few of us want to live beyond our capacity for meaningful participation in the many facets of life but, until then, we're happy to slow down (if necessary) and enjoy the rest of the journey.

Monday, August 12, 2013

Deluge on the High Plains

Heading back to Denver today, the weather cooperated through Missouri and Kansas except for some brief, heavy rain east of Kansas City.  In fact, it was so calm in central Kansas that the Smoky Hills Wind Farm was in off mode; only one turbine in the massive complex was spinning, a spectacle that I have never encountered on my many trips across the Great Plains.

Then, as I entered Colorado, a wall of towering thunderstorms loomed to the west.  The rain held off until I reached Arriba but, as I descended to Limon, a torrential downpour ensued; since visibility was near zero, I pulled into a truck stop to wait out the storm.  Almost an hour later, the rain and light hail began to let up and I ventured onto the Interstate to resume my journey; I suspect at least 3-4 inches of precipitation had fallen during my stop.  Climbing toward the Palmer Divide, I saw massive streams of floodwater pouring down the hillsides, filling the gullies along the highway and threatening to flood across I-70.  Higher up, snow plows were removing hail accumulation from the Interstate but the streams of floodwater had diminished; nevertheless, their flow would soon add to the crisis near Limon, which sits along the southern base of the Palmer Divide ridge.  North of the Divide, flooding was minimal along the I-70 corridor.

As I mentioned in a recent post (see Colorado's Monsoon Season), monsoon fed thunderstorms often dump a lot of water in a short period of time.  Flash flooding from these storms is further intensified by hilly or mountainous terrain, especially where burn scars from recent wildfires are present; such has been the case in Manitou Springs, Colorado, this week.

Sunday, August 11, 2013

Advice from Strangers

While taking advice from strangers is not often recommended, especially when it relates to investments, donations and other financial matters, there is good reason to ponder the input of those who have no emotional investment in our lives.

Back in my college days, a friend and I gave a lift to a blind hitchhiker.  After listening to our conversation for a period of time, he stated that my friend had a great voice for radio and should consider becoming a disc jockey.  While this unsolicited advice was laughed off by my friend, I have never forgotten the incident for one reason: I had already come to that conclusion myself (especially in light of his engaging personality and terrific sense of humor) but never mentioned it since I knew he was focused on another career.  During that same period, my English teacher took me aside after class to advise that I consider a writing career; while I appreciated her recommendation and had long engaged in a variety of writing activities, I was too focused on getting into medical school to give much credence to her comments.  Forty years later,  I realize that her advice has remained a significant source of inspiration and has influenced my life in many ways, especially my decision to undertake a side career as an author and publisher.

We often dismiss the casual comments and advice that we receive from strangers, telling ourselves that they don't know us well enough to provide valuable input.  Yet, this feedback deserves some consideration, especially since it is offered by persons who generally have nothing to gain from our response.  While the advice of family and friends tends to carry more weight, it is tainted by both a reluctance to derail our career and the hope (however subtle) that they might bask in our success.

Friday, August 9, 2013

The Hurricane Sweepstakes

The Atlantic Hurricane Season runs from June through November, peaking from August to mid October.  Before the season begins, several organizations, including the National Weather Service, the Weather Channel and Colorado State University, release predictions regarding the number of named storms, the number of hurricanes and the number of severe hurricanes that will occur that year.

As if to emphasize the folly of such long term predictions, they all revise forecasts in mid summer, increasing or decreasing their numbers in response to what happened early in the season and what current oceanic conditions appear to indicate for the coming months.  I would be surprised if many cities or businesses pay much attention to these educated guesses; what they want is advanced warning for any given storm, not a long term projection for the season, the validity of which won't be known until December.

While the Weather Channel and the National Weather Service provide valuable education regarding the nature of these storms and the preparations that should be made by those living in hurricane prone regions, they undermine their own authority by entering the hurricane projection sweepstakes.  If they would concentrate on reporting current conditions and projecting active hurricane or tropical storm paths, the public would be more likely to respect and heed their warnings.

Thursday, August 8, 2013

Cranes at Grand Pass

Yesterday, I visited Grand Pass Conservation Area, northwest of Marshall, Missouri.  Stretching south from the Missouri River, this refuge attracts large flocks of waterfowl during the spring and fall migrations and it is during those seasons that I have visited in the past.

Entering the refuge, I found that most of the ponds had been drained and were now covered by grasslands and various crops.  What few shallow pools remained attracted a fair number of shorebirds, dominated by least sandpipers; killdeer, some Baird's sandpipers and a few sanderlings were also present.  Other birds on the refuge included the typical mix of summer species such as cliff, barn and bank swallows, dickcissels, indigo buntings and eastern kingbirds, joined by a host of permanent residents.

The highlight of my visit was the sound of sandhill cranes; uncommon migrants through the western half of Missouri, cranes first successfully nested in our State last year, at Squaw Creek NWR, along the Missouri River south of Mound City.  The birds that I heard yesterday (two or three at the most) remained hidden behind a grove of trees but their distinctive vocalization belied their presence.  A few sandhill crane migrants have been visiting Eagle Bluffs Conservation Area, in central Missouri, every spring in recent years and I suspect that they, like American white pelicans, will become increasingly common migrants in our region.  Whether a summer population will become established in Missouri is yet to be determined but the current trend appears to favor that development.

Wednesday, August 7, 2013

Humans and the Supernatural

Once education, reason and experience convince many of us to abandon the simplistic beliefs of organized religions, we often retain a fascination with the supernatural.  In particular, we imagine that a spiritual plane exists (undetectable with our human senses) that will rescue us from the prospect of utter annihilation following death.

This vague hope, which has no basis in science, is exploited by self-proclaimed psychics and mediums who, for a fee, offer access to that spiritual realm.  Such enticements, comparable to the promises of organized religions, provide reassurance that life extends beyond the grave and that we will be able to reconnect with loved ones in the hereafter.

Acceptance of the supernatural is fueled by the realization that science is unable to explain everything that occurs (or has occurred) within the known Universe; of course, this point has been used to support religious beliefs as well.  Indeed, the unknown is a powerful source of hope and, though science has solved many mysteries throughout human history, the drive for self preservation (inherent in our genes), combined with our capacity for imagination, feed the conviction that we humans (and perhaps all life forms) possess spiritual traits that are beyond the detection of modern science.  Therein lies the foundation for supernatural beliefs: the conviction that life is both physical and spiritual; in other words, life has an immortal component.  Naturalists, myself included, are inclined to believe that supernatural phenomena, as well as our fervent hope that they exist, are products of the complex human brain.

Tuesday, August 6, 2013

The Pecos River

The Pecos River rises in the Pecos Wilderness of the Sangre de Cristo Range in north-central New Mexico; its uppermost tributaries gather east of Truchas Peak (13,102 feet), the second highest point in the State.  Flowing southward, the river passes through the Pecos National Historic Site east of Santa Fe and soon enters canyonlands south of the mountains; there it runs through Villanueva State Park before rumbling onto the High Plains of eastern New Mexico.

Angling SSE across the plains, the Pecos River has been dammed to form Santa Rosa Lake, Sumner Lake, Brantley Lake and Avalon Lake (north to south); constructed primarily for irrigation and water supply purposes, these reservoirs are also used for recreation and attract large flocks of migrant waterfowl, cranes and shorebirds that travel above the arid planes of eastern New Mexico.  The river also passes through Bitter Lake National Wildlife Refuge, northeast of Roswell,  a major wintering area for sandhill cranes,  and flows west of Bottomless Lakes State Park, which harbors deep, sinkhole lakes that formed in the Cretaceous limestone bedrock.  South of Carlsbad, the Pecos receives flow from the Black River (draining the east edge of the Permian Reef complex), its only significant tributary between the Sangre de Cristo Mountains and the Rio Grande.

As the Pecos River leaves southeastern New Mexico and enters western Texas, it flows through the Red Bluff Reservoir; the backwater of this lake, which was impounded in 1936 and has a surface elevation of approximately 2840 feet, marks the lowest elevation in New Mexico, almost 10,000 feet below the headwaters of the Pecos.  Below the Red Bluff reservoir, the river snakes through the High Plains and canyon country of West Texas, finally entering the Rio Grande just upstream from the Amistad Reservoir and nearly 930 miles from the alpine snow fields of the Sangre de Cristos.

Sunday, August 4, 2013

Grand Bluffs Conservation Area

Facing a warm, sunny afternoon and no specific plans, my wife and I decided to visit Grand Bluffs Conservation Area along the Missouri River, downstream from Jefferson City.  After a twenty minute drive along Missouri 94, on the north edge of the river's floodplain, we reached Portland, Missouri, and, five miles beyond that town, turned north to the refuge parking lot.

From the small lot, a jeep trail leads up into the oak-hickory forest, climbing eastward through private land and then entering the Conservation Area.  Gradually curving to the south, the trail crosses several clearings before reaching the crest of the ridge, one mile from and 300 feet higher than the trailhead.  The path then drops toward the river for another quarter mile, ending at an observation deck that offers a magnificent view of the broad Missouri Valley, including sections of the river, parcels of riverside forest, floodplain meadows, limestone cliffs and the wooded hills that rise along the south edge of the valley.  With few human structures in sight, one could almost see Lewis and Clark moving upriver.

While an abundance of wildflowers lined the trail, visited by numerous swallowtails, our spontaneous visit reminded both of us why we prefer to hike during the colder months of the year, when autumn colors paint the forest, when vistas are extensive, when wildlife is active in the cool, dry air and when annoying insects have succumbed to the frosty nights.  Nevertheless, our summer journey to that secluded overlook, one of the best in central Missouri, proved to be an excellent choice indeed.

Saturday, August 3, 2013

Green Herons

Formerly known as little green herons or green-backed herons, green herons are common summer residents of wetland areas throughout most of the contiguous U.S. and southernmost Canada.  However, unlike their large, long-legged cousins, these small herons feed along marshy shores, at the edge of secluded mudflats and beneath the cover of boat docks or riparian vegetation and are often missed by the casual birder; when accidentally flushed from their hunting site, they fly off, squawking their displeasure at the intruder.

Feeding primarily on small fish, green herons are known to attract prey by dropping insects or small twigs into the water; they also consume amphibians, lizards and large insects.  Nests are built by both parents and generally placed in a shrub or low tree branch near or above a favored feeding area; while they may nest in mixed heron colonies, they prefer an isolated nest site.  In like manner, green herons generally hunt alone though family groups may be encountered in late summer and congregations may appear along shrinking pools to feast on stranded schools of fish.

Green herons are permanent residents of California and the Coastal Plain, from South Carolina to Texas.  Those that summer farther north or inland may winter in these regions or head further south to coastal wetlands of Mexico.

Friday, August 2, 2013

Ding Darling of the Midwest

In December, 1974, I visited Sanibel Island, Florida, with my wife's family.  During that vacation we toured Ding Darling National Wildlife Refuge, world famous for its fabulous diversity of subtropical, aquatic wildlife.  Since that time, I have visited many other wildlife refuges across this magnificent country, including a conservation area near Columbia, Missouri, that has always reminded me of Ding Darling.

Like its famous counterpart, Eagle Bluffs Conservation Area protects wetland habitat and is accessed by a network of graveled roads and levees that permit close viewing of its resident and migrant wildlife.  A late summer visit is especially reminiscent of Ding Darling NWR, as a large number of herons, egrets, shorebirds, cormorants, white pelicans, rails and other aquatic birds visit this Missouri floodplain refuge, stopping to rest and feed on their journey to the south.

In reality, lying as it does within the seasonal diversity of the Temperate Zone, Eagle Bluffs attracts a greater variety of birds in the course of a year than does Ding Darling.  While it may not host many of the subtropical species that are found in South Florida, it sits on a major avian flyway, attracting a large variety of waterfowl and songbirds that breed to our north.  Furthermore, the avian population of Eagle Bluffs changes through the seasons as summer and winter residents mingle with permanent residents and with those cherished vagrant and irruptive species.  And, finally, since Eagle Bluffs does not enjoy the international fame of Ding Darling NWR, one can often explore its varied wetland habitats in relative solitude.

Thursday, August 1, 2013

The Tasmanian Bridge

During the Triassic Period, about 200 million years ago (MYA), the supercontinent of Pangea split into Laurasia (the northern Continents) and Gondwana (the southern continents).  Throughout the Jurassic and Cretaceous Periods (190-65 MYA), as dinosaurs roamed the globe, Laurasia and Gondwana rifted into the continents that we recognize today.

Late in the Cretaceous, about 80 MYA, Australia and Antarctica remained connected but a rift began to form from west to east, opening a long, narrow bay between the continents; nevertheless, they retained a connection via the Tasmanian Bridge.  Throughout most of the early Cenozoic Era (65-40 MYA), Earth's climate was very warm and, despite its gradual movement to the south, the Australian-Antarctic land mass harbored diverse, temperate ecosystems.  Then, near the end of the Eocene (about 38 MYA), the southern end of the Tasmanian Bridge split from Antarctica, the Tasmanian Strait opened and Australia drifted toward the north (a process that continues today).  This produced a circumpolar ocean current around Antarctica, cooling that continent and Earth's climate as well; indeed, the Antarctic ice sheet began to form at that time.

The connection between Tasmania and the Australian mainland has since opened and closed as sea levels have fallen (during glacial epochs) and risen (during warm interglacial periods), respectively.  Humans reached Australia about 60,000 years ago, crossing (perhaps accidentally) from Indonesia; by 30,000 years ago, some of these native Australians had colonized Tasmania, then a peninsula of southeastern Australia.  About 12,000 years ago, as the last Pleistocene glaciers receded, sea levels rose and Bass Strait reformed, isolating the Tasmanian residents from mainland aborigines.