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Showing posts from March, 2012

The Prolific Muskrat

Native to North America, muskrats are semi-aquatic rodents that inhabit wetlands and streams across the Continent; hunted and trapped for their dense fur and meat, they have also been introduced in Eurasia and South America. When spotted on lakes and ponds, muskrats are often mistaken for beaver; however, they are significantly smaller (weighing 5 pounds or less) and are easily identified by their long, narrow tail.

Muskrats dig dens in the banks of streams, canals and lakes or construct mounds of aquatic vegetation and mud; in either case, multiple entrances to the lodge chamber, both above and below the water line, permit escape routes from predators and access to aquatic food when the surface water is frozen. Primarily nocturnal and active throughout the year, muskrats feed on a wide variety of plant material and also consume amphibians, snails, turles and fish; they, themselves, are potential prey for coyotes, fox, otters, mink, raccoons, snapping turtles, snakes, eagles, herons…

An Odd Mix of Spring

Out back last evening, it looked, felt and smelled like late April. The lilacs and honeysuckle were in bloom, dandelions and violets speckled the lawn and the trees were nearly leafed out; even the late-leafing sycamores and black walnuts had a modest canopy of green. Toads were trilling, honey bees buzzed across the flower beds and a band of thunderstorms loomed to the west.

Yet, there were missing pieces to this late April scene. While our permanent avian residents moved about the yard, they were still joined by wintering juncos and white-throated sparrows. Many other birds, usually present in mid spring, were conspicuous by their absence; there were no chimney swifts in the evening sky, no house wrens singing in the twilight and no gray catbirds scouring the shrub line. Colorful warblers were not flitting about the shade trees and no northern orioles or indigo buntings had arrived to compete for attention with our resident cardinals and blue jays.

While plants, amphibians, rep…

The Porcupine Caribou

Named for the Yukon River tributary that drains most of their range, the Porcupine Caribou Herd inhabits northeastern Alaska and the northern Yukon Territory of Canada. According to the last official count, in the summer of 2010, the herd is now composed of about 169,000 individuals, making this one of the most spectacular concentrations of migrant mammals on our planet.

After wintering in mountainous regions south and east of the Brooks Range, the Porcupine Caribou begin their spring migration in March, led by cows and yearlings (bulls and juveniles follow a few weeks later). Using three primary routes across the Brooks Range of Alaska and British Mountains of the northern Yukon, pregnant cows reach the North Slope by late May and calving begins, synchronized to reduce the impact of predation by wolves, grizzlies and golden eagles; the formation of nursery groups and the rapid development of calves (able to run within 24 hours) also serve to diminish loss of the newborns. As the bu…

Future Exotic Terranes

The continents of planet Earth are composed of central, "stable" platforms to which smaller "exotic terranes" have accreted and from which other segments of crust have rifted away. In fact, the central platforms (or cratons) are, themselves, composed of ancient segments that fused together early in geologic history and possess aborted rift zones that could reactivate in the future.

Exotic terranes are segments of continental crust that either rifted from a larger land mass or formed above oceanic hotspots, mid-oceanic ridges or subduction zones as volcanic islands. Moving with the surrounding oceanic crust, they accrete to another continent where the intervening oceanic crust subducts into a trench. Looking at the current geologic map of our planet, we can thus identify land masses that will become exotic terranes in the future (as long as the current plate movements and subduction zones do not change).

Examples include Southern California and the Baja Peninsula…

Double-Dip of Winter

Lest we forget it is still March, wintery weather lingers in the Pacific Northwest and, thanks to a Canadian front, has re-invaded the Great Lakes and Northeast. Cloudy skies, chilly rain and snow showers will dominate those areas for the next few days while, between the dips, summer warmth persists across the Heartland, from the Central Plains to the Gulf Coast.

Despite the proximity of winter's advance, current forecasts suggest that neither trough will affect the mild (if not hot) spring that is entrenched from the Southern Rockies to the Southeast. Rather, the high-riding jet stream is expected to remain in Canada and warm air will return to New England by the end of the week.

After almost two weeks of summer-like weather, many under the central ridge of high pressure are tempted to plant the tomatoes. Nevertheless, here in Missouri, the historical risk of frost runs through mid April and we may yet encounter winter's final gasp before the heat is here to stay.

The Garth Wetlands

Stretching across the Bear Creek floodplain in north Columbia, Missouri, the Garth Nature Preserve harbors one of the best urban wetlands that I have yet to encounter. Accessed by a fine network of trails, it is visited primarily by joggers, dog-walkers and couples focused more on their conversation than on the natural beauty that surrounds them. For those of us who care to look, there is always much to see.

This morning I found the flora and fauna to be well ahead of schedule, as is occurring across much of North America in the midst of our ongoing heat wave. The rosy glow of redbuds brightened the greening woodlands while a background chorus was provided by northern flickers, chorus frogs, trilling toads and red-winged blackbirds. Though the latter songsters are commonly heard in late March, they were joined by the distinctive chortle of leopard frogs, the scattered call of cricket frogs and, if I was not mistaken, the deep croaks of a few groggy bullfrogs. Aquatic turtles were…

Mt. Salina

Having driven across the Great Plains on many occasions, I have come to know the cities and towns, their respective exit numbers and, most importantly, the amenities that they offer for the traveler. In addition, as a naturalist, I have come to recognize these human oases by their surrounding terrain (yes, the Great Plains harbor a mix of topography).

One of these natural landmarks is a small but prominent mesa just east of Salina, Kansas. While it has an elevation of only 1500 feet or so, it rises almost 300 feet above the city and its immediate surroundings. Nameless on the few maps that I have checked, I have christened it Mt. Salina and have noted that this erosional remnant rises south of the Smoky Hill River, near its junction with the Saline River.

While not nearly as majestic as Pikes Peak and other famous landmarks across the American West, this mesa must have played a significant role in guiding early settlers and native Americans to regional settlements and their vital w…

Pine Grosbeaks

Pine grosbeaks are among my favorite Colorado birds. Though widespread throughout the mountains and higher foothills, these large, colorful finches are not often seen by the casual hiker. However, once encountered, pine grosbeaks are amiable birds, allowing close approach and observation.

Residents of open coniferous forests, from Alaska to northern New England and southward through the mountain corridors of the West, these hardy birds pair off during the breeding season but spend most of the year in sizable flocks, roaming about in search of favorable seed crops. Easily recognized by their large size, stocky build, long tail and undulating flight pattern, the adult males have rose-colored plumage while females and juveniles are mostly gray with olive or burnt orange patches on their head and tail (all have white bars on their black wings). Like many northern finches, pine grosbeaks are irruptive, wandering erratically during the winter months and may turn up almost anywhere acros…

Morning at the Canyon

Facing another mild, sunny morning along the Colorado Front range, I headed to Deer Creek Canyon Park in the foothills of southwest Metro Denver. There I was greeted by cool, fresh air, the usual mix of wild residents and, for most of the visit, the joy of solitude.

As I hiked through a spectacular landscape of yucca-studded grasslands, Gambel's oak, mountain mahogany, junipers and scenic rock formations, I encountered scrub jays, Townsend's solitaires, rufous-sided towhees, ravens, canyon wrens and, of course, the ubiquitous chickadees, robins and juncos; mule deer were abundant and Colorado chipmunks scurried across the trail. At the top of the first ridge, which commands a magnificent view of the canyon and of rock formations to the east, I was rewarded by the sight of a golden eagle, soaring above the foothills that flank Deer Creek Canyon.

In another month, these permanent residents will be joined by black-headed grosbeaks, green-tailed towhees, Lazuli buntings, lesser …

The Caspian Sea

A remnant of the Paratethys Sea, the Caspian Sea is the largest inland body of water on Earth. Covering more than 143,000 square miles, it was cut off from the Black Sea when the Caucasus Mountains rose some 6 million years ago, a product of the Red Sea opening which forced (and continues to force) the Arabian Plate to collide with the Eurasian Plate. Retaining some salinity from the Paratethys, the Caspian Sea has become a massive basin lake, receiving inflow from more than 130 freshwater rivers but having no outlet to the sea; 80% of the inflow is via the Volga River while the combined flow of the Ural and Kura Rivers adds another 15%.

Since this inflow is primarily from the north and northwest shores of the Caspian Sea, its relatively shallow northern waters (only 20 feet deep) are fresh while the deeper waters of its southern section (exceeding 3000 feet in some areas) have a salinity that is 1/3 of that found in our oceans. Kara-Bogaz-Gol, a large lagoon on its eastern shore (w…

More like March

After a week of summer-like weather across most of the U.S., cooler air has moved east of the Continental Divide. Nevertheless, sunny skies and minimal wind in Metro Denver sent me down to the South Platte Valley for a morning hike.

Not fooled by the recent mild conditions, buffleheads and common goldeneyes still joined the Canada geese, mallards, shovelers, gadwall and pied-billed grebes on the valley ponds and lakes. Other signs of March included the loud, seasonal calls and drumming of northern flickers and nest building by a pair of black-billed magpies; the latter couple took a break from their work to harass a red-tailed hawk that had perched in a nearby cottonwood.

Perhaps the most potent reminder that we are still in early spring is the forecast for snow flurries overnight. Indeed, March is the snowiest month along the Front Range urban corridor and, lest we get too anxious for an end to winter, we must remember that April snowfall ranks just behind that of March. Fortunat…

Ground Turbulence

My regular trips between Missouri and Colorado are usually a bit tiring but today's journey was especially difficult. After leaving Columbia in a balmy haze this morning, I encountered a southwest wind in eastern Kansas which strengthened with every mile to the west, all the way to the Front Range. Though the skies were mostly sunny and I had neither supercells nor snow to complicate my travel, nine hours of bone-jarring turbulence was more than enough.

While the strong wind was my sole problem through eastern and central Kansas, dust plumes and tumbleweed armies posed additional distractions across the dry landscape of the High Plains. Fortunately, no trucks were overturned by the winds and few RV's ventured across the Great Plains today, a wise response to the high wind advisory. Though strong winds are common across this region, today's wind field is especially widespread and is posing a major fire threat from New Mexico and West Texas to Nebraska. Gusty winds alon…

Marsh Madness

While college basketball fans are focused on their brackets, a more natural madness is unfolding across our wetlands. Chorus frogs and spring peepers have entered the peak of their breeding season and their loud calls ring across the marsh. Joining the frenzy are the season's first insects, rising from the ponds and lakes, hoping to mate before encountering hungry tree swallows, eastern phoebes, eastern bluebirds or reawakening bats.

The hysterical calls of flickers and red-bellied woodpeckers also echo across the wetlands and the impatient, deafening calls of red-winged blackbirds signal the onset of their nesting season. Rafts of ducks and coot add their voices to the chorus while stately great blue herons wade through the shallows, feasting on the tree frogs and other hapless victims. While the color explosion of late spring birds and plants has yet to materialize, a greening landscape spawns the joy of rebirth across the March wetlands.

This year, following a mild winter a…

May in March

We awoke in Cincinnati this morning under clear skies and enveloped in balmy air; the temperature was 60 degrees F. By mid morning, as we prepared to return to Missouri, the leading edge of a storm system arrived with intense lightening, torrential rain and pea sized hail.

Taking the northern route through Indianapolis, we managed to dodge most of the severe weather, and continued west under puffy white clouds in a hazy, blue sky; stopping for gas in western Indiana, we stepped from our air-conditioned car into summer-like heat. All across the till plains, meadows were greening, barren fields shimmered with the purple of henbit and early fruit trees were in bloom. Canada geese were nesting along the farm ponds, killdeer raced along the shallow sloughs and mourning doves cuddled on the powerlines, swaying in a mild, south breeze.

After crossing another band of storms in eastern Missouri, we arrived in Columbia to find the magnolias and wild cherries in bloom and the community in ful…

Geophysical Provinces of Ohio

Though known primarily for its rolling farmlands, Ohio is a mosaic of geophysical provinces, defined by underlying geology, tectonic uplift and the erosive power of Pleistocene Glaciers. From a broad perspective, the State overlaps two major provinces; the northwestern 60% of Ohio lies within the Central Lowlands of North America while the southeastern 40% is occupied by the Appalachian Plateau. The border between these two geophysical regions runs SSW, from the northeast corner of Ohio to the Ohio River Valley at the southern edge of the State.

The Appalachian Plateau, composed of Carboniferous sandstones, limestones and shales, was lifted with the Southern Appalachian Mountains as North America and Africa collided during the formation of Pangea, some 300 million years ago. While the Plateau's western edge has been obscured by glacial erosion in northeastern Ohio, it stands out as a prominent escarpment through the southern half of the State, rising 500 feet above the adjacent…

Black Squirrels

Having lived among gray tree squirrels and golden-brown fox squirrels throughout my life, I am always caught off guard when I re-encounter the black squirrels of northeastern Ohio during visits to my wife's home town. These melanistic variants of eastern gray squirrels are not isolated mutants but, rather, represent the dominant phenotype of their species.

When European explorers and settlers first arrived in North America, almost all eastern gray squirrel populations were reported to be black in color. Thought to have evolved as camouflage from predators when these agile creatures inhabited the dark, mature forests of the eastern U.S. and eastern Canada, the coloration has shifted to gray or gray-brown in the open forests, woodlots and suburban areas that characterize most regions today. Nevertheless, the black race of eastern gray squirrels remains dominant in many areas of the Northeast, from southern Canada to northeastern Ohio and northern Pennsylvania and from Michigan to…

Visiting the Past

This coming week, my wife and I will visit our home State of Ohio to see relatives and, perhaps, a friend or two. Having lived in other parts of the country for most of our careers, we try to make the pilgrimage at least twice each year.

Of course, most of our old friends have since left Ohio and the urban landscapes have changed dramatically, including the demolition of past apartments and sentimental college hangouts. Nevertheless, driving through old neighborhoods or walking across modern versions of our campuses will remind us of those we left in the past, those who often surface in our memories and, of course, those who still haunt our souls.

There is a great deal of truth to the observation that you can't go home again. But you can still touch base with the landscape of your formative years and, by doing so, come to better understand the person that you have become. Living in the past, with its embellished joy and buried pain, can only produce regret and self-delusion bu…

Music of the Gods

While a minority of us enjoy a severe thunderstorm, the sound of distant thunder seems to comfort most humans. Like other universal emotional responses, I suspect that this reaction to thunder is inborn, buried in the collective soul of our species.

Though the distant rumble of thunder could be accepted as a warning, a signal to retreat from nature's fury, it also implies relief from the heat and the promise of rain for a parched earth. Considering the universal appeal of music, with its bass rhythm and percussion, early humans may have perceived thunder to be the music of the gods, a welcome sign of their providence.

For whatever reason, the sound of a thunderstorm has a soothing effect on most humans, yet more evidence that we are part of nature's domain; physically, mentally and emotionally attached to her web of life and death, we are ultimately dependent on her bounty, however fickle she may be in its delivery.

Mono Lake

Mono Lake is a 70 square-mile saline lake at the eastern foot of the Sierra Nevada Range, approximately 13 miles east of Yosemite National Park. Enclosed within a natural basin by the Sierra Batholith to its west and Pliocene-Pleistocene volcanic ranges to its north, east and south, the lake is fed by three primary streams (Lee Vining, Rush and Mill Creeks) and by freshwater springs along its floor. Having formed during the Pleistocene, about 1 million years ago, it is one of the oldest lakes in North America and is the largest lake completely within California.

As a basin lake, its size and depth are a balance between inflow from streams and springs and evaporative loss in the dry climate of the Basin and Range Province. Prior to 1941, its surface elevation hovered above 6400 feet but this was dramatically lowered by diversion of inflow to the Los Angeles Water System; legal challenges by conservation groups eventually restored most of the inflow by 1994.

Despite its high salinity…

A Blast of Summer

In its seasonal battle with winter, summer has launched a powerful invasion. Over the past 24 hours, strong southwesterly winds have raked the Heartland, pushing afternoon highs near or above 70 degrees F. After a mild, nearly snowless winter, we are now getting an early taste of summer; perhaps spring will be especially brief this year.

Of course, such intense winds and heat in March usually signify an approaching cold front and this, indeed, is the case. The winds are generated by a combination of high pressure to our east and low pressure along an atmospheric trough, to our west; as the latter pushes across Missouri tonight, thunderstorms will ignite and, by morning, the air will be chilly once again, exacerbated by a northwest wind behind the front.

Despite summer's early victory, the war will continue. Winter may have given us a break this year but we should not underestimate its staying power. An unexpected dip in the jet stream could open the door for its return, compl…

The Domestication of Animals

We humans have been domesticating animals for the past 12,000 years and they have played a crucial role in the rise of our civilization and in the formation of our varied cultures. We have used and abused animals for food, clothing, transportation, muscle power, laboratory experimentation, pollination, recreation and companionship.

Dogs were the first animals to be domesticated, used by clans of the Middle East for protection and hunting assistance some 12,000 years ago. Goats were domesticated in the Fertile Crescent about 10,000 years ago while sheep and pigs were raised in Turkey and Syria by 9000 years ago. About 8000 years ago, cattle were domesticated in Northern Africa and India, cats joined the households of Egypt and chickens were bred for eggs and meat in Southeast Asia. As the horse was domesticated by tribes of central Asia, some 6000 years ago, the Incas were utilizing llamas in the Andes of South America and donkeys were brought under human rule in Northern Africa, s…

Education, Liberalism & Faith

Rick Santorum's proclamation that higher education indoctrinates students with godless, liberal ideology unleashed a political firestorm among Democrats, Independents and moderate Republicans; of course, his disrespectful style, labeling President Obama a snob, did not help his cause. Nevertheless, there is some truth to Santorum's message that he may not wish to acknowledge.

There is little doubt that education and religious faith have an inverse relationship, especially when one defines faith by the rigid dogma of most Western religions. Though some studies refute the fact that liberalism and agnosticism (or atheism) are more common in the college-educated population, I suspect that these associations do prevail in certain fields of study. As a physician, I know many medical professionals who remain devoted to their Church but the great majority do so with a liberalized view of social issues, including birth control; they and other social service professionals come to app…

Restless Locals

While most summer songbirds won't arrive until April, some of our permanent and winter residents are often best observed during March, when they are most likely to turn up in our residential areas. Restless due to the approach of their migration and/or mating season, these birds begin to roam about, leaving their more secluded and less developed winter haunts.

In my experience, permanent residents such as hairy woodpeckers, eastern bluebirds, northern mockingbirds and barred owls are more often seen in suburban areas during this month than at other times of the year. So too are winter residents such as white-crowned sparrows, fox sparrows, purple finches and yellow-bellied sapsuckers.

Perhaps this observation is purely an illusion, the product of my increasing attention to our yard and its inhabitants during the milder days of late winter. But I suspect that birds, like us, are energized by the lengthening daylight of March and I know that we, like them, become restless with th…

White-Fronts at Eagle Bluffs

It was another spectacular morning at Eagle Bluffs Conservation Area today; the sky was clear, the air was cool and both raptors and waterfowl were abundant. Joining the wide variety of ducks were hundreds of American white pelicans, small groups of Canada and snow geese and a large flock of greater white-fronted geese.

Breeding across the Arctic tundra of Alaska and Canada, greater white fronted geese winter along the Gulf Coast, from Louisiana to Mexico, and along the Pacific Coast from Oregon to Mexico; a Greenland subspecies usually winters in the British Isles but may turn up along the Atlantic Coast of the U.S. Another subspecies, known as tule geese, breed in Alaska and winter in marshlands from Oregon to California.

Migrant flocks of greater white-fronted geese, often numbering in the thousands, are usually found west of the Mississippi Valley; there they stop to rest and feed on wetlands and crop fields and, from a distance, may be mistaken for Canada geese. Slimmer and m…

The Cost of Intelligence

We humans differ from "lower" mammals in several ways: the complexity of our large brains, our upright posture, our manual dexterity and our capacity for articulate speech. Our intelligence, the product of our complex brain, affords many advantages, including our ability to reason, imagine, theorize, create, communicate and plan, among many other cognitive functions. This brain power also comes with a price.

Relative to other mammals, we humans undergo slow physical development and remain highly dependent upon our parents for a decade or more. While this provides a wealth of vital experience for our developing brains, it puts us at risk for an early death; of course, this was especially true before the era of modern technology and medicine, when children were exposed to a wide variety of natural threats. Furthermore, our slow physical development delays sexual maturity, reducing the capacity of human populations to recover from catastrophic events.

On a more personal lev…

The Final Gauntlet

From a naturalist's point of view, the long march toward spring begins at the winter solstice as the days begin to lengthen and the amount of solar radiation gradually increases. Of course, the low sun angle precludes any significant warming effect until late in February and we must rely on southerly winds to provide respites from the winter chill.

By March, the first calendar month of spring, signs of the season unfold in earnest as bulb plants flower, lawns begin to green, buds swell, bird song intensifies, waterfowl migrate and mating rituals are seen and heard across the Heartland, from the frenzied calls of chorus frogs to the hysterical cries of flickers and the trilling of toads. Few would argue that this month offers our first significant taste of spring but, as residents of the Temperate Zone know, winter is reluctant to concede defeat.

For winter weary humans, tropical blood coursing through our veins, March represents the final gauntlet in our quest to escape the cold…