Friday, October 31, 2008

The Halloween Hunters

As if on cue, the distinctive call of a barred owl pierced the predawn darkness this Halloween morning. Owls, after all, are the quintessential Halloween birds: spooky, nocturnal predators. More often heard than seen, the night-hunting owls are recognized by their deep hoots, hissing rants, tremulous calls and chilling screams. When we hear them, images from black and white horror movies flash through our minds.

Of course, owls are of no threat to humans and play an important role in the control of mice, cottontails and other small mammals. But our species, ill-equipped to function in the dark, has long feared the mysterious creatures that rule the night. We sometimes find the remnants of their kill, body parts or a bloodied scene, the next morning and can only imagine the terror of the hapless victim.

So, after the witches and pirates leave your porch this evening, go out to listen for our Halloween hunters. Their dark, cold season is just beginning.

Thursday, October 30, 2008

Pleistocene Land Bridges

During the Pleistocene "Ice Age," which began 2 million years ago, four major glaciations occurred, separated by warm interglacial periods; whether the Pleistocene ended 10,000 years ago or if the current Holocene Period is just another interglacial phase remains a subject of debate among climatologists.

The most recent Pleistocene glaciation, the Wisconsin, began 70,000 years ago; at its peak expansion, about 23,000 years ago, one third of Earth's land mass was covered with ice. Since there is a finite amount of water on our planet, this extensive ice formation was accompanied by a dramatic fall in sea level; at the peak of the Wisconsin glaciation, sea level was 400 feet lower than it is today and the coastline of North America was 100 miles east of New York City. Elsewhere on the planet, land bridges opened between continents and islands, allowing humans and other animals to migrate across the globe.

DNA evidence suggests that the low sea level of the Pleistocene permitted man to walk from East Africa to Yemen, perhaps as early as 70,000 years ago, triggering the colonization of southern Asia. The major islands of the Indonesian Archipelago became a broad peninsula, allowing man to approach Australia by 65,000 years ago; he managed to cross the remaining ocean barrier (perhaps by accident) within 5000 years and then reached Tasmania via another land bridge. About 50,000 years ago, humans colonized Japan after migrating across a land bridge that extended eastward from the Asian coast. Finally, the most famous Pleistocene land bridge, Beringia, connected Siberia and Alaska, allowing humans, bison and mammoths to reach North America and, in the reverse direction, horses to enter Asia.

Wednesday, October 29, 2008

Children and Conservation

Children are the hope of mankind. They are the most compelling reason to end war, combat discrimination, eliminate suffering and foster freedom across the globe. They also represent our only opportunity to pass the conservation ethic to future generations.

Born into a world of advancing technology, today's children are enticed by an array of gadgets that offer instant messaging, social networking, online information and global communication. They are entertained by reality shows, computer games and the world wide web. Solitude is a lost art and an interest in nature is a potential victim of their lifestyle.

It is thus especially important that we introduce young children to the joy and wonders of nature. Impressions made in early childhood last a lifetime and a child's interest in plants and animals will instill a curiosity that carries through adulthood. So take your kids and grand kids to the nature preserves. Let them see mountains, deserts and seascapes. Buy them binoculars and telescopes. Introduce them to mushrooms, frogs and bighorn sheep. Talk about pollution, glaciers and dinosaurs. Our natural heritage will soon be in their hands; it must first live in their souls.

Monday, October 27, 2008

Midwest Wind Tunnel

Northwest winds raked the Midwest yesterday afternoon and continued into the night. Produced by a strong pressure gradient between high pressure over Colorado and low pressure over Ontario, the winds swept cold, dry, Canadian air into the Heartland. This morning, many Midwestern cities are below freezing for the first time this season; here in Columbia, we missed by two degrees.

As the system moves eastward, counterclockwise winds around the low pressure center will sweep across the Great Lakes, picking up moisture and dumping lake-effect snows on the higher terrain south and east of the Lakes. Meanwhile, the Great Plains and Midwest will be recovering from the damage wrought by this Canadian Express; winds gusted to 65 mph in some areas, toppling trees, tossing trailers and knocking out power. Just a preview of events to come!

Sunday, October 26, 2008

Rifts, Geography and Time

Over its 4.6 billion-year history, the surface of our planet has been steadily changing; the size, shape and position of our oceans and continents are in a constant state of flux. A map of the Earth today bears little resemblance to the surface features 200 million years ago and will be just as useless in the distant future.

The motion of the tectonic plates that form the crust of our planet is governed by the opening and closing of oceans; in the former case, a land mass rifts apart while, in the latter, continents are forced to collide and fuse. During the Permian Period, 250 million years ago, Earth's land masses had coalesced into the mega-continent of Pangea. Fifty million years later, the Tethys Sea began to open, rifting Pangea from east to west and separating Laurasia (the northern continents) from Gondwana (the southern continents). About 150 million years ago, the Atlantic opened, rifting these super-continents from north to south and, over the next 100 million years, arms of the Atlantic, Indian and Pacific oceans cut apart Laurasia and Gondwana, producing the map that we see today.

But rifting continues. The Red Sea-East African Rift complex began to develop 40 million years ago and will eventually open a seaway through Africa. Rifting on the east and west sides of Greenland occurred 30 million years ago, producing northern arms of the Atlantic and breaking up a land bridge that had connected Europe and North America. The Gulf of Aden and Rio Grande Rifts began to open 10 million years ago, the Gulf of California opened 5 million years ago and the Lake Baikal Rift began to develop 2.5 million years ago; the latter will eventually connect with the Arctic Ocean, cutting Russia in half. In like manner, further rifting across the Great Basin of North America will merge with the Gulf of California Rift, flooding the Intermountain West with an arm of the Pacific.

Saturday, October 25, 2008

The Big Chill

Yesterday's rain was the leading edge of a cold front that has pushed on to the southeast. High pressure behind the front has brought cold temperatures across the entire country; only South Florida and the extreme Southwest will be spared this first major cold wave of the season.

On my predawn walk to work this morning, a crescent moon hung in the eastern sky, Sirius sparkled to the south and Orion, our winter companion, loomed to the southwest; the temperature was 36 degrees F. Lows in the forties are as far south as Mississippi and, as this air mass is reinforced by a second cold front, lake-effect snows will develop along the Great Lakes.

Winter has won this round but the battle with summer continues and warmer air is expected by later in the week. But the tide has clearly turned and the slide toward winter will gain momentum. Just ask the juncos and white-throated sparrows that now feed in our thickets and woodlots; they've arrived from Canada to enjoy our Midwestern winter and will stick around until April.

Friday, October 24, 2008

Water Therapy

Water has a calming effect on most people. Waterscapes, from pounding surf to placid lakes to whitewater streams, are popular destinations for recreation and humans have long established settlements along shores and rivers. While the latter served a number of practical needs (water, food, transportation), man has undoubtedly received a great deal of comfort and inspiration from nearby waterways.

After all, life evolved in the sea some 3.6 billion years ago and did not emerge onto land until 400 million years ago. We, like other life forms, are composed primarily of water and humans spend the first nine months of their life floating in a uterine pool. We can't survive more than a few days without this precious substance and its presence or absence has governed man's colonization of the planet.

Even those of us who prefer dry climates relish an escape to the beach or mountains now and then. Water is entrenched in our souls and the sight, sound and feel of it calm our troubled minds.

Thursday, October 23, 2008

Human Nature

We humans, like other animals, are products of our genes and everything that we do in our lives is devoted, in some way, to their preservation. While this commitment is easy to appreciate in simple organisms, our complex lives, governed by intellect and emotion, shroud this basic, underlying imperative.

Our brain power supplants the instinctual behavior of other creatures. We think, reason, love, worry, ponder and anticipate. We wonder. We are curious. We communicate, debate, create, explore, judge and plan for the future. But, beneath this veneer of activity, thought and emotion, is the primordial drive to protect and sustain our genetic heritage.

We learn to survive. We work, beg or steal. We use our skills to provide for ourselves and our offspring or to con others for those resources. We may be kind or cruel. We may be generous or self-centered. We may be tolerant or judgmental. We may put our faith in gods or in science. We may expect to live forever or accept the temporal nature of our lives. In the end, our motivation is the same.

Wednesday, October 22, 2008

Dusk on the Beach

One evening last week, my wife and I walked out to the beach to watch the sunset on the Gulf of Mexico. Though we missed the main event, a blaze of orange ignited the western horizon, reflecting in the calm waters of the Gulf. As the intense color waned, the sky faded from pale blue to a metal gray and Venus, the "Evening Star" appeared in the western sky; Jupiter, less bright but no less inspiring, glowed high to the southwest.

Catching the last reflections from the evening sky, the Gulf became a sheet of gray and low waves, backlit by the fading dusk, moved toward the shore like a series of black bars. Ghost crabs scurried across the beach while the last flocks of gulls and egrets passed overhead, on their way to nocturnal roosts. The soft break of waves, disrupted only by the occasional squawk of a night heron, enhanced the serenity.

But just as the final glimmer of sunlight retreated below the horizon, something thrashed in the shallows. A ray or sand shark had apparently struck its target; the night hunters had begun their shift. It was time for us humans, ill equipped to function in the dark, to retreat to the condo.

Tuesday, October 21, 2008

Ghost Crabs

Residents of sandy beaches, ghost crabs live in burrows that they dig along the seaward edge of the dune line. These burrows are up to four feet deep and provide a cool, wet retreat where the crabs escape predators and keep their gills moist and functional. Though they are most active from dusk to dawn, scouring the beach for food and bathing their gills in the surf, ghost crabs are often encountered during the day and are easily identified by their pale color and prominent, dark eyes; the latter, which sit atop stalks, give these crustaceans a comical, alien appearance.

Ghost crabs were abundant on Longboat Key this past week; both immature and adult crabs scurried across the beach throughout the day, diving into their burrows or out into the water as walkers approached. They feed on a wide variety of plant and animal life, including seaweed, carrion, sand fleas, mole crabs, stranded fish and sea turtle hatchlings; their taste for the latter has led to their persecution in some turtle recovery areas.

Named for their pale coloration, nocturnal activity and rapid disappearance into burrows, ghost crabs are a food source for night herons, great blue herons, raccoons and gulls. They are also threatened by beach erosion and, ironically, often succumb to artificial beach restoration efforts. For now, their welfare seems assured on Longboat Key!

Monday, October 20, 2008

A Feast at Low Tide

Yesterday morning, a low tide had doubled the width of the beach on Longboat Key. Broad sandflats spread toward the calm Gulf, cut by braided channels of seawater and dappled with temporary pools. The latter, adorned by the tracks of marine snails, harbored schools of fry, starfish and a host of crustaceans.

A hundred or more brown pelicans rested on the calm waters of the Gulf; each would eventually rise into the air and then plunge toward another school of fish. Nearby, sandwich and royal terns circled above the surface in large, noisy flocks, diving in sequence to snare a fingerling. Cormorants and ospreys also moved in to share the bounty and, beyond the outermost sandbar, a pod of dolphins rejoiced in the morning feast, diving for fish or twisting into the air.

On the beach, laughing gulls, great blue herons, snowy egrets, willets and white ibis stalked the shallow pools while short-billed dowitchers, sanderlings, ruddy turnstones, black-bellied plovers and red knots hunted across the sandflats. It was a scene of plenty on a mild, sunny morning in South Florida.

Sunday, October 12, 2008

A Retreat to Summer

Just as the autumn colors are spreading and the first winter storm is pushing out of the Rockies, we'll be retreating to summer for the next week. Obliged to check on our Longboat condo, we will enter the world of perpetual balminess (at least relative to our dramatic seasons in Missouri).

We'll leave the world of deciduous forests, rock bluffs, cornfields and great rivers and enter the kingdom of mangroves, ocean surf, bays and sand. Walnuts and oaks will give way to pines and palms. Hawks will become ospreys and laughing gulls will stand in for the raucous jays. Brown pelicans will glide overhead, roseate spoonbills will glow from the shallows and the shorebirds that visited our wetlands over the past few months will be racing along the beach.

And, of course, the cool, autumn air will be supplanted by the heat and humidity of South Florida. It will be a week of summer in the midst of autumn; somehow I'll survive.

Saturday, October 11, 2008

Western Snow

The first major snowstorm of the season pushed into the Northern Rockies and Intermountain West, yesterday, dumping up to a foot of snow. While this may seem premature to many Americans, the snowfall is actually a bit late this year; snowstorms commonly occur in this region by mid September (occasionally by late August).

Considered a nuisance in many parts of the country, snow is absolutely vital to the American West; with the exception of the Northwest Coast, this region is arid or semiarid, receiving less than 15 inches of precipitation in the course of a year. Rain, which is generally limited to isolated, seasonal thunderstorms, is not sufficient to support the natural habitats and human communities that occupy the region. Rather, it is the snowpack of the higher mesas and mountains that feeds the streams, diversifies the ecology and allows man to inhabit this dry, sunny landscape.

Accumulating faster than it melts, the snowpack will build through the winter and early spring, generally peaking in late February or early March. In shaded cirques or on high, north-facing slopes, snow may persist through the summer and, over many years, develop into mountain glaciers. Today, as our climate warms, these glaciers are retreating and the annual snowpack has become even more important. Snow is always welcome in the West!

Friday, October 10, 2008

The Dow and the Hawk

Yesterday afternoon, I returned to my office, logged onto CNN and found that the Dow had dropped another 800 points. Preferring to ignore the details, I logged off, turned on some music, propped my feet on the desk and enjoyed the view from my window. A red-tailed hawk soared above the campus, drifting slowly to the north; I soon felt a lot better.

While politicians, financial gurus and a worried public grapple with the worldwide crisis, the natural world goes on as usual. Leaves change, elk bugle, waterfowl congregate along flyways and whales head for tropical birthing grounds. Reacting solely to biologic processes, plants and animals do not worry about tomorrow. We humans, hobbled by fear and uncertainty, can find relief from our stress by retreating, however briefly, to the peaceful world of nature.

The red-tail, unlike many bird species, is not programmed to migrate south as winter approaches; he has no knowledge of the Gulf Coast and is perfectly content (and equipped) to endure the cold, gray weather of a Midwestern winter. A few months from now, I may see him again, huddled on a limb along I-70, oblivious to the wind and snow as he scouts for mice in the dead grass below. Perhaps the Dow will have recovered by then; either way, it won't bother him!

Thursday, October 9, 2008

The Ferocious Loner

Ferocious yet reclusive, wolverines inhabit the vast northern forests of Russia, Europe and North America; the North American subspecies, which once occupied northern New England and the Great Lakes region, extends southward through the Cascades and Northern Rockies (some have been sighted as far south as California and Colorado). Since they are primarily nocturnal and favor remote areas, these hardy mammals are rarely observed.

Equipped with thick fur, broad paws and powerful jaws, wolverines are loners, canvassing their extensive territory for food; though they often consume berries, wolverines are primarily carnivorous, hunting small mammals and feeding on the remnants of larger animals killed by wolves, bears or mountain lions. Despite their relatively small size (adult males weigh up to 40 lbs.), wolverines will attack young deer, caribou or moose and have been known to kill adults stranded in heavy snow.

This largest member of the weasel family has also been called the devil bear or skunk bear; the former title reflects their ferocity while the latter is derived from their potent scent glands. Maintaining a territory of 200 square miles or more, the males mate with several females in the course of a summer; implantation is delayed and the females give birth to 2-3 kits by early spring. The young stay with their mother for two years and then move off to establish their own vast territories.

Wednesday, October 8, 2008

The Contrarian Bird

As the first hints of winter blow across North America, many birds begin their migration to southern climes. Those dependent on insects or nectar are the first to leave, staying ahead of the freeze line as it gradually dips across the Continent. More hardy species, capable of surviving on seeds, berries and hibernating insects, do not migrate or merely move from the North Woods to the Temperate Zone. Some, such as great gray owls, snowy owls and snow buntings are irruptive species, moving south only if forced to do so by heavy snows or dwindling food supplies.

Like the flatlanders, mountain birds escape the stress of winter by heading to milder climes; in many cases, this is limited to vertical migration, a descent to elevations with warmer temperatures and less snow. Along the Colorado Front Range, a variety of mountain birds visit the urban corridor during the winter months; these include mountain chickadees, red crossbills, Cassin's finches, Townsend's solitaires and gray-headed juncos, among others.

But there is one bird that defies this pattern, moving to higher elevations for the winter. The blue grouse, common throughout the western mountains, from northwest Canada to New Mexico, summers and breeds in the open, ponderosa pine woodlands of the lower mountains and foothills; there they feed on insects, seeds, berries, buds and pine needles. Come winter, they ascend to the Subalpine Zone, surviving on the foliage of conifers (pine, spruce and fir). There must be a good reason for this behavior......but it escapes me!

Tuesday, October 7, 2008

Heaven on Earth

Many religious zealots live to die. Their entire earthly existence is devoted to achieving eternal life and death is the portal to that reward. Focused on this goal, they overlook the many joys that our earth-bound life can bring. Curiosity about the natural world is often a victim of that zealotry.

One need not be a hedonist to appreciate the many wonders of this planet. Expensive journeys and high-tech equipment are unneces-sary. Relatively few people fully explore their own yards and neighborhoods, let alone the nearby marsh or woodlot. Just coming to grips with the night sky can keep us enthralled for decades and weather buffs have an endless source of entertainment.

Unfortunately, many find it hard to balance natural science and spirituality. It's often easier to take a simplistic view of life, devoid of uncertainties. If more of us accepted this Earth as our paradise, we'd be more committed to protecting and enjoying what we have. In the end, we'd all be better off.

Monday, October 6, 2008

Insect Deadline

The insects of the Midwest are approaching their deadline. With the first freeze only a week or two away, they are busily ensuring the survival of their genes. Most species do not overwinter as adults and must mate and deposit eggs before they, themselves, succumb to the cold.

Our current, balmy interlude is providing a perfect opportunity and the chorus of cicadas, crickets and katydids made last evening sound like August. Warm, sunny days have the bees combing the flower beds and the dragonflies making their last forays of the season. Harvestmen roam the woodpiles, butterflies still brighten the shrubbery and flying insects attract squadrons of chimney swifts, soon to depart for southern climes.

While honey bees overwinter in hives, pregnant bumblebees retreat to underground dens and some species survive beneath leaf litter or in man-made structures, most adult insects will die with the first hard freeze. Their species will live on in the eggs or cocoons attached to vegetation or as larvae in the ponds or soil. Come spring, those not eaten by birds, moles, mice and shrews will give rise to the next generation.

Sunday, October 5, 2008

Unicorn of the Sea

Narwhals are toothed, Arctic cetaceans, best known for the prominent tusk of the adult male. The latter is actually an outward eruption of the upper, left incisor, which develops into an elongated, twisted tusk; up to 10 feet long, it is used for mating jousts but may also serve other purposes (chemical sensing, communication etc.). A small minority of males have a pair of these structures and some females grow a short, narrow tusk.

Their name (Norse for "corpse whale") reflects their blotchy skin pattern, tubular shape and habit of lounging "belly up" on the surface of the ocean. After mating in spring, these highly vocal whales congregate in shallow, coastal bays for the summer months; there, females give birth to calves conceived the previous spring (gestation averages 15 months). The calf nurses for 4-5 months and will stay with its mother for almost two years.

As summer gives way to autumn, the narwhals break into small pods, spending the colder months among the ice flows of the Arctic Sea. Protected by a thick layer of blubber, they will feed on cod, halibut, shrimp, squid and young seals; adult males grow to a length of 16 feet and weigh up to 1.8 tons (females are about 2/3 their size). Narwhal predators include polar bears, killer whales and some Native American tribes; despite a lifespan of 50 years, this species may be among the early victims of global warming.

Saturday, October 4, 2008

October Marsh

The early October marsh is not your noisy, buggy wetland of late spring and summer. Gone are the colorful songbirds, flitting among the thickets. Absent is the croaking of frogs and the trilling of toads. Gone are the clouds of mosquitoes that draw squadrons of swifts and swallows to these prolific shallows.

This is a quieter place with subdued colors and patient hunters. Crickets and grasshoppers move among the dried vegetation, potential victims of leopard frogs and garter snakes that lounge in the shoreline grass. The frogs, now silent residents of the wetland, remain wary of predators (snakes, herons, mink) and spring into the shallows as you approach. Painted turtles, soon to winter in the bottom muck, crowd onto logs and bask in the warm sunshine of early autumn.

Out on the lakes and larger ponds, ducks and grebes are arriving from the north; their numbers will increase through the month as more intense cold fronts push across their breeding grounds. As the days continue to wane, winter songbirds grace the marshland thickets, content to feast on the seeds of summer's past glory.

Friday, October 3, 2008

Roxborough State Park

One of the most scenic destinations along Colorado's Front Range is Roxborough State Park, on the southwest edge of Metro Denver. Encompassing spectacular rock formations and varied habitat, it is a popular site for hiking, photography and wildlife watching. From C-470 in Littleton, exit on Santa Fe Drive, head south for 4 miles and turn west on Titan Road which eventually curves south, becoming Rampart Range Road; proceed another 2 miles to a firehouse near the hogback; the Park entrance road will be just east of this facility. Dogs are not permitted in this wildlife refuge.

Entering the Park, the visitor passes through the famous Dakota hogback, composed of Cretaceous sediments. West of the hogback is a broken chain of yellow-gray sandstone, the Lyons Formation, that dates from the Permian. Older yet are the salmon-red fins of the Fountain Formation, formed from the erosion of the Ancestral Rockies during the Pennsylvanian Period, some 300 million years ago. Finally, the western edge of the Park rises into the foothills of the Rockies, composed of Precambrian granite. Valleys between these ridges, now covered by Gambel oak thickets and yucca-studded grasslands, are underlain with softer sediments (primarily shale) that once separated the rock layers in a horizontal layer-cake. When the Rockies rose (70-60 million years ago), the cake was tilted upward (to the west) and subsequent erosion has produced the ridges of sandstone and valleys of shale.

By October, many of the summer birds have departed but visitors should still find scrub jays, magpies, canyon wrens, rufous-sided towhees, western meadowlarks and golden eagles. Mule deer are abundant at the Park; other mammals include rock squirrels, Colorado chipmunks, red fox, coyotes and the occasional mountain lion. Several trails loop through this scenic refuge and adventurous hikers can set their sights on Carpenter Peak (summit elevation 7175 feet), which commands a broad view of the Front Range foothills and Colorado Piedmont.

Thursday, October 2, 2008


One of the more conspicuous plants in the early autumn landscape is pokeweed. Growing in small stands or as scattered, individual plants, they are identified by their racemes of blue-black berries on plastic-pink stems and their large, drooping leaves that alternate from a thick, light-weight stalk. Sun-loving, pokeweed is most often found along fence lines or at the border of fields and woodlands.

The plant's tender, green, spring vegetation is edible if boiled twice to remove toxins. However, as the plant matures, the stalk and leaves take on a reddish tinge; by that time, the entire plant (including the berries and roots) is toxic to mammals (which, of course, includes us). Birds, immune to the toxin, love the berries and spread them by seeds passed in their droppings; cardinals are especially fond of this fruit.

Pokeweed, also known as inkberry, was once used by Native Americans to produce a dark-red, ceremonial dye. Today, it colors our landscape with its flowers, foliage and berries (and with the birds that stop to enjoy its bounty).

Wednesday, October 1, 2008

The Outdoors Month

October has arrived with its warm, sunny days and chilly nights. The oppressive heat and humidity of summer are now a distant memory and the glorious days of October coax us into the woods and fields. Mammals are more active, migrations are beginning to peak, autumn colors paint the foliage and the cool, dry air invigorates wildlife and humans alike. Almost any Midwestern naturalist would likely pick this month as their favorite; then again, it may be my personal bias showing through.

Nature centers, urban trails and State Parks probably see their largest crowds in October. It's a great month for hiking; dry trails offer good footing, insect populations are dwindling and the cool air boosts our endurance. Photographers love the month for its colorful foliage, clear air and deep blue skies. Those who adore summer may decry this step toward winter; for others, including myself, its a welcome reprieve from the heat and a portal to the best season of the year!