Wednesday, September 30, 2009

Samoa & Sumatra

Over the past 24 hours, powerful earthquakes have occurred along the west coasts of Samoa and Sumatra. A secondary tsunami has caused significant damage in Samoa but it is too early to know if the Sumatran quake will result in a tsunami across the Indian Ocean.

The Sumatran quake occurred south of the epicenter of the devastating earthquake and tsunami that shocked the planet earlier this decade but, like its many predecessors, it surely developed along the west Sumatran subduction trench, where the Australian Plate is dipping below the Eurasian Plate. In such regions, the overlying plate is pulled downward by friction with the subducting plate; this building pressure is intermittently released, producing an earthquake and, by lifting the overlying ocean water, often triggering a tsunami.

The Samoan quake is less easy to explain. Not lying along a plate margin, the Samoan Islands have long been characterized as volcanic hotspots, produced by the movement of the Pacific plate over a mantle plume; in this respect they would be similar to the Hawaiian Ridge and other mid-plate island chains. However, geologists who have studied the age of volcanic rocks on the Samoan Islands and other regional archipelagos, have not found the age progression that typifies a hot spot chain. Some believe that these islands have developed above a fracture in the Pacific plate, which may have resulted from stress within the ocean crust; such a fracture would permit mantle intrusion, leading to volcanism and island formation. Yesterday's earthquake seems to lend support for that theory.

Tuesday, September 29, 2009

Waterpocket Fold

The Waterpocket Fold is a 100-mile long warp of Earth's crust in southern Utah. Trending SSE to NNW, the Fold extends from the Colorado River valley to the area of Thousand Lake Mountain; most of the scenic terrain created by this geologic formation is now protected within Capitol Reef National Park.

Before the Waterpocket Fold developed, rock layers of this region were stacked horizontally, with older sediments below younger ones. Then, about 70 million years ago, pressure within the North American plate crumpled up the Rocky Mountains; in concert, the rock layers of southern Utah warped downward to the east. Subsequent erosion, augmented by uplift of the Colorado Plateau about 15-20 million years ago, has uncovered the various strata of this tilted layer cake, with older sedimentary rocks (Permian; 270 million years old) exposed on the west edge of the fold and younger deposits (Cretaceous; 80 million years old) on the east. Since some layers are more resistant to erosion than others, the Waterpocket Fold is characterized by an alternating pattern of ridges and basins, interspersed with geologic domes and spires.

The landscape that we observe across our globe today is a product of geology, tectonic activity and erosion; it is but a snapshot in the 4.6 billion-year history of our planet and will continue to change over the coming millenia. Few places on Earth offer a better illustration of these natural, terrain-sculpting processes than does the Waterpocket Fold.

Monday, September 28, 2009

The Bird of Autumn

Birders tend to associate certain species with specific times of the year. Of course, this is especially true for those birds that inhabit our area for limited periods of time and the identity of these seasonal species varies widely from one region to another.

Here in the Midwest, most birders likely associate warblers with mid spring, when these colorful and active species move through our region, challenging identification by even the most experienced naturalists. In summer, many of us are especially aware of avian residents that seem undaunted by the heat and humidity; chimney swifts and house wrens come to mind. Winter brings seasonal residents from the north; just the sight or sound of juncos and white-throated sparrows can produce a chilling effect and we come to admire the hardiness of these Canadian visitors.

For me, the white-breasted nuthatch is the bird of autumn. Though this common acrobat inhabits our area throughout the year, I have long associated his distinctive call with cool, sunny days and bright autumn foliage. Perhaps this hearkens back to my earliest days as a birder, when I first identified this amusing bird on a glorious October afternoon. Whatever the cause, the yank of a nuthatch is, for me, a sound of the season, as much a part of autumn as falling leaves, frosty nights and the nostalgic scent of wood smoke.

Sunday, September 27, 2009

Between Seasons

In Missouri, late September is a time of transition. The oppressive summer heat has moved to our south but the deep autumn chill has yet to arrive. Some color dapples the forest but late summer wildflowers still adorn the grasslands and, for the most part, greenery dominates the landscape.

Though a few summer birds have left with the heat, most linger in our woods and winter visitors have yet to leave their Canadian homeland. Frogs, snakes and aquatic turtles still haunt the wetlands, fiddlers still sing through the night and the hoot of the great horned owl is but a distant memory. Here in the Heartland, we are suspended between summer and fall.

But all will change within a few weeks. Autumn splendor will paint the countryside, a hard freeze will silence the insects, waterfowl will reclaim the wetlands and the culling season will begin. Nature may not always obey the human calendar but we can count on her cycle to endure.

Friday, September 25, 2009

The Champlain Basin

When the last of the Pleistocene Glaciers plowed through New England, it molded the landscape, sculpting the mountains and eroding broad valleys. One of the latter, stretching between the Adirondacks of New York and the Green Mountains of Vermont, would become the basin for Lake Champlain.

After peaking in its coverage, some 20,000 years ago, the Wisconsin Glacier began to melt back to the north, opening the newly formed basins. Some of these drained to the south or east, while others, including the Champlain Basin, drained northward. Blocked by the retreating glacier, the north flowing rivers gave rise to valley lakes, filled by mountain streams and by meltwater from the glacier itself. By 15,000 years ago, Lake Vermont, more extensive than today's remnant, spread across the Champlain Basin. Then, as the ice sheet retreated further into Canada, the rising ocean spilled through the St. Lawrence Valley and southward into the basin of Lake Vermont. Turning brackish, the latter became the Champlain Sea, an arm of the North Atlantic, and, for a thousand years or more, harbored a wide variety of marine life; fossils of these sea creatures are found across the basin today.

Finally, as New England rebounded from the weight of the glacier, the Sea slowly drained back toward the Gulf of St. Lawrence and freshwater reclaimed the basin, giving rise to Lake Champlain. Sustained by snowmelt and rainwater from the flanking mountains, the Lake drains northward via the Richelieu and St. Lawrence Rivers, flowing through a glacial valley that once admitted the sea.

Thursday, September 24, 2009

Columbia River Country

On our recent trip to Oregon, we spent some time along the Columbia River, the grand waterway of the Pacific Northwest. Rising in southeast British Columbia, it makes a curve to the north and then heads south, picking up flow from the Kootenay and Pend Oreille Rivers before entering the U.S. In eastern Washington, it is joined by the Spokane, Snake and Yakima Rivers and then heads westward along the Oregon border, taking in flow from the John Day, Deschutes, Williamette, Lewis and Cowlitz Rivers before entering the Pacific west of Astoria. Completing a journey of 1245 miles and collecting flow from a watershed of 258,000 square miles, the Columbia is the fourth largest river in the country and the largest west of the Continental Divide.

The current course of the Columbia has been molded since the rise of the Rocky Mountains, 65 million years ago. Once inundated by shallow seas, the region has experienced periodic volcanism over the past 40 million years and Pleistocene floods eroded the landscape 12-20 thousand years ago; the latter carved the famous Channeled Scablands of eastern Washington. Today, erosion continues, fed by heavy snows across the Rockies and Cascades, and, as many of us witnessed in 1980, regional volcanism continues to sculpt this rugged terrain.

Though beautiful and powerful, the Columbia has been used and abused by those who have settled across its vast watershed. Fourteen dams disrupt its flow, providing hydroelectric power, flood control and water for consumption and irrigation; however, these same structures have had a significant impact on the welfare of salmon populations, a threat only partially mitigated by the construction of "fish ladders." In addition, channelization of the river has augmented industrial development throughout its valley, offering a vital route of transportation; of course, this has resulted in significant water pollution, including material from nuclear plants. As is common across the globe, any attempt to balance conservation and resource exploitation tends to tip against the natural environment.

Tuesday, September 22, 2009

A Perfect Deluge

After enduring more than a year of severe drought, the residents of northern Georgia and bordering States had been hoping for a tropical storm that might restore the vegetation, recharge the streams and fill their reservoirs. Alas, in the middle of a lackluster hurricane season, relief came not in the form of a powerful storm but as the effects of a plodding cold front. Unfortunately, it was a gift that kept on giving, drenching the region with 10-20 inches of rain and producing catastrophic floods throughout the area.

The cold front, curving from the eastern Great Lakes to central Texas, established a clash zone, with warm, humid air to its southeast and cool, dry air to its northwest. As the front inched to the east, a southerly flow of Gulf air invaded the Southeastern States, priming the region for thunderstorms. The front and its low pressure center provided lift, pulling the soupy air up and over the invading wedge of cool air; the terrain of northern Georgia and its border areas, higher than the Gulf Plain to the south and east, augmented this lift as the warm, moist air streamed up from the south. All of these factors ignited thunderstorms along the edge of the front, which, lacking a potent shove from the jet stream, lounged over these uplands, dropping heavy rain before redeveloping and training over the same areas.

In effect, a Perfect Deluge was established and continued to intensify until the front moved further to the east. Despite a respite today, more precipitation is expected throughout the week as another cold front drops from the Midwest. Hopefully, that rainmaker won't linger over this flood zone which has no capacity to absorb additional moisture; any rain that falls will quickly move to the swollen streams and rivers.

Monday, September 21, 2009

Hikers, Naturalists & Life

Hikers are a motley group. At one end of the spectrum are the amblers, those who plod along the trail, distracted by everything that surrounds them. At the other extreme are the trail athletes, those who race along their route, focused on their goal, whether it be a summit or the end of a loop.

Naturalists tend to fall close to the amblers. More than a form of exercise, we hike as a way to connect with the environment, enjoying the sights, sounds and smells along the path. Trail athletes might argue that we are missing out on the aerobic benefits of hiking but I suggest that they are missing far more.

Our hiking style likely reflects our approach to life. Some race through it, always looking toward a future that they assume will make their journey worthwhile. Others choose to enjoy the trip itself, stopping to savor its many rewards.

Sunday, September 20, 2009

A Japanese Garden

On our last day in Oregon, we visited the Japanese Garden in Portland's Washington Park. With its manicured landscape, sand sculptures and reflection pools, it is an attractive and peaceful place. But, after a week of climbing rocky slopes, hiking through damp forests, trudging across sand dunes and taking in the sights, sounds and smells of Oregon's foggy coast, we recognized that this garden is a very unnatural place.

Nature, while representing an intricate interdependence of countless life forms, deplores uniformity, rigidity and control. In contrast to this Japanese Garden, she is messy, turbulent, unconfined and unpredictable. Nature yields to human intervention reluctantly and temporarily; if humans do not remain highly vigilant, their unnatural handiwork (homes, lawns, bridges, gardens) will soon succumb to her forces.

A Japanese garden places emphasis on tranquility and reflection but also celebrates the human impulse to control and mold our natural surroundings. Most naturalists believe that we can enjoy the former without resorting to the latter.

Saturday, September 19, 2009

Mystery Murrelet

Yesterday morning, my wife and I spotted a small, chunky bird in the mouth of the Columbia River. Bobbing in the gentle waves near shore, its shape and plumage immediately suggested that this loner was a murrelet, small members of the alcid family that breed on land but spend most of their lives at sea.

The marbled murrelet is the most common species to be found along the coasts of Washington and Oregon. Unlike most other sea birds, they are not colonial, often nesting well inland from the rugged shoreline. But our visitor had a mottled, light-gray face, with only a faint, dark stripe along the center of its crown; its body had dark-gray mottling, its feet and legs were black and its wings were dark gray with white streaking. Consulting the guide books, it seemed to be a Kittlitz's murrelet, an endangered sea bird that is found from Glacier Bay, Alaska, to Siberia; further research indicated that this species, which apparently nests on tundra along mountain glaciers, has not been observed south of Alaska.

Did we stumble on a wayward, juvenile Kittlitz's murrelet or was our discovery a case of mistaken identity? In the course of researching this blog, I have learned that little is known about the true range of this small sea bird; perhaps some individuals winter further to the south than currently documented. Then again, perhaps the Columbia River bird was merely a genetic variant of a more common murrelet species. Nature always keeps us guessing.

Thursday, September 17, 2009

Up the Oregon Coast

Mention Oregon and most Americans envision rugged seascapes, fog-shrouded cliffs, broad, sandy beaches, towering sea monoliths, luxuriant coastal forests and spectacular concentrations of marine animals. Travelling up Route 101 over the past three days, I can personally attest to the accuracy of that image.

Among our most memorable stops (to date) have been the Face Rock beach area (just south of Bandon), a noisy assembly of sea lions and sea birds at Cape Arago (off Coos Bay), the Oregon Dunes National Recreation Area (near Reedsport), the Cape Perpetua trail network (just south of Yachats), the Yaquina Head Preserve (just north of Newport) and Ecola State Park (at the north edge of Cannon Beach). En route, we have been inspired by the spectacular scenery and impressed by Oregon's effort to protect yet provide access to these natural treasures. Check a map of the State and you will find that its coast is lined with a fabulous variety of parks, historic sites, nature preserves and wildlife refuges.

Unexpected sitings (or lack thereof) often accompany travel to natural areas. On this trip, I have been amazed by the large number of brown pelicans that summer along the Oregon coast; having spent much time along the Southeast and Gulf Coasts, I have never seen this species in such overwhelming concentrations. On the other hand, sea bird sitings have been less varied than hoped for, an apparent indication that many species (puffins, murres, auklets) have already left their breeding grounds and have moved out to sea. A final day on this cool, damp coast will close out one of the most spectacular and memorable vacations that we have ever experienced; our thanks to Oregonians for their obvious commitment to environmental stewardship.

Wednesday, September 16, 2009

Following the Umpqua

The Umpqua River rises just northwest of Crater Lake National Park. We followed this beautiful, whitewater stream as it tumbled down the west face of the Cascades, flowed through the sheep country of the lower foothills and then curved through Roseburg, the wine capital of Oregon.

Roseburg sits in the broad Umpqua Valley, with hilly terrain to its north and west, appropriately reminiscent of the Napa Valley in California. Golden grasslands and oak savannas cover these hills, which are home to a host of wineries. After visiting a few of these appealing facilities, we settled on the Melrose Winery for a picnic lunch, complete with a glass of Pinot Gris.

Beyond Roseburg, the Umpqua winds to the northwest, negotiates the Coast Range and enters the Pacific at Reedsport, which sits at the heart of the Oregon Dunes National Recreation Area. There, we would cross the river once again, on our journey up the coast of this diverse and scenic State. To be continued!

Tuesday, September 15, 2009

Crater Lake National Park

Eight thousand years ago, Mt. Mazama, one of many active volcanoes in the Cascade Range, suddenly exploded, sending volcanic ash and rocky debris across the surrounding landscape and then collapsing to produce a broad caldera, six miles in diameter. Within a few hundred years, another volcanic cone began to develop within that caldera, which was gradually filling with snowmelt and rain water. Today, that second cone stands above the lake waters as Wizard Island and the lake itself, famous for its clear, blue waters, reaches over 1900 feet in depth, the deepest lake in the U.S. and the 7th deepest in the world. Filled with 5 trillion gallons of water, Crater Lake and its fabulous surroundings are now protected within a National Park.

From the Eugene area, we headed southwest along the Williamette River Valley, passing horse and sheep ranches before climbing into the mountain forests. Approaching the crest of the Cascades, we stopped to marvel at Salt Creek Falls, a spectacular cascade and the second highest waterfall in the State. We then crossed Williamette Pass (5100 feet) and headed south across the high but noticeably drier terrain of south-central Oregon before climbing back onto the spine of the Cascades and turning into Crater Lake National Park. As with most natural wonders, photos and descriptions only begin to represent the size and grandeur of this lake-filled caldera, set among pumice deserts, rocky mounds and a rich coniferous forest.

Climbing to a lookout above the rim, we enjoyed views extending along the Cascades, southward to the Klamath Basin and eastward across the mountains and deserts of southeast Oregon; on clear days, one can even see Mt. Shasta, in Northern California. In addition to the fabulous vistas, we encountered a variety of native wildlife, including golden-mantled ground squirrels, Steller's jays, gray jays, rock wrens, a lone Lewis' woodpecker and, of course, those ubiquitous ravens; of special note were the Clark's nutcrackers, more numerous than I have observed at any other location. After spending much of the day on or near the rim of Crater Lake, we took a side trip down to the Pinnacles (still within the Park); these spires of rock, lining a post glacial valley, were formed by the action of fumeroles within Mazama's volcanic debris.

Monday, September 14, 2009

Waterfalls & Whitewater

On our first morning in Oregon, we drove east from Portland, following Interstate 84 through the scenic gorge of the Columbia River. Along the way, we had the good fortune to exit onto the Old Gorge Road (a 7-mile detour from the highway), which took us past three spectacular waterfalls, among the highest and most beautiful in the State.

Turning south at Hood River, we climbed through orchard-covered hills and began to circle the isolated pinnacle of Mount Hood (11,240 ft.), Oregon's tallest and most famous peak. Southwest of the Mt. Hood region, at Estacada, we began a long, winding climb along the Clackamas River, which led southeast toward the crest of the Cascades. This scenic, whitewater stream, a popular destination for kayakers and fisherman, provoked photo stops at every turn and offered a fabulous route into the heart of mountains.

A bit farther to the south, we descended from the Cascades along the McKenzie River, another spectacular waterway. Several scenic waterfalls, easily accessed from Route 126, were spaced along this river, which eventually joins the Williamette near Springfield. At the end of our exhilarating day in the Cascades, we spent the night in Eugene, Home of the Oregon Ducks.

Sunday, September 13, 2009

Oregon's Two Climates

Yesterday, our flight took us over the sandhills of western Nebraska, above the desert landscape of southern Wyoming, across the glacier-studded peaks of the Wind River Range and, just south of the Teton massif, into Idaho. The vast, dry flatlands of the Snake River Plain, dotted with small cinder cones, spread toward the mountains of northern Utah as we crossed the rugged peaks of central Idaho and, crossing the stark chasm of the Snake River gorge, entered Oregon.

Despite its image as a land of luxuriant forests, whitewater streams and heavy precipitation (lowland rain and mountain snows), Oregon possesses two climates; its eastern half, lying in the rain shadow of the Cascades, is a sun-drenched region with desert and semiarid landscapes. Our view from above confirmed this fact as we crossed the dry, heavily dissected terrain of northeastern Oregon; placing emphasis on the arid conditions below, a large forest fire burned across the side of a ridge, its massive plume drifting to the west.

Then, as we glided past the scenic cone of Mt. Hood, the dry landscape gave way to verdant forests, lakes and more gently sculpted terrain, the scenery we all associate with the Pacific Northwest. Over the coming week, we will explore the green side of Oregon, with its massive trees, spectacular waterfalls, volcanic topography and rugged coastline. More to come!

Saturday, September 12, 2009

Off to Oregon

During my 59 years on this planet, I have had the opportunity to visit most regions of the lower 48 States; North Dakota, a good chunk of Minnesota, Northern California and western Oregon have, to date, remained out of reach. The latter is about to fall from the list as we fly out to Portland this afternoon and make a loop down the rugged coast and up through the Cascades. Of course, we will also get a chance to explore the Williamette Valley and the city of Portland itself, one of the most environmentally-conscious communities in our country.

Having been raised in a family with two vacation destinations (Florida or Lake Erie), I have since come to appreciate the opportunity to visit new places, whether near or distant. Such travels broaden our perspective of this planet, introducing us to new species, unfolding new landscapes and, perhaps most importantly, opening our minds to new points of view. I recall conversations with Australian citizens back in 2000, my first adventure outside of North America; their comments about the U.S. were enlightening and I can only imagine what lessons I might learn in non-Westernized countries.

This week, we'll enjoy the spectacular scenery of western Oregon, get plenty of exercise and gain new insights into the diverse ecology of our homeland. Travel challenges the body, opens the mind and recharges the soul.

Friday, September 11, 2009

The Pribilofs

The Pribilofs are a cluster of volcanic islands in the Bering Sea, 200 miles off the west coast of Alaska and 500 miles from Siberia. They are named for Gavriil Pribilof, a Russian explorer, who encountered them in 1786, triggering a wholesale slaughter of their northern fur seal colonies and the displacement of native Aleuts, who had occupied the islands for at least 7000 years. As the threat of extinction developed, fur seal hunting restrictions were imposed by an International accord in 1911, a year before the Alaska Territory was annexed by the United States; a full ban on the hunting of northern fur seals was passed in 1966, though resident Aleuts may kill them for sustinence.

In addition to the seals, the Pribilof islands are known for their large colonies of sea birds, including Pacific species of puffins, murres, auklets, cormorants and kittiwakes; birders also visit these outposts to view a wide variety of migrants from the Siberian mainland. The Aleut communities of St. Paul and St. George (on their respective islands) are sustained by rich crab and halibut fisheries. Other island residents, well adapted to the harsh climate, include Arctic fox and caribou.

The wealth of marine life on the Pribilofs is primarily due to their position along the North American continental shelf, where upwelling, deep ocean currents produce nutrient-rich waters. But these volcanic islands do not lie along a tectonic plate margin; in fact, the southern edge of the North American plate lies along the Aleutian chain, 250 miles to the south, and its western edge is in eastern Siberia. The islands, like the volcanoes of Yellowstone and northern Arizona, developed over a hotspot beneath the plate; in the case of the Pribilofs, this process occurred throughout the Pleistocene (beginning about 2 million years ago) and has continued through most of the Holocene, ending just 3000 years ago.

Thursday, September 10, 2009

Stuck in Heaven

For the past week, high pressure, centered over the Upper Midwest, has kept mid Missouri in a heavenly weather pattern, with afternoon temperatures in the 70s (F) and overnight lows in the 50s. A gentle breeze, out of the east, has keep the air pleasantly cool and dry, creating ideal conditions for outdoor activities.

The emplaced high pressure has diverted Pacific fronts to the north and south of its dome and has kept hot, humid air well to our south. Not far to our south and west, heavy rains have fallen across southeastern Kansas, southern Missouri and northeastern Oklahoma, the consequence of a stationary front along that edge of the dome. Safely within its protective confines, we have enjoyed glorious autumn weather.

Of course, the high pressure ridge will eventually break down when a more potent Pacific system, energized by a jet stream trough, invades our region. Until then, we'll make the most of these mild, sunny days and clear, cool nights, the signature conditions of a Midwestern fall.

Wednesday, September 9, 2009

Great White Sharks

Famous for their power, massive size and occasional attacks on humans, great white sharks favor temperate waters of Earth's oceans and are less common in tropical and polar regions. Known to be migratory, they are most often observed in coastal areas where their prey is seasonally concentrated. Among their more common feeding territories are the Pacific Coast of North and South America, Southern Australia, New Zealand, Japan, South Africa and the Mediterranean region. Nevertheless, these wandering predators may turn up along any shore (as has occurred in New England this week) and have been observed in the Gulf of Mexico.

Slow to mature, great whites do not breed until the age of 15 and may live up to 100 years; births are thought to occur in early summer. Adults average 15 feet in length and often weigh 2000 lbs; records include individuals over 30 feet long, with weights exceeding 5000 lbs. To sustain their massive bodies, great whites feed on a variety of marine life, including fish, seals, sea lions, dolphins, sea turtles and penguins; they also consume carrion and seem to be especially fond of whale carcasses. Attacks on humans, while sensationalized in the media, are uncommon and likely occur due to mistaken identity (i.e. surfers in wet suits look like seals). Equipped with rows of serrated teeth, the shark's initial attack, usually from below, stuns and cripples the victim and, as it bleeds to death, the great white circles back to consume it.

Humans and orcas pose the only threat to great white sharks, which represent the lone surviving member of the genus Carcharodon. Inducing both fear and fascination, these large predators have become the victims of a wide range of human activity, from hunting to the modern bating and cage-watching industry. As with many other species of wildlife, we either fail to appreciate their value or can't resist invading their space.

Tuesday, September 8, 2009

Grassland Formation

Grasslands have adorned our planet for the past 40 million years, a very short interval in Earth's natural history. More tolerant of drought, prolonged cold and poor soil conditions, grass began to replace woodlands during the Oligocene Period, leading to the rise of the Tertiary megafauna. Since that time, wildfires, high winds, glaciation and the grazing of massive herds of bison have played a crucial role in the evolution and maintenance of North America's grasslands; similar events have occurred across the globe (though the mammalian grazers vary with location).

Modern grasslands are found in a wide variety of landscapes where tree invasion is impaired by climate or soil conditions. Alpine and Arctic tundra grasslands occur at altitudes or latitudes where the annual growing season is too short to permit tree growth and survival. Many grasslands, like those across our High Plains, lie in the rain shadow of major mountain ranges; unlike trees, grasses can tolerate semiarid environments, where annual precipitation is below 20 inches. Grasslands also develop in areas receiving adequate precipitation but where the depth or nature of the soil is inadequate to retain the moisture; sandy shorelines, glades and karst areas are prime examples.

Of course, man has produced his own grasslands (lawns, parks, farms, strip mines, etc.) in areas that would otherwise support woodlands. If human activity is abandoned in these areas, the temporary grasslands are soon covered by shrubs and trees.

Monday, September 7, 2009

Hunting Refuge

Hunting Refuge. The words hardly belong in the same sentence, let alone in the same title. But many nature preserves and conservation areas permit seasonal hunting, designed to control wildlife populations and protect threatened habitat; for those species under assault, the sites are surely not refuges. Of course, this regulated hunting has become necessary due to human destruction of natural landscape and our long record of obliterating natural predators.

While I am not personally opposed to hunting (especially when it is a means of subsistence or has become necessary due to our own misguided practices), few would argue that a significant proportion of hunters enjoy the art of the kill; certainly, most trophy hunters fall into that category. Though many hunting organizations (e.g. Ducks Unlimited) contribute substantial funds to the protection of natural habitat, one suspects that their primary motivation is to sustain target populations rather than to promote wildlife conservation and ecosystem diversity.

Yesterday, our visit to Eagle Bluffs Conservation Area, southwest of Columbia, turned up many empty pickups, their owners posted at the edge of cornfields. Their quarry was the mourning dove, that mellow resident of Midwestern suburbs and farmlands. I doubt that these birds are a significant threat to the agriculture industry and I suspect that few of these hunters were counting on success in order to feed their family. But the doves, common and docile, are capable of rapid flight, offering a true challenge for these masters of the kill. We were rooting for the doves.

Sunday, September 6, 2009

The Shroud of Autumn

While the days are often warm and bright, the darkness of winter is building as we approach the autumn equinox. With each day, our commutes to and from work are increasingly devoid of sunlight, the daytime shadows lengthen and our slide toward winter steepens.

But there is a certain comfort that comes with this gathering darkness. Oppressive heat and intense sunshine have moved on to our south and outdoor activities are no longer restricted to the morning and evening hours. Sunny days are now warm and inviting and the longer nights provide more time for mundane, household chores.

And for the naturalist, this expanding shroud of autumn triggers some of the more spectacular displays of nature's year: the colorful turning of leaves and the stirring migration of waterfowl. Some may dread the growing darkness and all that it brings but we cherish this season of mellow days, dry air and frosty nights. Autumn is, after all, the most inviting season for outdoor adventure.

Saturday, September 5, 2009

Natural History of the Bahamas

The Bahamas, composed of 700 islands and more than 2500 cays, stretch for 650 miles, from the vicinity of southeastern Florida to eastern Cuba. The islands and cays are essentially the high points of carbonate banks, formed by the deposition of marine shells which have compacted into limestone and dolomite; these carbonates are up to 5 km thick, with the deepest layer dating back to the Jurassic.

The carbonate banks, deposited in warm, shallow ocean waters, sit on the basement rock of the North American Plate, which rifted from Africa as the Atlantic began to open, some 180 million years ago; this rifting occurred east of the original Pangean suture line and the segments that sit beneath Florida (and likely the Bahamas) were originally part of the African Plate. Though the exact origin of the plate segment beneath the Bahamas remains uncertain, it may have broken from the Florida Platform as the southern edge of the North American Plate subducted beneath the Caribbean Plate.

Over the eons, ocean currents, changing sea levels and surface erosion have molded the carbonate banks which, today, harbor 5% of our planet's coral reefs. The islands themselves, composed of porous limestones and dolomites, are rich in karst topography (few surface streams but many underground streams, caverns and springs). Native vegetation and wildlife either spread up from Cuba and Hispaniola during periods of low sea level (e.g. in concert with Pleistocene glaciation), drifted in on ocean currents or sprouted from the droppings of mainland birds. Since humans colonized Cuba about 7000 years ago, it seems likely that the first Bahamians appeared soon thereafter.

Friday, September 4, 2009

Zoos and Conservation

From my earliest years, I have been fascinated by wild creatures and, as a child, one of my favorite activities was a trip to the zoo. But, even as a preteen, I began to appreciate the negative effects that captivity can have on animals, locked away in paddocks of concrete and steel. While modern zoos have gradually transitioned to naturalized exhibits, more appealing to the human eye, these enclosures only begin the replicate the freedoms of wild habitat.

Nevertheless, zoos play an important role in public education and, by providing close encounters with wild creatures, sow the seeds of conservation in young children, a task that is vital to future generations of wildlife. These institutions also contribute to natural science research and, in some cases (e.g. California condors) have proved essential to the recovery of wild populations. And, unlike in the past, most of today's zoo animals were born in captivity and have not been taken from the natural environment.

But zoos will never be the answer to the conservation of wildlife on this planet. Only the protection of wild habitat, in adequate size and diversity, will achieve that goal. Unfortunately, human population growth, "development," agriculture, resource depletion and pollution are an ongoing threat to these natural ecosystems. By supporting conservation groups, such as those in the right column of this blog, you can help to ensure the protection of natural habitat and the future welfare of nature's wild residents.

Wednesday, September 2, 2009

Fire and Flood

Like the seasons themselves, recurrent human catastrophes, tied to natural forces, are spaced throughout the calendar. Spring floods bring misery to those who live on broad, Midwestern floodplains, hurricanes destroy coastal communities from June to November and fire sweeps the hills of Southern California in early autumn.

Yet, unwilling to accept the lessons of natural history, we rebuild in flood zones, populate the barrier islands and construct our dream homes amidst a tinderbox of dry woodlands. As individuals, we play the odds and hope for immunity from nature's cycle. Though our landscapes and historical records provide ample evidence of potential disaster, we assume the future will somehow be different.

So the annual parade of "natural disasters" provides plenty of fodder for the news media as humans endure the wrath of our seasons. Those who survive to rebuild are hailed for their fortitude but others question the wisdom of ignoring nature's power.

Tuesday, September 1, 2009

The Nature of September

September is a glorious month across much of America, taking us from the oppressive heat of August to the crisp nights of October. As the greens of summer fade, autumn colors paint the landscape and the waning sunlight, less direct and intense, casts a mellow light on nature's bounty.

Across the Heartland, the harvest has begun as flocks of shorebirds move toward southern shores. Songbirds will join the exodus within a few weeks and, by the end of the month, teal will gather on Midwestern Lakes. Out west, the first snows of autumn dust the higher peaks, elk descend toward mountain valleys and the glow of aspen builds toward a spectacular display in late September.

Of course, this month can also bring nature's fury. In the Southeast, hurricane season reaches its peak while, as is already evident, the fires of California take their annual toll, fed by the Santa Ana winds of early autumn. Nature is not sentimental; she can stir our souls and crush our dreams.