The Nature of Obesity

Obesity, the scourge of American society, is not a natural condition. While some mammals such as hippos, whales, walruses and seals have a thick layer of blubber for buoyancy or insulation, wild animals remain lean for two reasons: they must actively hunt for their food and they eat only when hungry. The same is true for "undeveloped" human populations, for whom physical activity is a matter of survival.

In Western Culture, obesity has become an epidemic. Not merely a lifestyle choice, obesity is a pathologic condition, increasing the risk for hypertension, heart disease, fatty liver disease, adult-onset diabetes, degenerative arthritis and certain cancers. While it does "run in families," this is more related to learned behavior than genetics. Childhood obesity, which develops due to poor dietary habits and inactivity, usually preceeds adult obesity and makes weight loss efforts much more difficult later in life.

Americans are obsessed with diets and "weight control systems" have become a growing segment of our economy. But special diets are unnecessary; obesity more often results from the amount and frequency of food intake and, most importantly, from a lack of exercise. Today, many children are much less active than in previous generations; TV, DVDs and computer games occupy far too much of their time. Only parents can turn the tide of obesity; they must serve as role models, encouraging their children to participate in sports, hiking and other outdoor activities. It is one of the best things your will ever do for them.

Columbia River Plateau

Covering most of central and eastern Washington, northern and northeastern Oregon and portions of western Idaho, the Columbia River Plateau formed from basalt lava flows, 17 to 6 million years ago; in fact, most of the lava, which spread across 65,000 square miles, poured out within a span of 2 million years (17-15 million years ago). Some 300 major vents have been identified and many more small ones are thought to have existed. One of the basalt flows, which ran from western Idaho to the Pacific, is the longest known lava flow in Earth's history. The thickness of the basalt varies across the Plateau, with some areas exceeding 8000 feet.

The cause for these numerous and massive lava flows is the subject of ongoing scientific debate. Most geologists feel that the rise of the Cascades, which began 36 million years ago and continues today, caused the basin between the Cascades and Rockies to stretch and thin out; the development of mantle plumes beneath the basin may have also played a role. Vents likely occured along fracture lines between the many terrains and island arcs that had merged to form the Pacific Northwest.

Today, the massive Plateau has been molded by the Columbia River and its numerous tributaries; the Snake River, which rises east of the Tetons and flows across southern Idaho, cuts through the southeastern portion of the Plateau before merging with the Columbia. As impressive as the Columbia River Plateau is, its total lava flow is but 10% of the flow at the Deccan Traps (India) and Siberian Traps.

Ted Shanks

One of the best birding destinations in the State, the Ted Shanks Conservation Area sits at the confluence of the Salt and Mississippi Rivers in northeast Missouri. A mix of man-made and natural wetlands, this fascinating refuge is accessed by an 11.5 mile tour road; adventurous birders can also walk some of the 35 miles of levees that lace the area. The entrance to the Ted Shanks refuge is via Route TT, off Missouri 79, 14 miles north of Louisiana.

May is an excellent time to visit the preserve; most summer residents have arrived and some spring migrants are still moving north along the Mississippi Valley. Nesting birds of note include least bitterns, king rails, American coot, little blue herons, hooded mergansers, bald eagles, willow flycatchers, Bell's vireos, worm-eating warblers, blue grosbeaks and Le Conte's sparrows. Among the regular spring migrants are horned and eared grebes, American white pelicans, ospreys, white-faced ibis, cattle egrets, Bonaparte's gulls and black terns.

Other common summer residents, such as great blue herons, great egrets, green-backed herons, wood ducks, belted kingfishers, red-shouldered hawks, barred owls, rose-breasted grosbeaks, indigo buntings, eastern phoebes, common yellowthroats and grasshopper sparrows round out the bird population. Resident mammals include beaver, muskrat, river otters, mink and white-tailed deer. Of course, a wide variety of reptiles and amphibians also inhabit the refuge.

Canadian High

After a week or more of warm weather, a Canadian front has dropped into the Midwest. Late this morning, it was 78 in Columbia; showers developed in the early afternoon and, by this evening, it was 56 degrees. Tonight's low is expected to be in the upper forties and, as the cool, dry air settles over the Heartland, we will have a few days that feel more like early October than mid May. Winds moving across the north side of the high pressure will bring more chilly weather to New England, with highs expected in the 50s and lows in the 30s.

Such Canadian Highs provide welcome respites from the hot, muggy days of summer and become increasingly common as autumn approaches. This cold front may have the added benefit of triggering showers and thunderstorms across the parched Southeast; the cool temperatures and precipitation should help combat the ongoing wildfires in southern Georgia and northern Florida. Unfortunately, this is forecast to be a "progressive front" which, rather than stalling out, will move rapidly to the east and and take the precipitation out to sea. As the Canadian High heads to the East Coast, backside winds will sweep heat and humidity up from the Gulf of Mexico and more typical, late spring weather will return to the Midwest.

Ruby-throated Hummingbirds

While twenty species of hummingbird can be found in the U.S., the great majority are limited to the southwestern States; only the ruby-throated hummingbird summers in the Midwest and East. Smallest of all birds, hummers are also the only birds capable of flying backward. They use their needle-like bill to feed on nectar from tubular flowers but also feed on small insects and tree sap; the latter is often obtained from sapsucker holes.

Ruby-throated hummingbirds generally arrive in the Midwest by late April and will stay until early October. Common in residential areas, they are easily attracted to red-colored, sugar water feeders; plantings of honeysuckle, trumpet vine, jewelweed, salvia, petunias, bee balm and mimosa will also bring these high-energy birds to your yard. When not feeding or chasing off rivals, hummingbirds rest on wires or thin tree branches.

Both sexes have a metallic green crown, back and wings and a white abdomen; only the male has the bright ruby throat which, at certain angles, may appear black. Females lay two, white, jelly-bean sized eggs in a small, cup-shaped nest; the latter is composed of plant down and spider silk and is usually covered with lichens; two broods may be raised in some years. By early October, the ruby-throats are off to Central or South America, departing before a hard freeze eliminates their food source; amazingly, many of these tiny birds will cross the Gulf of Mexico on their biannual journey.

Mom's Mitochondria

When we discuss DNA and inheritance, we are generally talking about nuclear DNA, half of which is provided by each parent. But there is also a small amount of mitochondrial DNA in each cell, 37 genes worth, that, in the great majority of species, is inherited purely from the mother. Since this DNA has a predicatable rate of mutation, genetic scientists have been able to use mitochondrial DNA to study the sequence of evolution and species dispersal patterns throughout the history of our planet.

Mitochondria are small organelles within the cytoplasm of our cells that are important in energy production and protein assembly. It is thought that they originated in the early stages of life's history on Earth, when bacteria became incorporated into other single-celled organisms; this likely occured before nucleated cells evolved. In animals that reproduce through sexual mechanisms, only the mitochondria of the egg are preserved; those of the sperm are destroyed during the process of fertilization.

So, on this Mother's Day, when you thank mom for all that she has done, don't forget to mention that mitochondrial DNA. You couldn't live without it!

The Cottontail Strategy

Cottontails face numerous natural enemies, including coyotes, fox, hawks, owls and snakes. Almost half of their newborns die before six weeks of age, succumbing to cold weather, flooding, lawn mowers and predation by cats, snakes, crows, magpies and weasels. Of course, many cottontails are also killed by human hunters and motorists.

To balance these threats and insure their survival, cottontails are very fertile and produce multiple litters through the course of a year. In Missouri, these common rabbits breed from mid February to early September with many females giving birth to seven or eight litters. Their gestation period is 4 weeks and litters average 4 to 6 bunnies; spring litters tend to be the largest. Some females born in the spring will give birth to their own offspring by late summer.

This survival strategy is also common among small prey animals such as mice, voles and lemmings. When conditions are favorable, such fertility may lead to population explosions and the potential for significant crop loss. It is then that we most appreciate nature's predators.

Humans and Rivers

This week's flooding in Missouri is just the latest saga in man's long, stormy love affair with rivers. Ever since early humans spread across the globe, we have been building camps, towns and cities along these streams, vital channels of water, food and navigation. But more than providing this inate utility, rivers touch something in our souls; despite their power, they evoke a sense of tranquility and we want to live near them.

So we have attempted to control rivers through our use of dams, levees and dredged channels. Confident of our mastery, we have built towns and cities on their floodplains, somehow ignoring how those flat valleys came to be. At the same time, we have destroyed most of the wetlands that once absorbed the seasonal flooding which now ravages our riverside communities.

The Great Midwest Flood of 1993 served notice that we have a limited (and temporary) ability to harness the power of rivers. The sooner we accept this fact, the sooner we'll take a more reasonable approach to floodplain "development." Restoring the wetlands would be a good start!

Lake Baikal

Lake Baikal, in southeastern Siberia, is surely one of the most fascinating places on Earth. Filling the deepest continental rift on the planet, this lake holds 20% of our liquid fresh water, more than all of America's Great Lakes combined. Baikal is 395 miles long, up to 50 miles in width and averages 1 mile in depth. The rift itself is 5 miles deep but the lake's sediment is 4 miles thick; both the rift and the lake are thought to be 25-30 million years old, making Baikal the deepest, largest (by volume) and oldest freshwater lake on Earth. Surrounded by mountains and filled by more than 300 rivers, Lake Baikal drains to the Arctic Ocean via the Lena River.

More impressive than its size, Lake Baikal is home to over 1000 plant species and more than 1200 animal species, 80% of which are endemic to the lake (they are found nowhere else on the planet). Baikal harbors 56 species of fish, including its famous omul salmon, and is home to the only freshwater seal on Earth, the Baikal seal, locally known as the nerpa. It is thought that these seals migrated from the Arctic Ocean during the late Tertiary Period, when the Lena was a much larger river.

The mountains and taiga surrounding the lake are also rich in wildlife, over 80% of which are endemic to the region. These include brown bears, sable, lynx, moose, reindeer, pikas and the Siberian chipmunk; among the unique bird species are white-tailed eagles and grey herons. The only threat to this natural paradise is, of course, human activity. Regional air pollution is a problem and the pristine lake waters are threatened by effluent from a pulp mill, built on the south shore of Baikal.

The Farallon Plate

During the Mesozoic Era, the Age of Dinosaurs, the oceanic Farallon Plate stretched along the west side of the North and South American Plates; at that time, the west coast of North America was at the longitude of central Utah. By the mid Jurassic, about 160 million years ago, the Atlantic Ocean began to open and the American Plates were pushed westward, forcing the Farallon Plate to subduct beneath their western edge.

This subduction of oceanic plate triggered the formation of the Andes in South America and, over time, added a large number of exotic terrains and island arcs to the west coast of North America, building up the Great Basin, California, the Pacific Northwest, British Columbia and Alaska. The Cascades of Washington and Oregon began to form about 36 million years ago as this process continued.

Today, most of the Farallon Plate has disappeared beneath the Americas but three remants persist: the Juan de Fuca Plate along the Pacific Northwest, the Cocos Plate along the west edge of Central America and the Nazca Plate along the west coast of South America. All three are still subducting and volcanism will persist in these areas until either the "Farallon fuel" is used up or the Atlantic stops expanding.

Death in the Shallows

Last evening, my wife and I took a walk at the Forum Nature Area, in southwest Columbia. Stretching along the floodplain of Hinkson Creek, this refuge is a pleasing mix of restored prairie, riparian woodlands and seasonal wetlands. On this warm, breezy evening, the frenzied song of cricket frogs echoed through the valley and a pair of barred owls, half a mile apart, called to one another from the creekside forest. Out on the grasslands, a trio of deer browsed in the shadows while bluebirds and tree swallows guarded their nest boxes.

Approaching the west end of the preserve, I noticed a movement in the shallows. We stopped to watch as the tail end of a large black snake writhed about in the water, its head hidden in the marsh grass. I initially thought it had trapped a frog or small mammal against the shoreline but, as its body went limp on the surface, it soon became apparent that the snake was losing this battle. My next thought: a snapping turtle had caught the snake. Sure enough, after a few more spasms from the victim, the monstrous head of a snapper emerged from the lake, the body of the snake protruding from its jaws.

Completing the trail loop, we passed the usually mix of families, couples and dog walkers, all enjoying the pleasant evening. Lost in their conversation and duties, few seemed to notice the abundant wildlife in their midst and none would likely see the remnants of the death struggle. By then, the snapper had towed its prize to the muddy bottom and was chomping away at its carcass. Nature is not always pretty.

Nighthawks

Several hot, humid days have brought the common nighthawks back to Columbia. After a winter in South America, they have been circling northward over the past month and no doubt took advantage of strong southerly winds this weekend to complete their journey.

Most active at dusk, nighthawks are easily identified by their halting flight, white wing patches and distinctive call, a sharp "peent." Flapping and gliding above our cities and suburbs, they feast on flying insects, often gathering near sports fields where the bright lights concentrate their prey. Nighthawks roost and nest on the ground or on flat urban roofs; they are occasionally active during the day, especially after heavy rains send clouds of insects into the air.

Watch for them on calm, summer evenings when they join bats and chimney swifts in the waning daylight. As August gives way to September, nighthawks drift southward in large flocks, never to experience the autumn chill.

Dome of Drought

For the past two months, a dome of high pressure has been sitting over the southeastern U.S., aggravating a prolonged regional drought. As Pacific fronts move toward this dome, they are deflected to the north and east, depriving the southeast of much needed moisture. Clockwise winds move along the outer edge of the dome, pulling humid Gulf air into the Heartland and bringing heavy rain and severe thunderstorms to the southern Plains and Midwest.

Within the dome, sinking air prevents the development of "pop up" thunderstorms which are usually common in the southeast. Furthermore, the prolonged drought has produced a dry landscape that feeds little moisture to the atmosphere; any showers that do manage to form drop their rain into a low humidity air mass and most of the precipitation evaporates before reaching the ground. Such conditions lead to wildfires, a lowering water table and widespread water shortages. A potent, slow-moving tropical storm may prove to be the only hope for breaking this cycle.

Many of Earth's deserts have developed under similar conditions. They occur at latitudes where high pressure dominates and where the air is sinking. Air warms up and dries out as it sinks and, as noted above, high pressure deflects fronts and prevents cloud formation. Where oceanic currents and jet stream patterns keep such domes in place, deserts form.

Oil and the Tethys Sea

In the late Triassic, 200 million years ago, Pangea began to rift apart as the Tethys Sea spread east to west, separating the northern and southern Continents. This seaway reached its maximum extent by the middle Jurassic, when it covered a swath that would later become northwest Australia, south-central Asia, southwestern Russia, the Middle East, the Mediterranean basin, the Gulf of Mexico and the Gulf Coast region. Keep in mind that the continents were still pushed together (east to west) at this time; the Atlantic had just begun to open and the Indian Ocean was yet to form.

Today, the Mediterranean Sea, the Black Sea and the Caspian Sea are remnants of the Tethys. Of more significance, oil formed within sediments of this ancient Sea, a degredation product of plankton and other organic marine debris . The oil that is pumped from the Gulf Coast region, the Gulf of Mexico, northern Africa, the Middle East and western Russia lies within Jurassic shale, a sediment of the Tethys. In like manner, the salt domes of the Gulf Coast States, most numerous in Louisiana, were deposited by the Tethys Sea.

It is both fascinating and disturbing to know that this prize of human culture, a source of so much misery and conflict, originated more than 100 million years ago, in the placid waters of the Tethys Sea.

Karst Landscapes

Karst landscapes develop where thick layers of soluble bedrock (limestones or dolomites) lie close to the surface and where plentiful moisture (past or present) has dissolved channels and caverns in this bedrock. Rainfall, snowmelt or groundwater enter cracks in the rock and gradually erode channels; these open tunnels allow more water to flow into the bedrock, leading to the formation of caves and underground streams.

Some of the caves eventually collapse, forming sinkholes and "stealing" flow from surface streams. Where overlying, insoluble rock (such as sandstone) protects the eroded limestone, large, extensive cave systems may develop and "dripstone" formations (stalactites, stalagmites and flowstone) adorn the caverns. All of this underground water eventually returns to the surface via natural springs or enters regional acquifers. Karst topography is thus characterized by rolling terrain with numerous sinkholes and few surface streams. Caves underlie the region and their underground streams may surface some distance away, often emerging from limestone cliffs along a major river.

Tennessee, Kentucky and Missouri harbor a wealth of karst landscape. Tennessee has more caves than any other State and Kentucky is the home of Mammoth Cave; eroded in Mississippian limestone, this is thought to be the most extensive cave system on Earth. Most of Missouri's caves are found across the Ozark Plateau, where Ordovician dolomites predominate; the Mississippian limestones of southwest and central Missouri are also renowned for their karst features.

The Appalachian Plateau

Stretching from the Catskills of New York to northern Alabama, the Appalachian Plateau is a broad uplift of horizontal, late Paleozoic sediments. The Plateau rose in concert with the southern Appalachian Mountains as North America and Africa collided; this occured during the assembly of Pangea, some 250 million years ago.

Today, the Plateau covers southwestern New York, western Pennsylvania, eastern Ohio, most of West Virginia, eastern Kentucky, central Tennessee and northeastern Alabama. Its component rock layers date from 350 to 250 million years ago (Mississippian, Pennsylvanian and Permian); the Pennsylvanian strata dominate across most of this province and harbor thick seams of coal. Numerous streams, dendritic in pattern, have carved the Plateau into a maze of ridges and valleys. Wild turkey, ruffed grouse, beaver and white-tailed deer typify the resident wildlife; black bear inhabit some portions of the Plateau.

In New York and northern Ohio, glaciation has obscured its northern and western margin but, from central Ohio southward, the western edge of the Plateau rises 500 feet or more above the Central Lowlands of the Midwest. In some areas, especially near Berea, Kentucky, a chain of knobs runs along the western edge, erosional remnants from the Plateau's original western boundary. Often called the Cumberland Plateau in southern Kentucky and Tennessee, the Appalachian Plateau gives way to the Ridge and Valley Province of the Appalachian Mountains on its east side. This boundary is especially conspicuous in Pennsylvania, where the "Allegheny Front" of the Plateau looms as a high wall to the west of the mountain ridges.

Colorado's Birding Capitol

Barr Lake State Park, northeast of Denver, is the undisputed capitol of birding in Colorado. Home to the Colorado Bird Observatory, this Park has recorded more bird species than any other location in the State. Early May is one of the best times to visit; most summer residents have arrived and migrants are still moving across the Plains, heading for the mountains or more northern breeding areas.

Centered on a large irrigation reservoir, this State Park is a mosaic of grasslands, marsh, riparian woods and open lake waters; an earthen trail encircles the reservoir and several boardwalks take visitors across the adjacent wetlands. Bald eagles, cormorants, western grebes and several herons nest here and American white pelicans summer on the lake. Regular migrants and visitors include snowy egrets, white-faced ibis, ospreys, Wilson's phalaropes and a wide variety of waterfowl, gulls, terns and shorebirds.

Woodlands along the southern and eastern shores of the reservoir fill with songbirds by early May. Northern orioles, house wrens, common yellowthroats and yellow warblers are especially common; migrants include Swainson's thrushes, Wilson's warblers, white-crowned sparrows and yellow-rumped warblers. Eastern and western kingbirds, black-billed magpies, Swainson's hawks, ring-necked pheasants, blue grosbeaks, western meadowlarks and loggerhead shrikes inhabit the Park's grasslands, where red fox and coyotes are often seen at dawn or dusk.

Cane Creek

Cane Creek State Park, in northern Ohio, sits on the south shore of Lake Erie, between Toledo and Sandusky. This relatively small Park, which lies along the east border of the Ottawa National Wildlife Refuge, harbors a tract of forest which fills with migrant songbirds in early May; it is especially well known for its large number and variety of migrant warblers.

Streaming north toward their Canadian breeding grounds, these birds suddenly encounter the broad expanse of Lake Erie and stop to rest and feed in the Cane Creek woods. A boardwalk leads birders and photographers through this lakeside woodland, yielding close encounters with an amazing variety of migrants. So, if you don't mind birding in a crowd and are still missing a few warblers from your life list, you should consider a visit to Cane Creek!

Cane Creek State Park is accessed off State Route 2, near Oak Harbor, Ohio. The Park lies at the northwest corner of the Magee Marsh Wildlife Area.