Monday, December 31, 2007

Arctic Blast

On this last day of the human calendar, the coldest air of the season is poised to drop into the Plains and Midwest. A center of low pressure, now over the eastern Dakotas, will move rapidly to the east, pulling down Arctic air in its wake; by later today, it will surely feel like winter once again.

Strong north winds will accompany this potent cold front and highs will remain in the teens or single digits across the northern tier of States. Further south, the front will produce snow flurries across Kansas, Iowa and Missouri, but the air is too dry for any significant accumulation; however, as the storm moves eastward, its strong north winds will bring heavy, lake-effect snow to the northeastern snow belt.

Here in Missouri, we will reach the middle thirties ahead of the front but the Arctic blast should arrive by late afternoon, dropping us into the upper teens overnight. Tomorrow's high is forecast to be 21 degrees F and all discussion of global warming will be put on hold!

Sunday, December 30, 2007

Riverlands

Established in 1988, Riverlands Environmental Demonstration Area is north of St. Louis, just across the Mississippi River from Alton, Illinois. This 1200 acre refuge, which stretches along the west side of the River, adjacent to the Melvin Price Locks and Dam, is a mosaic of riparian woodlands, wet meadows, ponds, marsh and crop fields; entrances are off U.S. 67, in Missouri.

During the winter, huge flocks of Canada geese inhabit the preserve, joined by smaller groups of snow and white-fronted geese; trumpeter and tundra swans may also winter here. A variety of surface-feeding ducks, including mallards, green-winged teal, gadwall, wigeon, pintail and American black ducks will be found on the ponds and marshes while diving ducks and grebes favor the deeper waters behind the dam; the latter include canvasbacks, redheads, lesser scaup, buffleheads, common and hooded mergansers, ring-necked ducks, common goldeneyes and pied-billed grebes. Each year, a number of rare visitors, such as Barrow's goldeneyes, oldsquaws, scoters or kittiwakes turn up at Riverlands; Missouri's first smew appeared at the refuge during the winter of 2000-2001.

Bald eagles and a variety of gulls feast on stunned fish below the dam while peregrine falcons patrol the restless flocks of waterfowl. Short-eared owls are regular winter residents at the refuge, as are northern harriers, rough-legged hawks and the ubiquitous red-tailed hawks. Winter songbirds include horned larks, white-crowned sparrows, golden-crowned kinglets, American tree sparrows and rusty blackbirds. Northern bobwhites and ring-necked pheasants are often spotted on the grasslands while snow buntings, Lapland longspurs and long-eared owls are among the irregular winter visitors. Resident mammals include white-tailed deer, coyotes, fox, raccoons, beaver and muskrats.

Saturday, December 29, 2007

Irruptives

Most birds adhere to predictable migration patterns, wintering and summering in specific geographic ranges. However, some birds, known as irruptives, demonstrate a fluctuating winter distribution, an adaptive response to variations in the availability of food or prey.

Perhaps the most famous irruptive in the U.S. is the snowy owl. In winters when lemming populations fall, these northern owls turn up across central latitudes of North America, attracting bird watchers from across the country. Great gray owls and boreal owls also demonstrate this pattern, though their potential range is usually restricted to more northern States.

Among songbirds, snow buntings, Bohemian waxwings, redpolls, crossbills and evening grosbeaks are the best known irruptives. Their numbers in the Heartland vary dramatically from year to year; when their northern or high country food crops are deficient (or covered by heavy snow), these erratic wanderers may suddenly appear in large flocks, providing a special treat for bird watchers. Unfortunately, they often disappear just as suddenly.

Friday, December 28, 2007

The Florida Platform

The peninsula of Florida is the exposed, "high ground" of the Florida Platform, a broad, southward extension of the North American Plate. Stretching from southern Georgia to the Florida Strait, the Platform's east edge is just a few miles offshore at Miami and about 30 miles off the Atlantic Coast at Jacksonville; on the other hand, the west edge is 100 miles west of the peninsula's Gulf Coast.

The deep, basement rocks of the Florida Platform were originally part of northwest Africa when the Continents merged into Pangea, 250 million years ago. Then, as Pangea broke apart and the Atlantic Ocean opened, this piece of crust broke from Africa and drifted westward with the North American Plate. Initially covered by the sea, parts of the Platform began to emerge late in the Mesozoic Era as sediments accumulated on its surface and sea levels waxed and waned. Fluctuating sea levels continued through the Tertiary Period and much of the limestone in northern and central Florida was deposited during that time (especially from the Eocene through the Miocene).

Dramatic changes in sea level occurred during the Pleistocene Epoch as Continental Glaciers advanced and retreated. It was during this time that the limestone of southernmost Florida and the Florida Keys was deposited; the springs and caverns of north-central Florida also formed during the Pleistocene and high, interglacial seas left remnant dunes across the peninsula. Finally, during the Holocene, which continues today, current vegetation patterns developed and the Everglades formed; south of the Keys, on the southernmost part of the Platform, living coral reefs dot the shallows, destined to become islands of future Florida.

Thursday, December 27, 2007

Swamp Ghost

The possible rediscovery of ivory-billed woodpeckers in eastern Arkansas sent a wave of hope through the conservation community in 2004-2005. Yet, like reported sightings in Florida and Louisiana, the discovery remains controversial. Despite an army of observers and the use of high-tech equipment, definitive evidence of surviving ivory-bills remains elusive.

Ivory-billed woodpeckers once inhabited floodplain woodlands throughout the Southeastern U.S., from East Texas to the Carolinas. Timber production, agriculture and other human "development" decimated these old growth, swamp forests and, by the mid 1900s, the ivory-bills were thought to be extinct. While the recent events offer hope, the lessons of this story have more to do with man's impact on nature than on the possible survival of a single species.

While extinctions have occurred throughout the history of our planet, usually related to climate change or the process of natural selection, man-induced extinctions have resulted from a variety of factors. And while over hunting and pollution receive much of the attention, it is the destruction of natural habitat that poses the biggest threat to most species. Our ability to protect the wilderness that remains will depend upon our willingness to contain human population growth and limit our consumption of natural resources. If these goals are not achieved, the ivory-billed woodpecker will remain just another symbol of man's self-centered stewardship of planet Earth.

Wednesday, December 26, 2007

Tale of Two Lows

Yesterday afternoon, a low pressure center, associated with a cold front, sat over southeastern Colorado. Its counterclockwise winds, dragging in moisture from the High Plains, produced "upslope" conditions along the Front Range, dumping up to a foot of snow in Metro Denver.

Meanwhile, an "upper level low," which formed over the Gulf of Mexico, drifted northward along the Alabama-Georgia line, bringing heavy rains to this drought-plagued region. Initially, since high pressure was parked over the eastern U.S., this disturbance was forecast to move eastward, across northern Florida. Fortunately, this "blocking high" retreated to the north and the isolated low, not associated with a front, was able to pull Gulf moisture into the drought zone. This morning, the low had moved into the mid-Atlantic region, producing beneficial rains across North Carolina and Virginia.

While most low pressure centers are associated with fronts, others develop in response to a rising column of warm air. Such isolated disturbances usually precede the development of tropical storms and "cutoff lows" over the Southwestern deserts play a major role in the annual monsoons of that region.

Tuesday, December 25, 2007

Christmas Moon

While a "star" plays a central role in the Christmas story, it was the moon that dominated the night sky this year. Rising on Christmas Eve, the near-full moon produced shadows on the snowy landscape and was still shining brightly in the western sky early this morning.

When the moon is full, we always see the same side of its sphere; however, with all due respect to Pink Floyd, there is no permanently dark side of the moon. And, contrary to popular belief, the phases of the moon are not produced by Earth's shadow across our lone satellite; rather, they represent our changing view of its lit surface. Like the Earth, half of the moon is lit by the sun at all times (except during a lunar eclipse), but, as it orbits our planet, we see an ever-changing image of its lighted surface. Since the moon's rotation rate is synchronous with its 28-day orbit, we always see the same side of the moon when it is full and, from Earth, never see about 40% of its surface.

Like the Star of Bethlehem, which may have been a comet or just a fictional image, all features of the night sky are interpreted by humans from our unique perspective on planet Earth. This often leads to false conclusions and, throughout human history, has produced many rituals and erroneous beliefs. Modern science, in its effort to understand and explain our Universe, must also confront these ingrained convictions, most of which are sustained by mythology and religion.

Monday, December 24, 2007

Postcard Morning

Walking to work this morning was like a stroll through a winter postcard. A full moon glowed in the cold, clear, western sky while Venus beamed from the southeast. A hint of dawn lightened the eastern horizon and a frosting of snow coated the ground. As if on cue, a large flock of Canada geese circled overhead, their honks breaking the silence of this early winter morning.

From man's perspective, nature is full of such beautiful scenes; after all, one usually admires his own home. But nature has many faces; beauty, grace, violence, birth, death and decay to name a few. Governed by physics and genetics, nature is focused on survival. But, conscious of our own mortality, we humans prefer to dwell on her beauty and this morning was a gem!

Sunday, December 23, 2007

Great Blues over Snow

Driving through Missouri farmland this afternoon, I saw two great blue herons fly across the highway, seemingly out of place in the snow-covered landscape. Yet, a minority of these large waders, which breed throughout most of the U.S. and southern Canada, are regular winter residents across central latitudes of North America. Despite their tropical appearance, many great blues manage to survive our Midwestern winter, gathering along the larger rivers and streams, where open water is found.

During the warmer months, great blue herons feed primarily on fish, amphibians, snakes, lizards and large insects, which they stab or grasp with their long, pointed bills. Those that remain through the winter are forced to broaden that menu, often consuming field mice, shrews, crayfish, invertebrates and small birds. Why some great blues stay for the colder months rather than migrate to southern climes (like most herons and egrets), is just another mystery of our natural world; some black-crowned nights herons also adhere to this pattern, foregoing a trip to the Gulf Coast in favor of a winter in the north.

While we are unable to explain such "choices," we should not attribute this behavior to any purposeful decision making. Survival instincts and genetics are at play here, nothing more. No doubt, many great blue herons succumb to severe cold, ice storms or heavy snow each year. That is nature's way.

Saturday, December 22, 2007

Solstice Storm

On this shortest day of the year, a powerful winter storm is sweeping across the Plains and Midwest. This morning, the center of the storm is over Iowa and a secondary low has formed above northern Texas. The connecting cold front separates spring-like conditions to the east from cold, dry air to its west.

The combination of high pressure over the Intermountain West and the deep low over Iowa is creating a pressure gradient that produces strong, north winds behind the front. The secondary low is dropping snow throughout the central Plains and, as the primary storm center moves into the Great Lakes Region, blizzard conditions will develop across the northern Midwest. Here in Missouri, morning temperatures in the low fifties will give way to cold, north winds by evening, with rain changing to snow; 2-3 inches are expected.

On the bright side, the winter solstice marks the darkest day of the year and, from now until June 21, the days will gradually lengthen. In concert, the solar radiation will become more direct and winter will fade to spring; of course, this process will occur over three months and weather conditions will remain volatile along the way. In the meantime, we might as well enjoy the many natural highlights of winter, an unfairly maligned season.

Friday, December 21, 2007

The Milky Way

Some 1.7 billion years after the Big Bang, galaxies began to form, appearing in clusters across the expanding bubble of the Universe. Hydrogen and helium comprised 98% of this primordial matter and the fusion of these atoms within stars would produce the other elements that now comprise the building blocks of planets and, where existent, life itself.

Our home galaxy, the Milky Way, formed about 12 billion years ago, one member of a cluster that contains thirty major galaxies and many smaller ones. As galaxies go, the Milky Way is very large, harboring 600 billion stars (ten times the average); on the other hand, our galaxy cluster is quite small (the Virgo Cluster, 50 million light years away, contains 2500 galaxies). In all, the Universe is thought to contain 100 billion galaxies, many of which have collided and changed form through time; indeed, scientific evidence suggests that the Milky Way has impacted at least two other galaxies and is on a collision course with the massive Andromeda Galaxy.

The Milky Way, a disc-shaped, spiral galaxy, is centered on a massive black hole; our sun, which developed 5 billion years ago, lies within the periphery of the galaxy, in the Orion Arm. The entire galaxy revolves around the black hole and, since we are 26,000 light years from the center, it takes our sun 200 million years to complete one revolution; the sun is now on its 25th lap (its 24th circuit began at the dawn of the Mesozoic Era). Since our solar system is near the outer edge of the Milky Way, we have a limited view of the Galaxy and far fewer stars in the night sky than we would if we were closer to its center (in which case we would have no night).

It's truly difficult to ponder these facts without feeling insignificant! To believe that we are the only intelligent beings in the Universe is either blind arrogance or pure folly.

Thursday, December 20, 2007

Morning Fog

Dense fog shrouded much of the Midwest this morning; the visibility in Columbia was less than a third of a mile. Extensive fog is most common during the early spring and late autumn; in the spring, it is generally due to warm, moist air settling over cold ground while, in the fall, it is usually caused by cold air interacting with warm, moist soil. In either case, the air near the ground reaches its dew point, i.e. it becomes fully saturated with water vapor, and fog develops; calm conditions or light winds favor this process while stronger winds mix the air and disrupt the saturation.

The fog will last until the surface air temperature rises above or falls below its dew point. Should the air cool, precipitation occurs and the fog dissipates; if the air warms, it expands and becomes less saturated, in which case we say that the fog has "burned off."

Today, the dense, early morning fog was associated with an air temperature of 38 degrees F. Five hours later, the temperature has risen into the mid forties and the ground haze has given way to a low overcast (the fog has lifted to an elevation where the air is at its dew point). Should the day continue to warm, the cloud cover will continue to rise and may clear altogether.

Wednesday, December 19, 2007

The Winter Nuthatch

Just outside our family room window is a large, deciduous magnolia, a single feeder filled with black sunflower seed and a hanging block of suet. Yesterday afternoon, the usual feeding group stopped by, composed of chickadees, titmice, white-breasted nuthatches and house finches. They were soon joined by a flicker, a small flock of pine siskins, a few cardinals and a curious group of starlings. Mourning doves, white-throated sparrows and dark-eyed juncos gathered beneath the feeder, searching for fallen seen.

While I watched this motley group, a quick movement from the periphery caught my eye and a small bird dangled from a terminal branch of the magnolia. Within a few seconds, this red-breasted nuthatch darted to the feeder, grabbed a seed and flew off. Unlike the polite chickadees, which patiently defer to larger birds at the feeder, the aggressive red-breast flew right in with each return, directing his sharp bill at any patron that challenged his appearance; only an occasional stop at the suet block disrupted his recurrent visits. Though most of the birds moved on over the next twenty minutes, this tiny nuthatch continued his forays for an hour or more, storing his larder in tree bark, the cracks of our deck and even beneath the gravel of the backyard walkway.

Red-breasted nuthatches summer and breed in the coniferous forests of Canada and the U.S. mountains. Wintering throughout the country, their numbers vary widely from year to year, likely related to weather conditions and regional food supplies. Though they may join the roaming flocks of chickadees, titmice and finches, this small but hardy bird is often found alone, able to fend for himself in our fickle, Midwestern winter.

Tuesday, December 18, 2007

December at Eagle Bluffs

On this sunny, December morning, I headed down to Eagle Bluffs Conservation Area, southwest of Columbia. Stretching along the Missouri River, most of the refuge was covered with ice and snow and a large portion remained closed for waterfowl hunting.

The preserve's largest lake, kept open by flow diverted from the Missouri, harbored a large number of ducks and coot, seemingly oblivious to the shotgun blasts in the distance. Mallards, gadwall and American coot were most common, joined by smaller flocks of shovelers and ring-necked ducks. Along the frozen shoreline, a sharp-shinned hawk dined on the remains of a duck and, off to the south, an adult bald eagle surveyed the scene from a cottonwood.

Away from the lake, noisy flocks of Canada geese roamed the refuge, horned larks scoured the ice-crusted roadways and northern harriers patrolled the snowy fields. Weedy thickets teemed with goldfinches and sparrows and the call of red-bellied woodpeckers rang through the woodlands. The highlight of the morning was the sight of an immature bald eagle swooping into a patch of tall, dry grass; as he descended, a male harrier flapped away and, I presume, the eagle dined on the harrier's catch.

Monday, December 17, 2007

The Permian Extinction

Today, as global warming threatens the welfare of many species, including humans, we tend to believe that this is a unique, man-induced phenomenon. And though we are surely contributing to the process, many upheavals in Earth's climate have occurred over the past 4.6 billion years, some of which led to mass extinctions.

While the most famous is the Cretaceous-Tertiary extinction, likely caused by an asteroid strike and leading to the demise of the dinosaurs, the most severe mass extinction in the history of our planet occurred near the end of the Permian Period, 225 million years ago. The continents had merged into the giant land mass of Pangea during this Period and, by its end, the era of extensive tropical "coal forests" was fading and the climate had begun to cool. This cooling increased dramatically at the end of the Permian, likely due to massive volcanism in Siberia; altered ocean currents and a change in sea chemistry may have also played a role.

During the Permian Extinction, 70% of land species and 95% of marine species were lost; the latter included trilobites (present for over 300 million years), sea scorpions, placoderms and ancient corals. Whatever the primary cause may have been, this extinction set the stage for the rise of the dinosaurs, one of the most successful and diverse groups in Earth's history.

Sunday, December 16, 2007

Secondary Low

After blanketing Kansas and Missouri, the latest winter storm was centered over southern Illinois last evening, dropping heavy snow across the Great Lakes region. Its cold front bowed southward, across Kentucky, Tennessee and Alabama and thence southwestward over the Gulf of Mexico. A secondary low had developed along this front; centered in northern Alabama, this circulation reinforced the primary storm, pulling in copious, tropical moisture across the drought-plagued Southeast.

Producing heavy rain, thunderstorms and tornadoes throughout Georgia and the Carolinas overnight, this secondary low moved to the northeast and, this morning, is parked above the mid-Atlantic coast. Meanwhile, the primary storm has moved into northwestern Ohio and will track across northern Pennsylvania and southern New England. Pulling in warm, moist air that was injected northward by its secondary low, the storm will produce rain to the south and east of its path and heavy, wind-blown snow to its northwest.

As it continues to move eastward, strong, northwest winds will develop behind the storm, dumping lake-effect snows across the snowbelt counties of Indiana, Ohio, Michigan, Pennsylvania and New York. Finally, the secondary low will merge with the primary storm off the Northeast coast; after bringing heavy snow to the Northern Appalachians, this powerful winter storm will move out to sea.

Saturday, December 15, 2007

Birding in the Snow

Conditions were not ideal for Columbia's annual Christmas Bird Count this morning. Snow had fallen through the night and the temperature at dawn was 23 degrees. Fortunately, the wind was rather light.

Experienced birders know that weather conditions can have a significant impact on birding "success." Heavy rain and high winds pose the greatest challenge, usually keeping birds in sheltered areas. Cold weather, in itself, is rarely a factor and often makes the birds more active and more visible; the effects of snow are variable, depending on the depth and rate of fall. Whenever ice or snow cover the ground, birding is generally best at feeders, near and within coniferous woodlands, along open streams or in areas where dense thickets offer food and protection.

About three inches of snow had fallen through the night and, this morning, the snowfall was light to moderate; our birding success turned out to be fairly good. As usual, starlings, grackles, red-winged blackbirds and dark-eyed juncos were found in the greatest number though crows and red-tailed hawks were less common than expected. Sparrows were out in force, especially in thickets along the major creeks; song, tree, white-throated, swamp and fox sparrows were well represented; northern cardinals were also common in these areas, the males looking radiant against the backdrop of snow. Highlights of the day included a couple of pileated woodpeckers, a large flock of purple finches at a feeder and a lone barred owl; the latter was perched in a barren hardwood amidst a cedar grove, oblivious to the cold and snow.

Friday, December 14, 2007

Our National Scavenger

Once endangered, the bald eagle has made a dramatic comeback over the past few decades and is now fairly common along the larger lakes and rivers of North America, especially during the colder months. But having survived illegal hunting and environmental poisons, our National Bird is now the victim of character assassi-nation, often labeled a scavenger that is unworthy to be the symbol of the mighty U.S. of A.

And, indeed, the majestic bald eagle is a scavenger. Though we are all impressed by its soaring flight and admire its ability to snatch a fish from the surface of a lake, we also know that bald eagles gather along rivers to feast on dead or dying salmon, follow flocks of waterfowl to take advantage of sick or injured birds and feed on the carcass of a moose or elk that has succumbed to the winter snows.

We humans are enamored with symbolism, impressed by speed, power and beauty. But nature values survival, nothing more. And bald eagles are survivors!

Thursday, December 13, 2007

Christmas and Conservation

Christmas, at least in its western, secular form, is not conservation friendly. Though it was established to celebrate the birth of a man who, by all accounts, lived rather simply, it has turned out to be the holiday of consumerism.

For most Americans, conservation means the protection of endangered species, the designation of wilderness areas and the recycling of trash; but it should also refer to a lifestyle that minimizes our impact on our natural environment, limits our use of natural resources and maximizes the longevity of the products that we consume. Too often, the citizens of "developed countries" possess far more than they need and discard items (cars, appliances, houses, clothing) well before their utility is over. Unfortunately, during this season of "giving," those patterns are encouraged and exaggerated.

So, during the Christmas holidays, I often find myself in agreement with religious leaders, a group with whom I rarely concur. As they say, we would be better off focusing on the spirit of the season rather than wallowing in materialism. And, lest I be labeled a Scrooge, Merry Christmas to all!

Wednesday, December 12, 2007

The Resilient Cottontail

After denning up through the ice storm, the cottontails were out in force this morning, moving about in the predawn light. Yesterday's heavy rain and moderating temperature scoured away the hard surface glaze and opened up patches of vegetation, providing sustenance for these hardy rabbits. They will use this break in winter's wrath to feast on grasses, seeds, herbs and the buds of low shrubs, always wary of the fox, coyotes, hawks and owls that prey on them.

While many will succumb to predators, heavy snows and ice storms, more than enough will survive to replenish their population, with the first litters arriving by February. We humans, always focused on our personal turmoils, should be inspired by these resilient creatures; patience and perseverance is their motto!

Tuesday, December 11, 2007

Cousin Hairy

Downy woodpeckers range throughout most of the U.S. and are common in residential areas throughout the year. These small, black and white woodpeckers, often seen in pairs, are rather tame and usually feed in the company of chickadees, titmice and nuthatches.

In contrast, their larger cousin, the hairy woodpecker, is somewhat reclusive, favoring dense forest and rural woodlands. Come winter, however, they often visit residential areas, chasing downies and their cohorts from the suet block. Though their black and white markings are nearly identical to those of downy woodpeckers, hairies are significantly larger (jay-sized) and have longer, heavier bills; the males of both species have a red patch on the back of their head. Loners, hairy woodpeckers are wary birds and usually fly off if you get too close.

While he may not be neighborly, the hairy woodpecker plays a major role in the control of bark beetles and other harmful insects. If for no other reason, that service should make him welcome in our back-yards.

Monday, December 10, 2007

The Unnatural Salton Sea

Created by faulty irrigation engineering in 1905, which triggered a 2-year flood from the Colorado River, the Salton Sea covers 376 square miles of a broad, desert basin and sits 227 feet below sea level. Once the flooding was controlled, this unnatural oasis, the largest lake in California, attracted opportunistic developers and a chain of resorts soon appeared along its shores. To bring in sportsmen, a variety of fish were introduced, most of which failed to thrive in this warm, shallow saline lake.

Receiving only 3 inches of precipitation each year, the Sea is replenished by agricultural and urban runoff from the Imperial, Mexicali and Coachella Valleys; unfortunately, this water brings salt and high-nitrogen waste into the Lake, gradually increasing its salinity (it is already more saline than sea water) and producing algal blooms. The latter result in huge fish kills and pose a secondary threat to the resident and migrant birds that feed on the Sea; American white pelicans and eared grebes are among the most affected species.

Current efforts to "rescue" the Salton Sea and its "vital wetlands" are being spearheaded by the Salton Sea Authority and the U.S. Department of the Interior. A variety of solutions have been proposed, including direct conduits from the Colorado River or from the Gulf of California. One wonders whether this motivation is derived from concern for the environment or concern for the developers. While an effort to eliminate pollution from the agricultural areas is laudable, it seems to me that man has already done more than enough to disrupt this desert basin. Let nature decide its fate!

Sunday, December 9, 2007

Ice Storm

As a cold front settled across Missouri last night, a series of sleet thunderstorms dropped over an inch of ice on Columbia. This morning, the front, which stretched from the Southern Plains to New England, nudged a bit to the north, producing a shallower layer of cold air in our region; the sleet gave way to freezing rain.

Though not accompanied by a powerful storm, the cold front separates dramatically different air masses. At noon, today, it was 71 in Memphis and 38 in St. Louis; Lexington was 60 degrees while Cincinnati sat at 39. It is along and near the freezing zone that the icing is most severe; further north, where the cold air mass is thick, snow is falling while, to the south, the precipitation is rain.

Ice storms pose significant travel problems for humans but are also one of the more deadly weather events for wildlife. Birds and small mammals that usually sift through leaf litter for seeds and insects find that their hunting grounds are glazed over by a thick layer of ice. Those of us who stock backyard feeders will surely notice an increased number and variety of visitors today!

Saturday, December 8, 2007

The Darkest Month

We are now entering the darkest month of the year, the two weeks before and after the winter solstice. During this period the Northern Hemisphere is maximally tilted away from the sun and solar radiation is least direct. The Arctic is in the heart of its perpetual winter dark-ness and, those of us at more southern latitudes, are experiencing the shortest days of the year.

While this is the darkest month, it is generally not the coldest period in the Temperate Zone. The ground is not yet frozen solid and the larger lakes remain open; as a consequence, the surface of the Earth is still radiating heat into the lower atmosphere. By mid January, this warming effect is significantly reduced and, though the days are lengthening, the coldest temperatures occur.

As darkness extends its reign, the night hunters gain an advantage; equipped with superior night vision, these predators also benefit from longer hunting periods. It is, indeed, the season of the owl and, in concert with this hunting advantage, their breeding cycle will soon begin.

Friday, December 7, 2007

A Weddell's Winter

Should the cold, gray Midwestern winter begin to depress you, think of the Weddell seal. This large pinniped, the southernmost mammal on the planet, spends its winter in the dark, frigid waters beneath the Antarctic ice. In order to keep from drowning, these seals must keep their breathing holes open by gnawing away the sea ice that threatens to close off their air supply; over time, this activity wears away their teeth and, though most face little threat of predation, many end up starving to death.

When not tending to its vital portholes, the Weddell seal dives for fish, squid, octopi and small invertebrates, including krill. Protected from the cold by a thick layer of blubber, this true seal is able to dive 2000 feet below the surface and remain submerged for more than an hour; a rich supply of myoglobin in its body stores and releases oxygen to its muscles and vital organs, permitting these prolonged dives. Averaging ten feet in length, Weddell seals may weigh up to 1200 pounds; females are generally larger than the males.

Now, as we enter our winter season, Weddell seals are hauling out on the ice to deliver and raise their pups. Enjoying the Antarctic summer, they will bask in temperatures comparable to our Midwestern winter!

Thursday, December 6, 2007

First Snow

Columbia's first significant snowfall of the season began at noon today, about a month later than usual. Though only a few inches fell by evening, the snow brought a pleasing change to the drab, winter landscape.

A stationary front draped across the central Midwest throughout the day, keeping the temperature within a narrow range (29-32 degrees F) and allowing a low-pressure "disturbance" to move west to east along its track. This mobile center of lift produced a broad swath of snowfall across Missouri, with the heaviest accumulations along and north of I-70.

While the snow will drift eastward overnight, the cold air will remain entrenched and the white blanket may persist until another storm arrives over the weekend. Though the winter solstice is still a couple of weeks away, the season has now officially arrived. I'll take snow over cold rain any day!

Wednesday, December 5, 2007

Inland Gulls

Most Americans associate gulls with coastal beaches, seaports and, perhaps, the Great Lakes. However, gulls are fairly common inland, sometimes far from any large body of water.

California, Franklin's and ring-billed gulls are common summer residents in the Mountain and Great Basin States of the West and a variety of gulls visit the interior during the colder months. Herring and ring-billed gulls are the most common winter gulls in the Midwest, usually congregating on reservoirs or along the larger rivers; scavengers, these species also gather at landfills and restaurant parking lots. Uncommon but regular visitors include Thayer's, glaucous and black-backed gulls; these wanderers are usually seen in small numbers, mingling with their more common cousins.

Some of the best places to see a variety of winter gulls are the major dams along the Mississippi and Missouri rivers. There, the gulls usually gather beneath the dam, snatching fish that are stunned by the turbulent flow. This opportunistic behavior is also seen in bald eagles, another common winter visitor at these sites.

Tuesday, December 4, 2007

Mattamuskeet

While almost all wildlife refuges are interesting throughout the year, some were established for specific, seasonal reasons and, thus, are especially rewarding during those months. Mattamuskeet National Wildlife Refuge, in eastern North Carolina, provides an excellent example.

Established in 1934 to protect wetland habitat for migrant and wintering waterfowl, this Refuge, centered on the State's largest natural lake, attracts huge flocks of geese, ducks and tundra swans from late autumn through early spring. The preserve is a mosaic of crop fields, marsh, cypress swamps, pine-hardwood forest and the shallow, 40,000-acre lake. Tundra swans are certainly the highlight for most birders; after a summer in the Arctic, an average of 30,000 swans winter at Mattamuskeet. Canada geese, snow geese, Ross' geese, white-fronted geese and a large variety of ducks also rest and feed at the refuge, patrolled by bald eagles and peregrine falcons that move south with these flocks. Resident mammals include deer, bobcats, gray fox and river otters; an occasional red wolf (reintro-duced to this region) or black bear may also be seen.

Mattamuskeet National Wildlife Refuge is in Hyde County on the north side of Pamlico Sound, approximately 8 miles east of Swan Quarter, North Carolina.

Monday, December 3, 2007

The Wildlife Advantage

In dealing with the harsh conditions of winter, wild creatures have a definite advantage (both mentally and physically) over we humans. Equipped with thick pelts or insulating feathers, they remain active, searching for the prey, edible plants or carrion that they need to stay alive. Unlike their human counterparts, they neither anticipate nor experience the regular shift from heated to unheated environments and thus (one would assume) barely notice the gradual change in temperature that occurs throughout the day and night.

Unhampered by technology, they are neither bombarded by dire weather forecasts nor reminded of the wind chill several times each day. Since they do not consult thermometers, they, unlike data-conscious humans, are likely unaware of the difference between 18 and 28 degrees F. We, on the other hand, often let the weather rule our lives or, at the very least, use it as an excuse to put off unpleasant chores. Besides, we have a warm house to retreat to!

Sunday, December 2, 2007

Thunder in December

While we usually associate thunderstorms with warm seasons and warm climates, they can occur at any time of year. In fact, snow thunderstorms are not at all uncommon.

As the recent winter storm pulled away to the northeast, a warm, southerly flow developed; yesterday, after a wet and chilly morning, the temperature rose through the day and, by late evening, we were in the mid fifties. The balmy flow continued through the night and, this morning, we awoke to sixty degrees in central Missouri; however, dark clouds on the western horizon foretold a coming change. A strong Alberta Clipper would soon end our December respite.

Sure enough, thunderstorms developed by 10 AM, dropping torrential rains; within two hours, the temperature had dropped from sixty to thirty-eight and strong, northwest winds made it seem even colder. Following a night in the fifties, tonight's low is forecast to be 23. That should bring us back to reality!

Saturday, December 1, 2007

Winter Storm

After forming off the coast of Southern California and bringing much needed rain to the Desert Southwest, the first major winter storm of the season is dumping heavy snow in the southern Rockies and will move across the Northern Plains today. Icy conditions will prevail in western Kansas, southern Nebraska and northern Missouri, with significant snowfall to the north of that swath. Southward, steady rains will drench the Central Plains and lower Midwest.

Tomorrow, the storm will move across the Great Lakes and into the Northeast, bringing a mix of ice and snow to that region. Finally, gaining strength off the New England Coast, it is forecast to dump heavy snow on the Northern Appalachians.

Contrary to popular perception, such storms are not a massive swirl of moisture that drains itself as it moves across the country. Rather, the storm is a low pressure center (and its associated cold front) that pulls in moisture from the south and forces it to collide with or override cold air to the north; depending upon the depth and temperature of the cold air, the precipitation falls as rain, freezing rain, sleet or snow. If the storm encounters air that is deficient in moisture, precipitation will be limited or not occur at all.

Friday, November 30, 2007

Solitary Hunter

As the cold, dark season envelops the land, hikers are more likely to encounter our resident carnivores; stirred by the cold and intent on survival, even nocturnal hunters may be active during the day. But only the most observant (and lucky) backcountry visitors will see a fisher, one of our more reclusive predators.

Limited to coniferous and mixed forests of Canada and the mountainous regions of North America, this mid-sized mustelid is solitary for most of its life. Identified by its long, stocky frame, dark brown body and light brown face, the fisher, like most mustelids, is a voracious hunter. Prey includes grouse, mice, hares, muskrat and beaver; fishers are well known for their prowess at killing porcupines and have been introduced in some areas to control this quilled herbivore. While primarily terrestrial, fishers, like their smaller cousins, the martens, are excellent climbers and may den in tree cavities. Mating occurs in late winter and an average of three kits are born in spring of the following year (implantation is delayed).

Like many reclusive animals, such as mountain lions, a loss of natural habitat is forcing this solitary hunter to adapt to human "development." Sightings have reportedly become more common in New England and, before long, they will be labeled a menace; how dare they invade our territory and kill our pets!

Thursday, November 29, 2007

Clouds and Heat

Clouds, as beautiful as they can be, are nothing more than water vapor suspended in the air. Their formation requires the presence of adequate humidity in air that is cooled to its dew point; further cooling leads to precipitation, in the form of rain or snow. When this process occurs near the ground, fog develops; when it occurs higher in the atmosphere, we see clouds.

Humid air is less dense than dry air and cannot get as hot or as cold. As a result, we find the highest and lowest temperatures in areas where the humidity is very low, i.e. deserts and the polar regions. Humidity thus moderates air temperature but clouds generally have different effects on our surface temperature in the summer and winter. During the warmer months, clouds reflect the sunlight, shade the ground and provide a cooling effect at ground level; if the humidity is very high, producing a high heat index, this cooling effect will be less noticeable. In contrast, clouds tend to warm the surface air during the winter, when the sun angle is low and the solar heating effect is reduced; in this case, clouds provide a blanket effect, reflecting radiant heat from the ground back toward the surface. Such cloud blankets are especially noticeable on cold, winter nights; in dry areas of the West, where clouds tend to dissipate through the evening, overnight lows often plummet into the teens and single digits.

This morning dawned clear as a bell, not a cloud in the sky. The temperature was 21 degrees!

Wednesday, November 28, 2007

The Pleiades

As earth hurtles through space, on its annual journey around the sun, we are treated to an ever-changing view of the night sky. For any given time of night, the frame shifts gradually from east to west and, due to the earth's rotation, the stars appear to move from east to west throughout the night.

One of the more striking features of the Northern Hemisphere's winter sky is the Pleiades cluster; also known as "The Seven Sisters," due to the prominant, hot blue stars within the group, this bright, compact cluster is "M45" to astronomers. Visible to the naked eye, the Pleiades begin to rise above the eastern horizon in late October and are now high in the eastern sky by 9PM. Viewed with binoculars, this cluster is seen to contain many more stars that the Seven Sisters and has a hazy, nebular appearance; this, in fact, is not a star factory but, rather, a hydrogen cloud through which the Pleiades are currently moving. The cluster is actually composed of nearly 1000 stars, many of which are brown dwarfs.

Perhaps the most interesting feature of the Pleiades cluster is its youth, having formed just 100 million years ago, during the reign of Tyrannosaurus rex! Currently some 440 light years from Earth, this brilliant star cluster is (from our perspective) moving toward the Orion constellation and will eventually be torn apart by gravitational forces. For now, unlike most of the star patterns that man has named, the Pleiades are truly grouped in space, not merely an optical illusion produced by earth-based viewing.

Tuesday, November 27, 2007

Below the Jet

On its annual push to the south, the jet stream has settled down across the northern States this week, guiding a series of Pacific storms across the country. Acting as a barrier, this steering current is also keeping the frigid, Arctic air to the north of its flow.

Here in Missouri, buffered from extreme cold, we are experiencing the ups and downs of each frontal passage. Ahead of the storms, southerly winds bring mild conditions, with highs in the fifties; behind the fronts, the wind shifts to the northwest, dropping overnight lows into the 20s and afternoon highs into the upper 30s. Since the storm centers are well to our north, most of the rain and snow will occur across the northern Rockies, the Dakotas and the Great Lake States, including lake-effect snows east of the Lakes.

Such roller coaster patterns are typical of early spring and late autumn, when the jet stream is caught between summer and winter. For now, we'll enjoy the brief, dying gasps of autumn, but our descent into the cold, dark season has begun.

Monday, November 26, 2007

Fear of Winter

Many humans despise winter, blaming the season for their blues and inactivity. But I suspect that a true "fear of winter" resides within the collective human psyche. Appropriately called the "Naked Ape" by Desmond Morris, man evolved in the Tropics and spread across the globe before his body changed in any significant way. Rather, the power of the human brain intervened, giving us the ability to fashion warm clothing long before any fur-bearing, northern subspecies evolved.

Humans are equipped with efficient cooling mechanisms (primarily through the skin and lungs) but our heat generating capacity is limited (via shivering, muscular activity and the metabolism of food and stored nutrients). Given adequate fluid and nutrition, a naked human is able to maintain his vital core temperature across a fairly broad environmental range (generally between 55 and 130 degrees F). Hypothermia is of no concern in the Tropics and a naked human could survive in the Temperate Zone for much of the year. But without adequate shelter and clothing, he would quickly succumb to winter conditions.

In this modern industrial and technological age, we seldom consider the limitations and environmental threats that our species once faced. But deep inside, we remember.

Sunday, November 25, 2007

The Katy Trail

One of the best Rail-to-Trail projects in the country, the 200-mile Katy Trail hugs the north edge of the Missouri River floodplain, from St. Louis to Boonville; there, it crosses the River and angles to the southwest, leading through the rolling farmlands of west-central Missouri. This wide, graveled path runs atop the old bed of the Missouri-Kansas-Texas Railroad, which ceased operations in 1986. Managed as a State Park, the Katy Trail and its immediate surroundings attract hikers, trail bikers, joggers, fishermen and naturalists throughout the year; however, trail use diminishes significantly throughout the colder months and those who enjoy solitude will find this route an appealing destination for winter nature hikes.

On its route along the floodplain, the Katy Trail winds through swamp forest, crosses wooded meadows and fords numerous streams and wetlands. Birders should see an excellent variety of bottomland residents, including wood ducks, belted kingfishers, red-headed woodpeckers, barred owls, red-shouldered hawks, winter wrens, song sparrows and American tree sparrows. Turkey vultures often soar above the limestone cliffs while bald eagles, ring-billed gulls and a variety of waterfowl are common along the river. Floodplain mam-mals include white-tailed deer, beaver, muskrat, mink, raccoons, opossum, skunk, red fox and coyotes.

The historic town of Rocheport, Missouri, reached via Exit 115 from I-70, is one of the more appealing access points along the Katy Trail. Ample parking is provided and the hike southward is especially scenic, characterized by towering cliffs, river views and floodplain wetlands.

Saturday, November 24, 2007

Santa Ana Winds

The Santa Ana Winds are scouring Southern California once again and destructive wildfires have reignited. These hot, dry, powerful winds typically occur during the fall and winter months, as periods of high pressure develop across the Great Basin. Like a giant piston, this high pressure zone creates sinking air over the high deserts of the Basin; in concert, winds flow clockwise around the center of this pressurized air mass and are directed into the mountain ranges of Southern California. Much of this flow is forced to rise over the mountains while some is funneled through the major passes (espe-cially Cajon Pass, between the San Gabriel and San Bernardino Mountains).

As the pressured air descends from the high desert and mountains into the Los Angeles Basin, it compresses, dries out and heats up, often bringing the highest temperatures of the year to the coastal cities. The speed of the wind is augmented in canyons of the Transverse and Peninsular Ranges, sometimes reaching 100 mph or more; while the power of these winds is destructive in itself, the winds also fan the flames of any wildfires that develop, making efforts to control them nearly impossible.

Once the high pressure in the Great Basin moves on to the east, the winds subside and "onshore westerlies" bring cooler, more humid air in from the ocean. Of course, Southern California residents hope that this marine flow will also bring rain to the valleys and foothills, nourishing and restoring the vegetation before the next round of Santa Ana winds.

Friday, November 23, 2007

The Common Stranger

Suburban residents are generally familiar with most of our common bird species. They know cardinals, blue jays, chickadees, robins, mourning doves, crows and goldfinches, among others. But one of our more common and conspicuous neighbors, the tufted titmouse, is known only to those who actively feed and observe our avian visitors.

A bit larger and heavier than a chickadee, this species is easily identified by its tufted crown, gray head and back and its white abdomen with buff-colored sides. Its ringing call, usually described as "peter, peter, peter," is commonly heard in residential areas and is especially noticeable in winter, when other birdsong is subdued. Like chickadees, titmice feed on insects and seeds, often scouring bark and twigs for insect eggs or hibernating larvae; they are also common at feeders and seem to have a special fondness for safflower seed. Ranging throughout the central and eastern U.S., tufted titmice are replaced by plain and bridled titmice in the Southwest.

Tufted titmice are among our permanent residents that move about in loose flocks, often in the company of chickadees, nuthatches and downy woodpeckers. Walking a woodland trail, the birder may see or hear little activity before coming upon these "feeding groups." It often appears to me that there is more to these mobile gatherings than a cooperative effort to find prey; rather, they seem to enjoy each other's company!

Thursday, November 22, 2007

Thanks to Gramps

All of us who are fascinated by nature have someone in our past who instilled and fostered that enthusiasm. For me, it was Gilbert Siegel, my maternal grandfather. Always introducing me to the plants and animals in his suburban, Cincinnati yard, he had a special fondness for birds and squirrels, some of which fed directly from his hand. On one occasion, he took me to visit the farm of a friend and we toured the property on a tractor; for the first time in my life, I was immersed in the sights, sounds and smells of a rural landscape.

Though he died when I was twelve, I still think of him often and have long recognized the major influence that he had on my life. So today, on this annual Day of Thanksgiving, I want to publicly thank my grandfather for his love, his time and his inspiration. Thanks, Gramps!

Wednesday, November 21, 2007

Feeding the Birds

As cold weather grips the country, many Americans will begin filling their backyard feeders. Some will perform this ritual purely out of concern for their feathered friends, worried that they may otherwise succumb to the cold and snow. Most just enjoy watching the birds, though many know them only by their shapes and colors. And then there are the avid birders who know that feeders are the best way to attract rare, unusual or vagrant species to their yard.

Regardless of your motive, remember that birds would get by just fine without our assistance; of course, some would perish in the harsh winter conditions but, then again, that's nature's way. And, if you do feed the birds, know that simple, home-made feeders are just as acceptable to them as the high-tech, expensive models. Fill them primarily with black sunflower seed, a low cost brand (especially when purchased in bulk) that attracts the widest variety of birds; adding a source of fresh water, a hanging block of suet and, perhaps, a tube of Niger (thistle) for the finches, will augment the diversity of visitors.

Our well-intended generosity can have negative consequences. Unnatural crowding of birds around feeders increases the risk of disease transmission and backyard feeding stations concentrate the targets of predators such as sharp-shinned hawks and domestic cats.

Tuesday, November 20, 2007

The Tularosa Basin

Looking at a satellite map of New Mexico, one is struck by two prominent features in the south-central part of the State. The first is a narrow, elongated swath of black, resembling spilled ink; this, in fact, is a basaltic lava flow. South of this flow is a blotch of white, representing extensive dunes of gypsum, the famous White Sands of New Mexico. Both of these geographic features are within the Tularosa Basin, which is flanked by the San Andres Mountains, to the west, and the Sacramento Mountains, to the east. The valley itself has an average elevation of 4000 feet.

During the Permian Period, some 250 million years ago, this portion of North America was invaded by shallow seas. Sedimentary rocks from these seas were uplifted as the Rocky Mountains formed, 70 million years ago. Then, about 30 million years ago, tectonic forces began to pull this region apart; the crust began to thin, upwellings of magma developed and the Permian Uplift was split in two. Today, the San Andres and Sacramento Mountains are remnants of that Uplift and are separated by the Tularosa Basin, the northernmost extension of the Chihuahuan Desert.

Throughout the wet climate of the Pleistocene, rain and snow eroded these mountains, sending mineral-laden waters into the enclosed Basin; with no outlet to the sea, Lake Lucero formed, covering the western half of the valley. As the climate began to dry, at the end of the Pleistocene, the Lake gradually retreated, leaving extensive, gypsum-covered playas in its wake. Southwesterly winds began to create the dunes of white, gypsum sand about 7000 years ago; the process continues today and the dune field now covers more than 275 square miles (half of which is protected within the White Sands National Monument).

Partly stabilized by drought tolerant plants such as dropseed, sandhill muhly, gyp gramma and soaptree yucca, the gypsum dunes are home to a fascinating variety of wildlife; some species, including the bleached earless lizard, Cowles prairie lizard and Apache pocket mouse, have evolved a white coloration, camouflaging them against the white sands. Other residents include kit fox, pallid bats, kangaroo rats, bobcats, western coachwhips, Sonoran gophers, western diamondback rattlesnakes and Texas horned lizards; orynx, an African antelope, have also been introduced to the area, threatening the fragile environment (they are fenced out of the National Monument).

Formation of the Tularosa Basin occurred in concert with regional volcanism; several Tertiary volcanoes dot the northern section of the Sacramento Mountains and are responsible for the formation of their higher summits (including Sierra Blanca). A smaller volcano, now represented by the Little Black cinder cone, west of Carrizozo, released the basaltic lava flow north of the White Sands; this flow occurred about 5000 years ago and lasted 30 years or more. Known as the Malpais (Badlands), the Carrizozo basalt flow is 40 miles long and up to 60 feet thick. The Valley of Fires Recreation Area, on the east side of the lava flow, is accessed by U.S. 380.

Monday, November 19, 2007

Warm before the Storm

Strong southerly winds are pushing temperatures into the mid seventies across the Plains and Central Midwest today. When such unusually mild conditions develop during the colder months, one can generally assume that a Pacific or Arctic Front is approaching and, as suspected, that's the case this week.

A strong cold front is moving across the northern and central Rockies today, bringing heavy snow to the mountainous areas of Montana, Idaho and Wyoming. This frigid air mass will push on to the south and east over the next few days, igniting thunderstorms and heavy rain along its leading edge (and snow behind the front). Meanwhile, ahead of the storm, a southerly flow is producing high temperatures some 15-20 degrees above the mid November average.

Hopefully, the storm will retain its power and draw plenty of Gulf moisture into the drought-plagued Southeast. If so, Thursday will be a true day of Thanksgiving for those folks!

Sunday, November 18, 2007

Saved by Wildlife

Long drives can be tedious, especially when they cover familiar terrain. On my frequent, I-70 treks, between Missouri and Colorado, I rely on music and wildlife watching to quell my boredom.

Leaving our Littleton farm early this morning, I noticed our resident fox sitting next to the barn, as if to bid a farewell. Accepting this as a good omen, I put in a Neil Young CD and headed out of Denver. East of the city, several groups of mule deer browsed in the predawn light, the young bucks clearly agitated by the rut. Further along, on the prairie north of Limon, scattered herds of pronghorn moved among the cattle and, near the Kansas line, a rough-legged hawk perched on a fencepost.

Meadowlarks and horned larks were fairly common across the Plains, though significantly outnumbered by starlings and pigeons. Near Quinter, a red-tailed hawk rose from the crop stuble, lunch in his talons, and, just west of WaKeeney, a northern harrier flapped low across a hay field; both of these hawk species became far more common as I continued to the east. Surprisingly, a Swainson's hawk soared above the highway in central Kansas, apparently late for his trip to Argentina.

East of Junction City, a lone coyote roamed the Flint Hills and, as woodlands thickened in eastern Kansas, wild turkey appeared on the meadows. Dusk descended as I crossed into Missouri, bringing squadrons of ducks and V's of Canada geese across my path; hoping to spot a migrant flock of snow geese which, in my opinion, is one of the most stirring sights (and sounds) in nature, I scanned the darkening sky. Alas, the snows were not to be found and I completed my trip in the dark, watching for deer in the headlights.

Saturday, November 17, 2007

Waterton Canyon

Waterton Canyon, southwest of Denver, represents the South Platte's final journey through the Rockies before rumbling onto the Colorado Piedmont. Accessed by a six-mile, gravel roadway that parallels the River, the Canyon is a popular destination for hikers, fishermen, bikers and naturalists.

Towering walls of rock, foothill shrublands, pine-fir forest and the winding, vibrant River attract a wide variety of wildlife. Golden eagles, canyon wrens, dippers, scrub jays, belted kingfishers, Steller's jays and black-billed magpies are among the permanent residents; during the warmer months, they are joined by lesser goldfinches, rock wrens, black-headed grosbeaks, rufous-sided and green-tailed towhees, white-throated swifts and violet-green swallows. Resident mammals include mule deer, bighorn sheep, rock squirrels, yellow-bellied marmots, golden-mantled ground squirrels, Colorado chipmunks, coyotes and the occasional mountain lion. The bighorn sheep are usually found on the sun-scorched, south-facing slopes of the canyon; since their breeding season begins in November, this is a good time to see the head-butting duels of the adult rams.

The popularity of Waterton Canyon often leads to congestion on warm weather weekends; I recommend an off-season and/or weekday visit if possible. To protect the resident wildlife, dogs are not permitted in the Canyon.

Friday, November 16, 2007

Earth's Brown Cloud

After a day in the clean, clear air of the Front Range mountains, I returned yesterday afternoon to find Denver enveloped in a brown haze. Many western cities, including Denver, Phoenix, Salt Lake City and Los Angeles, are known for their "brown clouds;" located in valleys or basins and fully or partly hemmed in by higher terrain, these cities experience frequent inversions, where a layer of cold air, trapped beneath warmer air, fills with pollutants. The brown haze is primarily due to particulates, which are a special problem in the dry, dusty West.

In reality, the western "brown cloud" cities are just poster children for a worldwide dilemma. All major cities are prone to air pollution and the "developing" regions, where industry is outpacing technology (and will power), the problem is especially severe; the upcoming Olympics in Beijing will surely highlight this issue. Yet, all of us are polluters; if we drive a car, heat our home or use electricity, we are complicit in this threat to the global environment. And who pollutes more: the country resident who commutes forty miles per day in his SUV or the urbanite who takes a bus, subway or bicycle to work?

We humans are multiplying at an unsustainable rate. Having no natural predators other than microbes, parasites and other humans, we seem to be unable or unwilling to control our own exponential growth. Technology, designed to minimize our impact on the environment, will never eliminate the need for human population control.

Thursday, November 15, 2007

North Fork Valley

Leading southwestward from Metro Denver, U.S. 285 climbs through Turkey Creek Canyon and then undulates across the foothills. After descending Crow Hill, this scenic roadway begins a westward run along the North Fork of the South Platte River; the imposing wall of the Platte River Mountains forms the south edge of the Valley while the Mt. Evans massif and Continental Divide loom to the north. Forty six miles from the edge of Denver, the highway crosses Kenosha Pass (elevation 10,000 feet) and drops into South Park; the pass, which represents the western end of the North Fork Valley, connects the Platte River Mountains with the Continental Divide.

Several trailheads along U.S. 285 provide access to the Platte River Mountains and three Forest Roads lead to campgrounds, jeep trails and hiking paths into the Mt. Evans Wilderness or onto the Continental Divide. One of these Forest Routes, the Guanella Pass Road, heads northward from Grant, crosses Guanella Pass (11,669 feet) and then descends to Georgetown, on I-70; this road is especially popular with birders since the Pass is one of the best spots in North America to find white-tailed ptarmigan.

Sunny, mild weather made my visit to the Valley especially pleasant today. Though the birding was average (dominated by ravens, Steller's jays and mountain chickadees), I did spot some bighorn sheep near Grant, found a few dippers along the North Fork and saw a large herd of elk in South Park. The view from Kenosha Pass was spectacular, with the snow-capped peaks of the Mosquito Range rising west of the broad grassland; to the southwest, a few of the rugged Sawatch Mountains completed the scene, poking into the clear, blue sky.

Wednesday, November 14, 2007

Vertical Migration

Almost everyone knows that birds fly south for the winter. Even those who have no interest in nature have heard of this phenomenon in songs, poems or common folklore. But few are familiar with the concept of vertical migration, the seasonal movement of birds and mammals in mountainous areas.

Rather than changing latitudes, many mountain residents adapt to the seasons by altering the elevation of their residence. Heavy snows and severe winter weather can impair the survival of mountain dwellers and they have thus developed the instinct to move on to lower terrain as the days shorten. Elk, mule deer and bighorn sheep adhere to this pattern, as do the carnivores (mountain lions, wolves and coyotes) that prey on them. The same is true for a number of mountain birds; an exception among Colorado birds is the blue grouse, which summers in the footills but winters in the higher mountain forests.

Contrary to popular perception, winters are relatively mild across the Front Range urban corridor. Though overnight lows often drop into the teens, January highs are usually in the low 40s (in contrast to the low 20s across the Upper Midwest); combined with abundant sunshine and modest winter snowfalls (the heaviest snows arrive in early spring), the region is downright balmy when compared to the mountain conditions. Our Littleton farm, which sits at 5400 feet, welcomes a number of mountain migrants each winter; among them are Townsend's solitaires, red-breasted nuthatches, dark-eyed juncos (gray-headed race), Cassin's finches, pine siskins, mountain chickadees, red crossbills, golden-crowned kinglets and yellow-rumped warblers.

Tuesday, November 13, 2007

River Walk

Though snowy peaks rose to the west, it was warm and sunny in the South Platte Valley this morning. The River, high for most of the spring and summer, had fallen to its typical flow but few waterfowl fed along its channel; once the Front Range lakes and ponds freeze over, their number and variety on the South Platte will increase significantly. There were a few mallards, gadwalls and common goldeneyes, joined by a lone female hooded merganser. And, of course, the ubiquitous Canada geese were there, flying overhead or grazing on the floodplain meadows.

The onset of the quiet season was surely evident as I strolled the riverside trail. Juncos and sparrows chirped from the thickets but, except for the gab of magpies and the occasional chatter of kingfishers, the rapids made most of the noise. Even the northern flickers were silent as they moved among the cottonwoods. Mammals were likewise quiet and, if you don't count the fox scat on the trail, were represented only by fox squirrels in the trees and a single muskrat on the riverbank.

You would think that such a beautiful morning would really bring out the wildlife. But they don't share our obsession with "nice days;" they know that every day brings its life and death struggles and they are better than we are at pacing themselves. Tomorrow morning is forecast to bring cold rain or wet snow; most of us will find something to do indoors but the wild creatures will be out there, perhaps in numbers greater than today. After all, they have to be!

Monday, November 12, 2007

The Highway Hawk

The most common and widespread buteo in North America, the red-tailed hawk is especially abundant on the farmlands of the Midwest. Favoring open country with nearby woodlands, these raptors often perch on limbs, fenceposts or phone poles along highways, scanning the roadside grassland for cottontails, mice and voles. Any heavy-bodied, white-breasted hawk perched along a U.S. interstate is a red-tailed hawk until proven otherwise; their pale, red tail becomes conspicuous when they soar above the pastures and cropfields.

Driving west on I-70 today, I saw at least 100 red-tails between Columbia, Missouri and Salina, Kansas. Further west, where few trees dot the High Plains, red-tails are much less common; this is the domain of Swainson's hawks (summer residents), ferruginous hawks, rough-legged hawks (winter) and prairie falcons. Red-tails become common once again across the Front Range urban corridor; here, woodlands line the South Platte River, Arkansas River and regional reservoirs, offering sites for roosting and nesting. Of course, these buteos also inhabit the many parklands of the Colorado Piedmont and Front Range foothills. Rather silent for much of the year, their piercing call is often heard in late winter as their breeding season begins.

Sunday, November 11, 2007

Crab Orchard Mountains

On my recent trip to Florida, our flight crossed Tennessee just west of Knoxville. From my east side window on that clear, sunny after-noon, I could easily see the broad swath of the Ridge and Valley Province in the distance. The rolling landscape of the Appalachian Plateau (known as the Cumberland Plateau in this region) lay beneath our path while the more rugged profile of the Smokies stretched across the southeastern horizon.

Nearing the Tennessee and Clinch River Valleys, I noticed a cluster of mountains northwest of Knoxville. Rising along the north edge of the Ridge and Valley swath, these peaks were clearly higher than the adjacent plateau and their topography was more typical of the Smoky Mountains to the south. Confused by what seemed to be an outlier of the Smokies on the north side of the Ridge and Valley, I began looking for an explanation over the following days. I soon learned that this rugged piece of terrain is known as the Crab Orchard Mountains and that it represents the southwestern end of the Cumberland Mountains.

The Cumberland Mountains stretch along the southeast edge of the Appalachian (Cumberland) Plateau; faulting and uplift along this margin, which coincides with the Kentucky-Virginia border and then penetrates central Tennessee, has produced the highest elevations of the Plateau and has given the terrain a rugged, mountainous character. The same is true along the eastern edge of the Appala-chian Plateau in Pennsylvania and West Virginia, where the "Allegheny Front" is typified by high, imposing terrain.

The Crab Orchards harbor fourteen peaks over 3000 feet, the highest landscape in the State outside of the Smoky Mountains. Like the adjacent Plateau, they are composed of Pennsylvanian sedimentary rock (in their case, a thick layer of reddish Crab Orchard Sandstone); by comparison, the core of the Smokies is composed of Precambrian igneous rock, which is at least 500 million years older. Though the age of their component rocks differ, the uplift of the Appalachian Plateau, Cumberland Mountains and Smoky Mountains occurred in concert, as North America collided with Africa, some 250 million years ago.

Friday, November 9, 2007

Hibernation

Mammals of the colder latitudes prepare for winter in a number of ways. Some, including whales, elk and caribou, migrate to wintering areas where food will be more available or where conditions will favor their survival. Others, such as chipmunks, pikas, tree squirrels and voles, store seeds, nuts or dried vegetation to get them through the winter. Many mammals remain active, putting on fat and a dense coat of fur through the autumn; while some den up during periods of intense cold or heavy snow, they will continue to forage and hunt through the winter months. Finally, there are the true hibernators: woodchucks, marmots, ground squirrels, some bears and most bats; they will spend the winter in caves or dens, surviving on a dense layer of brown fat.

Hibernation is a complex and risky adaptation to cold weather, used primarily by mammals of the Temperate Zone. Tropical mammals have no need to hibernate and few Arctic mammals attempt the feat (Arctic winters are too long and too severe to permit their survival). True hibernators eat voraciously during the late summer and autumn, putting on a layer of brown fat that will fuel their metabolism through the winter; at the same time, they gradually decrease their activity, helping to insure that their calorie storage will be sufficient.

Shortening daylight, periods of cold weather and diminishing food supplies are thought to trigger hibernation, which generally occurs after several false starts. Distinct from sleep, hibernation is an active process in which reduced respiration and heart rate precede a fall in core body temperature. At some point, the hibernating mammal enters a coma-like state and its metabolic rate falls to a level just adequate to support cellular metabolism; these mammals have an innate ability to tolerate hypothermia, hypoxemia and lactic acidosis. Should their energy supply be insufficient to fuel arousal in the spring, the animal will die.

Thursday, November 8, 2007

Climate Cycles

The Pleistocene "Ice Age," which began 2 million years ago and ended 10,000 years ago, was just the latest of at least six glacial epochs in the 4.6 billion year history of our planet. And if the Pleistocene was typical of the other ice ages, they were characterized by intermittent periods of glacial formation and glacial retreat, as the climate cooled and warmed. During the Pleistocene, there were four major episodes of glaciation, separated by warm, interglacial periods.

We live in the Holocene Period, which began 10,000 years ago. Most climatologists believe that this is just another interglacial period and that our climate will begin to cool in another 5-10,000 years. In fact, a brief period of cooling, often called the Little Ice Age, occurred from about 1300 to 1850 AD, when global temperatures dropped by 2-3 degrees C.; during this period, glaciers advanced, northern com-munities collapsed and crop failures were widespread. The cause for this brief ice age is uncertain but most evidence points toward decreased solar activity.

Today, as we hear several times each day, Earth's climate is warming. While man is certainly contributing with his indus-trial "greenhouse gases," other factors are surely at play. Most of the Pleistocene interglacials were much warmer than our present-day climate and climate cycles have occurred throughout Earth's history. Our focus on man's role, which began with the industrial revolution (120 years at most) is a reflection of our human-centered view of the Universe; we are, after all, "the culmination of God's creation." To think that our current global warming might be due to factors out of our control (like the solar activity level) is to question our own self-importance. And while we must try to minimize our impact on the ecosystems of our home planet, we cannot forget that nature's cycles developed long before we graced the scene.

Wednesday, November 7, 2007

The Mogollon Rim

The Mogollon Rim is a prominant escarpment that curves across Arizona from the western end of the Grand Canyon to southwest New Mexico. More than 200 miles long, this wall of late-Paleozoic sediments, broken by numerous canyons, represents the south-western edge of the Colorado Plateau. Its upper surface of Permian Coconino Sandstone rises 7000 to 9000 feet above sea level; the highest areas are near the Arizona-New Mexico border. Sedona and Payson sit near the base of the Mogollon escarpment while Williams, Flagstaff, Holbrook and Winslow are atop the plateau, some 6000 feet higher (and two life zones colder) than Phoenix.

South of this spectacular Rim, the land falls away as a network of mountain ranges and foothills, molded and drained by the Verde, Salt and Gila Rivers, which merge in the low desert of Greater Phoenix. The surface of the Colorado Plateau is covered with vast tracts of ponderosa pine, dotted with Tertiary volcanic peaks and incised by the deep canyons of the Colorado and Little Colorado Rivers. Forests of ponderosa pine cover higher elevations of the mountains south of the plateau while pinyon-pine woodlands adorn the lower slopes. At elevations near 3000 feet, saguaro cacti grace the scene, distinctive figures of the Sonoran Desert landscape.

Tuesday, November 6, 2007

North Winds

Yesterday dawned with sunny, mild conditions in Columbia. A gentle breeze from the south had pushed the temperature into the low 50s and there was no sign of coming change in the sky or on the radar. Then, about 11 AM, the winds shifted to the north and grew in strength throughout the day, dropping the temperature ten degrees by late afternoon. Our first freeze of the season occured overnight and we awoke to a clear sky and 31 degrees this morning.

The polar front that dropped through Missouri yesterday morning has moved on to the east and south, bringing the first taste of winter to the eastern U.S. While a lack of moisture prevented the development of showers (or even clouds) with the frontal passage in Missouri, the northwest winds and cold air produced lake-effect snows in the Upper Midwest and Northeast. And in the Southeast, where the humidity was higher, the front brought much-needed rains and thunderstorms in Tennessee and Mississippi.

Still early in the season, this polar outbreak will soon be replaced by a surge of warm air from the southwest. Eventually, as the Arctic cold deepens and solar heating diminishes, the jet stream will retreat to the south and these polar outbreaks will become more frequent, more intense and longer lasting. Winter will then grip the Heartland.

Monday, November 5, 2007

Winter Song

For the first time this season, the song of white-throated sparrows rang through the neighborhood as I walked to work this morning. Natives of the Canadian North Woods, they generally arrive with the first pulse of winter, content to vacation in the cold, gray Midwest.

These hardy sparrows spend most of their day scratching for food among shrubs and thickets, often gathering beneath feeders to feast on fallen seed. Along with northern cardinals, they are the last birds to return to their roost each evening, making the most of the short winter days. And their hearty song, "Oh my Canada, Canada, Canada," brightens the dark season for all of us.

As spring approaches, their chorus will intensify and, by mid April, they will return to their homeland. Until then, I thank them for their company.

Sunday, November 4, 2007

The Beloved Bluebird

One of the more beloved birds in North American, the eastern bluebird is common east of the Rocky Mountains and is the State Bird in both New York and Missouri. Bluebirds that inhabit Canada and the northern U.S. move south for the winter but those that reside throughout most the the central and southern States stay through the year.

While they feast primarily on insects during the warmer months, eastern bluebirds shift to a diet of berries from late fall through early spring; wild grapes, chokecherry, sumac, cedar and juniper berries are among their favored foods. And while they pair off in spring and early summer to raise their young, these sociable birds form loose flocks for much of the year and may roost together in tree cavities or nest boxes to conserve heat in winter.

Eastern bluebirds favor wooded meadows and farmlands and often gather on powerlines or fences. Come spring, potential parents look for nest cavities in trees, fence posts or man-made boxes; competition for these sites comes from tree swallows, starlings and house sparrows, posing a threat to the welfare of this attractive and beloved native.

Saturday, November 3, 2007

Tropical Storm to Nor'easter

After forming in the eastern Caribbean and bringing deadly rains to the Dominican Republic, Tropical Storm Noel crossed Cuba and lost some of its punch. Redeveloping over the Bahamas, it then lolled about for several days, lashing the coast of Florida with a steady east wind and eroding many of its beaches.

Yesterday, with little fanfare, the storm gained strength and developed into the fifth Atlantic hurricane of the season. With sustained winds of 80 miles an hour, Noel drifted northward and became "extratropical," no longer sustained by the heat engine of warm, tropical waters. Entering the temperate latitudes, it was now energized and steered by an approaching front.

This morning, Noel, centered off the mid-Atlantic coast, is lashing eastern Long Island, Martha's Vineyard and Nantucket with tropical force winds. The storm is expected to move rapidly to the northeast (along the approaching front), raking Cape Cod and the east coast of New England before making a direct hit on Nova Scotia.

Friday, November 2, 2007

Waterfowl Highway

Rising along the Continental Divide in southwestern Montana and northwestern Wyoming, the Missouri River exits the Rocky Mountains at Great Falls and then flows eastward across the Northern Plains. In eastern South Dakota it turns to the south, forming the common borders of Nebraska, Iowa, Kansas and Missouri; at Kansas City, it flows eastward once again, dipping through Missouri and merging with the Mississippi just north of St. Louis.

Before modern man dammed and channelized it, the Missouri was a wide, braided, meandering river as it crossed the vast, semiarid Northern Plains. Numerous oxbows and extensive wetlands bordered its channel, offering irresistable reststops for migrant waterfowl. As the only major river system in that part of the Continent, the Missouri became a natural highway for these migrants, guiding them from their arctic and prairie breeding grounds to wintering areas along the lower Mississippi Valley and Gulf Coast.

Though man has altered its flow and drained most of its wetlands, the Missouri remains the primary route for migrant waterfowl in the Central Flyway of North America. Numerous wildlife refuges line its corridor and November is one of the best months to visit these preserves. The DeSoto National Wildlife Refuge, on the Iowa-Nebraska line, and Squaw Creek National Wildlife Refuge, in northwest Missouri, are two of the best.

Thursday, November 1, 2007

The Nature of November

Were it not for Thanksgiving, November would not be welcomed by many Midwesterners. Usually depicted as a gray, windy month, it often brings the first significant cold wave of the season and heralds the onset of winter. And it doesn't help that November arrives on the heels of sunny, colorful October!

But November brings many natural highlights to the Heartland. Early in the month, when the weather is still relatively mild, the waterfowl migration is peaking and a wide variety of geese, ducks, grebes, loons and cormorants gather on our lakes and reservoirs. By the middle of November, huge flocks of snow geese are moving south along the Missouri and Mississippi valleys, stopping to rest and feed as they head for coastal marshes. In the woods and wetlands, resident mammals are increasingly active and visible as they engage in their annual rut or collect food for the lean months ahead.

November also brings a change in our regional bird population as visitors from the north (juncos, hermit thrushes, red-breasted nuthatches, winter sparrows) replace our summer songbirds. Finally, by the end of the month, as their mating season begins, our resident owls become more vocal and conspicuous, filling the night with their love calls.

Wednesday, October 31, 2007

Pumpkins

On this day of the Jack-O-Lantern, it is interesting to look at the natural history of pumpkins. Native to Central America, the pumpkin is a member of the genus Cucurbita, which also includes squash, cucumbers and gourds. This genus is complex in that its various species are comprised of some representatives from all of the above groups; in other words, one type of pumpkin may be related to a certain squash but not to other pumpkins. Furthermore, members of the same species group, while designated as pumpkin, squash or gourd, are capable of cross-fertilization.

Current evidence suggests that pumpkins have been used by man for 9000 years or more. Initially collected for their edible seeds and pulp, they were eventually cultivated and, by the time European explorers arrived, their shell was being used to construct mats. Classified as a fruit, the pumpkin is an annual vine squash which produces both male and female flowers on the same plant. Early in the growth cycle, only male flowers are produced (likely to entice local pollinators); as the plant matures, the ratio of male to female flowers remains high (10:1) though all are short-lived, blooming for only 24 hours. The pumpkins develop at the base of the female flower and mature over several months.

Now cultivated across the globe, pumpkins come in a wide variety of shapes, colors and sizes; giant pumpkins may reach 1000 lbs or more. Illinois leads the U.S. in the production of pumpkins, which are destined for both human and lifestock consumption. Rich in beta-carotine, a natural antioxidant, pumpkins are also consumed by a many small mammals (raccoons, opossum, woodchucks, mice) which feast on their flowers, seeds and pulp.

Tuesday, October 30, 2007

Fishing Frenzy

One of the highlights of my recent trip to Longboat Key was the development of a feeding frenzy on Sarasota Bay. The event began when a scattered group of Forster's terns discovered a large school of fish near the surface. Their chatter and repeated dives attracted the attention of brown pelicans and at least twenty soon joined the feast; though they usually dive from ten feet or more, the plentiful bounty allowed the pelicans to feed by rising only a few feet and then lunging forward, scooping fish into their net-like bills.

Opportunists that they are, laughing gulls moved in from all directions, raising the noise level with their piercing calls; some picked small fish directly from the surface but most settled next to the pelicans, waiting for a meal to drop from their pouch. Double-crested cormorants also joined the fray, diving from the surface to catch their prey, and a pair of belted kingfishers flew in from the nearby mangroves, their distinctive chatter adding to the din. Overhead, a couple of osprey flapped above the frenzied crowd but moved on to open waters, in search of larger prey.

Other highlights included the appearance of a manatee and her small calf in our shallow harbor and the dusk arrival of a huge flock of white pelicans; numbering 200 or more, these travelers were returning from a summer on the Great Plains and would spend the winter feeding on the tranquil bays of the Florida Gulf Coast.

Monday, October 29, 2007

Quarryland

Enroute to Tampa last week, my flight made a stop in Louisville, Kentucky. As we descended across the forested hills of southern Indiana, I was delighted by the autumn colors and amazed by the large number of quarries that dot the landscape. This is, of course, limestone country.

Traveling east to west across the southern half of the Hoosier State, one encounters bedrock that gradually decreases in age. The southeast corner of Indiana sits atop Ordovician shales and limestones; further to the north and west, these give way to Silurian dolomites and then a band of Devonian sediments. In south-central Indiana, Mississippian limestones dominate the scene, including the famous Salem Limestone (commonly referred to as Indiana Limestone); deposited in a shallow sea, 340 million years ago, this exceptionally pure and workable stone has been used to construct many of America's landmark buildings, including the Empire State Building. Forming a jagged swath from northwest of Bloomington to southeast of Bedford, the Salem limestone is up to 60 feet thick. Further west, Pennsylvanian sandstones, harboring seams of coal, stretch into southern Illinois.

Living as we do on the outermost, thin veneer of Planet Earth, we tend to ignore the layers of history that lie beneath our feet. Miners and geologists know better!

Friday, October 19, 2007

Flying South

Like many birds, I will be flying south this weekend. But, unlike the feathered travelers, I will be coming back next week. And, as one who prefers seasonal change to year-round heat and humidity, that's fine with me.

While I always enjoy a visit to our place on Longboat Key, off Sarasota, a week or two of summer like conditions is more than enough to make me yearn for cool, dry air. I have not been a summer person since I turned in my lifeguard whistle, 35 years ago, and, the older I get, the less I tolerate the Midwest steambath. Which explains my fondness for our Colorado farm!

But Florida can be a fascinating place to visit, with its subtropical foliage, diversity of birdlife and unique fauna. For anyone who has an interest in meteorology, it also offers an awesome mix of cloud formations and thunderstorms. And, of course, a daily walk on the beach can be good for the soul!

Thursday, October 18, 2007

April in October

Yesterday felt more like late April than mid October. A potent Pacific storm had pulled out of the Rockies and, by late afternoon, was centered in southwestern Nebraska. Its associated cold front stretched from northern Minnesota to northern New Mexico and, ahead of the front, warm, moist air streamed northward from the Gulf, pushing highs into the 70s as far north as Chicago and Detroit.

As the front nudged eastward, bands of thunderstorms developed across the Southern Plains, moving northeastward and spawning at least 17 tornados in Oklahoma and Missouri. Further east, the southerly flow was bringing much needed rain to the lower Mississippi and Ohio Valleys.

By this morning, the central low pressure was in northwestern Iowa and continued to creep to the northeast. The squall lines have shifted east of the Mississippi River and beneficial rains were moving into Alabama and Tennessee. Since the center of the storm is well north of Missouri, our "backside" winds are from the west, sparing us from the cold, raw conditions that typically move in behind these fronts. Near 60 at dawn, our mild weather will continue, with a forecast high of 77.

Wednesday, October 17, 2007

Rocks on Ice

Those of us who have hiked through forest or traveled across plains in the northern U.S. or Canada have occasionally noticed a large rock or boulder that seemed totally out of place. Surrounded by trees or half-buried in the soil, these monoliths appear to have either risen from the ground or dropped from the sky. On closer inspection, we find that their composition (usually igneous or metamorphic) is different from other rocks in the area.

These alien boulders are "glacial erratics," having been transported to their current location by the Pleistocene glaciers. Wrenched from a mountainside or scooped from the bedrock, they were carried atop or within the Ice Sheet as it advanced southward and then released as the glacier melted back. Often transported hundreds or even thousands of miles, these massive rocks are a testament to the power of flowing ice. Found across the glaciated areas of North America, they are but the largest and most obvious component of glacial cargo; smaller rocks, well known to farmers as "field stones," pebbles and fine till were produced and deposited in the same way.

A few of the more famous North American erratics include the 5000 ton Madison Boulder in Madison, New Hampshire, Doane Rock in Eastham, Massachusetts (on Cape Cod) and the Okotoks Erratic in Alberta, Canada. The latter, weighing in at 16,500 tons (the largest known glacial erratic on Earth), was transported from the Canadian Rockies by a mountain glacier. Not limited to terrestrial areas, these well-traveled boulders also dot the floor of the northern oceans, dropped there by icebergs that calved from coastal glaciers.

Tuesday, October 16, 2007

Isolation Lost

The land that would become New Zealand formed along the western coast of Gondwanaland throughout the Paleozoic Era. Beginning 500 million years ago and ending 100 million years ago, recurrent episodes of deposition, compression and uplift added this land to the great Southern Continent. Then, about 85 million years ago, future New Zealand was torn from Gondwanaland as the Tasman Sea began to open, triggering the Island's long period of isolation.

From 55 to 25 million years ago, the ocean gradually opened between Australia and Antarctica; this process increased tectonic forces in New Zealand, which lies along the boundary of the Australian and Pacific Plates. The North Island sits above the edge of the Australian plate; subduction of the Pacific Plate below the Australian Plate in this area has produced volcanism across the North Island. New Zealand's South Island, on the other hand, straddles the two plates and the prominant Alpine Fault marks the boundary; compression east of the fault forced up the Southern Alps while the western side of the Island creeps northeastward along the fault. South of the South Island, the Pacific Plate subducts beneath the Australian once again. There is certainly no mystery why New Zealand is prone to earthquakes!

Since New Zealand rifted into isolation 85 million years ago (a time when Tyrannosaurus rex ruled the land), its only native terrestrial mammals have been bats, which flew in more than 30 million years later; neither has it ever been home to snakes, which evolved after the rift occured. Indeed, New Zealand's native fauna has been limited to invertebrates, fish, amphibians, lizards, birds, bats and marine mammals (pinnipeds, whales and dolphins). Since they had no land predators, some of the birds became flightless, represented today by the kiwi and kakapo (a flightless parrot). Polynesian explorers finally arrived in 800 AD, making New Zealand the last land mass (other than Antarctica) to be colonized by man; bringing in dogs and rats, the Mauri soon altered the flora and fauna forever!

Monday, October 15, 2007

The River Otter

As the days shorten and the weather begins to cool, most of us feel energized and become more active. This is also true for wildlife; stirred by the autumn chill and driven by the need to prepare for the winter months, many of our native mammals become restless, and thus more visible, during the waning days of fall. What better time to set out in search of one of our more interesting and entertaining residents, the river otter?

A member of the mustelid family, which includes badgers, mink and weasels, river otters were once common along most wooded streams in North America. Though extirpated from many areas during the 1800s, they are now making a gradual comeback due to hunting restrictions, habitat restoration and reintroduction programs. Nevertheless, "development" and pollution remain a threat in most regions.

River otters favor woodland rivers, lakes and swamplands where they feed primarily on fish, crustaceans and amphibians; on occasion, they also consume aquatic birds, eggs, turtles and small mammals. Equipped with dense fur and a streamlined body, adults weigh 15-20 pounds and adapt well to a variety of climates. Breeding occurs in late winter or early spring but implantation is delayed and a litter of 2-5 kits is born a year later; their lifespan in the wild averages 8-10 years.

Males become solitary and territorial during the breeding season and females are reclusive when their kits are young. But, for much of the year, river otters are sociable and playful creatures, exhibiting a zest for life that we don't see in some mammals (including many humans). Those hoping to absorb some of this energy should look for the otters at dawn or dusk, when they tend to be most active.

Sunday, October 14, 2007

Red Heads

Found throughout southern Canada and the eastern two-thirds of the U.S., red-headed woodpeckers favor open woodlands. While often seen on farmlands, orchards and rural parks, these attractive birds are especially common on floodplains and in the backwater areas of our larger lakes and reservoirs; there they find stands of dead trees in which they prefer to nest. Once abandoned, their nesting cavities are used by tree swallows, bluebirds, prothonotary warblers and starlings.

Easily recognized by their bright, red head and large white wing patches, these woodpeckers have a varied diet. While feasting on bark insects like most of their cousins, red heads also "flycatch" from fence posts or dead snags, generally pursuing larger insects such as mayflies, damselflies and cicadas. And, like flickers, they often feed on the ground, consuming ants, beetles, grasshoppers, nuts and fallen fruit. Finally, like their western cousin, the acorn woodpecker, these versatile birds cache acorns and beechnuts in tree cavities or crevices, a ready supply for the leaner months.

Permanent residents throughout most of their range, red heads that inhabit southern Canada and the western High Plains tend to move south and eastward for the colder months. As a result, they are often more common in Midwestern and southern swamplands during the winter, where their striking plumage contrasts with the bleak, gray landscape.

Saturday, October 13, 2007

Collision Zone

Looking at the weather map this morning, sunny skies dominated the Northeast, Southeast, Southwest and Northwest. But here in the Heartland, a large swath of showers and thunderstorms covered eastern Kansas and much of Missouri. Though no major fronts are moving across the region, light winds from the surrounding areas are converging over the Central Plains.

High pressure over the Northwest and a low pressure system over the Northeast are pumping cool, dry air southward across the Northern Plains. Conversely, low pressure over the Southern Plains and high pressure over the Southeast are combining to produce a flow of warm, humid air from the Gulf of Mexico. While pressure gradients are low and the winds are weak, these moving air masses are merging along the Kansas-Missouri axis, producing a concentrated area of heavy rain and thunderstorms.

Since there are no strong fronts or steering winds in the region, this blob of precipitation is moving very slowly, waxing and waning as it creeps eastward over the same areas. While we certainly need the moisture, flooding will likely develop along streams and across low-lying terrain.

Friday, October 12, 2007

Life in Perspective

Current scientific evidence indicates that life first appeared on Earth 3.6 billion years ago. To put this evolutionary span in perspective, it is helpful to telescope the entire process into a single year. By doing so, 1 day represents 10 million years, 1 hour covers 417,000 years, 1 minute spans 6950 years and 116 years flash by in 1 second.

Using this condensed calendar of life, chemoautotrophic bacteria, feeding on sulfides and other organic chemicals, develop along the mid-oceanic ridges early on January 1. By January 10, stromatolites of photosynthetic cyanobacteria appear in shallow bays across the globe. Eukaryotic cells, which contain cytoplasmic organelles, turn up by mid June and multicellular algae have evolved by late September. Complex, soft-bodied organisms, such as sea worms, jellyfish and soft corals evolve in late October and, by November 1, shelled marine life has appeared.

Early in November, star fish, mollusks, sea urchins and trilobites scour the ocean floor and jawless fish evolve by the middle of the month. Around November 20, plants and animals colonize the shore for the first time, a momentous event in the course of evolution. Sharks, boney fish, primitive arachnids, early amphibians and ferns grace the scene by November 24 and flying insects take to the air by the end of the month.

Horseshoe crabs and primitive reptiles are the newcomers on December 1, followed by frogs, lizards, modern corals and modern conifers on December 6. Turtles, crocodiles and the earliest dinosaurs appear by December 9 while the first mammals turn up on December 11. Flowering plants first adorn the Earth on December 16 and, 5 days later, ants and early marsupials make their appearance. Social bees and snakes evolve by December 23 while the dinosaurs become extinct on the next day (of course, some dinosaur lines live on as birds).

Primates first appear on December 25, followed by bats, whales, canids, ancestral horses, early ruminants and true monkeys on the 26th. Pigs and mastadons roam the land on December 28 and both apes and pinnipeds turn up the following day. Gorillas evolve in the early hours of December 31, followed by the first hominids at 7 AM, mammoths at 12 noon and polar bears at 11:15 PM. Modern man finally graces the planet at 11:42 PM and all humans living today have been present for less than a second!