Sunday, February 28, 2016

Spectacles of Early Spring

Arriving at Eagle Bluffs Conservation Area this morning, a friend and I encountered six flocks of American white pelicans, totaling at least 250 individuals; they had stopped to rest and feed at this floodplain refuge on their way to breeding grounds across the Northern Plains and Intermountain West.  Indeed, by the time we left the area, two hours later, most of the pelicans had already departed up the Missouri River Valley.

Other sightings at Eagle Bluffs included a half dozen bald eagles (one of which was on the massive nest), a large number of northern shovelers and green-winged teal and an exceptionally large congregation of northern pintails; we also observed American coot, mallards, gadwalls, great blue herons and a lone mink.

Later in the day, my wife and I visited Forum Nature Area, in Columbia.  Though bird sightings were limited at that refuge, were were treated to the din of chorus frogs, awakened from their winter slumber by the recent thaw.  These tiny tree frogs, difficult to observe even at close range, are among the earliest harbingers of spring, often delivering their mating calls while chunks of ice still rim the shallows.

Saturday, February 27, 2016

Back to Wonderland

Since a limestone gorge in Cincinnati played a significant role in my development as a naturalist (see Wonderland), it seemed appropriate to take our grandsons to one in Columbia, Missouri, on this warm, February day.  After grandma packed a picnic lunch, we all headed down to the Gans Creek Wild Area, just east of Rock Bridge State Park.

Selecting a two mile loop in the southeast portion of the refuge, we hiked out to a chain of clifftop overlooks that offer spectacular views of the gorge.  We then descended to the creek where we enjoyed our lunch on the rocky stream bed and spent an hour searching for fossils, colorful stones and crawdads.  Finally coaxing them away from the creek, we began a long, winding ascent to the trailhead, passing a recessed cave, climbing along a side stream and then hiking through a mixed forest of oak and eastern cedar.  Of course, several rest stops were necessary along the way.

Enchanted with their exploration of the "river" and their "mountain climbing" to and from Gans Creek, the boys will surely remember their visit to the gorge.  Hopefully, this natural wonderland will have the same long-lasting effects on them that the Cincinnati gorge had on me, fifty five years ago.

Thursday, February 25, 2016

Swans in the Stubble

Most of us picture swans gliding across calm lakes or feeding in shallow wetlands; golfers might also picture them lounging near water hazards.  After all, Swan Lake, the famous ballet, is renowned across the globe and hundreds (if not thousands) of "Swan Lakes" dot northern latitudes of our planet.

Today, however, while driving across the dry Glaciated Plain of north-central Missouri, I encountered twenty trumpeter swans, feeding in the corn stubble of a large crop field; the location was about 5 miles east of Mexico, Missouri, some 20 miles south of Mark Twain Lake.  No doubt, this was a migrant flock of trumpeters, among the thousands that have been reintroduced across the Upper Midwest since the 1980s (see Midwest Trumpeters).

Though I was not actively birding at the time, the large white birds were easy to spot amidst the dull brown stubble.  I pulled over for a better look and did not observe any neck bands among the distant swans; leg bands, if present, were hidden by the stalks.  Modern farming practices, which leave waste grain for wildlife, have played an important role in the successful reintroduction of these magnificent birds; fortunately, we can anticipate that sightings of trumpeter swans will become increasingly common across the American Heartland.

Wednesday, February 24, 2016

The Fruits of Obstructionism

Throughout President Obama's two terms, the Republican Congress has made every effort to block funding for his projects, deny consideration of his proposals and repeal programs that he has established; cooperation and compromise have been viewed as shameful traits among their ranks.  As a result, the Affordable Care Act was launched without their participation, revision of our immigration policies has been placed on hold, infrastructure improvements have been delayed, efforts to address global warming and social injustice have been ridiculed and military conflict continues without a declaration of war.  Most recently, the Republican leadership has indicated that they will refuse to consider any Supreme Court Justice nominated by Obama.

Smug about thwarting the President's programs, an achievement tinged with racism, the Republican Party is now reaping the fruits of their obstructionism.  Having instilled anger and mistrust among their legions, they have fueled the candidacy of Donald Trump, who appeals to an angry populace by promising isolationism, intolerance and, from all indications, a crass style of leadership.  Their primary weapons for derailing Trump are a religious zealot who is disliked by most of his colleagues and an inexperienced young Senator who has yet to win a primary race.

In the end, their eight years of obstructionism may hand the Presidency back to the Democrats and the process will begin all over again.  The do-nothing Congress will embark on another course of criticism and inaction.

Monday, February 22, 2016

February in the Country

Having returned to Missouri, I decided to take our VW Beetle out for a spin.  After all, it's the closest that I'll ever get to a sports car and a country drive is one of my favorite activities.  I thus set out for the farmlands east and south of Columbia.

Though the clean edges and brown landscape of winter still dominated the scenery, the recent moisture and warm temperatures had produced a faint greenery on the lawns and pastures.  Enjoying the cool, sunny day, American kestrels and eastern bluebirds lounged on the power lines while a fair number of red-shouldered hawks struck their chin-down pose, perched and perhaps snoozing in the barren trees.  On the other hand, red-tailed hawks, in the midst of their breeding season, had paired off and engaged in their noisy mating flights.  Blue jays and northern mockingbirds drifted across the country roads while flocks of horned larks and dark-eyed juncos burst from the roadside as my sporty car approached.  While I encountered numerous flocks of snow geese on my way back from Colorado, none were observed in the clear blue sky this afternoon.

Gone for almost two hours, I had recharged both the Beetle's battery and my country-loving soul.  In either case, it is a duty that I need to address on a regular basis.

Sunday, February 21, 2016

Seven Rivers Road

On my frequent trips between Colorado and Missouri, I cross seven major rivers of the Great Plains.  Less than a mile from our Littleton farm, I ford the South Platte, which has just dropped through the Front Range foothills and is beginning its journey toward western Nebraska where it will merge with the North Platte River.  My eastward route along Interstate 70 will keep me in the South Platte watershed until I climb to the crest of the Palmer Divide, north of Limon, when I briefly drop into the watershed of the Arkansas but do not come near that river.

Curving to the east, the highway climbs back onto the High Plains and crosses the upper reaches of the Republican River just east of Flagler, Colorado; from there, the river flows NNE, crossing the northwest corner of Kansas and then winding through southern Nebraska before joining the Smoky Hill River at Junction City.  Though I cross many small tributaries (mostly dry washes) throughout western Kansas, the Interstate does not ford another river until I reach Salina, where the Saline River flows southward to join the Smoky Hill.  Farther east, I cross the Solomon River, another tributary of the Smoky Hill; both the Saline and the Solomon Rivers drain the northwestern quadrant of Kansas.

At Junction City, Interstate 70 fords the main channel of the Smoky Hill River, which rises in eastern Colorado and flows eastward through central latitudes of the Sunflower State.  Just north of Lawrence, I cross the Kansas River, which carries the combined flow of the Republican and Smoky Hill Rivers; the highway crosses this river again at Kansas City, just before it enters the Missouri.  Finally, a few miles west of Columbia, I ford the broad, scenic floodplain of the Missouri River, which rises in the Montana Rockies and has received the waters of all the streams theretofore crossed.

Friday, February 19, 2016

A February Chinook

Raked by gusty southwest winds yesterday afternoon, the Front Range urban corridor enjoyed temperatures in the low to mid seventies (F); in Denver, an 86 year-old record high for the date (71F) was exceeded by two degrees.  It felt as if we had skipped late winter and early spring and had moved on to May.

In truth, such "chinook" events are common in this region and can occur during any month of the year, often mimicking a seasonal change in the course of a day.  Produced by high pressure west of the Front Range and low pressure over the High Plains, the intense, often damaging winds spill across the mountains, descending 5000 feet or more to the Colorado Piedmont.  As the air mass plummets, it compresses, heats up and dries out, bringing warm temperatures and low dew points to the urban corridor.  Any snow that might still coat the Piedmont rapidly vanishes (hence the mistaken belief that chinook means "snow-eater" when it actually refers to Native American tribes of the Pacific Northwest, a region from which the wind-producing storms often originate).

Generally short lived, the chinook winds are usually followed by a brief period of calm, mild weather.  However, depending on the movement of the storm system that produced them, winds may suddenly shift from a different direction and, if an upslope flow develops, winter chill and snow may return to the Front Range cities, changing the season once again.

Thursday, February 18, 2016

Dietary Phosphate & Heart Disease

Yesterday, I attended a conference at the University of Colorado Medical Center that focused on the relationship between dietary phosphate, renal (kidney) disease and heart disease; the presenter was Dr. Myles Wolf from Northwestern University.

As reported by Dr. Wolf, our serum phosphate level is maintained within a narrow range, balancing intake through the GI tract and excretion through the kidneys; elevation of our serum phosphate may result from a high dietary load or from defective clearance due to renal disease.  Most foods contain a large amount of phosphate; however, phosphate in meats, dairy products and processed foods is readily absorbed while that in legumes, vegetables and fruits is not nearly as bioavailable.  Researchers have discovered that FGF23, a hormone, is secreted in response to high serum phosphate levels; released from bone cells, it acts on the kidneys to increase excretion of phosphate in the urine (assuming the kidneys are not diseased).  In rat studies at Northwestern, FGF23 was also found to act on the heart, increasing the size of heart muscle cells, leading to thickening of the left ventricle.  This latter development, which is common in patients with end stage kidney disease, leads to heart failure and ventricular arrhythmias.

It thus follows that a diet high in bioavailable phosphate (meats, dairy products, processed foods) may increase the risk of heart failure; indeed, the higher rate of congestive heart failure in African Americans may reflect socioeconomic factors that lead to a high phosphate diet.  No doubt, other factors play a role as well (uncontrolled hypertension, high sodium intake and obesity to name a few) but the action of FGF23 is intriguing and appears to offer evidence that a vegetarian diet may help to prevent left ventricular thickening and secondary heart failure.  In addition, the potential development of drugs that block the effects of FGF23 on heart muscle may provide new tools in the management of this common and often fatal disease.  My thanks to Dr. Wolf for a fascinating presentation.

Wednesday, February 17, 2016

Bark Damage by Squirrels

Since purchasing our Littleton, Colorado, farm in 1990, we have observed significant damage to our Siberian elms by resident fox squirrels.  Since these "weed trees" pop up frequently and grow rapidly, the squirrel activity has generally been tolerated.  However, upon returning to the farm this month, I found that the squirrels had inflicted the same bark damage on our lone apricot tree.

While theories abound regarding this destructive behavior (from the agitation of late pregnancy to teeth maintenance activity), most experts note that bark stripping is especially common in late winter or early spring when other food sources are scarce; once the outer bark is removed, the squirrel has access to the nutritious cambium.  In addition, bark strips may be used to build or repair nests before the newborns arrive.

It may seem counterintuitive that these mammals, so dependent on trees, would inflict damage on plants that provide food, safety and nesting sites.  Of course, this behavior developed long before humans established parks, suburbs and orchards and healthy forests rely on natural enemies (fire, insects, cavity makers and other arboreal residents) to remain healthy.  Unfortunately, what is surely a natural process in forests is an unsightly and destructive behavior in the eyes of homeowners and human arborists.

Monday, February 15, 2016

A Seismic Shift in Oklahoma

The State of Oklahoma sits on the "stable craton" of North America, far from active tectonic regions.  Nevertheless, prior to 2011, it had a history of occasional earthquakes, likely induced by pressure shifts along old suture lines in the deep, Precambrian basement rock (see Unsettled Basement).

Over the past five years, however, the incidence of earthquakes has exploded across Oklahoma.  Following a magnitude 5.6 earthquake near Prague, in November of 2011 (the strongest recorded in the State's history), the number of quakes has been climbing dramatically from year to year.  Before 2008, Oklahoma experienced an average of 1-2 magnitude 3.0 or greater earthquakes per year; more than 900 occurred in 2015 and a magnitude 5.1 quake occurred near Fairview this past weekend.

State officials have reluctantly come to conclude that this seismic shift is directly related to the use of deep disposal wells in the fracking process.  As one might expect, the oil and gas industry has attempted to minimize this association and has fought efforts to be held financially responsible for damage caused by the earthquakes.  They might want to consult the tobacco industry, which has managed to evade public responsibility for many decades now.

Sunday, February 14, 2016

The Susquehanna River

The largest American river east of the Appalachians, the main (North) fork of the Susquehanna rises from Otsego Lake at Cooperstown, New York.  Flowing southward and then southwestward, the river and its tributaries drain much of south-central New York; after passing through Binghamton, the Susquehanna makes a broad curve to the west before passing through Wilkes-Barre, Pennsylvania.  From that city, it flows southwestward to Northumberland, where it receives its West Fork.

The West Fork of the Susquehanna rises on the Appalachian Plateau, west of Altoona, Pennsylvania.  Flowing northward and then eastward, the river drops to the Ridge and Valley Province at Lock Haven and then passes through Williamsport, the largest city along its course; from there, the Susquehanna flows southeastward to its junction with the North Fork.

From Sunbury, Pennsylvania, the combined flow of the Susquehanna angles SSW to Harrisburg and then southeastward to the northern tip of Chesapeake Bay.  In fact, the Bay is the drowned valley of the lower Susquehanna and its tributaries; before the last Pleistocene Ice Sheets melted back into Canada, the Susquehanna River flowed another 200 miles to the Atlantic. While its current length is listed as 464 miles (from Otsego Lake to Chesapeake Bay), the river once flowed for 664 miles to the sea, draining half of Pennsylvania along the way.

Saturday, February 13, 2016

Tale of Two Domes

This morning, an atmospheric dome of high pressure, centered over Minnesota, was bringing cold, Canadian air to most of the central and eastern U.S.; another high pressure dome sat over the Desert Southwest.  Beneath the center of atmospheric domes, air sinks while, along their rims, air flows in a clockwise direction; the eastern dome lies within a broad atmospheric trough (a dip in the jet stream which allows cold air to plunge southward) while the southwestern dome is the heart of an atmospheric ridge (a northward curve in the jet which allows warm air to flow northward).

Northwesterly winds created by the cold, eastern dome were producing lake-effect snows in the Great Lakes region and sweeping frigid air as far south as the Mid-Atlantic States.  The western edge of this dome had backed up against the Colorado Front Range, creating dense morning fog as cold air settled above relatively warm, moist ground.

As the Southwest dome expands eastward, warm conditions are returning to the Front Range and will spread across the Southern Plains, eventually pushing into the Heartland.  In concert, the eastern dome will also drift eastward, bringing the coldest air of the winter to New England, the Great Lakes States and the Mid Atlantic region.

Friday, February 12, 2016

A Walk through Elk Meadow

On this beautiful, warm February afternoon, I joined my daughter and her two bassets for a walk through Elk Meadow Open Space, just north of Evergreen, Colorado.  Stretching along the base of Bergen Peak, at an elevation of 7800 feet, the meadows and their groves of ponderosa pine attract wintering herds of elk.

This afternoon, birds were few and far between along our 3 mile circuit; a few Steller's jays and pygmy nuthatches were observed in the pines and a lone red-tailed hawk soared above the meadow.  However, we were treated to the presence of two elk herds, resting beneath pines at mid-day; elk graze primarily at dawn and dusk and are best observed during those periods.

Following their autumn rut, which peaks in early October, the bulls settle down and allow their harems to disperse.  Large mixed herds of male and female elk live in peaceful coexistence during the winter months, descending to lower elevations where snow cover is less of a problem.  As spring advances they reverse course, moving to higher and cooler terrain; females generally spend the warmer months on Subalpine meadows, where conditions are less harsh for their newborn calves, while males tend to move higher, often grazing on alpine tundra near timberline.

Thursday, February 11, 2016

South Valley Park

A hogback of Cretaceous sandstone forms the eastern edge of the Colorado Front Range, rising sharply from the Piedmont.  Just west of this hogback is the Morrison Valley, underlaid with Jurassic shale; at its western edge is the Lyons Formation (Permian in age), a yellow-gray ridge of sandstone.  West of this ridge are the scenic red rocks, outcrops of salmon-colored Pennsylvanian sandstone known as the Fountain Formation.  Shrublands of Gambel's oak, junipers and yucca-studded meadows cover the lowlands between the rock ridges, spreading onto lower slopes of the Front Range foothills.

South Valley Park, part of Jefferson County's Open Space System, stretches north from Deer Creek Canyon to Ken-Caryl Ranch; the refuge provides access to the foothill shrubland ecosystem and offers spectacular views of both the rock formations mentioned above and the foothills to the west.  A combined loop using the Coyote Song and Swallow Trails, perhaps the most popular route in the Park, yields a hike of 2.7 miles; parking lots are located on Deer Creek Canyon Road and along South Valley Road (just south of Ken-Carly Ranch).  Permanent avian residents of South Valley Park include golden eagles, scrub jays, black-billed magpies, spotted towhees, canyon wrens and gray-headed juncos; among the summer residents are white-throated swifts, Say's phoebes, black-headed grosbeaks, lazuli buntings, green-tailed towhees, lesser goldfinches, rock wrens and Virginia's warblers while Townsend's solitaires, Steller's jays, northern shrikes, golden-crowned sparrows and rosy finches may visit during the colder months.  Mammalian residents include mule deer, red fox, coyotes, rock squirrels, and Colorado chipmunks; black bear and mountains lions are rarely encountered and herds of elk winter in the valley.

Today, thanks to the ongoing thaw, patches of slushy snow and sandy mud coated the trails but the mild air and clear skies made my hike especially pleasant.  Scrub jays, towhees and magpies provided a steady background chorus and small herds of mule deer browsed along the meadows.  Though I repeatedly scanned the foothill meadows, no elk were observed; an early morning or late day visit would have been more productive in this regard. 

Tuesday, February 9, 2016

Winter takes a Hit

Down at South Platte Park this morning, crunchy snow still covered the ground and a layer of ice coated the larger lakes.  Winter ducks congregated on the river and open pools; northern shovelers were most abundant, joined by buffleheads, common goldeneyes, lesser scaup, American coot, ring-necked ducks, common mergansers and a pair of redheads.

A great blue heron hunted in the shallows and red-winged blackbirds, sensing spring, called from the icy wetlands.  Red-tailed hawks and black-billed magpies basked in the bright Colorado sun while downy woodpeckers scoured dead limbs for hibernating insects.  Finally, a pair of belted kingfishers chattered above the river, seemingly in celebration of the mild, sunny weather.

Indeed, the extended forecast calls for highs in the fifties and sixties (F) over the next ten days, putting a significant dent in winter's handiwork.  Then again, March and April lie ahead, two of the snowiest months along the Colorado Front Range.

Monday, February 8, 2016

A Field of Snows

My journey back to Colorado, across the Great Plains of North America, was mostly uneventful. Except for strong northwest winds across the High Plains, the weather cooperated and the usual mix of raptors and grassland songbirds made their appearance.  A common snipe did zigzag across the highway west of Salina, a lone trumpeter swan claimed a small farm pond east of Russell and, to my amusement, a pair of adult bald eagles sat in the middle of a Kansas crop field, far from any large lake or river.

But the highlight of my excursion came west of Russell, Kansas, where snow covered much of the landscape.  Coming over a rise, I saw what appeared to be a snow covered field; seconds later, to my surprise and pleasure, the snow exploded into the air, breaking into a thousand or more pieces.  A massive flock of snow geese circled into the bright blue sky, beginning the next segment of their journey to the Arctic.

They were my first snows of the season and are always an inspiring sight.  Traveling at 70 mph, I put down my window to enjoy their calls but the intense northwest wind drowned out any noise from the swirling flock.  While I was escaping to spring-like warmth along the Colorado Front Range, they were heading into the teeth of the latest Canadian Clipper; one has to admire their fortitude.

Sunday, February 7, 2016

Parents & Football Trauma

Within a few hours of my writing this post, the 50th Super Bowl will be underway.  I will not be watching; that's the least I can do.

Having played football in grade school, I switched to swimming and baseball in later years.  Our son also shunned football, opting for soccer, tennis and swimming, evoking reference to "sissy sports" from some extended family members.  Indeed, a large number of boys choose to play football, encouraged by fathers who played the sport or by those who wish they had experienced the glory.  Chasing the promise of wealth and fame, fueled by the same public voyeurism that filled the Roman Coliseum, those with exceptional talent stay the course, ignoring the risk of serious injuries that include spine fractures and traumatic encephalopathy.

Finally acknowledging these risks, the NFL and the NCAA have enforced a number of safety rules and are seeking to improve the protective gear.  While such efforts are no doubt sincere, the financial windfall is too great to significantly alter or abolish the sport; besides, rabid fans, the media, the sporting goods industry and wealthy alumni would not condone such a drastic move.  In the end, it will be up to parents to turn the tide, discouraging their boys from playing football (at least in its present form).  Those who ridicule such an idea, seeing it as just another move to "pamper" our kids, are either blindly committed to the sport or insensitive to the growing list of tragedies.

Saturday, February 6, 2016

Introducing Grandkids to Eagles

Watching our grandsons for the day, we decided to coax them away from their cartoons and computer games by suggesting a visit to Eagle Bluffs Conservation Area.  The promise of seeing bald eagles seemed to do the trick and we set off with our binos and field guide amidst an air of enthusiasm.

Arriving at the refuge on this cool, sunny morning, we were fortunate to spot an adult eagle within a few minutes, perched near its massive nest; the boys were thrilled by the encounter and they remained attentive for a half hour or so.  We saw mallards, Canada geese, American coot, great blue herons, ring-billed gulls, red-tailed hawks, white-tailed deer and several more eagles as we circled through the refuge but their interest rapidly waned.  Attempting to boost their enthusiasm, we stopped to skip pebbles across a frozen slough and to watch a freight train beyond the swift flowing Missouri.  Alas, reports of hunger and boredom shortened our visit.

Too young to fully appreciate the floodplain refuge, their focus had turned toward the digital entertainment awaiting at home.  But I have no doubt that they will remember our trip and will surely mention the eagles to their schoolmates and friends.  Hopefully, it will spawn requests to return to Eagle Bluffs in the months and years to come, gradually expanding their interest in the magnificent diversity that nature has to offer.

Friday, February 5, 2016

Wintering Tundra Swans

Breeding across the Arctic tundra of Alaska and Canada, North American tundra swans are represented by two populations, each currently comprised of about 100,000 birds.  The western population, which breeds in Alaska, winters on estuaries of the Pacific Northwest and on lakes of California's Central Valley and the Great Basin.

The eastern population, which often stops to rest and feed in wetlands along the Great Lakes during migrations, winter primarily on coastal bays of the Mid-Atlantic region.  Nevertheless, small flocks may turn up anywhere between these major wintering areas, including lakes along the Front Range of Colorado and New Mexico, reservoirs of the Great Plains and riverine wetlands along the Missouri, Mississippi, Arkansas and Ohio Valleys.

Resting on open waters, these magnificent birds feed primarily on aquatic vegetation and on waste grain in nearby agricultural fields; they are also known to consume clams and other marine invertebrates.  Like snow geese, their spring migration (which peaks from February to March) is often more gradual and less direct than their autumn flights and the swans generally travel in smaller flocks.  Smaller and slimmer than trumpeter swans, tundra swans are also identified by their high-pitched calls (hence their nickname: "whistling swans") and by a small yellow patch at the base of their bill.

Thursday, February 4, 2016

Labels, Partisanship & Freedom

To date, candidates in the Presidential primaries seem to be more focused on labels than on policies.  Quick to question one another's conservatism or liberalism, they are playing to the extreme elements of their parties, favoring partisanship rather than independence.

We humans, tribal by nature, have long been enamored with labels, using them to declare our allegiance to certain groups; nationalism, political party affiliation and church membership are among the most common social labels in modern society.  Of course, such partisanship is one of the most divisive forces as well, fomenting discrimination and intolerance and derailing efforts to cooperate.

In the end, our personal freedoms are threatened by partisanship, potentially placing us at the mercy of extreme elements within society.  Admitting one's commitment to moderation and compromise may be political suicide in American political primaries but a willingness to discard labels and partisanship offers the only hope for our dysfunctional government.

Tuesday, February 2, 2016

Into the Light

Forget the silly groundhog ritual, spring is on its way.  By early February, the higher sun angle and lengthening daylight are evident to all who venture from their winter caves.  Though Old Man Winter has yet to lose his grip, Mother Sun is beginning to reclaim the American Heartland.

Snow and greater white-fronted geese are taking notice of the change and will soon invade our region, stopping to rest and feed on their way to the Arctic.  Periods of thaw are taking their toll on the landscape and the green tips of crocuses, snowdrops and hyacinths are peeking through the barren flowerbeds.  Perhaps most noticeable, morning birdsong is starting to intensify as the nesting season approaches; robins, cardinals, mourning doves, Carolina wrens and white-throated sparrows tend to be most vocal.

Of course, there will be blizzards, ice storms and raw weather ahead but the tide has surely turned.  As long as we humans can adopt the patience of our wild neighbors, we'll enjoy our journey into the light.

Monday, February 1, 2016

The Laurentian Divide

The Continental Divide of North America stretches from Alaska to Mexico, generally following the Brooks Range and Rocky Mountain corridor; this divide is commonly known to separate the streams flowing toward the Pacific Ocean from those draining toward the Atlantic Ocean and Gulf of Mexico.  Actually, the northern section of the Continental Divide, from Alaska through the Yukon Territory of Canada, separates streams flowing toward the Pacific from those flowing into the Arctic Ocean.  As far south as the U.S.-Canada border, it divides streams heading for the Pacific from those flowing toward Hudson Bay.

Geographers and hydrologists thus recognize the Laurentian Divide (also known as the Northern Divide), which stretches west to east between the Continental Divide and the Labrador Sea, dividing streams that flow northward to the Arctic or to Hudson Bay from those that flow southward toward the Gulf of Mexico or eastward to the Atlantic Ocean.  From Triple Divide Peak in Glacier National Park, this divide straddles the U.S.-Canada border through Montana, separating the watersheds of the Saskatchewan and Missouri Rivers.  Farther east, it angles southeastward through North Dakota and then northeastward through Minnesota, dividing the watershed of the Red River (which flows northward to Lake Winnipeg and thence northeast to Hudson Bay via the Nelson River) from those of the Missouri, Minnesota and Mississippi Rivers.  Running north of the Great Lakes, the Laurentian Divide follows the northern edge of the St. Lawrence watershed, eventually running atop the crest of the Laurentian Mountains as they curve through Quebec and Labrador.

The Laurentian Divide ends at the mouth of the Hudson Strait on the Labrador Sea.  While some argue that Hudson Bay and its Strait are hydrologically part of the Atlantic Basin (which they are), the ecology of the Hudson Bay region is closer to that of the Arctic than to Temperate latitudes to the south.  For purists, the Arctic Divide runs north of the Saskatchewan watershed and north of Hudson Bay, demarcating the southern edge of various watersheds (including that of the MacKenzie River) that empty into the Arctic Ocean.