Monday, August 29, 2016

Down from the Mountains

After nesting in thickets along the shores of alpine lakes, Wilson's warblers are descending from the Colorado mountains and have been turning up in Metro Denver over the past week; this morning, I discovered a female on our Littleton farm.

These small, brightly colored warblers nest across Canada and Alaska and southward through the ranges of the American West.  Insectivores, they prefer willow thickets that line streams, ponds and lakes, where their nest is placed in low shrubs or directly on the ground.  They generally arrive along the Front Range urban corridor in early-mid May and soon head for higher terrain, often spending the summer near timberline.

Retreating from the alpine and subalpine zones as the first snows dust the higher peaks, Wilson's warblers move across the Colorado Piedmont in late summer, heading for wintering grounds in Central America; there they feed in tropical forests, coastal wetlands or mangroves.  When you consider the Temperate forests, desert canyons and lowland swamps that they visit during migrations, one concludes that few birds utilize such a wide variety of natural habitat in the course of a year.

Sunday, August 28, 2016

Quiet and cool at South Platte Park

On this cool, cloudy morning along the Colorado Front Range, I returned to South Platte Park in southwest Metro Denver.  Except for the friendly chatter of chickadees and the distant calls of belted kingfishers, the refuge was noticeably quiet as I walked north along the river and then turned west above the north shore of Eaglewatch Lake.  Double-crested cormorants were abundant, their flocks streaming overhead on their way to Chatfield Reservoir, and seven snowy egrets foraged on the shores of the lakes and ponds.

When I reached the woodlands west of Eaglewatch Lake the noise level rose a bit as gray catbirds mewed from the thickets and whispering flocks of cedar waxwings moved among the trees; many other species, including great horned owls, kestrels, northern flickers and a pair of western kingbirds, remained mute.  But the morning silence was eventually broken by the strident calls of a black-billed magpie, perched atop the reservoir wall; thrilled by this disruption, I could now include a magpie on my eBird report from South Platte Park, the first that ventured into my count area since I started keeping records last spring (see No Magpie Zone).

Overall, it was a pleasant and rather quiet morning at South Platte Park.  Though my species tally was modest, a nice mix of birds turned up along the trail.  Besides, the autumn-like weather offered both a comfortable respite from the summer heat and a subtle reminder that the first flurries of the season may be less than a month away.

Thursday, August 25, 2016

Italy's Complex Tectonics

Yesterday's tragic earthquake in central Italy (magnitude 6.2) was the result of complex tectonic forces that are at work in the region.  Torn from the Eurasian Plate as the Tethys Sea opened (some 200 million years ago) the land that is now Italy became part of the African Plate, moving southward in concert with the other Continents of Gondwanaland.  Over the past 60 million years, as the Tethys Sea was closing, Africa moved back to the north (and continues to do so today), crunching into Eurasia and forcing up the Alps (Italy serving as the leading edge of that collision).

On the surface, the Mediterranean Sea, a remnant of the Tethys, appears to represent an oceanic plate, sandwiched between the land masses of Eurasia and Africa; yet, Italy lies on the north side of the Mediterranean.  In fact, as the African and Eurasian Plates began to collide, the northern edge of the African Plate shattered into a cluster of microplates, some of which are composed of both oceanic and continental crust.  Several of these small plates, separated by fault lines, lie across or near Italy; as pressure is maintained by the northward movement of the African Plate, these microplates and the adjacent major plates collide, rift apart, subduct or scrape past one another, triggering earthquakes and, in a few areas, igniting volcanoes (e.g. Mt. Etna).

Though the movement of tectonic plates is too slow to observe, friction builds and the stored energy is suddenly released in the form of an earthquake, making the power of tectonic force all too apparent.  Unfortunately, depending on the fault's location and depth, massive destruction and numerous deaths may occur, as happened in Italy yesterday.

Monday, August 22, 2016

Killer at the Window

Looking out our picture window this afternoon, I saw a killer perched in the magnolia, less than five feet from the glass.  Tiger stripes adorned his thorax, appropriate for a predator and especially for one here in Columbia (home of the MU Tigers).

Waiting to pounce, he remained perfectly still except for a chewing motion of his jaws.  Watching closely, I saw potential prey cross his path but he was apparently satiated and content to lounge in the bright summer sun.

We naturalists often gaze out our windows, searching for unusual birds or wandering mammals.  If we look close enough, we may also see some of nature's smaller species, like the colorful dragonfly that I encountered today.

Sunday, August 21, 2016

No Sabbath for Skinks

On this mild, sunny, Sunday in central Missouri, five-lined skinks were especially numerous and active on our back deck and along our rock wall.  No doubt hunting for insects and spiders in the many crevices, these reptiles included adults and juveniles alike; the latter, adorned with bright blue tails, have inspired their common title of "blue-tailed skinks."

Inclined to bask in the sun like many other reptiles, these wary skinks quickly respond to any nearby movement, escaping between the rocks or beneath the deck.  After all, they are potential prey for snakes and shrews that share their favored domain; less common threats include opportunistic predators such as opossums.

While lacking the intelligence of humans, many species of wildlife are more keenly aware of their environment due to highly developed sense organs.  Furthermore, they are neither distracted by rumination nor encumbered by mysticism.  When it comes to the Sabbath and Holidays, they cannot afford to take the day off; their very survival depends on being active and attentive.

Saturday, August 20, 2016

A Touch of Canada

After weeks of hot, humid weather and a morning of intermittent showers, cool, dry air has moved into central Missouri, a touch of Canada amidst an oppressive Midwest summer.  No sparkling lakes stretch across the horizon, no forests of spruce and birch invite exploration and the eerie calls of loons do not echo across the landscape but the invigorating air is enough.

Diving south behind a potent cold front, the autumn-like chill will last only a few of days.  More hot, humid weather surely lies ahead but the promise of seasonal change rides on this northern breeze and those of us enamored with the glorious months of fall welcome the omen.

As if to reinforce the tide of autumn, the yanks of nuthatches rang from our backyard shade trees and the squeaky gnawing of gray squirrels signaled the onset of the walnut harvest.  Sitting on the back deck, breathing in the crisp air, I could almost hear the flocks of migrant snow geese.

Thursday, August 18, 2016

A Feast in the Shadows

On my visit to Eagle Bluffs Conservation Area this morning, I encountered a feeding spectacle near the south end of the refuge.  A shallow pool below an outlet canal teemed with small fish, clearly stressed by the falling water level and unable to escape to an adjacent creek.

Their wriggling masses attracted green herons that enjoyed easy pickings from the muddy shore or overhanging limbs; four of those small waders were spaced around the secluded pool.  In concert, several northern water snakes criss-crossed the shaded waters or lounged on logs that broke the surface.  Watching from above, I empathized with the fish, scattering in response to the hunters' sudden movements; on the other hand, a quick death in the beak of a heron or jaws of a snake may be preferable to slow suffocation in an evaporating pond.

Such spectacles remind us that nature's cycle of life and death is not always pretty to watch.  She is not sentimental when it comes to young creatures and, more often than not, they are choice targets for predators.  While we admire nature's beautiful landscapes from a distance, up close encounters give us a more intimate and realistic image of her complex ecosystems.

Tuesday, August 16, 2016

The Grindstone Trail

Grindstone Creek rises on the farmlands east of Columbia, Missouri, and flows westward, entering Hinkson Creek in the Grindstone Nature Area.  A parking lot for the latter is accessed from Old Highway 63, just south of Stadium Blvd. in southeast Columbia.

From that lot, a 1.72 mile paved trail leads eastward through the Grindstone Creek Valley, passing creekside woodlands and intervening meadows.  On this sunny and relatively mild (low 80s F) summer day in central Missouri, my wife and I completed a roundtrip hike along The Grindstone Trail, serenaded by Carolina wrens, northern cardinals and black-capped chickadees.  Eastern phoebes, red-headed woodpeckers and eastern wood pewees joined more common woodland species while turkey vultures, which roost in large numbers above Hinkson Creek, soared overhead in the bright blue sky.  A variety of goldenrods adorned the valley meadows, a visual promise that our long, hot summer is coming to an end.

The Grindstone Trail is one of the latest additions to Columbia's superb trail network that follows the major creek valleys as they lead WSW toward Perche Creek, a tributary of the Missouri River.  The lower segment of Perche Creek (which is paralleled by the Katy Trail, a Missouri State Park) flows southward along the eastern edge of Eagle Bluffs Conservation Area, a magnificent floodplain refuge.

Monday, August 15, 2016

Poisoning Democracy

As a narcissist, Donald Trump cannot accept rejection.  Despite his brutish behavior and his rants against immigrants and globalization, he blames the media for his falling poll numbers and warns his admirers that a rigged system may cost him the election.

Having already instilled fear and anger is his constituents and encouraged violence as a potential tool, Trump threatens to dismantle our democracy by fomenting rebellion from within.  Unfortunately, his legions are comprised primarily of uneducated individuals who feel powerless in American society; rather than encouraging their political participation by laying out a reasonable approach to the problems that they face, Mr. Trump prefers agitation.

Such a choice poisons our democracy, implying that the majority of Americans have no control over their lives.  In reality, most of us reject Trump and his self-serving Tweets, knowing that we must send him back to "reality television" or suffer the consequences of having an unhinged racist as our Commander in Chief.  I have long been convinced that Trump does not truly want the responsibilities of being President but we cannot allow him to destroy our democracy in the course of his sham campaign.

Sunday, August 14, 2016

Humans & Houseflies

We humans are annoyed by houseflies.  They become trapped in our home and buzz about our face.  When not bothering us they feast on garbage and lay their eggs in feces or carrion.  Unlike flies that pollinate flowers, they seem to play no significant role in nature's complex web of life.  What good are they?

By contrast, we humans represent the pinnacle of evolution, the most intelligent and creative species to walk this planet.  We have constructed magnificent cities, visited the moon, explored Earth's many landscapes and sent probes throughout the solar system.  We have come to understand biochemical processes, natural ecosystems and nuclear reactions.

But what have we contributed to nature herself.  We have destroyed her forests, dredged and dammed her rivers, plowed her prairies, gouged her mountains, tainted her air, threatened her wildlife, drained her wetlands, altered her climate and polluted her oceans.  When it comes to the welfare of Mother Nature, we, like houseflies, have little to offer and, compared to houseflies, we are far more destructive.  And though we have learned how to minimize our impact, too few care to make the effort.

Saturday, August 13, 2016

Louisiana Flooding

Southern Louisiana has been inundated with rain over the past few days; almost two feet have fallen in some areas and widespread flooding has developed.  The culprit is a subtropical low, the same system that brought heavy rain to Florida's Gulf Coast earlier in the week.

A persistent dome of high pressure, centered off the Southeast Coast, deflected the low toward the west, where it has churned for several days, pulling in copious moisture from the Gulf of Mexico.  Meanwhile, a cold front has approached from the northwest, stalled by the same high pressure dome that shrouds the Southeast.  Thunderstorms, firing along the stationary front have brought heavy rain to northern Arkansas, southeastern Missouri and the Ohio Valley region; unfortunately, the tropical moisture plaguing Louisiana will be drawn northward along this frontal boundary, producing more floods along the outer margin of the high pressure dome.

Until the "blocking high" breaks down or moves off to the east, this pattern will continue, exacerbating the floods in Louisiana and fueling torrential rain from Arkansas to New England.  Beneath the dome, oppressive heat and humidity persist, relieved only by scattered pop-up showers that merely add more moisture to the steam bath at the surface.

Friday, August 12, 2016

The River Tern

A wide variety of gulls, terns, geese, ducks and other water birds migrate along the Mississippi and its tributaries but few nest along the rivers themselves.  One exception is the least tern, the smallest tern in North America.

Common along southern coasts during the summer months, least terns also breed along major rivers of the Heartland, especially the Missouri, Platte, Arkansas and Red Rivers as well as the lower Mississippi.  Nesting on sandbars to escape fox, coyotes and other terrestrial predators, they have been threatened by the construction of dams which create lakes, divert water and alter river flow, all disrupting the braided channels and intervening sandbars that originally attracted these birds.  Indeed, the riverine population of least terns is endangered and their welfare is not likely to improve without a significant change in our approach to river management.

This morning, we were fortunate to observe a least tern at Eagle Bluffs Conservation Area on the Missouri River floodplain.  Identified by his small size, buoyant flight and habit of hovering before making rapid dives, the tern was fishing above one of the deeper pools.  In other areas, large flocks of great blue herons, great egrets and shorebirds stalked the shallows where the carcasses of stranded carp awaited the vultures.

Wednesday, August 10, 2016

A Back Door Front

Returning to Missouri today, I was greeted by hot, humid air.  Having just endured the same conditions across Kansas, it seemed that no relief was in sight, at least for the next few days.

Then, about 5 PM, I heard rumbles of thunder.  Checking the local radar, I observed a band of thunderstorms, moving in from the northeast; since fronts almost always arrive from the southwest, west or northwest, I scoured the National weather maps and regional temperatures.  While 90s (F) predominated across most of Missouri (exacerbated by dew points in the 70s), temperatures across the northeastern quadrant of the State were in the mid 80s.  A cold front, extending across the Northern Plains and Great Lakes region, had buckled southward, undercutting the hot, humid air and igniting a line of thunderstorms from south-central Iowa to east-central Missouri.  Torrential rain fell in Columbia, providing temporary relief but sure to boost the humidity in its wake.

Such transient dips in cold fronts are generally produced by disturbances (centers of low pressure) moving along the front from west to east.  Ahead of the trough, storms move in from the northwest (as usual) while, on its "back edge" they arrive from the northeast.  When it's this hot, we'll take rain from any direction!

Monday, August 8, 2016

Counting on Javier

To date, the Southwest Monsoon has been a dud along the Colorado Front Range.  Unlike the upslope storms of spring, which douse the entire region with rain or snow, monsoon rains are generally associated with thunderstorms and precipitation coverage is often spotty.  Indeed, over the past week I have watched as impressive thunderheads passed to our north or south, offering no benefit to our parched Littleton farm.

Fueled by high pressure over the Southern Plains and low pressure over the Baja region, the Southwest Monsoon begins in June for Arizona and New Mexico and generally arrives in Colorado by mid July; in most years, its welcome rains fall intermittently through August (see Colorado's Monsoon Season).  Depending on the position and strength of the atmospheric engines, the monsoon season may bring copious precipitation or barely dent the summer heat and drought.

Many of us have an eye on Tropical Storm Javier, currently churning south of Cabo San Lucas.  As it moves northward, up the Baja Peninsula, it may inject tropical moisture into the monsoon flow, igniting thunderstorms across the Four-Corners region and, hopefully, drenching the Front Range.  We should know by this coming weekend.

Sunday, August 7, 2016

The Nature of Sport

As the Olympics begin in Rio de Janeiro, one wonders what drives athletes to excel, especially those devoted to individual, non-team sports.  No doubt, most have natural talents that were recognized at an early age and then nurtured and encouraged by parents and coaches over the years.  The thrill of personal achievement surely kept them engaged and their innate perseverance allowed them to hone their skill while colleagues became distracted, discouraged or disinterested.

A minority may have achieved Olympic status due to less wholesome factors in their lives.  Some represent the "projects" of zealous parents who prodded their dedication to sport, shielding them from other childhood interests along the way; in such cases, the child athlete is often living out the failed dreams of the parent.  Then there are young athletes who use their natural physical skills to escape a troubled home life, to counter the ridicule of other children or to hide personal inadequacies that have diminished their self-esteem.

Whatever their motivation, those of us less-gifted (and/or less devoted to sport) admire their skills and dedication.  Many root for the underdogs while others (myself included) want to see the best athletes take home the gold (see Rooting for Champions).

Friday, August 5, 2016

A Bushtit Invasion

Large flocks of bushtits invaded our Littleton, Colorado, farm this evening.  Joining chickadees, downy woodpeckers and a pair of red-breasted nuthatches, they scoured the trees for insects, their high-pitched calls ringing across the farm.

As I have indicated in past posts, the population of these tiny insectivores is highly variable on our property.  A pair or two often nest here in the spring but they may otherwise be absent for months at a time.  Then they suddenly appear in large flocks, sometimes hanging around for a week or more.

I suspect the cool weather may have had something to do with this evening's invasion since the other insectivores, including a flock of cedar waxwings, were especially active, numerous and vocal as well.  Whatever the reason, these rather tame birds are always welcome on the farm; they surely consume a large number of harmful insects and their friendly banter never fails to raise my spirits.

Thursday, August 4, 2016

No Magpie Zone

When I joined eBird and started filing reports from South Platte Park (the section near C-470), I assumed that black-billed magpies would be among my most commonly sighted species.  After all, these gregarious and noisy birds are abundant along the Colorado Front Range and often visit our Littleton farm, a couple miles north of the Park.

To my surprise, having filed at least a dozen reports since early April, I have yet to encounter a magpie on my two mile walks.  While I saw 1800 violet-green swallows one day and 300 yellow-rumped warblers on another, not a single magpie has crossed my path.  Ironically, I usually see a half dozen or more on my journey to and from the Park and a few are often hanging around the Park entrance; yet, they seem to avoid my count area, at least while I am present.

On this cool, cloudy morning I saw 30 species, including a bald eagle, an osprey, more than 20 cormorants, a black-crowned night heron and three snowy egrets.  Though I kept hoping that a black-billed magpie would make an appearance, none were observed.  Such is the fickle nature of birding; we often encounter uncommon residents or visitors without spotting their more abundant neighbors.  On the other hand, after writing this post, I'll probably see dozens of magpies on my next visit to South Platte Park.

Wednesday, August 3, 2016

A Bone Dry Farm

Returning to our Littleton, Colorado, farm after a month in the Midwest, I found that it was bone dry.  Our unwatered "lawns" consisted of broken patches of dusty ground cover and the leaves of our perennial shrubs were wilted and limp.  Our fruit trees, responding to the drought, had dropped much of their crop ahead of schedule; only the larger trees showed no signs of the recent hot, dry weather.

Fortunately, almost all of our shrubs are native to Colorado and thus well adapted to the semi-arid climate; others, such as lilacs and Rose-of-Sharon, are also drought-tolerant and will rapidly recover when monsoon rains return to the Front Range.  In fact, cooler air and showers are forecast for the next few days.

When landscaping property in a semi-arid environment, it certainly helps to plant native trees, shrubs and wildflowers.  By doing so, one can avoid irrigation all together (or at least minimize its use) and need not worry that a prolonged period of excessive heat and drought will decimate the plants.  For those of us who live at a distance for periods of time, such an ecologic approach also offers carefree maintenance.

Tuesday, August 2, 2016

Missouri: the Trailhead State

On my many trips between Missouri and Colorado, I often think of the emigrants who crossed the Great Plains via wagon trains.  Of course, they were preceded by explorers and trappers on horseback who scoured the West during the 17th and 18th Centuries and by the Lewis & Clark Expedition that followed the Missouri and Columbia River Valleys from 1803-1805.  Like the latter expedition, most of the early emigrants began their journeys in what is now the State of Missouri.

Within a decade of Lewis and Clark, emigrants were following the Santa Fe Trail, which began in Franklin, on the north bank of the Missouri River (not far west of Columbia); this was the farthest upstream that steamboats could reach at the time.  The wagon trail crossed the river at Arrow Rock, passed through Lexington and continued on to Independence; within a few years, this latter city became the primary steamboat destination.  Leading west to Olathe, the Santa Fe Trail angled WSW through what is now Kansas, passing through Great Bend and Dodge City en route; just beyond Garden City, it split into its Mountain and Cimarron Forks, the former cutting through southern Colorado to Bent's Fort and the latter crossing northwest Oklahoma and northeast New Mexico on their way to Santa Fe.

The Oregon, California and Mormon Trails began at Independence, Missouri, splitting from the Santa Fe Trail in eastern Kansas, southeast of Lawrence.  They then followed a common path northwestward (crossing the Kansas River at Topeka) and entered Nebraska, continuing westward along the Platte, North Platte, Sweetwater and Snake Rivers, thereby skirting the high ranges of Colorado and Wyoming.  At Fort Hall, in southeastern Idaho, these three trails split, heading toward Oregon, California and Utah.  By the late 1860s, railroads crossed the Great Plains and Intermountain West, putting an end to the wagon train era.

Monday, August 1, 2016

The Ellicott City Flood

Ellicott City, Maryland, a scenic and historic town on the west bank of the Patapsco River, endured a tragic flash flood this past Saturday.  A line of intense thunderstorms "trained" across the hilly terrain, dropping up to 8 inches of rain in three hours.

Unfortunately, several creeks merge in Ellicott City's downtown area and rapid runoff from the adjacent hills sent a torrent of water through the Main Street corridor, destroying structures and vehicles and killing two individuals.  As occurred in West Virginia in late June, torrential rainfall and steep terrain combined to produce the tragic flood, which caused the Patapsco River to rise 14 feet within 90 minutes.

Videos of the flood and its aftermath offer a stunning illustration of the power of flowing water.  Of course, such torrents also provide insight into the role that stream erosion has played in the evolution of our landscapes and is a potent reminder that living along rivers and creek valleys carries some risk (however rare) of destructive floods.