Wednesday, July 31, 2013

Waterspouts on the Great Lakes

Yesterday's outbreak of waterspouts across Lakes Erie and Ontario developed along a cold front that was moving over the warm lake waters, an event that most often occurs in early fall.  These were "fair weather waterspouts" which form from rising columns of water vapor beneath the developing clouds; spin is produced by wind shear at the leading edge of the front.

Common in both tropical and temperate regions, fair weather waterspouts form from the water surface upward; they tend to be relatively weak and short-lived though they occasionally produce mild damage to marinas or other coastal structures.  As mentioned above, these weather phenomena are especially common on the Great Lakes in early autumn, predecessors of the lake effect snowstorms that follow during the colder months.

Tornadic waterspouts, on the other hand, form within hurricanes and coastal storms or when terrestrial tornadoes move offshore.  Generally associated with severe thunderstorms, these waterspouts form at the base of the cloud layer and move downward; like tornadoes that develop over land, they are powerful and potentially destructive vortices.  Indeed, tornadic waterspouts are responsible for the rare occurrence of fish or frog "rain" as these aquatic creatures are pulled from the lake or sea and fall back to land, often miles from the coast.

Tuesday, July 30, 2013

Prairie Blazing Star

Following a two week hiatus, we returned to the Forum Nature Area, in Columbia, Missouri, to find brilliant purple spikes rising from the restored bottomland prairie.  These were the flower stalks of the prairie blazing star, a perennial herb native to the tallgrass prairie of the American Heartland.  The component flowers, festooned with fuzzy white anthers, bloom from the top to the bottom of the stalk, yielding a cat-tail appearance as the season progresses; indeed, this plant is also known as the cat-tail gayfeather.

Favoring the wet prairies of stream valleys and river floodplains, this attractive wildflower grows from a tuber (or corm) and spreads by windblown seed as well; the colorful flower spikes bloom from mid July into September.  Pollinators include various bees, butterflies and moths while the plant itself is consumed by deer and other large herbivores; rabbits and groundhogs feed on seedlings while prairie voles feast on the corms.

Hardy and easy to establish, prairie blazing star is found in natural and restored prairies from Minnesota to the Gulf Coastal Plain and from the eastern Dakotas to the eastern Great Lakes region; in light of their attractive flower spikes, they are also planted in urban parks and suburban gardens throughout the country.  In concert with black-eyed susans, thistles, various goldenrods and sunflowers, blazing stars herald the season of purple and gold wildflowers that typifies Midwestern grasslands from late summer to mid autumn.

Monday, July 29, 2013

Western Kingbird Highway

As we returned to Missouri yesterday, low, gray clouds shrouded the Great Plains and we knifed through banks of dense fog, drizzle and chilly rain on our route along Interstate 70.  Such conditions kept most of the wildlife in their shelters but western kingbirds were especially numerous and conspicuous.

Summer residents of open country throughout the Western U.S. and the southern tier of the western Canadian Provinces, these attractive and aggressive birds have expanded their range over the past century and may be encountered east of the Mississippi River during migrations.  Insectivores, they fly-catch from fenceposts, saplings and utility poles and also pounce on ground beetles, grasshoppers and other terrestrial prey; indeed, the latter seemed to be their primary means of hunting yesterday, when the raw weather may have nearly immobilized some of their victims.  In my experience, western kingbirds are more opportunistic than their eastern cousins, often hanging out at truck stops to snare insects from the cattle carriers and light posts; while they generally nest in riparian woodlands, they also use human structures such as barns and windmill platforms.

Highly territorial, western kingbirds aggressively defend their nest area from a wide range of predators (real and imagined) and may raise two broods in southern latitudes.  Come fall, they head for wintering grounds in Mexico, Central America and, in recent decades, South Florida.

Saturday, July 27, 2013

Colorado's Monsoon Season

The Southwest Monsoon generally begins in June as high pressure over the Southern Plains and low pressure near the upper Baja Peninsula combine to sweep moisture north from both the Gulf of California and the Gulf of Mexico.  This precipitation, combined with the summer heat, ignites thunderstorms over the Desert Southwest in early-mid summer and the pattern shifts northward over the following weeks.

Here in Colorado, the monsoon rains tend to peak from mid July to mid August, bringing much needed relief to the parched landscape.  While most of the annual precipitation along the Front Range falls from March to May, in the form of upslope snowstorms and widespread rain events, the monsoon thunderstorms can dump excessive amounts of rain in a very short time, often producing a flash flood; on the other hand, these storms are hit and miss in nature and some areas benefit while others remain dry.  This year, for instance, heavy rains have fallen near and north of Denver while our Littleton farm has received only a few brief showers.

All could change over the next few days as the monsoon flow is expected to increase across the Front Range.  Building over the mountains, the storms wax and wane as they move toward the urban corridor, where anxious residents watch their approach and hope for a direct hit on their parched lawn and gardens.  Alas, for any given round of storms, most of us are losers.

Thursday, July 25, 2013

Guest Nature Photos

Take only photos and leave only footprints.  That motto of the conservation movement expresses the sentiment that we can enjoy nature without impacting her ecosystems.  Furthermore, photography offers a means of capturing the beauty of her landscapes, flora and fauna for a variety of purposes: to promote conservation, to educate, to encourage tourism and to document our travels, among others.

In that spirit, I will add a Guest Nature Photo to this blog, beginning today.  I am fortunate to have visited many parts of North America and a few other regions of our magnificent planet but I hope to enlist others in providing photos of their home environment.  In the course of any given month, Nature's Blog attracts visitors from all 50 U.S. States and from at least 60 other countries; hopefully, many of those visitors will share photos of their native landscape and/or wildlife with the rest of us.

Please submit your photo (jpg format preferred) to; photos will be published in the order that they are received (assuming their content is appropriate for this blog). While you will be credited for the photo, I cannot offer reimbursement and will not use the photo to advertise specific businesses or equipment.  Thanks in advance for sharing your nature photos with the readers of Nature's Blog.

Wednesday, July 24, 2013

The Outlet Mall Ouzel

Returning from Vail yesterday afternoon, my wife spotted an outlet mall in Dillon and wanted to do a bit of shopping.  While she perused the merchandise, I wandered through the complex and came across a wooded stream that flowed past the stores.  It was Straight Creek, which rises on the Continental Divide near the Eisenhower Tunnel and enters the Blue River just below the Lake Dillon dam.

There I saw a common dipper, also known as a water ouzel, feeding in the cool, turbulent waters.  Our only aquatic songbird, dippers inhabit whitewater mountain streams of western North America, from Alaska to Mexico.  They feed on insects, larvae and fish eggs, repeatedly dipping, diving, swimming and walking on the rocky bed to catch their prey.  Females build their nest under bridges, on rock ledges, behind waterfalls or in other areas secure from flooding and up to five chicks are produced; a second clutch may also be raised in southern latitudes.  Though nonmigratory, dippers often move from higher to lower elevations during the winter months, when ice and heavy snow cover many subalpine streams.

While birders associate these chunky, gray songbirds with pristine mountain wilderness, they adapt to streams near towns and cities as well (assuming the water is clear and unpolluted).  Indeed, one might hike for miles along a remote whitewater stream without seeing one and then spot an ouzel in their suburban creek.  Such is often the case with wildlife species; we might search for a particular bird at a nature preserve for hours without success, only to encounter the bird later in a roadside slough, on a golf course pond or in a trashy, weed-choked lot.

Tuesday, July 23, 2013

Hiking down to Vail

Taking a break from work on our Littleton, Colorado, farm, we headed up to Vail this morning for a bit of hiking, lunch and window shopping.  Once there, we elected to take the Lion's Head Gondola to Eagle's Nest, eat lunch atop that scenic ridge and then hike back down to Vail.

From Eagle's Nest, 2200 feet above the famed resort, one enjoys a broad view of the Gore Creek Valley, backed by the high spine of the Gore Range, and, to the west, the majestic peaks of the Holy Cross Wilderness.  Heading down, we first crossed open meadows adorned with an abundance of subalpine wildflowers and home to both mountain and western bluebirds.  The trail then snaked down through pine-spruce forest, now heavily damaged by the pine beetle blight but still alive with the sights and sounds of subalpine wildlife; most conspicuous were mountain chickadees, gray jays, hairy woodpeckers, gray-headed juncos and red squirrels.  Half way down, we entered beautiful aspen groves, their white trunks gleaming beneath the green forest canopy.  After four miles of ankle-wrenching descent, we had returned to the resort where violet-green swallows cruised past the upscale shops and broad-tailed hummingbirds zipped among the numerous flower displays.

While our visit to Vail Mountain was highly enjoyable on this mild, sunny day, I was concerned about the welfare of the many overweight, de-conditioned, middle aged men whom we passed on the trail, chugging and puffing their way to the summit.  Many of those vacation athletes, intent on proving their stamina, had arrived from homes at low elevation and were in no condition to be climbing through mountain forest.  Too often, they are egged on by fit spouses or younger family members, a challenge that can have deadly consequences.

Monday, July 22, 2013

Retirement & Relationships

Ask a middle aged couple to enumerate the difficult stages of marriage and they will likely mention the "what have I done" weeks that follow the honeymoon, the years raising teenaged children and, of course, the challenges of the middle age crisis (for one or both partners).  Few would think to include retirement, that blissful reward for the trials of life, filled with relaxation, travel and carefree coexistence.

Yet, relationships are stressed during retirement for a number of reasons.  For some, financial insecurity and healthcare expenses become major concerns.  For others, the meaning of retirement, itself, is a source of conflict, arising from different interpretations of what is productive activity and what is pure idleness.

Of major significance is the fact that retirement brings a 24/7 togetherness that was never present during  earlier years of the relationship, even during those initial months of romance.  While, over the years, we have come to accept and joke about one another's curious and annoying habits, we must now face them on a daily (if not hourly) basis.  Older, bickering couples have long been a staple on television sitcoms and, in concert with the aging of liberal-mined baby boomers, divorce rates have climbed dramatically for those over fifty.  In my opinion, the marital challenges of retirement are best approached like those of middle age (see The Middle Age Syndrome): regular periods of independent activity, respect for one another's interests, a willingness to take on new challenges (education, volunteer activities, new hobbies, etc.), a commitment to activities that both partners enjoy and a mutual desire for open and honest communication.

Sunday, July 21, 2013

Moonrise over Thunderstorms

Last evening, massive storms blossomed east of Denver, their thunderheads lit by the setting sun.  Rising 50,000 feet into the atmosphere, that turbulent wall was more than three times the height of the Front Range, to our west.

As if that scene was not spectacular enough, a full moon rose atop the thunderstorms at 8:30 PM, its tranquil disc gleaming through the clear skies west of the menacing swath.  Then, as dusk enveloped the region, lightening flashed within and beneath the storms, producing a fabulous light show for those of us in the Front Range urban corridor.

Highlighting nature's beauty and power, the event was also a reminder that one's perspective is governed by location and geometry.  Viewed from the moon, almost 239,000 miles above the Earth, last evening's storms would appear as a narrow band of sunlit clouds above the darkening plains of eastern Colorado, one of many thunderstorm complexes across the globe.  Yet, from our Littleton farm, the moon appeared to be an intimate player in that dramatic weather event, grazing the top of the storms as they pummeled the High Plains with hail and heavy rain.

Saturday, July 20, 2013

Gulls vs. Humans

An article on the ESPN website today reports that the San Francisco Giants and their fans have been dealing with gull invasions since the new bayside park opened in 2000.  The intelligent, omnivorous, opportunistic gulls, long drawn to handouts at our garbage dumps, learned that fans leave a great deal of food in the stands; initially arriving during the post-game cleanup, they have begun to appear earlier, anticipating the feast and disrupting the ball game.

Per the article, a resident red-tailed hawk kept the gulls at bay in the past but that raptor has since moved on or died.  Current suggestions to control the unwelcome flocks include hiring a falconer and his/her predator for home games (a costly solution) or placing fake hawks and owls on the stadium roofs (a solution unlikely to fool the intelligent gulls).  Of course, a domed stadium has also been suggested.

What struck me about the article is that blame has been placed on the avian invaders, not on those who entice them with their garbage.  Americans waste more food than many small countries consume and our propensity for littering the environment extends well beyond our ball parks.  More waste containers and more responsible fans may be the best solution.

Friday, July 19, 2013

Stable Flies

Scraping and painting an old barn has never been one of my favorite activities and the presence of stable flies has made that chore even less pleasant.  Unfortunately, these annoying insects seem to have arrived with the horses that we are boarding at our Littleton, Colorado, farm.

While they look very similar to house flies, stable flies (also known as barnyard flies or biting house flies)  do not merely buzz your face or land on your meals.  Since they feed on the blood of mammals and birds, the adults produce a sharp sting when they bite, usually attacking the ankles and lower legs, causing horses to stomp and humans to swat (and perhaps deliver an expletive or two); protection is limited to repellants and clothing coverage.

Females lay their eggs in rotting vegetation, silage, soiled hay or similar farmyard debris.  These hatch into larvae which molt through three stages, pupate and then emerge as adults.  Under warm, summer conditions, this entire process takes about 3-5 weeks, slowing down in the cooler autumn weather and suspended altogether during the winter months (adults live for a few weeks and succumb to the first hard freeze).  Common across much of the globe, stable flies are a scourge for penned livestock and unwelcome visitors for their human handlers; fortunately, they seldom venture indoors and are not known to transmit disease to humans.

Wednesday, July 17, 2013

A Brief History of Racism

When humans evolved in Africa, 130,000 years ago, we were dark-skinned, tropical hominids; for the first 80,000 years of our history, there were no significant racial divisions. Then, as our species spread across the globe, various races emerged in response to both genetic variation and the physical character of our environment (primarily climate and solar radiation).  It would not be until trade routes were established and global exploration began (i.e. within the last few thousand years) that racial and cultural differences were recognized and exploited, setting in motion the indignities of imperialism, prejudice, slavery and racism.

While human enlightenment, including the advance of democracy and public education, has spawned civil rights legislation in many regions of our globe, an undercurrent of racism persists, the effect of familial and cultural attitudes passed through the generations.  Fortunately, as globalization and liberalism have fostered immigration and interracial marriage, racial distinctions are beginning to blur and, centuries hence, may disappear altogether.  In concert, the notion of racial supremacy should be relegated to history.

Of course, the end of racism will not ensure social harmony.  Those prone to intolerance, zealotry and bigotry will focus on other differences among us and the struggle for human rights and personal freedom will continue.

Monday, July 15, 2013

The Evolution of Cats

While I am not fond of domestic cats, I must express my admiration for the hunting prowess of those strict carnivores.  Today, 37 species of felids inhabit our planet, all of which originated from a common ancestor that lived in Asia during the late Oligocene, some 25 million years ago.

DNA studies indicate that at least 8 felid lineages have evolved since that time and that cat species have been native to all Continents except Australia and Antarctica.  Migration of species between the Americas, Eurasia and Africa has been occurring for at least 12 million years (during periods when low sea levels opened the Bering land bridge) and genetic evidence suggests that the migrations have occurred in both directions.  For example, the cheetah, now limited to Africa, actually arose from a North American lineage and is more closely related to cougars than to the lions, tigers and leopards of Asia and Africa.  Some felid lineages, including one that gave rise to the saber-toothed cats, are now extinct .  Those lineages that still exist are grouped within two sub-families: the Pantherinae (including lions, tigers, leopards and jaguars) and the Felinae (including cougars, cheetahs, lynx, bobcats, ocelots and the domestic cat, among others).

Current archaeologic evidence suggests that cats were first domesticated in Egypt, about 4000 years ago.  While most of their wild cousins are endangered by habitat destruction, hunting, poaching and other human-related factors, domestic cats (many of which are feral) thrive in towns and cities across the globe; their numbers far exceed the population of all other cat species combined.

Sunday, July 14, 2013

The Nature of Arthritis

Arthritis is the inflammation of one or more joints.  Inflammation occurs in the synovium (the lining of the joint) and is usually accompanied by excess fluid accumulation within the joint space; both factors result in joint swelling.  The inflammation may be due to a variety of causes and, over time, will lead to destruction of the joint with limitation of function.

The most serious form of acute arthritis is caused by bacterial infection; in most cases, a single joint becomes red, swollen and very painful.  Such a clinical presentation should prompt immediate medical attention since both early surgical drainage and intravenous antibiotics are indicated to prevent joint damage.  Another form of acute arthritis, involving one or more joints, is due to crystal accumulation in the joint space; gout and pseudogout are the classic disorders and the specific diagnosis is made by examining the joint fluid.  A host of inflammatory arthritis conditions, usually involving multiple joints, are due to immunologic reactions to exogenous agents (viruses, bacteria, drugs, other allergens) or to one's own body tissues (autoimmune diseases); the latter include conditions such as rheumatoid arthritis, systemic lupus erythematosis and various forms of vasculitis, among others.  Finally, the inflammation may be due to injury (acute or chronic) to the joint capsule; the incidence of this condition, known as osteoarthritis or degenerative arthritis, increases with age and is predisposed by genetic factors, body habitus (e.g. obesity) and one's occupation.

The treatment of arthritis varies with the specific condition but generally involves direct management  of the underlying cause (bacterial infection, hyperuricemia), elimination of offending agents or conditions, exercise, physical therapy and the use of anti-inflammatory medications.  The treatment of autoimmune diseases may also include immune suppression therapy which is best administered and monitored by a rheumatologist (an arthritis specialist).  In some cases, damaged joints may require joint replacement surgery; this is especially common in the management of osteoarthritis of the knees and hips.

Saturday, July 13, 2013

Common Chicory

By mid summer, the landscape of the American Heartland is dominated by various shades of green.  While suburban yards and urban parks are festooned with a wide variety of flowering plants, only a handful of wildflowers add color to natural areas.  One of these is common chicory.

Native to Europe and introduced to North America and Australia, common chicory grows along our roadways, offering a regular splash of color from July through early October.  Its bright blue flowers, often called blue daisies, sprout from a tall woody stem and offer a pleasing contrast with the verdant background.  For thousands of years, humans have used the leaves and roots of this hardy perennial for salads, coffee, dietary supplements and a variety of herbal remedies; chicory is also widely utilized for livestock forage.

To most of us, however, common chicory is that ragged but attractive wildflower that brightens our country roads during the hot, dusty months of mid and late summer.  It lends itself more to our mental health than to our physical well being.

A Word to Old Friends

We humans, even those of us who enjoy periods of solitude, are social creatures.  Once we learn to communicate, we begin to establish relationships with other humans, first with our family members and then with a life-long chain of friends.  Unfortunately, while we generally retain a close connection with relatives, we tend to discard friendships as we move through the stages of our life.

Losing touch is often the result of moving to other cities, developing new social relationships and focusing on the new priorities in our life (children, career and personal interests).  Though we may retain loose contacts with old friends, primarily via holiday cards or group emails, meaningful correspondence is often lacking.  Recognizing that the course of our life is significantly influenced by our relationships, most of those old friends affected our life choices and were a source of inspiration in some way or another; it is unfortunate that their role, however minor, is often never acknowledged.

Yet, there seems to be a social taboo about reconnecting with old friends.  Some suggest that we are escaping to our past or invading the privacy of those we contact.  While these points have some validity when it comes to past lovers (a potentially dangerous and painful exercise), they seem to be convenient excuses for those too busy to rekindle old friendships.  Being remembered and being acknowledged for one's importance in the lives of others are key to our emotional health and, by contacting past friends, we pass along that support.  Too often, such sentiments are expressed only to their family members, posthumously.

Friday, July 12, 2013

Australia's Devonian Reef

The Kimberley Plateau of Australia, which forms the northwest corner of that Continent, is composed of ancient Precambrian rock.  During the Devonian Period (some 350 million years ago), when sea levels were significantly higher than today, the Plateau was ringed by a limestone barrier reef; lime-secreting bacteria and algae and primitive coral produced the reef as the first sharks and boney fish were evolving in Earth's oceans.  As sea levels fell and erosional debris accumulated, sections of that reef were incorporated into the mainland of Australia, now outcropping as limestone ranges along the southern edge of the Kimberley Plateau.

Several streams, rising on the Plateau, have cut spectacular canyons through the Devonian Reef complex (the Napier, Oscar and smaller ranges) as they flow southward into the Canning Basin; the latter is a layer cake of Upper Paleozoic and Mesozoic sediments, eroded from adjacent highlands.  Windjana Gorge (cut by the Lennard River), Gelkie Gorge (sculpted by the Fitzroy River) and Tunnel Creek are protected within National Parks and offer the best locations to explore the Devonian Reef.

Australia's Great Barrier Reef, the latest reincarnation of which has been forming over the past 8000 years, will eventually become part of the mainland as well.  By then, Australia, which is slowly drifting to the north, will be much closer to (if not contiguous with) Southeast Asia.

Thursday, July 11, 2013

Reboarding Verne's Nautilus

Fifty years ago this summer, as I approached the ripe old age of 13, I read 20,000 Leagues Under the Sea, by Jules Verne.  Hoping to relive that adventure, which was instrumental in spawning my naturalist philosophy (see Four Books), I retrieved that book from the library.  As I read Verne's saga for a second time, the memory of its initial impact comes flooding back, confirming its effect so many years ago.

A novel of adventure and exploration with a story line that stretches across the globe, this book reveals both Verne's knowledge of the sea and his prescience with respect to the future of technology.  Though it was written in 1870, the story remains applicable in our modern world, placing emphasis on man's conflicted relationship with his natural environment.  In fact, 143 years after its initial publication, the deep sea, Earth's largest wilderness, remains relatively unexplored and many of its mysteries are yet unsolved.

Reading this book will take me back to the summer of 1963.  Having just lived through the Cuban Missile Crisis, my innocence would soon be further shattered by Kennedy's assassination and the turmoil of Vietnam.  Somehow, through the varied trials, joys and challenges of my life, Verne's epic has retained its influence.  We can only hope to offer such inspiration to others.

Wednesday, July 10, 2013

Scolded by a Stranger

Having missed my morning walk yesterday, I opted for an afternoon stroll despite the heat and humidity.  I chose the MKT trail, a shaded old rail bed that follows a series of creeks in Greater Columbia.  Though I rarely hike on hot summer afternoons, there were advantages; in particular, the sensible crowds were absent and I only encountered the occasional biker and lunatic jogger.

The woodland birds, protected from the intense sun by the forest canopy, were surprisingly active and a few skinks dashed across the trail as I approached.  Also, the afternoon lighting increased visibility in the creek waters and I stopped on the bridges to watch the fish, crawdads, water striders and whirligig beetles.  But the highlight was my encounter with a male summer tanager, a bird that I have not come across in recent years; I might have mistaken him for a northern cardinal if he had not broken into his distinctive rant as I neared his perch.  Indeed, male summer tanagers are highly territorial and this one scolded me with his "pity-tuck" calls until I moved on; he was still on the overhanging limb when I returned and he resumed the tirade.

Summer tanagers prefer open deciduous forest and breed across the southeastern U.S. (from southern Iowa, the Ohio Valley and mid Atlantic States, southward); they also nest in riparian woodlands of the Desert Southwest, wintering in Mexico, Central America and northern South America.  Feeding on both insects and berries, these tanagers have a preference for bees and wasps, which they snare in flight and then beat against a limb before consuming (hence the nickname bee-bird).  A loose nest of dried vegetation is placed on a horizontal fork by the female and 3-5 eggs are generally produced.  As I found out yesterday, the excitable male often guards the site.

Tuesday, July 9, 2013

Collared Dove in Columbia

The call was very familiar.  I have been hearing it on the barrier islands off Sarasota, Florida, since we purchased a condo there in 2003.  In July of 2008, I heard it for the first time on our Littleton, Colorado, farm and it has since become a ubiquitous sound on that property.  Yesterday morning, while walking through a parking lot in Columbia, Missouri, I heard it for the first time in a city that has been our second home for over 15 years.

The call, echoing down from the top of a light pole, was delivered by a Eurasian collared dove, a native of India and the Middle East that has spread through much of North America over the past 30 years (see March of the Collared Dove).  A larger cousin of the morning dove, the collared dove was released in the Bahamas in 1975 and first turned up in Florida in the early 1980s.  It reached Colorado by 1996 and was first observed in Missouri in 1998; while this dove has been observed in central Missouri throughout the past decade, I did not encounter one in Columbia until yesterday.  As one who regularly ventures into natural habitats, maintains backyard feeders and has been an avid birder since the mid 1970s, it certainly took long enough!

As veteran birders know, being at the right place at the right time plays a major role in bird sightings.  On the other hand, I have never set out with the specific goal of finding a collared dove in central Missouri and seldom consult rare bird reports.  Hardly a birding fanatic, I engage in the hobby in concert with hiking and general nature exploration and may have ignored the familiar call at times in the past.  Based on my experience in Colorado, however, it will soon be impossible to miss these prolific and highly adaptable immigrants in Columbia.

Monday, July 8, 2013

Mid Summer Dusk

Dusk is especially welcome after a long, hot summer day and it triggers activity in a wide range of suburban wildlife.  Last evening, fireflies drifted into the cooling air as a chorus of annual cicadas waxed and waned.  A young cottontail scampered across the backyard, stopping to nibble on pockets of clover.

Squadrons of chimney swifts, common nighthawks and purple martins cruised overhead, feasting on rising clouds of insects.  Closer to earth, house wrens, cardinals and chickadees made their final rounds of the day as a garter snake waited for a field mouse, beetle or nightcrawler to wander within range.  Little brown bats strafed the treetops, snaring hapless mosquitoes and a pair of eastern gray squirrels gathered the first walnuts of the harvest season.

Some of us, not fond of summer heat, relish the hour of dusk, a sign that the oppressive sun is in full retreat.  A few weeks past the solstice, we begin to sense the shortening days and anticipate the cool, crisp weather of fall.  Indeed, some species of shorebirds, the first fall migrants, are already moving through the Heartland, on their way to southern beaches; summer heat will eventually follow in their wake.

Sunday, July 7, 2013

The Nature of Divides

A hydrologic divide is the line of high ground that separates the watersheds of two streams; any given divide can be subdivided into the contributions made by the watersheds of each stream's tributaries.  For example, in northern Colorado, the Continental Divide separates the watersheds of the Missouri and Colorado Rivers; each of these major watersheds is composed of secondary watersheds that rise along the Continental Divide (e.g. the South Platte and North Platte watersheds of the Missouri River system) and each of those secondary watersheds are composed of tertiary watersheds; such division can continue down to the watersheds of the smallest creeks and rivulets that rise along that segment of the Continental Divide.

The geometry of divide networks coincides with the nature of the landscape.  A typical mountain range harbors a divide that runs along it crest which radiates divides to either side, separating the watersheds of the streams that drain its flanks.  The divides of a mesa or plateau generally radiate out from central high ground, separating the watersheds of the streams that rise atop the tableland and drop along its walls.  While the divides of mountain ranges and plateaus often zig-zag along the crest and side ridges, divides in flat landscapes tend to run in a parallel or gradually converging formation.

One need not visit dramatic natural landscapes to study divides.  Indeed, they run through our towns and cities as well, separating the various creek watersheds that cover our home area; in fact, should you live on a ridge (however modest) between stream valleys, a divide may run through your property.  Those of us who are fascinated by geography and topography realize that an appreciation for divides and watersheds is key to understanding any landscape.

Saturday, July 6, 2013

The Secretive Shrub Bird

Though fairly common throughout the eastern and south-central U.S. during the warmer months, white-eyed vireos prefer shrubby habitat where they are more often heard than seen.  Such areas include abandoned farms, recovering clear-cuts, riparian thickets, mangroves and shrubs along wood borders or in forest clearings.

Remaining close to the ground, this insectivore gleans its prey from leaves and stems, hopping through the dense foliage; it may also consume small berries.  When in view, it is easily identified by its white eyes, yellow spectacles and a pair of white wing bars; its back is olive colored, its flanks are pale yellow and its chest and abdomen are white.  While this secretive summer resident is not often seen by the casual birder, its loud, varied song is commonly heard in the habitats listed above, especially in late spring.

A shallow cup nest is suspended from forked limbs within the shrubbery; both parents take part in its construction and share feeding duties once the eggs hatch.  Unfortunately, white-eyed vireos are frequent victims of brown-headed cowbird parasitism.  By late summer, the parents and their young depart for wintering grounds that stretch from the Gulf Coast States to Central America and the Caribbean islands.

Friday, July 5, 2013

Bookend Highs

For the past week, high pressure domes over the Desert Southwest and off the Southeast Coast, separated by a deep low pressure trough through the middle of the U.S., have brought extreme weather to portions of the country while producing a pleasant, relatively cool summer across the Heartland.

Beneath the domes, air is sinking, heating up and spreading outward, creating a clockwise spiral of wind along their rims.  The southwestern dome has produced excessive heat; the sinking air dries out as well as heating up, negating cloud formation and intensifying both solar radiation and evaporation.  Record or near record highs have been set across the region and Pacific storm systems have been shunted to the north, allowing wildfire conditions to worsen.

In the Southeast, the winds around the Bermuda High are sweeping copious moisture onshore from the Gulf of Mexico and the Atlantic Ocean.  Interacting with the low pressure trough, which provides the lift, this soupy air has ignited thunderstorms; training across the same areas, the storms have dropped up to 20 inches of rain in parts of western Florida and southwestern Alabama.  Farther north, most of the Piedmont and Coastal Plain set precipitation records for the month of June and, unless the current weather pattern breaks down, the same may occur in July.  Of course, those of us beneath the relatively cool central trough would be pleased to see our mild summer continue.

Thursday, July 4, 2013

Threats to our Freedom

Today we celebrate the birthday of the United States and honor those who established and have protected the freedoms that we enjoy.  Despite ever-expanding oversight from the NSA, Google and credit card companies that catalogue our every phone call, text, click or purchase, we are relatively free to pursue our interests and personal happiness.

Mention threats to our freedom and most Americans think of terrorism, foreign cyber attacks, rogue states and illegal immigration; in reality, the primary threats come from within.  Political and religious zealotry have produced a dysfunctional Congress, incapable of addressing the many problems that threaten our financial, educational, commercial and environmental welfare.  Personal priorities, extreme positions and the search for national celebrity derail concern for the common good and ridicule now trumps respect and compromise.  Well-financed lobbies, such as the NRA, push agendas that defy common sense and political maneuvers (including gerrymandering and voting regulations) serve to silence the voice of minority groups.

As we are witnessing in Egypt this week, democracy is fragile.  Democratic elections do not ensure democratic rule and failure to address the rights of the electorate will, in the end, threaten the effectiveness and very survival of that democracy.  As the income gap continues to widen in the U.S. and as powerful organizations impose their will on American society, one wonders how and when the tide will turn in this country.  In the end, demands for personal freedom will prevail.

Wednesday, July 3, 2013

The Nature of Ticks

Ticks are external parasitic organisms that feed solely on the blood of birds, mammals and some reptiles.  Not insects, ticks are arachnids and, like spiders, have eight legs in the nymph and adult stages (their larvae possess only 6 legs).  In North America, hard ticks (represented by more than 700 species worldwide) are the only group that parasitize mammals.

Hard ticks mature through a three year life cycle.  Adult females lay their eggs in the soil by late summer or early fall; these hatch into larvae which overwinter in the soil and attach to their first host (a bird or small mammal) in the spring.  By late summer or early fall, the larval tick drops from its host and molts to a nymph (a small replica of the adult), which overwinters beneath dead vegetation or leaf litter, surviving on engorged blood; the nymph repeats this cycle the second year, generally using a larger host and molting to an adult by autumn.  Adult females emerge in spring and attach to large mammals (cattle, goats, deer, humans) to feed and mate; the adult males do not feed during their spring/summer phase and die off after mating.  Once the adult female lays her eggs, she also dies, generally by mid autumn.

The number and diversity of tick species are greatest in tropical regions, decreasing toward colder and drier regions of our planet.  They locate hosts by waiting on tall grass or other vegetation, jumping to or grabbing the host as it passes by; this behavior is often noted by hikers who become festooned with dozens of ticks after crossing a meadow or using an overgrown trail.  Unfortunately, ticks are vectors for a wide variety of rickettsial, viral and bacterial infections (including tick fever, ehrlichiosis, Rocky Mountain spotted fever, Lyme Disease, meningoencephalitis and tularemia, among others) and should be removed as soon as possible.  Ticks, themselves, are consumed by birds and reptiles and are victimized by parasitic wasps.

Tuesday, July 2, 2013

From Refuge to Park

A couple of years ago, our central Missouri city bought a farm south of town, setting it aside as a nature and fishing preserve.  A trail was built around the lake, a few shelters were placed for picnics, restroom facilities were established and a boat launch was constructed (to be used for small fishing craft).  My wife and I visited the pastoral refuge several times, noting that its rural environment was marred only by a nearby highway and a new high school that looms above the southwest section of the lake.  Otherwise, broad, rolling grasslands, parcels of forest and shoreline wetlands characterized the preserve, which attracted a wide variety of resident and migrant wildlife.

On our visit today, we were dismayed to see an army of bulldozers, steam shovels and earth movers destroying the east end of that tranquil site; on closer inspection, we saw survey markers running along the south edge as well, barely 50 yards from the lakeshore.  As we hiked along the trail, it became painfully clear that a large commercial and/or residential development will soon abut the once quiet and scenic preserve, likely converting the refuge to your typical suburban park, complete with hordes of  joggers, dog-walkers, kite flyers and cell-phone addicts.

Don't get me wrong.  I'm all for urban and suburban parks, which bring greenery and some wildlife to our concrete jungles and which offer oases for family picnics and sporting activities.  While they are, to some degree, nature preserves, they do not provide the serenity and natural ecosystems of a designated refuge.  To find the latter, one must now head for conservation areas, State and National Wildlife Refuges, wilderness areas and undeveloped federal lands; even State parks, catering to the masses, are often uninviting for a true naturalist.  I, for one, will check the old farm site off my destination list.

Monday, July 1, 2013

The Global Egret

Cattle egrets evolved on the vast savannas of East Africa where they followed herds of elephants, water buffalo and other herbivores, feasting on the insects that they stirred from the soil or that were attracted to the animals and their dung.  Avoiding deserts and mountainous areas, these grassland herons eventually spread to coastal regions of Africa and thence to the Iberian Peninsula and southern Asia; it is likely that their dispersal was in response to human domestication of cattle, goats and camels, which became surrogates for the wild African herds.

By the late 1800s, cattle egrets (more closely related to herons than to other egrets) had spread to the Caribbean islands and then to northern South America.  Their presence in both Florida and Australia was first documented in the early 1940s and a breeding population was established in Florida by 1953.  In North America, they have since spread northward along the Atlantic Seaboard, westward along the Coastal Plain and northward across the Great Plains; they now breed in all but a handful of States and were introduced in Hawaii in 1959.  Rather hardy, cattle egrets have been found in Newfoundland and southern Canada and visit both Tasmania and New Zealand during the warmer months; they have also colonized the British Isles over the past decade.

Cattle egrets are colonial nesters, sharing riparian woodland rookeries with herons and other wading birds.  Non-breeding birds are nomadic and may turn up well beyond their documented range; of course, that range has expanded so rapidly that almost any land mass (short of Antarctica and other permanent ice sheets) is fair game for these adventurous and adaptable birds.