Saturday, July 4, 2015

Shark Attacks on Humans

The plethora of shark attacks along the Carolina Coast this summer has spawned headlines across the country and, I assume, around the globe; reading or hearing those accounts, one might think that cosmic forces have aligned to drive us from the beaches. After all, we humans look at ourselves as custodians of this planet, immune to the predator-prey relationship that lower creatures must endure.

Yet, during our 130,000 year history on Earth, we have been attacked, killed and/or eaten by a wide variety of predators, including big cats, bears, wolves, hyenas, snakes, bees and mosquitoes, to name just a few.  Once we entered marine environments, some 70,000 years ago, we became susceptible to sharks and other ocean predators as well.  Of course, in recent centuries, we have come to adore the beach, crowding there during the warmer months to lounge in the sun and surf like so many seals and walruses.

Entering the domain of sharks, we place ourselves at the mercy of natural killers that have inhabited the oceans for 350 million years.  While they may be drawn toward shore by other prey (schools of fish, sea turtles, etc.) they have no reason to ignore thrashing human beings, just another convenient source of food.  After such attacks, the media tends to report that the shark "mistook" the person for a seal or large fish; in fact, we humans, despite our superior intelligence, are just hunks of meat to a shark.  The only way to totally prevent shark attacks is to stay out of their habitat (or, perhaps, to swim in a suite of armor).

Thursday, July 2, 2015

The Asteroid Belt

As the sun formed, 5 billion years ago, surrounding gas and debris gradually coalesced into the planets, four inner solid planets and four outer gaseous giants; Pluto's status as a planet is a matter of debate (see The Orphaned Planet).  Additional debris aligned within the Asteroid Belt, between the orbits of Mars and Jupiter, the Kuiper Belt (which includes Pluto), beyond the orbit of Neptune, and the Ort Comet Cloud, near the outer edge of the solar system (see The Nature of Comets).

The Asteroid Belt consists of millions of orbiting rock units, ranging in size from the dwarf planet Ceres down to pebble-sized debris; three proto-planets (Vesta, Palias and Hygiea) also orbit within the belt.  Ceres accounts for 30% of the mass of the Asteroid Belt while this dwarf planet combined with the three proto-planets harbor 50% of the total mass.  Though the Belt is relatively stable at this point in time, such was not the case during the chaotic early history of our solar system; during that period, they were slung about space, slamming into the planets and pockmarking their moons (as we observe on Mars and our cratered Moon today).  Of course, asteroids within the Belt also collided with one another, a process that continues today; such collisions, combined with gravitational effects from Jupiter, still send wayward asteroids into space, threatening Earth with disastrous impacts.

Space probe Dawn, launched by NASA in 2007, explored Vesta in 2011-2012 and is now orbiting Ceres, sending back fascinating photos of the asteroid's cratered surface.  Of most interest are bright white spots, up to 4 miles across, which may represent mineral deposits left behind by melted surface ice; the presence of water vapor has previously been documented on this dwarf planet.

Wednesday, July 1, 2015

Season of Discovery

Naturalists and birders look forward to the cooler months of the year when large flocks of migrant cranes and waterfowl stop to rest and feed in their region, when irruptive species move south to join (and compete with) winter residents, when rare vagrants turn up on reservoirs, at refuges or in backyards and when a wide variety of raptors are especially conspicuous in the barren trees and across the bleak farmlands.  However, for most of us, new discoveries in nature are more likely to occur during the warmer months of the year.

Surveying their property or meandering through local nature preserves, veteran and amateur naturalists observe a tremendous diversity of plants and animals; new personal discoveries most often involve wildflowers, fungi, insects and other invertebrates but might also include certain amphibians, reptiles and small songbirds (warblers, vireos, flycatchers) that theretofore had not been identified by that individual.

Such discoveries, however meager, add to our appreciation of the complexity and diversity of regional ecosystems.  Hopefully, they also fuel our commitment to preserving and protecting each and every species; indeed, all species on our planet, including humans, play vital roles in the health of our natural environment.

Sunday, June 28, 2015

Religion & Individual Rights

When national laws or rulings assert individual rights (access to birth control, abortion, gay rights) that clash with their beliefs, religious leaders claim that there is a "war on faith" in America.  Of course, conservative politicians, conscious of the large evangelical voting block, tend to side with that argument.

In fact, there is no effort to abolish or diminish religious freedom; members of any given church are free to live in accordance with the teachings of their faith.  What they cannot do, on the other hand, is force their beliefs on the rest of society; indeed, the Constitution, while granting religious freedom, also guarantees freedom from religion.  We are not a homogenous Christian nation nor are we all religious.

Recent surveys have demonstrated that organized religions are losing support and membership, especially among younger, well-educated Americans.  The reason for this is that the antiquated doctrines of traditional religions have not changed in concert with the advance of human knowledge (not to mention scandals that have exposed the hypocrisy of many priests and pastors).  There is no war on religion in American; religion is imploding from within, the victim of its own rigid mysticism.

Saturday, June 27, 2015

Our Cottontail Colony

Over the years of writing this blog, I have related the saga of cottontails on our Littleton, Colorado, farm.  During the first two decades of owning the property, we did not observe any rabbits on the lawns and pastures; the reason, of course, was that red fox were denning beneath our barn.  Once the fox were extirpated by coyotes (which we later managed to dislodge as well), cottontails began to appear.

Three years ago, a pair spent the winter on our farm and, during the next spring and summer, produced at least two litters of bunnies.  Two years later, we have dozens of cottontails on the property; having colonized the farm in our presence, they are oblivious of our activity, often lounging on the driveway or beneath the shade of a tree.  Active throughout the day, the cottontails are ever present; we can't look out a window without seeing two or three of them.

Of course, sooner or later, a fox, hawk or owl will take notice of their abundance and their population will begin to dwindle; no doubt, they will also become more skittish and nocturnal in their behavior.  Long an admirer of both the placid nature and hardiness of cottontails, I hope the predators are not overly successful.

Friday, June 26, 2015

Justice & Enlightenment

Today, the U.S. Supreme Court ruled that same-sex couples have the right to marry throughout the United States.  Decades late in coming, this decision demonstrates that, in time, social justice will prevail and that, over time, humans have the capacity for enlightenment.

Of course, opposition to this ruling comes primarily from religious conservatives who live their lives (and judge others) based on the teachings of ancient Scripture.  Ignoring scientific evidence that homosexuality is a genetic trait, no less a choice than one's height or eye color, they insist that it is a sinful lifestyle, not worthy of rights enjoyed by the heterosexual community.  Declaring that marriage is a sacred bond, sanctioned by God between a man and a woman, many of these zealots have surely been unfaithful in their own marriage, have been married and divorced multiple times or, in some cases, have expressed their anti-gay views to hide their own homosexuality.

Thanks to today's ruling (which, sadly, passed by a slim 5-4 margin), Americans have taken another step away from entrenched mysticism and toward the social justice that comes with intellectual honesty and scientific enlightenment.  Congratulations to the many gay couples who can now affirm their love and commitment through marriage and will enjoy the legal, financial and social benefits that heterosexual partners have long received.

Thursday, June 25, 2015

Ladybirds in the Thistle

The "crop" of bull thistle on our Littleton, Colorado farm is exceptional this year, no doubt fueled by the wet spring.  While guide books and websites suggest that this thorny wildflower may grow to 6 feet in height, we have one stand that exceeds 8 feet.

Considered a weed by most suburbanites and ranchers, bull thistle does attract a wide variety of wildlife.  The numerous pink-purple flowers are magnets for bees, butterflies and hummingbirds while the abundant seeds are eaten by finches, field mice and meadow voles; even the spiny foliage is consumed by deer and cottontails.  Of special interest this year is a large number of ladybird beetles in one of the thistle stands; close observation revealed colonies of aphids and scale insects that have attracted these predatory beetles.  I also observed tiny clusters of yellow eggs on the leaves; voracious ladybird larvae will hatch from these eggs, feast on the invasive insects, molt several times and then pupate before emerging as adults.

Here is a case where a maligned "weed" is hosting a large colony of beloved beetles that will go on to protect many other plants on our farm.  The diversity of plants and animals in a landscape, however small, is perhaps the best sign of its health.  Using herbicides to eliminate "weeds" diminishes that diversity and introduces toxins that, no doubt, threaten the welfare of all life forms in the ecosystem.

Wednesday, June 24, 2015

Supercell over Denver

Though we enjoyed a warm, sunny day in Metro Denver, a stationary front stretched across northeastern Colorado, adding instability to the atmosphere.  As the daytime heating peaked in late afternoon, thunderstorms began to form above the Front Range, drifting eastward across the urban corridor.

About 4:30 PM, one of these storms suddenly intensified.  Drawing in heat and moisture from the surrounding Piedmont, it rapidly grew into a massive supercell, rising to an altitude of 50,000 feet.  Soon, torrential rain, hail, 60 mph winds and intense lightning ravaged the northern 2/3 of the Metro area.  Moving slowly to the ESE, the storm dropped two inches of rain in 30 minutes, triggering flash floods.  While radar and the observation of weather spotters indicated the presence of a tornado, no evidence of a touchdown (i.e. surface damage) has yet to be documented.

Within an hour, the storm was moving off across the Eastern Plains and had lost some of its intensity.  Here on our Littleton farm, in southwest Metro Denver, we received torrential rain but were spared any wind or hail damage. However, until that stationary front lifts to the north or drops southward through our region, it will be a focal point for recurrent storm development.

Tuesday, June 23, 2015

Yellow Goat's Beard

By June, yellow goat's beard (yellow salsify) is blooming on our Littleton, Colorado, farm and will continue to do so for the next month or so.  Native to Europe, this tall, showy wildflower was introduced to North America and is now found throughout most of the U.S. (except the extreme Southeast) and southern Canada.

A member of the aster family, yellow goat's beard favors fields, roadsides and disturbed areas; along the Colorado Front Range, it has colonized open areas of the plains, piedmont and foothills.  The plant is easily identified by its erect, hollow stem (up to 4 feet tall) and large yellow flowers with both inner and outer rays; the latter open on sunny mornings and close by noon (hence the folk name: Noon Flower).  The globular, brownish seed heads, four inches across, mimic those of dandelions.  Meadow salsify, also known as meadow goat's beard, is shorter in height (up to 2 feet) and is characterized by curved stems and leaves; this European species also adorns our farm.

Both species of goat's beard attract a variety of bees and butterflies; I have observed house finches nibbling on their petals and a host of birds feast on their numerous seeds.  Grazing mammals, on the other hand, tend to ignore these wild herbs due to their milky sap.  Among many wildflowers absent on manicured, herbicide-doused lawns, goat's beard is a welcome and beautiful addition to the summer landscape of our farm.

Monday, June 22, 2015

An Unexpected Gift

Just after 7:30 this morning, strong northeast winds raked Metro Denver, dropping the temperature by ten degrees (F) or more.  In the midst of our early summer heatwave, the chilly air is more than welcome.

The cause for this sudden change is an atmospheric trough, a dip in the jet stream that has been separating hot air to its south from cool air to its north.  High pressure over Montana has temporarily won out over the hot, high pressure ridge of the Desert Southwest.  In concert, our warm, southwesterly winds have temporarily shifted from the northeast, producing an upslope flow along the northern Front Range; while the temperature in Denver is in the 60s F this morning, it is 82 degrees in Colorado Springs (south of the Palmer Divide).

Our chilly atmospheric respite is expected to be brief and hot air is forecast to return by tomorrow.  Then again, this morning's rapid change was unexpected and the whimsical nature of the jet stream is hard to predict.  In the meantime, we'll enjoy the natural air conditioning.  

Sunday, June 21, 2015

Fathers & Sons

Today, Americans celebrate Fathers Day, honoring those who have stayed involved in the care and nurturing of their children.  While it is yet another Hallmark Holiday, associated with a host of commercialized events and special retail offers, it highlights the fact that fathers are an endangered member of the family in some segments of society.  Indeed, as occurs in many animal species, some human fathers are nothing more than sperm donors, playing a transient role in the lives of their offspring.

Many factors account for the dwindling role of fathers in modern society.  A growing acceptance of divorce, even when not triggered by domestic violence, is a leading factor and the choice of single motherhood, spawned by career-oriented women is an increasing trend.  Of course, teenage pregnancy and a culture of unwed motherhood continue to plague some segments of human society.

Unfortunately, this trend, however natural it may be (see Marriage: an Unnatural Union), continues to produce negative consequences.  Boys need involved fathers.  Without their love and guidance, the testosterone fueled behavior of young males often leads to crime, violence and the procreation of other unwanted and unloved children.  We cannot solve these social ills by building more prisons; what we need are more involved fathers.

Saturday, June 20, 2015

The Prairie Owl

Burrowing owls are summer residents of the Western U.S., from the High Plains through the Intermountain West; they are also permanent residents of Florida and the Desert Southwest.  Come fall, northern residents migrate to the Desert Southwest or Mexico.

Favoring open grasslands and deserts, burrowing owls are named for their use of underground burrows for roosting and nesting; while some dig their own cavity, most use the abandoned burrows of prairie dogs, badgers, ground squirrels or armadillos.  These small, long-legged owls are active day and night and are best observed at dawn or dusk when they often stand near their burrow, ready to pounce on a grasshopper, lizard or mouse.  Attempting to draw beetles and other insects within close range, these opportunistic raptors are known to place cattle, horse or bison dung near the opening of their burrow.  Seldom observed in flight, burrowing owls prefer to hunt on foot; however, they occasionally perch on fenceposts to survey the area, gliding down to snare their prey.

Here in southwest Metro Denver, burrowing owls are perhaps best found in the large prairie dog colonies along Roxborough Park Road, south of Titan Road; this dirt-gravel road is south of Chatfield State Park.  Since they are summer residents in Colorado, look for them from April through early October.

Friday, June 19, 2015

Front Range Heat Wave

After six weeks of intermittent rain and heavy thunderstorms, sunny, hot weather is forecast to invade the Front Range over the next five days; afternoon highs are expected to be in the 90s F, with overnight lows in the lower 60s.  The culprit will be a high pressure ridge, moving up from the Desert Southwest, which will divert Pacific storms to the north and produce a downsloping air flow east of the Continental Divide.

While this hot, sunny period will surely dry out the soggy landscape, it may actually exacerbate flooding along the South Platte and its tributaries.  A heavy snowpack persists in the higher mountains and snowmelt will accelerate in the mild air (even though afternoon temperatures on the alpine tundra are, on average, some twenty degrees cooler than those along the urban corridor).

Having griped about cloudy, cool, rainy weather for much of the spring, we are now free to rant about oppressive summer heat, at least for the next five days.  We humans love to complain about the weather even though many glorious days are spaced throughout the year, a fact that is especially true in the dry, sunny climate of the Colorado Front Range.

Thursday, June 18, 2015

Popes & Climate Change: Round 2

Pope Francis' proclamation that global warming is real and that humans are primarily responsible is causing indigestion for Catholic Republican Presidential Candidates.  As for myself, I will defer to my post from July of 2008: The Pope and Global Warming.

Illness & Guilt

Having practiced medicine for almost forty years, I am well aware that persons diagnosed with a serious illness must also deal with guilt.  While some of that guilt may arise from the comments of family, friends or health care providers, most of it is self-imposed.

Facing the emotional, physical and financial trials of their illness, many patients blame themselves for poor lifestyle choices or a lack of preventive health care that might have contributed to their plight.  They also regret the inconvenience, stress and economic hardships that family members, friends and employers must endure.  Some even feel guilty about the costs and work assumed by their insurance company, physicians, therapists and other health care workers.

After all, we humans often attribute illness to personal weakness.  In reality, it is the result of a complex mix of genetic, behavioral and environmental factors; bad luck plays a significant role in most cases.  The commitment to undertake what is often a difficult course of treatment is impaired by the presence of guilt and the success of that treatment will depend, in part, on the patient's ability to maintain a positive attitude.  Too often, physicians and family members do not recognize the emotional impact of guilt, a complication that might undermine the many therapeutic tools of modern medicine.

Wednesday, June 17, 2015

Geology of the Baraboos

An elongated ring of hills and ridges rise in south-central Wisconsin.  Known as the Baraboos, they represent outcrops of ancient Precambrian quartzite, 1.5 billion years old.  Folded downward by tectonic forces and buried by younger Paleozoic sediments, erosion has since exposed the edges of this geologic syncline; due to the tilt of this quartzite basin, its southern rim is far more prominent than its northern edge.  The primary axis of the range, 30 miles in length, is oriented west to east; the shorter north-south axis is about 10 miles in length at the center of the Baraboos.

Between the north and south ridges is the Baraboo River Valley; flowing west to east (where it joins the Wisconsin River), the Baraboo and its tributaries have sculpted a landscape of hills and buttes from the Paleozoic sediments that filled the inner gap of the syncline.  The river also passes through gorges (the Upper and Lower Narrows) in the northern Baraboo Ridge; geologists believe that the Wisconsin River initially sculpted the Lower (eastern) Narrows (see below).

Adding to the geologic complexity of the Baraboos is the presence of a terminal moraine, deposited by a lobe of the Wisconsin Glacier late in the Pleistocene.  Bisecting the ranges from north to south, the glacier and its moraine blocked the course of the Wisconsin River, diverting its flow east of the Baraboos and leaving Devil's Lake in the river's abandoned gorge through the southern Baraboo ridge.

Tuesday, June 16, 2015

A Rim of Storms

A dome of high pressure over the Southeastern U.S. is causing two interconnected weather problems.  Beneath the dome, air is sinking and heating up, producing hot and humid conditions; afternoon highs have been in the mid to upper 90s F with heat indexes above 100.  Along the outer rim of the dome, winds are moving clockwise, drawing Gulf of Mexico moisture northward through the Heartland, eastward across the southern Great Lakes and then southeastward to the Mid-Atlantic Region.

This rim of moisture, caught between the hot central dome and the cooler air to its north and west, is feeding bands of thunderstorms, some of which have spawned tornadoes.  Training over the same swath, the storms are also dropping heavy rain and producing regional floods; last evening, the worst of the conditions were affecting Greater Chicago and no doubt sending travel disruptions across the country.

Today, moisture from Tropical Storm Bill in the western Gulf will add fuel to the fire.  Pulled inland along the edge of the dome, this copious moisture is expected to produce torrential rain in eastern Texas and Oklahoma, exacerbating the floods that have been plaguing the region.  Further north, the plume of moisture is expected to stay south of Chicago, cutting eastward through the Ohio Valley and into southern New England.  Until the dome breaks down, this stormy pattern will continue.

Monday, June 15, 2015

Genetics, Gender & Sexuality

From a purely anatomic point of view, one's gender is determined at conception; if the mother's egg is fertilized by a sperm with a Y chromosome the fetus is genetically male (XY) while a sperm with an X chromosome will produce a female fetus (XX).  Anatomic differentiation of the fetus' genitalia is evident by 6 weeks and secondary sexual characteristics develop at puberty; however, a variety of chromosomal, hormonal and genetic abnormalities may interfere with this process, leading to ambiguous genitalia in approximately 1 of 4500 births.

Increasing scientific evidence suggests that an individual's sexual orientation and gender identity are also genetically determined, involving genes that are distinct from those directly related to anatomic gender.  Recent DNA studies involving identical twins indicate that genes on Chromosomes X and 8 may play a role in homosexuality while studies in animal models have demonstrated the presence of many hormone-sensitive genes that might determine gender identification (i.e. these genes may have increased or diminished sensitivity to pituitary and gonadal signaling).

Clearly, based on social observations, one's anatomic gender, sexual orientation and gender identity are independent traits; the great majority of homosexuals identify with their own anatomic gender while transexuals, whether homosexual or heterosexual, identify with the opposite gender.  While definitive evidence of a genetic basis for sexual orientation and gender identity currently remains elusive, we do a disservice to members of the LGBT community by denying the complex nature of human sexuality.  In time, despite the self-righteous proclamations of religious zealots, science will provide the answer.

Sunday, June 14, 2015

Magpie Invasion

Black-billed magpies are common residents along the Colorado Front Range and we often observe pairs or small flocks on our Littleton farm.  Yesterday, however, we had a full-fledged magpie invasion, consisting of thirty or more birds.  All were adult in size and their feeding activity was erratic; indeed, they spent most of the afternoon noisily moving about the property.

Breeding magpie pairs are thought to be monogamous (at least for several seasons) and pair off by late winter to build their nest.  Using the same territory each year, they generally produce six young which fledge by late summer.  Local non-breeding birds, most of which are yearlings, account for about half of the magpie population and wander about in flocks, a behavior that improves their chance of survival and their opportunity to secure a breeding partner; such flocks also include older magpies that are widowed or were displaced from a previous partner.  Magpies are also known to congregate at the site of a dead magpie (so called "magpie funerals") but I could not find a carcass to explain yesterday's gathering.

The flock moved on by early evening and not a single magpie visited the farm today.  Presumably, they have moved on to greener pastures though most magpies remain within a few territories of their birth site in the course of their lives.  Such a limited range is made possible by their aggressive nature and their omnivorous diet; the latter consists of insects, larvae, seeds, nuts, grain, eggs, fruit, carrion, nestlings, lizards, small snakes, frogs and mice (not to mention discarded human food).

Saturday, June 13, 2015

Woodhouse's Toad

On my many hikes at South Platte Park, I occasionally run across a Woodhouse's toad, especially during their breeding season of April through June.  This medium sized toad inhabits Central and Western regions of North America, from the Great Plains through the Intermountain West and from the Canadian border to Mexico; four subspecies have been recognized.

Like most toads, they prefer riparian corridors where vegetation provides cover and attracts insects and where seasonal pools and ponds are available for breeding.  Primarily nocturnal, Woodhouse's toad is best identified by the sheep-like bleating of the males and is best observed at dawn or dusk.  During the day, these amphibians burrow into loose soil or leaf litter to escape the drying effects of the intense western sun; deeper burrows are utilized for winter hibernation.

In Colorado, Woodhouse's toads inhabit stream channels across the Plains, riparian corridors of the Piedmont and foothill canyons to an elevation of 8000 feet.  They consume a wide variety of insects and other invertebrates and are preyed upon by herons, raccoons and snakes.

Friday, June 12, 2015

Climate Change & Human Migration

We humans evolved about 130,000 years ago in East Africa; at that time, the last of the Pleistocene's warm interglacial periods was underway.  As a result, for the first 50,000 years of our history, humans were confined to Sub-Saharan Africa, hemmed in by vast deserts to the north and deep seas to the east, south and west.

Then, about 80,000 years ago, the climate began to cool and the Wisconsin Glaciation began.  As the Continental and mountain glaciers enlarged, sea levels fell and a cool, wet climate caused vegetation and active streams to appear across the deserts.  In concert, humans spread from Africa, moving along the southern coast of Asia and into the Middle East; Pleistocene land bridges opened as sea levels fell, providing access to southern Indonesia, Japan and the Americas.  By the peak of the Wisconsin Glaciation, some 20,000 years ago, man had colonized all Continents except Antarctica.

From that nadir of the global climate a steady warming occurred, glaciers retreated and sea levels rose.  Accelerated by human activity, especially by our use of fossil fuels, global warming is now threatening polar ecosystems and will soon have dramatic effects on island nations and coastal regions across the globe.  As sea levels rise by 25 feet between now and the end of the Century, lowlands will be inundated by the oceans and saltwater will spread far into estuaries, deltas, coastal wetlands and our larger rivers.  Humans living in coastal areas will be displaced inland, triggering the second major climate-related migration in our history; there they may face other challenges imposed by global warming, including droughts, severe storms and food shortages.  Mass extinction, induced by the alteration or destruction of natural habitats, will unfold as well, placing additional stress on human populations.

Thursday, June 11, 2015

A Three-pronged Attack

Two days ago, just after noon, a blue jay began to shriek from a treeline behind our Littleton house.  He was soon joined by three other jays and I assumed that their frantic cries were triggered by an owl, a hawk or a cat.  Indeed, blue jays are the watchdogs for many neighborhoods across the country, aggressively chasing raptors and other predators from their territory.

In this case, the jays were soon joined by a pair of robins and a few broad-tailed hummingbirds; the whistling calls of the latter tiny birds, while well-intended, were a bit comical.  Unable to see the agent of their distress, I walked past the corner of the house to get a better look.  Suddenly, a sharp-shinned hawk bolted from a stand of lilacs, no victim in his talons.  As he made a beeline for one of our larger Siberian elms, the jays, robins and hummingbirds joined in pursuit, calling as they trailed the accipiter.

After perching in the elm for a few minutes, tormented by his noisy pursuers, the sharpie flew beyond the limits of our farm.  Chasing him from the property, the courageous defenders then re-convened at the site of the initial threat, basking in the glory of their successful attack.