Thursday, November 30, 2017

Vanishing Lakes

An article in the New York Times this week highlighted the gradual disappearance of the Great Salt Lake.  While one might suspect global warming is the cause, the article points out that the diversion of inflow for irrigation and other human activities is the primary culprit.

No doubt, climate change has long played a role in both the formation and disappearance of lakes.  During the cold, wet climate of the Pleistocene, massive lakes covered most of the Great Basin (see Lake Bonneville and Lake Lahontan) while glaciers scoured out lake basins across the northern half of North America (the Great Lakes and Finger Lakes offer prime examples).  As the climate warmed during the Holocene (now augmented by human activity), the Great Basin lakes shriveled in size, waxing and waning in response to the mountain snowpack and human consumption; how future global warming will affect the snowpack remains uncertain but the pressure of a burgeoning human population will clearly be a problem.

Lakes have long been transient features of Earth's landscape, forming in the wake of floods, landslides, glacial erosion, volcanism and tectonic rifting.  Their disappearance may result from diminished inflow, increased evaporation, catastrophic drainage (e.g. from earthquakes) or the gradual deposition of sediments that fill in their basin; the later is a common problem in man-made lakes and reservoirs where dredging is eventually required.

Tuesday, November 28, 2017

Eruption of Mount Agung

Mount Agung, 9944 feet, is in western Bali.  One of 78 active volcanoes in Indonesia, its last major eruption occurred in 1963 but another is expected within the next few weeks.  Earthquakes developed on and near the volcano back in September and the release of smoke and ash has been intermittent throughout October and November.

The volcanic islands along the western and southern edge of Indonesia have formed as the Indo-Australian Plate has been subducting beneath a southeastern extension of the Eurasian Plate.  As it is forced downward, toward the Earth's mantle, the leading edge of the subducting plate melts and plumes of magma push up through the crust of the overriding plate.  Initially producing a volcanic island arc, the ongoing subduction and volcanism has culminated in the large islands that we observe today (Sumatra, Java, Bali and others to their east).

Another major eruption of Mount Agung will likely produce widespread devastation but will not come close to the effects of Mount Toba's eruption, on Sumatra.  That supervolcanic eruption, which occurred 74,000 years ago, temporarily cooled the Earth's climate and had a major impact on the human population of our planet; indeed, a significant percentage of early humans had left Africa and colonized the southern rim of Asia by that time (see The Toba Winter).

Friday, November 24, 2017

A Holiday Skunk

Yesterday afternoon, as our family gathered for a Thanksgiving meal, a striped skunk was observed, ambling across our farm.  Festivities were placed on hold as everyone watched the solitary creature, not often seen on a sunny afternoon.

Indeed, striped skunks are primarily nocturnal, though they may be encountered at dawn or dusk.  Omnivorous, they feast on insects, small mammals, eggs, seeds and fruit.  During the colder months, they utilize abandoned dens or dig one for themselves; there they wait out periods of severe weather but often emerge to forage during warm interludes.  Rarely killed by fox or coyotes, skunks may fall prey to great-horned owls, hawks, golden eagles or, of course, automobiles.

Striped skunks breed in late winter or early spring.  During that time, the male may gather a small harem and defends his territory.  Litters generally range from four to eight pups and the newborns are weaned within two months; the family breaks up by late summer and the young disperse to establish territories of their own.  Striped skunks range across most of North America, from southern Canada to northern Mexico.

Thursday, November 23, 2017

Thanksgiving Visitors

On this morning's survey of our Littleton farm, I encountered a large flock of bushtits, roaming among the junipers and pinon pines.  These small, energetic birds are often observed in sizable flocks but their presence is erratic.

Twittering as they scour mixed woodlands, they feast on insects and their larvae, providing a valuable service for homeowners and foresters alike.  Despite their small stature, bushtits are hardy creatures and can be observed along the Front Range during all seasons; some years, they nest on our property, constructing a "sock nest" from a variety of natural and man-made materials.

I am always grateful when they visit the farm and can't help but be inspired by their energy and cheerfulness.  Just another gift to acknowledge on this Thanksgiving Day.

Saturday, November 18, 2017

Counting Ducks

On this cold, sunny morning, I took part in the first winter waterfowl count of the season at South Platte Park.  Organized by personnel at Carson Nature Center, the counts occur monthly through the colder months, documenting the number and variety of waterfowl that winter at the refuge.

While the highlight of this weekend is a massive flock of common mergansers on Cooley Lake (estimates were over 900 at one point), our group was assigned several of the "Middle Lakes" which are on my routine eBird survey route at South Platte Park.  American wigeon were most abundant, followed by northern shovelers and gadwall.  Other species included Canada geese, mallards, hooded mergansers, buffleheads, common goldeneyes, American coot, ring-billed ducks, green-winged teal, two northern pintail and a lone pied-billed grebe.  Of course, a couple of hours in the field offers the opportunity to observe other species as well and we were fortunate to observe an immature bald eagle as it flapped across the refuge, no doubt looking for a potential meal of duck. 

Replicated throughout the country and across the globe, bird counts are conducted primarily by volunteers and are important in assessing the health and distribution of avian populations.  Such data fuels the protection of natural habitat, documents the effects of human activity and, in the case of waterfowl, helps to establish hunting regulations and restrictions.

Friday, November 17, 2017

The Art of Listening

Effective communication is vital to human relationships and the art of listening is its key component.  While we admire those who can express their ideas in efficient or creative ways, communication is a two-way street and an attentive listener is equally important.

Too often, we humans equate communication with debate.  But debate is all about winning an argument and the debater listens just enough to formulate his or her counterattack.  Waiting to pounce on their opponent, the debater only gleans the highlights of the points that are made.

Unfortunately, most humans are more comfortable being the speaker than the listener.  Intimately connected to their own ideas, beliefs and experience, they easily become disinterested (if not bored) with the stories or reasoned arguments of others.  The art of listening is the ability to stay engaged, focusing on what is being said (without prejudgment) and willing to fully consider the views of the speaker.  If we all adopted that art, human communication would be greatly improved and the spectrum of intellectual logjams, such as the one that stymies the U.S. Congress, would be cleared from the paths of personal growth and human progress.

Thursday, November 16, 2017

A Summer Day in November

An atmospheric ridge over the Western U.S., combined with downsloping, southwesterly winds east of the Front Range, has brought summer-like conditions to Metro Denver in the middle of November; our afternoon high today was 74 degrees F.

Anyone who has not spent much time in this region likely imagines Denver to be a cold and snowy place; after all, it is the gateway to many ski areas.  But, while it may snow here from September through early June, we enjoy a relatively mild, sunny climate.  Warm weather interludes, like today's, occur throughout the colder months and are often followed by brief periods of rain or snow.

Indeed, the weather of the Front Range urban corridor is all about wind direction.  As storm systems approach from the west, we often receive downsloping, southwesterly winds ahead of the cold front; as the air is forced down from the Continental Divide to the Piedmont, it compresses, dries out and heats up, producing the summer-like conditions.  But once the storm moves east of the Divide and onto the High Plains, we usually receive upsloping, northeasterly winds; as the air is forced to rise by the regional topography, it cools down and it's moisture condenses as rain or snow.  In fact, rain and chilly air are forecast to arrive by tomorrow afternoon. 

Wednesday, November 15, 2017

Goose Season

Returning to Colorado a few days ago, I noticed a significant increase in the Canada goose population since I left town in late October.  While the arrival of wintering geese has been late in recent years, the current flocks are right on schedule, apparently chased southward by potent cold fronts and snowstorms up north.

Of course, many suburbanites, park managers and golfers are not thrilled by the influx of our messy Canadian neighbors but some of us enjoy watching their large, noisy flocks as they move above the urban corridor.  Typically arriving in early November, the wintering geese occupy the region until early spring when they begin their journey to breeding grounds across Canada and the Northern Plains (see Front Range Geese).

The arrival of wintering Canada geese is of interest to birders for another reason.  Though they account for the great majority of geese along the Front Range, other species often get caught up in their autumn migration.  Just yesterday, I observed a snow goose in one of the flocks and a variable number of greater white-fronted geese join the Canadas each year.  Cackling geese, nearly identical in appearance but smaller in size and smaller billed, often mingle with the Canada geese; once thought to be a subspecies, they are now recognized as a separate species that breeds farther north and west than their larger cousins.

Tuesday, November 14, 2017

Males & Sexual Abuse

The recent spate of sexual abuse revelations involving men (politicians, pundits, broadcasters and entertainers, among others) offers clear evidence that we humans are part of the animal kingdom and that our large brains do not always protect us from ingrained animal behavior.

Throughout the animal kingdom, from invertebrates to mammals, the primary role of the male is to impregnate as many females as possible.  This often involves combat with other males (which may prove fatal), coercive behavior toward females and, in some cases, the instinct to kill the offspring of other males.  In almost all species, the male engages in sexual dominance, which may include the gathering of harems, and he plays a minimal role in nurturing and raising the young.

Early humans, like our hominid ancestors, most likely practiced polygamy.  As our civilization advanced, laws were established to protect families, women and children, though the nature of these laws (and their enforcement) varies widely among human cultures.  Unfortunately, the male sexual drive, influenced by parenting, personal experience and psychological factors, often overrides these social constraints (especially when those individuals occupy positions of power) and sexual abuse repeatedly occurs.  While knowledge of our natural history should not serve to condone such behavior, acknowledging male traits and tendencies is the first step in dealing with this issue.  Appropriate law enforcement, counseling and zero tolerance must then follow.

Monday, November 13, 2017

Iran-Iraq Earthquake

A magnitude 7.3 earthquake struck the Iran-Iraq border region yesterday; the initial death toll is over 450 individuals and is almost sure to rise.  The quake occurred in an active tectonic zone where the Arabian Plate is colliding with the Eurasian Plate.

About 40 million years ago, the Red Sea began to open, rifting the Arabian Plate from the African Plate; this rift continues southward as the East African Rift that will eventually split the Continent.  Twenty million years later, during the Miocene Period, the Gulf of Aden began to open as well and the combined forces of these active rifts zones are pushing the Arabian Plate to the NNE; its collision with the Eurasian Plate has been crumpling up the mountain ranges of Iran and Turkey, a process that continues today.

While the tectonic drift of continents is too slow for humans to observe during our brief life spans, the sudden release of pressure along fault lines, resulting in earthquakes, attests to the massive forces involved in this process.  Having sculpted the surface of our planet long before our species evolved, we must now live with the consequences of plate tectonics (See also The Eurasian Mountain Arc).

Sunday, November 12, 2017

Swans at Phillips Lake

On this damp, cloudy and chilly morning, my wife and I decided to take a walk around Perry Phillips Lake, in south Columbia.  After all, from now through the end of January, Eagle Bluffs Conservation Area is occupied by duck hunters and Phillips Lake is one local alternative for those hoping to observe migrant waterfowl.

To our surprise, two swans turned up as we circled the lake, gliding across the calm waters.  Initially assuming they were trumpeter swans that are increasingly common in the Heartland (see Midwest Trumpeters), I zeroed in with my binoculars.  I noticed that they had pinkish bills with black tips, indicating a juvenile status, and could not find a yellow spot at the base of their bills, present in most (but not all) adult tundra swans.  On the other hand, their necks extended straight up from their chests without the curve typical of trumpeter swans.  They also seemed a bit slim for trumpeters, especially when they flew away at the end of our visit, and leg bands were not observed as they passed overhead (most reintroduced trumpeters are banded).  Unfortunately, the visitors remained silent and thus could not be identified by their calls.

Distinguishing juvenile trumpeters from juvenile tundra swans is a bit of a challenge for most birders, especially when a direct, simultaneous comparison cannot be made in the field.  While tundra swans are far more numerous in North America, most migrate to coastal estuaries and relatively few are encountered in the Heartland; then again, a fair number turn up along the Missouri and Mississippi Valleys.  By contrast, trumpeter reintroduction programs have become widespread across the Upper Midwest and this largest species of American waterfowl is increasingly common in the Heartland.  I'm leaning toward the decision that this morning's visitors were juvenile tundra swans but, either way, it was a pleasure to see them.

Friday, November 10, 2017

Irruption of Crossbills

Over the past few weeks, red crossbills have been reported across Metro Denver and here in central Missouri; no doubt, these irruptive migrants have been spotted in many other areas of the U.S. as well.  Residents of Southern Canada, New England, the Great Lakes region and the Western Mountains, red crossbills occasionally appear at lower elevations or in more southern latitudes.

Irruptive species, while usually non-migratory, expand their territory when food (seeds, berries or prey) becomes scarce in their homeland; the scarcity may be do to normal fluctuations in prey populations, severe weather, insect blight, wildfire or, perhaps, climate change.  Red crossbills are among the more common irruptive migrants and have been known to nest outside their usual breeding range if they encounter sites with a large supply of pine cones; indeed, this species may nest during any season of the year.

On the other hand, irruptive species tend to be restless, moving about the landscape in search of food.  Here one day and gone the next, they are often a source of frustration for hopeful birdwatchers, as a friend and I found out yesterday.

Thursday, November 9, 2017

Thomas Hill Reservoir

Located about ten miles southwest of Macon, Missouri, Thomas Hill Reservoir was formed by damming the Middle Fork of the Little Chariton River.  The 4950 acre lake and the surrounding Conservation Area are on property owned by the Associated Electric Cooperative, which built the reservoir to providing cooling water for its power plant.

For those who live in the region, Thomas Hill Reservoir is best known for its excellent fishery and birders flock to the lake to observe resident and migrant bald eagles, gulls, terns and waterfowl.  Today, accompanied by a friend and fellow birder, I had the opportunity to view several sections of the reservoir; there we observed two large rafts of lesser scaup, joined by smaller flocks of buffleheads, coot, hooded mergansers, redheads and northern shovelers.  A large number of Bonaparte's gulls wheeled above or settled on the choppy waters and small groups of pied-billed grebes foraged in the shallows.  Other sightings included two bald eagles, a red-shouldered hawk, a northern harrier, great blue herons, ring-billed gulls, double-crested cormorants, killdeer, Wilson's snipe, mallards and a lone northern pintail.

A unique feature of Thomas Hill Reservoir is a warm channel near the power plant that remains open through the winter months.  This unnatural hot-tub concentrates wintering waterfowl and is always a good place to look for rare vagrants that might wander into north-central Missouri.

Tuesday, November 7, 2017

A Ruckus of Robins

On this raw November morning, a large congregation of American robins had taken over part of the Columbia Audubon Sanctuary.  Concentrated along the creek, the massive flock created both a visual and an auditory spectacle.

Flying between the stream and the surrounding trees, the robins attracted many other species, including a large flock of cedar waxwings.  The sudden appearance of a barred owl only added to the frenzy, drawing in a blue jay posse that soon dislodged the raptor with their raucous calls.  Other attendees included a yellow-rumped warbler and a ruby-crowned kinglet among more common avian residents.

Non-birders associate American residents with their well-trimmed lawns where these common thrushes hop about, stalking earthworms.  But during the winter months, when the surface soil hardens and the worms move to deeper layers, robins gather in large flocks that wander about, feasting on berries or scouring the soggy soil of wooded marshlands.  This morning's chilly, damp weather surely intensified their activity.

Saturday, November 4, 2017

Cuyahoga Valley National Park

Since the rain had stopped and sunshine returned to northeastern Ohio, my wife and I headed over to Cuyahoga Valley National Park this morning.  Formerly a National Recreation Area, established in 1974, the preserve became a National Park in 2000; the refuge stretches along 22 miles of "the Crooked River" Valley, between Akron and Cleveland.

Entering via westbound 303, west of Hudson, we first stopped at the Happy Days parking area and hiked southward and upward to the magnificent Ledges, outcrops of Pennsylvanian Sharon Conglomerate that offer broad views of the Cuyahoga Valley.  Heading north along the River, we then stopped at the Boston Mills Visitor Center before heading over to Brandywine Falls near the east edge of the Park where a wooden stairway offers spectacular views of the cascade.  After a lunch in Brecksville Station, we continued northward along the Cuyahoga and then climbed eastward through the scenic gorge of Tinkers Creek, where overlooks, scenic waterfalls and picnic areas are connected by a hike-bike trail.

The Buckeye Trail cuts through Cuyahoga Valley National Park and the Towpath Trail follows the Ohio & Erie Canal that parallels the river from Cleveland to Akron; constructed in 1827, the canal was abandoned as railroads offered more efficient freight transportation in the 1860s.  In addition to the scenic topography, interesting geology and historical features of the Park, stands of Canadian hemlock (remnants of the Pleistocene) mix with the hardwood forest, offering a rich diversity of habitat for resident wildlife.

Friday, November 3, 2017

Kent State Wetlands

Obtained from the Frank family in 1967, Stark Pond has since become the centerpiece of an Environmental Education Center at Kent State University, characterized by riparian woodlands, cattail marshes and spring fed ponds.  The 200 acre refuge, accessed by a paved hike-bike trail, stretches along the southeast edge of the campus.

Today, I used that trail to explore the wetland.  Despite the cool, cloudy weather, I encountered an excellent variety of birds, including wood ducks, gadwall, pied-billed grebes and a host of songbirds; among the latter were white-throated and song sparrows, dark-eyed juncos, northern cardinals, downy and red-bellied woodpeckers and blue jays.  American robins were especially common in the riparian woodlands, feasting on berries, insects and earthworms.

The highlight of my visit was a red-shouldered hawk, surveying the scene from a dead tree.  Often associated with marshlands, this buteo typically hunts from a perch, looking for small mammals, snakes and a variety of amphibians.  Huddled in the chilly air, he was clearly the king of this wetland.

Thursday, November 2, 2017

Autumn at Sandy Lake

We have returned to my wife's family cottage on Sandy Lake in northeastern Ohio.  Autumn colors are peaking though a gray overcast and intermittent showers have cast a pall on the annual display.

Hiking around the lake this afternoon, I encountered the usual mix of permanent and winter residents, including mallards, great blue herons, belted kingfishers, red-bellied woodpeckers, black-capped chickadees and dark-eyed juncos.  A tardy double-crested cormorant was fishing on the choppy waters and blue jays were especially numerous and conspicuous in the lakeside woodlands.  Ospreys, common here during the warmer months, have apparently departed for warmer climes and bald eagles, present throughout the year, did not make an appearance on this mild, cloudy day.  The highlight of my walk was a lone golden-crowned kinglet, foraging in thickets along the inlet canal.

We'll spend a few days here before returning to Missouri and I hope to visit other birding hotspots before we leave town.  More on those excursions in the coming days.