Wednesday, June 26, 2019

Into the San Juan Watershed

From Wolf Creek Pass (elevation 10,850 feet), in the southern San Juan Mountains, I left the Rio Grande watershed and entered that of the San Juan River, the Great River of the Navaho Nation.  Following a steep descent to Pagosa Springs, U.S. 160 fords the San Juan and begins to undulate westward through the foothills, crossing the Piedra, Los Pinos and Florida Rivers in sequence (all tributaries of the San Juan River); in doing so, the highway gradually moves away from the high wall of the Southern San Juans Mountains.

Nearing Durango, however, the road offers spectacular views of the La Plata Mountains, sculpted from a massive granite dome, which rise northwest of the city.  On the eastern side of Durango, I turned south on US 550, driving atop then within the canyon of the Animas River, among the largest tributaries of the San Juan.  With every mile toward the south, the landscape became noticeably drier, characterized by sage grasslands and mesas covered with piƱon-juniper woodlands.

The Animas River joins the San Juan in Farmington, New Mexico, where I will spend the night, and the latter continues westward to Shiprock.  From there, it bows northwestward, passing near the Four Corners Monument before reaching Bluff, Utah; beyond that town, the San Juan snakes westward to join the Colorado River within Lake Powell.  Tomorrow, my wanderings will remain in the San Juan watershed until I cross a low divide between Cortez and Dolores, Colorado, thereby entering the watershed of the Dolores River.

Tuesday, June 25, 2019

Southwest to the Four Corners

Looking ahead to several days with no commitments, I have decided on a road trip to the Four Corners region, where the States of Colorado, New Mexico, Arizona and Utah meet.  Though I have been to that area in the past, there are several routes through its varied landscape that will give me a new perspective on the terrain and topography.  Now that we have entered the summer tourist season, I will skip Mesa Verde National Park which I had the pleasure to visit almost thirty years ago.

Geologically, the Four Corners is a land of volcanic features, superimposed on uplifted and eroded late Paleozoic and Mesozoic sediments.  Tributaries of the Colorado River drain the landscape; the San Juan rises from numerous rivers and creeks along the south flank of the the San Juan Mountains and then heads westward to join the Colorado in Lake Powell while the Dolores River drains the west flank of both the San Juans and the Uncompahgre Plateau as it flows NNW to merge with the Colorado northeast of Moab, Utah.  Other prominent natural features include Ship Rock (a remnant volcanic neck), Sleeping Ute Mountain, the  La Sal Range (east of Moab) and the Chuska Mountains (on the New Mexico-Arizona line).

Planning to leave Denver early tomorrow morning, I will follow U.S. 285 southwest, crossing Kenosha Pass to drop into South Park.  From there, the highway crosses Trout Creek Pass to enter the Upper Arkansas River Valley and then turns southward, climbing over Poncha Pass to reach the broad San Luis Valley.  Within that valley I will switch to U.S. 160, heading west and then southwest, climbing along the South Fork of the Rio Grande River to Wolf Creek Pass.  Beyond that pass, a long descent will take me through Pagosa Springs and into Durango, where I will likely spend the first night.  More details in coming posts.

See also: San Juan Volcanism

Monday, June 24, 2019

Yellow Sweet Clover

Perhaps due to our wet spring, stands of yellow sweet clover are especially large and brilliant along the Front Range this year.  That fact, combined with questioning from a friend, encouraged me to look into the origin and nature of this plant.

Native to Eurasia, yellow sweet clover is a legume and not a true clover.  It is a biennial plant, having a two-year life cycle; during the first year it is low-growing and flowerless while, in its second year, it produces branching stems, up to six feet tall, adorned with racemes of small, yellow, fragrant flowers.  The latter, which bloom from June to September, yield seeds that may be viable for up to 35 years if conditions for germination are not ideal; for that reason, yellow sweet clover is often invasive in areas with poor, dry soil.  A deep tap root also makes the plant drought tolerant and, like other legumes, sweet clover improves soil quality by adding nitrogen to the soil through its root system.

Known to provide large amounts of nectar for honeybees, yellow sweet clover has also been used to stabilize soils and to provide nutritious forage for livestock.  However, this plant contains coumarin, an anticoagulant used in the production of warfarin and rat poison; low-coumarin subspecies have thus been developed for use in hayfields and pastures. 

Sunday, June 23, 2019

Mulberry Days

The mulberries are finally ripening on our weeping mulberry and large mulberry trees, about two weeks late due to our relatively chilly spring.  The wildlife, unlike myself, have been more than patient but are now indulging with gusto.

American robins, house finches and fox squirrels are always the primary consumers, joined by cedar waxwings, blue jays, magpies, Bullock's orioles, spotted towhees and, if they are still around, western tanagers.  Indeed, almost all of our avian and mammalian residents partake of the tasty fruit at some point.

Drought tolerant, mulberry trees are ideal for semi-arid landscapes and our wet spring may have taken a toll; a dead branch or two adorn most of the trees and one of our larger mulberries appears to be on its way out.  But I have learned to wait before taking a saw to these trees; they are notoriously late to leaf out in spring and may appear dead well after our other trees are green and flowering.  Needless to say, I am very pleased that our mulberry days have finally arrived!

Saturday, June 22, 2019

Insect Control on the Farm

As I have mentioned in the past, we do not use insecticides on our Littleton, Colorado, farm.  However, we do host hundreds of assistants that keep the insect population in check, working for nothing more than their meals.

Chickadees, nuthatches, bushtits, woodpeckers, warblers, gnatcatchers, catbirds, house wrens, western tanagers and Bullock's orioles glean insects from the trees and shrubs.  Flycatchers, Say's phoebes, cedar waxwings, tree and barn swallows, broad-tailed hummingbirds and western kingbirds snare them from mid air, joined by little brown bats and common nighthawks at dusk.  American robins, crows, starlings, grackles, flickers, blue jays, magpies, kestrels and spotted towhees scour the ground for insects and grubs, assisted by garter snakes, lizards and the occasional toad.  Even a few insects (primarily dragonflies, ladybird beetles and wasps) take part, not to mention most spiders.

In return for their work, we offer a wide diversity of native foliage (including berry crops), brush piles, a source of fresh water and an insecticide-free landscape.  Quite a deal for us and a choice that all property owners can easily make in our joint effort to protect the environment.

Thursday, June 20, 2019

Back in Drier Country

After ten days in the soggy Midwest, I am back at our Littleton, Colorado, farm, enjoying drier air and warm temperatures.  While the greenery here reflects an unusually wet spring, we are not dealing with flooded rivers and muddy landscapes.

On the other hand, late afternoon thunderstorms continue to lash the region, disrupting air traffic and posing the threat of damaging hail.  Indeed, as I write this post, a severe thunderstorm over Denver International Airport is slowly drifting eastward, allowing arrivals and departures to resume.  Other storms tower east of the Front Range, creating an atmospheric wall that is forcing air traffic to be routed well to the north and south of our region.

But away from these brief and widely scattered downpours, there is no humidity to suppress outdoor activity and sunny skies dominate in most areas.  Unlike the Midwest, we are far from the plume of Gulf moisture that storm systems tap as they move across the country; in addition, the mountain ranges to our west "take out" precipitation arriving from the Pacific.  Our semiarid climate may come with spring snow, June thunderstorms and a late summer monsoon, but I'll take the dry air, cool nights and abundant sunshine.

Tuesday, June 18, 2019

Flooding and Our Future

Driving back from Northeast Ohio, where heavy rains had brought Sandy Lake, southeast of Kent, to a record level and closed local roadways, we passed through flooded terrain from central Ohio to eastern Missouri.  Every creek and river was bank-full or had spilled across its floodplain and rain was still falling in most areas; across the water-logged fields, crops were unplanted or well behind schedule.

Of course, extensive flooding in the Missouri, Arkansas and Mississippi Valleys has been in the news for months, including structural damage in towns and cities and disruption of agriculture and transportation in those massive watersheds.  Meanwhile, hurricane season is underway and the first tropical system of the year brought torrential rains to the western Gulf Coast.  Even if they dodge tropical storms and hurricanes, coastal cities are threatened by rising sea levels, a problem that will only worsen over the coming decades.

Mention global warming and most humans (assuming they accept the science) worry about drought and water shortages.  Those problems will certainly be severe in some regions but warmer air can transport larger quantities of water from oceans and lakes, providing more fuel for thunderstorms, snowstorms, tropical storms and hurricanes.  Combined with coastal flooding from rising seas, which is already displacing human settlements across the globe, excessive precipitation may be the primary threat unleashed by climate change.

Monday, June 10, 2019

The Nature of Family Reunions

Since I depart for my wife's family reunion in northern Ohio today, I have been thinking about the nature of such events.  Of course, families are very limited in nature since, in most species, the young disperse early in life to prevent inbreeding; indeed, with few exceptions, unicellular organisms, invertebrates, fish, amphibians and most reptiles never even meet their parents.

Families, as we know them, only exist in certain birds and mammals and humans are among the few species to retain long-term familial relationships.  Throughout most of our history, a nomadic lifestyle broke up extended families and, even today, a global economy has encouraged (if not required) the spatial separation of family members.  One might argue that family reunions have become especially important in modern human society.

On the other hand, whatever interpersonal tensions existed during childhood tend to persist, and reunions may reignite those emotions.  Then there is the additional influence (positive or negative) that spouses and children have had on family dynamics and now "bring to the table."  It is no wonder that family reunions have been fodder for so many novels and movies (some dramatic, others comedic); I expect a little of both over the coming week.

Sunday, June 9, 2019

A Chilly Morning in June

Following a week of hot, stormy weather, a cold front dipped across the Front Range overnight, bringing cool, cloudy conditions to the region this morning.  Down along the South Platte, insectivores had once again gathered to feast on their prey above and along the fast moving waters of that relatively warm stream.

Dominating the scene were hundreds of violet-green swallow, forced down from the foothills to join their rough-winged, barn and cliff cousins; the latter have been nesting beneath the Bowles Avenue bridge since early May.  Other insectivores along the river were Say's phoebes, cedar waxwings, American robins, red-winged blackbirds, Bullock's orioles, common yellowthroats and yellow warblers.  By this late date in spring, mallards and a few common mergansers were the only waterfowl on the South Platte though double-crested cormorants have become increasingly common.

Once the intense Colorado sun breaks through the overcast, afternoon temperatures will rise to near sixty (F) and a steady recovery toward more seasonable conditions is forecast for the coming week.  On the positive side, the cool air should stabilize the atmosphere for a few days, temporarily suppressing the development of severe afternoon and evening thunderstorms.

Saturday, June 8, 2019

Matted Hair in the Brush Pile

Now that summer has set in and the bird population on our farm has stabilized for the season, I am more inclined to roam the property, looking for unusual insects and plants.  This morning, while exploring our "wild corner," I came across a clump of matted hair in the brush pile.

Initially assuming it was the remnants of a mouse or small cottontail, I used a stick to investigate further but found no bones or other material to confirm my suspicion.  I then concluded it was a type of fungus and, after some investigation, settled on a species of Phycomyces; these fungi produce long, hair-like sporangia which terminate in tiny spheres that contain the spores.  Feasting on (and recycling) a wide variety of rotting organic matter, the fungal bloom was likely triggered by our recent heavy rains.

My identification may or may not be correct but, in more than sixty years of exploring natural ecosystems, it was the first time I encountered such a fungus; just the latest confirmation that nature's diversity is endless, even for a life-long naturalist.

Friday, June 7, 2019

A Shower of Larvae

Reading outdoors early this afternoon, I had placed my chair in the shade of a large Siberian elm that overhangs our driveway.  Off to the west, a thunderstorm had begun to form and I hurried to finish a chapter before I was forced inside.

Just before my goal was realized, something struck the chair that sounded like a drop of rain; several other impacts soon followed as a breeze picked up from the approaching storm.  As it turned out, the "raindrops" were tiny, yellowish slugs, a fact that was made clear when one struck the book.  Looking around my chair, I found dozens of the larvae on the asphalt, writhing about in search of vegetation.  Before I was forced indoors by rain, a robin turned up to feast on the hapless invertebrates, efficiently picking them off the driveway.

I suspect the tiny victims were the larvae of elm-leaf beetles, known to favor Siberian and Chinese elms and to lay two broods of eggs, one in late spring and the other in late summer.  After falling from or traveling down the tree, the tiny, translucent larvae find a safe spot to pupate into the adult stage.  Of course, an asphalt driveway is not an ideal landing spot and the robin surely enjoyed the windfall. Since we do not use insecticides on the farm, there should be plenty more larvae for our resident insectivores.

Sunday, June 2, 2019

The Month without Migrants

Avid birders look forward to the spring and fall migration seasons, when seasonal residents and migrants mingle with permanent residents, greatly increasing the diversity of avian species in any given area.  By June (in the Northern Hemisphere), spring migration is usually complete and the "autumn migration" will not begin until July; one might thus suggest that June is the least interesting month for birders, especially with regard to unexpected sightings.

By mid July, shorebirds begin to migrate southward and will continue to do so for several months.  Waterfowl, songbird and some raptor migrations are underway by late summer, continuing into December for certain species of geese.  Some might argue that January is also devoid of migrants but vertical and irruptive migrations occur throughout the winter.  By February, geese, sandhill cranes, American white pelicans and other select species begin to head northward and the spring avian migration will continue through May.

That brings us back to June, a time when summer residents have settled in and, in many cases, already have a brood to raise.  June can certainly be a pleasant month to scour the fields, forests and wetlands for additions to one's personal life list but migrants (except for a straggler or two) will not likely grace the scene.

Saturday, June 1, 2019

The Storms of June

Following a period of cool, rainy weather, temperatures are heating up along the Colorado Front Range and so is the severe weather.  Indeed, severe thunderstorms and tornados generally peak in this region during the month of June.

While late afternoon thunderstorms are common from May to September, damaging hail and wind coincide with rising mid-day temperatures and a still unsettled jet stream.  Seemingly modest thunderstorms, drifting eastward from the mountains, suddenly explode into powerful monsters, ravaging all that lies beneath their path while adjacent areas, bathed in sunshine, go unscathed.

As I drove a friend to the airport this afternoon, a few showers obscured portions of the Front Range. By the time I headed home, some twenty minutes later, most had dissipated; one, however, sitting over western Arapahoe County, had fed on their energy.  Characterized by intense rain, high winds and large hail, it was drifting eastward (per the radio warning) and I changed my course to avoid its wrath.  One would be foolish to drive into that atmospheric maelstrom! 

Thursday, May 30, 2019

Olive-sided Flycatcher

Of all those brown-olive-white flycatchers that migrate through the U.S., the olive-sided flycatcher is perhaps the easiest to identify.  Relatively large, with an over-sized head, long thick bill, short tail and "vest-like" plumage on his chest, this migrant prefers to hunt from a dead limb near the top of a tree; from that conspicuous perch, he flies out to snare a large insect and then usually returns to the same spot.

Breeding in coniferous forests across Alaska and Canada and southward through mountain ranges of North America, most of these long-distance migrants winter in South America though some shorten their journey, staying in Central America.  Among the last migrant flycatchers to move through the U.S. in spring, they are most often observed in late May; apparently fond of their wintering grounds, most head south again by late August.

Olive-sided flycatchers are more common in the Western U.S. (at least in my experience) and I encountered two at South Platte Park this morning.  Seemingly sure of themselves, they are less skittish than their smaller cousins and will usually pose at close range, disturbed only by a juicy insect that flies near their perch.