Escape to North Park

Not facing any major problems on the farm this trip, I decided to visit North Park, my favorite area in Colorado. Drained by the North Platte River and its high country tributaries, this broad basin, covered with sage grasslands, hay fields and cattle ranches, is laced with ribbons of willow thickets and riparian woodlands. Indeed, North Park is known to many Coloradans as the site where moose were reintroduced in the late 1970s; since that time, those large herbivores have thrived, spreading across the Continental Divide to the Upper Colorado and Fraser River Valleys (and beyond) and transplanted to other areas of Colorado by Division of Wildlife biologists.

Offering scenic, uncluttered landscape, broad vistas, abundant wildlife and traffic-free roadways, North Park takes the visitor back to an earlier period in the history of the Mountain West, before large, congested cities, interstate highways and tourist resorts changed the character of the region. Bordered by the high walls of the Medicine Bow Mountains and Never Summer Range to the east, the Rabbit Ears Range to the south and the Park Range to the west, this glacial basin is relatively unknown to most Colorado residents and visitors, reserving its fabulous landscape for those who have a keen interest in its bounty: naturalists and hunters.

Of special interest to naturalists is the presence of the Arapaho National Wildlife Refuge, the highest refuge (8200 feet) in the lower 48 States. Encompassing over 23,000 acres of the Illinois River watershed, a tributary of the North Platte, this spectacular preserve is a mosaic of sage grasslands, ponds, wetlands, and riparian woodlands. Resident and migrant wildlife of note include moose, pronghorn, wintering elk, coyotes, badgers, greater sage grouse, prairie falcons, northern harriers, Swainson's hawks, golden eagles, white-tailed prairie dogs, a wide diversity of waterfowl and shorebirds, American white pelicans and a host of grassland sparrows; the refuge Headquarters & Interpretive Center, east of Route 125 between Rand and Walden, provides an excellent introduction to the North Park ecosystem and its varied wildlife.

Evicting the Hunter

What first drew my attention was the frenzied squabbling of house finches in a large elm near the back of our property. As I grabbed my binoculars to check out the cause for their alarm, the high pitched calls of lesser goldfinches joined the protest. Then, always looking for a good fight, a group of blue jays drifted in and their raucous voices soon echoed across the farm.

Expecting to find an owl roosting in the clump of trees, I headed back for a closer look. My approach was the final straw and a large Cooper's hawk bolted from cover, heading for another shade tree. A comical parade followed in his wake, including the finches, the blue jays and, to my amusement, a pair of broad-tailed hummingbirds, tiny but courageous. A second round of protest ensued, sending the raptor away for good.

Like other accipiters, Cooper's hawks hunt by stealth, hoping to snare an unwary songbird while zig-zagging through forest or open woodlands. Unless the initial attack is successful, the alarm will be sounded and his potential victims soon become annoying combatants, intent on evicting their nemesis from the neighborhood. This morning, the hunted were the victors.

Our Resident Mule Deer

A young doe mule deer has lived on our Littleton, Colorado farm over the past year and, this summer, presented us with a spotted fawn. Likely born in June, it did not make an appearance until July and has since bounded around our property, bleating like a lost lamb if it looses touch with its mother. The fawn will continue to nurse and keep its white spots until late summer and will then remain with mom until she is ready to deliver once again; female mule deer usually produce a single fawn with their first pregnancy but thereafter give birth to twins or, occasionally, triplets.

Mule deer are common from the High Plains to the Pacific Coast and from southeast Alaska, British Columbia and Alberta southward into Mexico. Favoring open woodlands and rocky, shrub-covered hillsides, they are easily distinguished from white-tailed deer by their large ears, stocky build and black-tipped tail. Browsers, mule deer feed on a wide variety of plant material including buds, twigs, leaves, fruit, mushrooms, wildflowers and grasses. The annual rut peaks in November and fawns are usually born in June; however, they are kept secluded for their first month of life. Natural predators of adult mule deer are limited primarily to wolves and mountain lions but disease and starvation also cull the herds and their natural life expectancy is about ten years. Young mule deer are especially susceptible to the stress of winter and fawns are often taken by coyotes, bears, bobcats and golden eagles. Of course, mule deer are avidly hunted and many others fall victim to rail or highway traffic.

Our doe and her fawn are certainly welcome to stay at the farm; with the South Platte Greenbelt close by and a large variety of plants on our property, there is little risk of significant damage and their calm demeanor in our presence is always a soothing experience. Next year, we expect twins.

The Human Era

When the Earth formed, 4.6 billion years ago, the Universe was already 9 billion years old; in other words, the Universe is three times as old as our home planet. For Earth's first billion years there was no life on the gradually cooling crust or in the primordial seas; then, some 3.6 billion years ago, bacteria-like organisms evolved, most likely in shallow, coastal waters or at "hot-smoker" vents along the mid oceanic ridges. It would be another 3.2 billion years, about 400 million years ago (MYA), that some plants and animals began to leave the ocean to colonize the land.

While the first mammals appeared in the Triassic Period, about 200 MYA, ancestral primates did not appear until the Paleocene Epoch, some 60 MYA. Another 52 million years would go by before hominids (the genus to which we belong) split from chimpanzees and man would not walk the Earth until 150,000 years ago (per the earliest estimate). Roaming about and living in small clans for most of our history, humans finally began to establish permanent towns about 10,000 years ago; this marked the rise of human culture, domestication, cultivation, established trade routes and our first significant impact on other species. Since then, advances in agriculture, industrial production, technology, communication and travel have led to the growing problems of habitat destruction, pollution, resource depletion and man-induced extinctions.

Put in perspective, the Human Era covers only the last 10,000 years of Earth's 4.6 billion year history. Yet, in that brief time, we have managed to place the future viability of our planet at risk. Some say we are the pinnacle of God's creation, the chosen species. Looking at the scientific evidence, one might argue that we were sent to destroy nature's handiwork; let's hope we evolve into more intelligent and insightful creatures before we fulfill that assignment.

Irene's Welcoming Party

After several uneventful years and a slow start to the current season, the hurricane stuntmen from the Weather Channel have taken up posts along the East Coast, from the Carolinas to New England, ready to bring us eyewitness reports on the devastation wrought by Hurricane Irene. Now churning off the Georgia shore, the storm is forecast to move northward across eastern North Carolina and then sweep across the heavily populated corridor of the Northeast. While Irene has weakened to a Category 2 storm, her wind field is very broad and storm surge is the major concern, potentially bringing catastrophic flooding to coastal areas.

With bags packed since the first of June, the weather stuntmen (and stuntwomen) are waiting for the opportunity to stand in the wind and rain while, at the same time, are admonishing coastal residents to heed warnings and evacuate the region. If luck holds, they will be in the right spot to endure the brunt of the storm and, if their antics are dramatic enough, end up on future Weather Channel newsreels of severe weather events. Jim Cantore, the acknowledged king of weather disaster reporting, is stationed in New York City where Irene's impact could be especially devastating.

For all of the good work that the Weather Channel performs in the interest of public safety and education, it is prone to place too much emphasis on entertainment and its heroic hurricane stuntmen send the wrong message to citizens who, too often, are reckless in the face of threatening storms. Indeed, the Channel has spawned the dubious industry of storm chasing which, unfortunately, places entertainment ahead of science and personal safety. Let's hope that Irene veers out to sea and leaves the stuntmen safe, dry and disappointed.

Powder River Basin

On my recent journey through Nebraska and eastern Wyoming, I was amazed at the number of coal trains that were streaming eastward; each more than a mile long, the trains were spaced by no more than a few miles. Originating at surface mines in the vicinity of Gillette, Wyoming, this caravan delivers a million tons of coal per day to power plants across the central and eastern U.S.

The Powder River Basin is defined by both its geography and its geology. Covering most of northeast Wyoming and part of southeast Montana, the basin stretches between the Bighorn Mountains of north-central Wyoming and the Black Hills of western South Dakota. Its southern border is the topographic divide between the North Platte watershed, to the south, and the watersheds of the Powder and Cheyenne Rivers to the north; more northern parts of the basin are also drained by the Tongue and Little Missouri Rivers. Geologically, the Powder River Basin is a broad bowl of Precambrian basement rock that gradually filled with sediments from the Paleozoic, Mesozoic and Cenozoic Eras; Cretaceous sandstones and shales, deposited by an inland seaway, form the thickest layer of sediments and lie just beneath Paleocene coal, the remnant of vast swamps and peat bogs that covered this region 60 million years ago. Compressed by younger Tertiary sediments, the plant debris turned to coal, since brought near the surface by the Miocene Uplift and subsequent erosion.

Powder River Basin coal, desired for its low sulfur and ash content, provides 40% of the coal used in the United States. Unfortunately (for coal advocates), much of this coal, buried under thick layers of Tertiary rock, is not economically accessible; nevertheless, seams near the surface should last for another 20 years or so and mining leases are still being granted by the U.S. government. While most Americans remain dependent on coal for their electric power, environmentalists continue to push for cleaner, renewable sources of energy; the Powder River Basin is, after all, the leading source of carbon-bearing fuel in our country.

Crescent Lake NWR

Crescent Lake NWR, in Nebraska's western panhandle, is certainly one of our more remote National Wildlife Refuges. Take your pick: 28 miles north of Oshkosh (on US 26, northwest of Ogallala) via a winding, sand-gravel road or 28 miles south of Lakeside (on Route 2, east of Alliance) via a single lane of asphalt; during my three hour tour I encountered only a refuge employee in his pickup and the driver of a cattle truck. Whatever route you take, the visit will be well worth your effort (just make sure you have plenty of gas in the tank).

Stretching across 46,000 acres in the westernmost section of Nebraska's famous sandhills ecosystem, Crescent Lake National Wildlife Refuge protects a chain of lakes and wetlands that lie in valleys between the grass-covered dunes. Established in 1931, the refuge provides nesting habitat, wintering grounds or a migration reststop for at least 279 bird species. Nesting birds of note include eared and western grebes, American bitterns, tundra swans, canvasbacks, bald eagles, sharp-tailed grouse, black-necked stilts, American avocets, long-billed curlews, Wilson's phalaropes, black terns, burrowing owls, marsh wrens and blue grosbeaks, among many other species. High Plains grassland residents, best observed along the roadways, include northern harriers, Swainson's hawks, American kestrels, dickcissels, lark sparrows, lark buntings, vesper sparrows, grasshopper sparrows, bobolinks, yellow-headed blackbirds and both eastern and western meadowlarks. Flocks of American white pelicans soared above the refuge yesterday morning and I also encountered a large number of white-faced ibis; late summer is also ideal for shorebird watching and Crescent Lake NWR attracts a wide variety of resident and migrant species.

In addition to the birdlife, this scenic preserve is home to coyotes, swift fox, white-tailed and mule deer, pronghorns, muskrats, kangaroo rats and an excellent variety of reptiles and amphibians; yellow mud turtles inhabit the preserve and bullsnakes are often encountered on the roadways. Of interest, Crescent Lake itself actually lies just south of the refuge boundary and is protected by the State of Nebraska; efforts to establish a sandhills wilderness area, just east of the refuge, are currently under consideration.

The Eastern U.S. Quake

Since we tend to associate earthquakes with active plate margins, as occur along the Pacific Rim, in southern Asia and in the Mediterranean, many Americans along the Eastern Seaboard and Midwest were surprised by today's quake, centered in Virginia. But the truth is, there are few places on Earth (if any) that are immune to earthquakes.

Indeed, both New England and the Southeastern Piedmont are, geologically speaking, a puzzle of exotic terrains, plastered to the "stable" craton during the Precambrian and early Paleozoic Eras, hundreds of millions of years ago; for that matter, the craton itself has old suture lines from the earliest days of continent formation. Though relatively quiescent when compared to the active faults of the Pacific Rim, these cemented pieces remain under pressure as the Atlantic continues to open and both subduction and lateral compression occur along the West Coast. Minor readjustments go unnoticed but more powerful slips, especially when relatively shallow, get our attention. In addition, these old continental fragments, welded together for eons, conduct pressure waves better than the relatively loose contact zones out West and, as a result, are felt across a broader area; indeed, today's quake was felt from South Carolina to Toronto.

While quakes from old suture lines are more likely to be isolated and, in general, less powerful, aftershocks may occur as pressure is transferred down the fault line. Planning for and living with earthquakes is not just a problem for our neighbors in California and Alaska as today's quake (and yesterday's in Colorado) remind us.

A Road Less Traveled

Heading back to Colorado, I decided to take a different route from Columbia since the landscape along I-70 has long been committed to memory. The alternative, hardly off-the-beaten-path, was to take I-29 north from Kansas City and then I-80 west from Omaha.

Driving north on I-29, my decision was rewarded by a spectacular lightening display over eastern Kansas. Just north of Mound City, Missouri, flooded fields began to appear, attracting huge flocks of egrets and white pelicans; then, at Rock Port, I-29 was closed almost all the way to Council Bluffs, the victim of persistent flooding along the Missouri River. A one hour detour took us across the hills of northwest Missouri and southwest Iowa, carpeted with crop fields and studded with wind farms. After finally crossing the Missouri at Omaha, I soon crossed the Platte River as well; though some sandbars broke the surface, the Platte was full and sluggish, presumably due to backup from the Missouri River, just downstream.

I would not encounter the Platte River again until I reached Grand Island, which lies between its meandering channels. From Grand Island westward, I-80 is paralleled by the Platte; its scenic, braided waterways, dunes and woodlands provide a welcome diversion from the monotony of crop fields and, nearing North Platte, the River's broad floodplain becomes sharply defined as the High Plains escarpment looms to the south and a landscape of sand hills stretches off to the north. Tomorrow morning, I plan to leave the Interstate highway to visit Crescent Lake National Wildlife Refuge, in western Nebraska.

Morning Nighthawks

Over the past week, I have noticed an increasing number of nighthawks on my walks to work, flapping and calling in the cool morning air. An obvious explanation is that the days are waning; two months after the summer solstice, I am now heading out into the faint light of dawn. Since nighthawks are crepuscular, hunting for flying insects at dawn and dusk, their morning routine has shifted with the diminishing period of sunlight.

Another reason is that these fair-weather birds are getting restless as their fall migration rapidly approaches. Now that the day length is comparable to that of late April, when they begin to arrive in North America, they likely sense that it's nearly time to leave. Indeed, large flocks of nighthawks will begin to circle southward in the coming weeks, ensuring that they escape to South America before the chilly nights of autumn kill off their prey.

As an observor who has lived at the same general latitude for my entire life, I have always been fond of nighthawks and have spent many hours watching their erratic flight across the evening sky. But I suspect that my attraction is rooted in the seasonal travels of these aerial acrobats, arriving as the warmth of May rescues us from a long, cold winter and departing as the cool evenings of late August and September bring a reprieve from the heat and humidity of a seemingly endless summer.

North American Porcupines

Favoring mixed woodlands, the North American porcupine is found from Alaska to New England, southward through the Appalachians (to Tennessee and Virginia), across the Upper Midwest and throughout the Western U.S., from Canada to Mexico; prone to wander, these large rodents may also be encountered along wooded valleys of the Great Plains. Solitary for much of the year, porcupines mate in early autumn and a single kit is born in mid spring; though it will nurse for several months, the newborn is able to forage soon after birth and remains with its mother through the summer.

Sporting a dense undercoat with thick guard hairs, the porcupine is best known for the hollow, barbed quills that cover most of its body, an effective defense against many predators; those carnivores that feed on porcupines, including coyotes, fishers and bobcats, learn to attack their face or abdomen, the only areas devoid of quills. A nocturnal life style and the habit of resting in trees during the day also offer some degree of protection for these slow moving rodents, which are active year-round and may live for ten years or more.

Porcupines are herbivores and consume a wide variety of plant material, including twigs, buds, berries, nuts and tender vegetation; during the winter, they also feast on conifer needles and bark. Known to crave salt, these "quill-pigs" often wander into towns to nibble on axe handles, oars, plywood and other sweat-tainted items; this craving also tempts them onto highways where, unfortunately, they soon join the motley assortment of roadkill.

The Largest Fish on Earth

Compared to its marine cousins, the whale shark, the largest fish on Earth, is a relative newcomer to the ocean ecosystems of our planet. While ancestral sharks and boney fish appeared in the Devonian Period, some 375 million years ago (MYA) and modern sharks arose in the Jurassic (160 MYA), current fossil evidence suggests that whale sharks did not evolve until the early Tertiary Period, about 60 MYA; ironically, this was the same time that their unrelated namesake, the mammalian whales, where returning to the sea.

Solitary for much of the year and known for their long migrations, whale sharks favor tropical and subtropical seas where they filter-feed near the surface, scooping in plankton, krill, small squid and small fish with their wide mouths. They do congregate at certain feeding grounds during specific times of the year, drawn by the seasonal spawning of coral or by plankton blooms; perhaps the most famous whale shark rendevous is at the Ningaloo Reef, off the west coast of Austalia.

Often exceeding 40 feet in length and weighing over 20 tons, whale sharks live for 70 years or more (perhaps as much as 120 years). Females give birth to hundreds of live young, each about 2 feet long; those that survive predation by other sharks and large fish will be sexually mature by the age of thirty. Despite bans, adult whale sharks are hunted by various human cultures, especially in Southeast Asia. Since they move slowly and feed near the surface, they are also prone to injury from motorized boats and, like many other marine species, have become the target of eco-tourism.

Geology of Australia's Blue Mountains

The beautiful city of Sydney, Australia, sits on a thick slab of Triassic Hawkesbury sandstone, some 200 million years old. Below this bedrock are older Triassic sediments, shales, mudstones and conglomerates of the Narrabeen Group. All of these deposits, swept into the Sydney Basin by ancient rivers, lie atop Permian strata; containing seams of coal, these latter rocks were emplaced about 250 million years ago, when Earth's land masses had merged into the mega-continent of Pangea.

Just west of the Sydney metropolitan area are the scenic Blue Mountains, a broad, dissected plateau that rose during the Jurassic Period, some 170 million years ago, when Australia was still part of Gondwanaland. The geologic strata of the plateau is identical to the bedrock below Sydney; Triassic sandstone, capped at high points by Miocene basalt, forms massive cliffs which sit atop the older Narrabeen Group and underlying Permian deposits. Metamorphosed Paleozoic rock, from the Silurian and Devonian Periods, lies at the base of the Mountains.

As this elongated block of crust warped upward, vertical fractures developed in the sandstone cap, setting the stage for magnificent canyons to erode through the plateau as streams and rock falls gradually widened the gaps. Now home to a spectacular diversity of plant and animal life, much of the plateau, a component of the Great Dividing Range and named for the blue haze produced by its eucalytus forests, is protected as a World Heritage Area.

Glacial Lake McConnell

Near the end of the Pleistocene, about 11,800 years ago, a massive lake formed across the Northwest Territories of Canada, extending southward into northeast Alberta and northwest Saskatchewan. Occupying a broad basin between the mountains to the west and the retreating Wisconsin Glacier to the east, its shape and size changed continuously, a balance between the inflow of meltwater and evolving drainage patterns due to glacial deposits, ice dams and periodic floods. The maximum extent of Lake McConnell, reached about 10,500 years ago, was 210,000 square kilometers (about 2/3 the size of glacial Lake Agassiz, to its southeast).

Inflow to Lake McConnell came primarily from the lobes of the continental ice sheet but also from mountain glaciers to the west and directly from Lake Agassiz via a corridor now occupied by the Clearwater and lower Athabasca Rivers; indeed, geologic evidence suggests that these large glacial lakes were intermittently connected and that water flowed in either direction, depending on the region's changing hydrology. At times, Lake McConnell drained southeastward into Lake Agassiz while, during other periods, the connected lakes drained northwestward, into the Arctic Ocean via the MacKenzie River. Eventually, as the ice retreated and the land rebounded, this connection was lost and both lakes began to diminish in size.

While Lake Winnipeg is the primary remnant of Lake Agassiz, a trio of Canadian lakes have been left in Lake McConnell's wake: Great Bear Lake, the largest in Canada, Great Slave Lake, the deepest in North America (2014 feet), and Lake Athabasca. All three of these postglacial lakes now drain to the Arctic Ocean via the MacKenzie River system.

Gust Fronts

The tragedy at the Indiana State Fair this weekend, in which at least five persons were killed, was caused by a gust front. As many of us have surely noticed, the strongest winds from an advancing line of thunderstorms often arrive before the rain and lightening; caught off-guard, those killed or injured in Indiana may have been waiting for the rain before seeking shelter.

Thunderstorms generally form just ahead of an approaching cold front, drawing in the warm, moist air that lies in their path. Swept into the upper atmosphere, this cargo of moisture precipitates and plunges to the ground as heavy rain within the storm. Rain-cooled air accompanies this rainfall and, upon striking the ground, is forced outward in all directions; in advance of the storm, these high velocity winds produce a gust front, often reaching 60-70 mph, which arrives before the storm itself. A shelf cloud signals the presence of this rapidly moving, cold air, as warm, humid air is displaced above it, creating the cloud.

Since gust front winds move out in all directions, they may impact adjacent or trailing storms, depriving them of warm, moist inflow and causing them to dissipate. But it is the leading gust front that is of major concern to humans, plowing down trees, barns and, as we saw in Indiana, outdoor structures.

An Evening Buffet

Granted a mild, sunny evening, we headed down to the Forum Nature Preserve, a local, prairie-wetland refuge that we ignored in recent weeks due to the oppressive heat and humidity. In our absence, the prairie grasses had grown to five feet or more and were now adorned with the golds and purples of late summer: goldenrod, yellow coneflowers, black-eyed susans, thistles and blazing star. Indigo buntings sang from atop the prairie saplings while goldfinches and yellow-billed cuckoos foraged across the woodland border.

But the highlight of this evening was at the large seasonal lake, which, following two months of excessive heat, had nearly evaporated, leaving a broad, shallow, meandering pool. Frogs and turtles peered from the deeper areas and small fish splashed about, desperate to find a path to safety. Taking advantage of this evening buffet, great blue and green-backed herons, stalked the shallows, feasting on the hapless victims, while, along the expanding mudflats, killdeer, spotted sandpipers and a host of migrant shorebirds, fed on aquatic invertebrates, exposed by the shrinking lake.

Away from this center of activity, white-tailed deer browsed in the fading sunlight, nighthawks circled overhead and a barred owl called from the creekside forest. Were it not for a persistent and annoying horsefly, it would have been a peaceful, evening stroll.

Backyard Crustaceans

Mention crustaceans and most of us think of aquatic creatures such as lobsters, crabs, shrimp and crayfish. But, unless you reside in an arid environment, you have many crustaceans in your own backyard.

Pill bugs, known affectionately as rollie pollies, have segmented bodies like their aquatic cousins but have the unique ability to curl into a tight sphere when threatened. Since they, like other crustaceans, breathe through gills, they must remain in moist areas and are typically found beneath logs, rocks, leaf litter or man-made structures; they might also be encounterd in the moist recesses of your garage or basement. Pill bugs feed on a variety of organic matter, such as rotting vegetation and carrion, and thus play an important role in recycling nutrients; while they also feed on living plants, they are rarely a problem for gardeners.

After mating, the female pill bug produces up to a hundred eggs or more, which are carried in a brood pouch for almost a month. Once these eggs hatch, the tiny offspring, miniature replicas of the adult are on their own; each will molt at least five times before reaching adult size and, unless consumed by birds, toads, spiders or other predators, may inhabit our yard for up to three years.

The Suburban Hibiscus

As the color of spring and early summer begins to fade and the greenery looses its luster, Hibiscus syriacus, commonly known as Rose of Sharon, begins to bloom, adorning the suburban landscape through early autumn. Late to leaf out in the spring, this Asian shrub produces large, showy flowers after most cultivated plants have already gone to seed.

Favoring full sun or partial shade, this plant is drought tolerant and thrives in the dry, sunny climate of the Front Range; we have multiple cultivars on our Littleton farm, with flower colors ranging from white to pink to light blue. Beyond providing a colorful display, the flowers of Hibiscus syriacus attract hummingbirds, butterflies and other insects, and are thus especially appealing to the backyard naturalist.

Seed pods, which overwinter on this shrub, contain numerous, fuzzy seeds that, in moist, warm, climates, can be a nuisance, yielding a forest of seedlings each year; this is less of a problem in more northern or semiarid regions, where the seeds are more likely to be consumed by wildlife than to germinate. Of course, for those of us who prefer wild borders to manicured fencelines, natural proliferation is never a concern.