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Showing posts from April, 2016

Avocets at Eagle Bluffs

A dozen American avocets graced Eagle Bluffs Conservation Area this morning, feeding in a shallow pool with blue-winged teal, American coot and a host of shorebirds.  Having wintered along the Gulf Coast or in Florida, they are headed for ephemeral wetlands, alkaline lakes and prairie ponds across the High Plains.  Many of those that winter in Mexico breed in the Intermountain West while permanent populations reside in the Central Valley of California.

These elegant birds, equipped with a long, up-curved bill, feed on aquatic invertebrates, sweeping the shallows to locate their prey.  Monogamous for the breeding season, avocets are highly territorial, aggressively defending their offspring from intruders and predators.  Following elaborate mating displays, the nest is placed on the ground, generally within a shallow scrape near the edge of a lake or pond; 3-4 eggs are normally laid though avocets sometimes parasitize the nests of black-necked stilts (and vice versa).

American avocets …

The California Cascades

According to the USGS, there are more than 500 volcanic vents in California.  The great majority of these are located in the northernmost portion of the State where the southern end of the Cascade Range extends across the Oregon border.  Seven hundred miles long, the Cascade Volcanic Arch began to form 37 million years ago as the Juan de Fuca Plate and its associated microplates (all remnants of the Farallon Plate) were subducting beneath the North American Plate; this process continues today as demonstrated by the spectacular eruption of Mt. St. Helens in 1980.

The Cascades of California result from the subduction of the Gorda Plate, a southern fragment of the Juan de Fuca Plate.  Mt. Shasta (14,179 feet) is second in size among modern Cascade volcanoes (exceeded only by Mt. Rainier) and, over the past 4000 years, has been the second most active of the major Cascade volcanoes (exceeded only by Mt. St. Helens).  Lassen Peak (10,461 feet), which last erupted from 1914-1917, sits among …

The Nuthatch Warbler

When you're warbler hunting and a nuthatch catches your eye, look again!  Black-and-white warblers are often mistaken for nuthatches due to their habit of creeping along tree trunks and large limbs, searching the bark for insects, spiders and their larvae.  Easily observed and identified (unlike many of their cousins), they are aggressive birds, often chasing other insectivores from their feeding site.

Fairly common summer residents of deciduous and mixed forests in the eastern U.S. and southern Canada, they are often encountered in suburban woodlots and city parks during migrations.  Once in their breeding territory, these agile arborists place their nest on the ground, hiding the cup of vegetation beneath understory shrubs, in rock crevices or among fallen limbs; nuthatches, by contrast, nest in tree cavities.

As chilly autumn nights spread south through the Continent, black-and-white warblers head for warmer climes where their prey remains active; their wintering grounds extend…

The Missouri Plateau

The Missouri Plateau is an unglaciated region of the Great Plains of North America, extending from central Montana and northeast Wyoming across western portions of North and South Dakota.  Bounded by glaciated plains to its north and east, by the Rocky Mountains Province to its west and by the High Plains to its south, the Plateau is drained by the the Missouri River and tributaries arriving from the south and west: the Yellowstone, Little Missouri, Grande, Moreau, Cheyenne and White Rivers.

Since the Missouri Plateau is coated with relatively soft Tertiary sediments, eroded from the Rockies, many of these tributaries have produced "badlands" along their valleys; the most famous of these, protected within Badlands National Park, was eroded by the White River of southwestern South Dakota.  The most prominent geographic feature within this province, however, is the Precambrian dome of the Black Hills, that rose through the younger sediments.  Another region of topographic reli…

Backyard Safaris

Our property in Columbia, Missouri, is of modest size but has enough variety of foliage and landscape to attract an interesting diversity of creatures.  Raccoons, opossums, cottontails, squirrels, field mice, shrews, moles and occasional white-tailed deer are among the mammalian residents and visitors.  Amphibians and reptiles include American toads, garter snakes and blue-tailed skinks and, of course, we host the usual mix of resident and migrant birds.  Then there are the various insects, spiders and crustaceans that, in the end, are of most interest to young children.

Indeed, having grandchildren sets the stage for regular backyard safaris.  While the excursions are not always successful when it comes to finding reptiles and mammals, these mini-adventures are sure to turn up a variety of interesting creatures.  Our oldest grandson has become an amateur birder (spurred on by the gift of a field guide) while his younger brother is most fascinated with ladybugs, daddy-long-legs and ro…

Prince & Ecuadorans

A few days ago, upon learning of the tragic earthquake in Ecuador, I tuned into our "most reliable" cable news network to get the details.  Unfortunately, they were waiting for a news conference with Donald Trump; worse yet, they have given the tragedy very little attention ever since, deferring primarily to coverage of dysfunctional American politics.  This is despite the fact that nearly 500 persons were killed in the earthquake and the economy of Ecuador will likely suffer for many years to come.

Yesterday, the news of Prince's death, an icon of American music, sent that channel into overdrive, providing continuous coverage of his career, a commitment that lasted most of the afternoon and evening and resumed this morning.  While his contribution to music was surely significant and his life deserves tribute and coverage by the mainstream media, the current ongoing marathon is clearly the product of American celebrity worship (and the dollars that it brings) not a journ…

A Grove of Warblers

On my tour of Eagle Bluffs Conservation Area this morning, the expected mix of birds was found.  Blue-winged teal were abundant, joined by lesser numbers of northern shovelers, American coot, gadwall, wood ducks and mallards.  Shorebirds included greater and lesser yellowlegs, common snipe, spotted sandpipers, pectoral sandpipers and a small flock of dowitchers.  The resident bald eagles (2 pair) were present and I encountered the first green herons of the season.

The highlight of my visit occurred on my way out when I noticed two small birds flitting about a grove of trees that line the central channel.  Pulling over for a closer look, I soon discovered that the grove was alive with small insectivores; yellow-rumped warblers were most abundant, joined by palm warblers, Tennessee warblers, prothonotary warblers, a northern waterthrush and a pair of blue-gray gnatcatchers.  Among these relatively common species was a lone male blackpoll warbler.

This collection of small, colorful songb…

Beautiful but Deadly

Over the past week, several clumps of star-of-bethlehem have appeared in our flower beds and along our wood border.  Also known as grass lilies, these beautiful immigrants are native to Eurasia; they escaped cultivation in North America and are now widely dispersed in moist, Temperate regions of the Continent.

Characterized by showy, white, star-shaped flowers and grass-like leaves, star-of-bethlehem produces small seeds but reproduces primarily by division of their bulbs; like daylilies, these geophytes are thus often found in dense clumps.  Botanists have long argued whether this wildflower should be grouped with lilies, hyacinths or members of the asparagus family; depending on latitude, they bloom from April to early June.

As is often the case in the plant world, the beauty of grass lilies comes with a price.  All portions of the plant are toxic to mammals (humans included) and this wildflower, which often adorns pastures, has been known to kill livestock.

The Best Birding Month

Most birders across Temperate latitudes of North America would likely agree that April is the best birding month of the year.  While migrant swans, geese and cranes move through in February and March, the waterfowl migration is peaking as April begins.  Winter visitors and residents can still be found through the middle of the month and permanent residents are especially active and conspicuous in April due to the onset of their breeding season.

Shorebird migrations peak during April and summer songbirds begin to arrive early in the month; by mid April, a mix of winter and summer residents join permanent residents in our parks, suburbs and refuges.  As the winter birds begin to depart, migrant and summer songbirds arrive in increasing numbers; among these are the first waves of warblers and flycatchers, which can be difficult species to identify.  Fortunately, nature provides some assistance as leaves remain rather small and unobtrusive throughout most of April.

By the end of the month…

Deluge in Houston

The ongoing deluge in Houston, Texas, is the product of a stalled cold front in East Texas and a "blocking high" over the eastern U.S.  The latter dome of high pressure has caused the cold front to become stationary and, at the same time, is funneling a plume of Gulf moisture into the area.  In the Northern Hemisphere, winds flow clockwise around high pressure domes and, in this case, are sweeping across the Gulf of Mexico and into Metro Houston; there, the cold front lifts the moisture-laden air, producing copious precipitation.

In northwest Houston, more than 15 inches of rain have fallen, 5 inches more than the previous record for the entire month of April.  As one might expect, severe flooding is widespread, snarling traffic, damaging structures and threatening lives.  As I write this post, the dome and its moisture plume are slowly shifting eastward and rain is beginning to dissipate in the city.

Indeed, the western edge of the high pressure dome is now entering Louisia…

Ecuador's Subduction Earthquake

A massive earthquake struck the Ecuador coast, northwest of Quito, yesterday evening.  Triggered by pressure release between the South American and Nazca Plates, the magnitude 7.8 quake was 20 times more powerful than the most recent 7.0 earthquake on Kyushu Island, Japan.

The Nazca Plate, a remnant of the Farallon oceanic Plate, is subducting beneath the South American Plate along the western coast of that Continent; the volcanic Andes Mountain Range formed (and continues to form) as the leading edge of the Nazca Plate melts near the outer surface of the Earth's mantle.  As the Nazca Plate advances (about 2 inches per year), friction builds between the Plates; this may release as a series of small quakes or as a mega-thrust event as occurred this weekend.

Numerous aftershocks typically follow such mega-thrust subduction earthquakes and have done so in this case.  To date, more than 260 persons have been killed and more than 2500 have been injured; considering the power and extent…

The Kyushu Earthquake

The islands of Japan sit at the convergence of four major tectonic plates: the Eurasian, North American, Pacific and Philippine Plates.  Throughout most of their history, the Pacific Plate was moving northwestward, bringing in terranes and producing volcanic island arcs as it subducted beneath the North American and Eurasian Plates.

About 45 million years ago, the movement of the Pacific Plate shifted to a westward direction (as evidenced by the angle change of the Hawaiian Ridge), creating the Philippine Plate as the Pacific Plate began to subduct along the Izu Bonin Trench.  Surrounded by subduction trenches, the Philippine Plate now subducts beneath the southern half of Japan (which lies on the Eurasian Plate), including Kyushu Island, fueling volcanic activity and triggering earthquakes.

This week's earthquake on Kyushu Island, which killed at least 9 and injured hundreds, was a magnitude 6.2 quake, centered beneath the Island just west of Kumamoto.  While subduction forces in…

Mid-Day Nature Walk

In general, mid-day nature walks are not very productive during the warmer months, especially if you hope to encounter a good variety of wildlife.  But when you're locked out of the house and your spouse is not due home for two hours, what's a guy to do?

So I headed down to Forum Nature Area, in Columbia, and sauntered along the two-mile loop; fortunately, my decision was rewarded.  Chipping sparrows, the first I have encountered this season, were abundant along the tree line while eastern bluebirds and eastern phoebes hunted on the central meadow; northern cardinals, red-bellied woodpeckers and white-throated sparrows were especially noisy in the floodplain woodlands.  Cricket frogs and leopard frogs called from the shallows of the seasonal lake and American toads trilled from an adjacent pond.  Blue-winged teal, mallards, song sparrows and turkey vultures were also encountered but the highlight of my visit was a yellow-throated warbler feeding in a grove of sycamores; close …

First Warbler!

Attempting to read on the back deck this afternoon, I looked up to see the first migrant warbler of the season, flitting about, high in a neighbor's tree.  Don't ask me what it was.

I immediately knew it was not one of the yellow-rumped warblers that winter in our area; they are somewhat larger and more methodical in their feeding habits.  It seemed to have a yellowish breast with no streaking and I think it had a faint wing-bar or two; from some angles, it seemed to have a narrow eye ring.  I know it had a brownish-green back or maybe it was a dark shade of olive.  Watching from a distance with my binoculars, I am reluctant to be more precise, especially since the bird never sat still for more than a second.  I'm guessing it might have been a female pine warbler or maybe an immature female bay-breasted warbler.  Such is the joy and challenge of warbler watching!

One might think that after 40 years of birding I would be embarrassed to admit my confusion but I've never …

The Homewreckers Arrive

As color explodes and birdsong intensifies across central Missouri, the first pair of brown-headed cowbirds arrived on our property.  Moving about the yard, the male engaged in his courtship display, anxious to mate with his bride; unfortunately, neither is willing to accept parental responsibilities.

Throughout the warmer months, the female will lay eggs in the nests of other songbirds; once they hatch, the young cowbirds, often larger and more aggressive than their nest mates, are raised by the adoptive parents, who may lose some of their own offspring in the process.  By turning over parental duties to other birds, cowbirds augment their breeding efficiency and boost the population of their own species.

Birders thus tend to despise these homewreckers, empathizing with the exploited parents.  But nature is neither fair nor sentimental and her web of life is festooned with unpleasant and seemingly cruel forms of animal behavior.  In the case of cowbirds, their instinctual disruption …

A Morning for Snipe

On this stormy morning at Eagle Bluffs Conservation Area, a dense cloud deck blocked out the April sun, extending the dim light of dawn.  Such conditions are favored by common snipe, chunky, long-billed "shorebirds" that inhabit inland swamps and wetlands of North America and Eurasia.  Breeding in Alaska, Canada and the Pacific Northwest, these reclusive birds winter across central and southern latitudes of our Continent.

A fair number were observed at Eagle Bluffs this morning, probing mudflats and flooded fields for a wide variety of invertebrates.  Drawn from the cover of cattails and marsh grass by the relative darkness (they generally feed at dawn and dusk), the snipe mingled in the shallows with lesser yellowlegs, American golden plovers, killdeer and blue-winged teal.  The latter ducks were abundant at the refuge, outnumbering American coot, northern shovelers, green-winged teal and lesser scaup on the lakes and pools.  A few dozen American white pelicans were present…

Encounter at Fossil Lake

On my frequent trips between Colorado and Missouri, I always glance at a small lake just south of the Russell, Kansas, Exit.  The lake reliably attracts a variety of seasonal migrants, including gulls, snow geese, American white pelicans and double-crested cormorants.

This morning, on my way back to Missouri, I decided to stop for a closer look and found that Fossil Lake is easily viewed from a central, paved roadway and from dirt-gravel roads to either side.  A large flock of cormorants and several pairs of Canada geese were observed on the deeper waters, to the east, while the western shallows had attracted small flocks of northern shovelers, blue-winged teal and green-winged teal and a restless flock of western sandpipers; a great blue heron stalked the shoreline and a pair of marbled godwits huddled on a mudflat.

Turning around near the end of a graveled lane, I was approached by an older gentleman in classic farmer's garb; concerned that I may have invaded his property, I was…

The Nature of Statesmanship

A statesman (or stateswoman), unlike typical politicians, provides leadership by inspiring confidence, offering well-considered policies and demonstrating the willingness and capacity to work with those who oppose his/her positions.  Rather than ridiculing opponents by questioning their motives or competence, the statesman relies on personal skills and persuasive ideas to attract supporters.

Generally calm, thoughtful and well-informed, the statesman shuns brash comments and avoids bombastic arguments.  Inclined to think before she speaks and drawing on long-held beliefs, the statesman does not readily change her position but remains receptive to new, evidence-based information.  Neither is he likely to ignore or ridicule data that is derived from scientific research; mysticism does not inspire or influence a statesman's judgment.

While a few of our current Presidential Candidates have demonstrated moments of statesmanship, most fall back on the traditional tools of American polit…

Dust Storms & Wildfires

It was mild and sunny along the Front Range urban corridor this morning but a dense band of clouds obscured the Continental Divide to our west.  Arriving just after noon, this cold front unleashed strong winds, gusting to 50 mph.

In many areas across Metro Denver, plumes of dust were generated by the winds, a common development in this semiarid region; quarries, construction sites and plowed fields often provide most of the particulates.  The winds themselves were the product of high pressure across the Pacific Northwest and low pressure over the Southern Plains (currently centered over southeastern Colorado); as the front pushed across the city, intense winds plummeted from the Front Range and scoured the Piedmont, dropping temperatures from the mid 60s F to the upper forties.

Far to our southeast, wildfires are burning across Oklahoma, aggravated by dry vegetation, air temperatures in the mid 80s F and potent winds ahead of the same cold front.  Since the atmosphere over the Great P…

A Disappointing Survey

On this mild, sunny morning along the Colorado Front Range, I decided to submit my first checklist report to eBird from South Platte Park, a refuge that I have birded hundreds of times over the years.  I chose my usual loop in the southern portion of the Park, which takes me along the river, past several lakes, across a wooded ridge and up to South Platte Reservoir.  Given the weather conditions, I had reason to expect a large number of birds and a wide variety of species.

Unfortunately, my expectations were not met.  Of the 23 species that I encountered, only American robins, red-winged blackbirds and buffleheads were abundant; I did observe my first tree swallows of the season (at this particular site) and certainly enjoyed the walk.  The only unusual observation (and the highlight of the morning) was the presence of three long-tailed ducks on the reservoir; in fact, long-tails have graced the Park for the past several winters.

Filing my report on the eBird website, I was a bit disa…

Bushtit Thievery

Bushtits are common residents and visitors on our Littleton, Colorado, farm but their numbers vary widely throughout the year.  This week, a single pair has been twittering about the property and, on this warm, sunny morning, I noticed that they were constructing a nest.

Using a wide variety of soft natural materials (including spider webs), nesting bushtit pairs construct a hanging, sock-like nest; this project may take several weeks or more and is usually placed in a conifer.  Other bushtits may assist with the construction and, once the job is completed, are permitted to sleep in the nest with the parents and their offspring (until the eggs hatch and the young fledge); a second brood and social sleep-in may follow, using the same nest.

Known to use human materials for their nests as well, our current pair has located a source of insulation material, retrieved from a crack in the garage wall.  As I sat reading (sort of) beneath the adjacent crabapple tree, the bushtits made dozens o…

A Roof-top Heron

Working on our Littleton, Colorado, farm this afternoon, I was accompanied by the usual mix of birds.  House finches, blue jays and black-capped chickadees invaded the feeders, northern flickers delivered their hysterical calls, common bushtits flitted about the shrubbery, robins stalked the pastures, downy woodpeckers tapped on dead snags and a variety of juncos foraged along the driveway.

Then, as I was dragging snow-broken limbs back to our brush pile, a great blue heron flew low overhead before landing on the peak of a neighbor's roof.  While I have encountered these common waders in a wide variety of habitats throughout all seasons (most do not migrate to southern climes) and though they often perch on docks, channel markers and wood duck boxes, I had yet, in my forty years of birding, seen one land on the roof of a house.  Tall and slender, the great blue certainly looked out of place on the roof-top, reminding me of European storks that nest on village roofs; after taking i…

Born Again Naturalists

We are all naturalists at birth.  Functioning in response to our instincts and nurtured by our parents, we are stimulated by our surroundings and nourished with the products of plants and animals that share our planet.

As we approach school age, however, human mysticism invades our world.  Rather than retaining an intimate relationship with nature, we are taught that man is distinct from its realm, endowed by a divine creator with dominion over our planet and its many species.  Our focus is directed toward human welfare which, we learn, includes protection from the dangerous wilderness that surrounds, threatens and may ultimately destroy our civilization.

Fortunately, as we achieve physical and intellectual independence, many of us reject human mysticism.  We conclude that man is an integral part of nature and that the welfare of our species is directly tied to the health and diversity of natural ecosystems; we also realize that scientific progress is vital to understanding and foster…