Snow before the Arctic Blast

Following several mild, sunny days along the Front Range, snow is expected to arrive this evening and last through much of tomorrow.  It will develop along the leading edge of the latest Polar Vortex as it sinks across the Heartland, eventually bringing freezing temperatures as far south as the northern Gulf Coast.

When these domes of dense, Arctic air plunge southward, they often track east of the High Plains, guided by the topography of the Continent.  On occasion, as will occur this week, they back up against the Front Range and slide southward along the mountains.  In general, this pattern brings frigid air to the urban corridor but does not usually produce much snow.

On the other hand, the cold, dense air may sit in place for several days until displaced by a new Pacific Front.  Unfortunately, the intense Colorado sunshine pierces the atmosphere at a low angle in mid winter and adds little warmth under such conditions. 

Clouds of Longspurs

Crossing the frozen, snow-covered Plains today, I witnessed large, swirling clouds of longspurs; though I could not identify their species as we raced along the Interstate, they were most likely Lapland longspurs.

These songbirds breed on the Arctic tundra and winter primarily across the Great Plains, unfazed by the frigid temperatures and strong winds that they encounter.  Scouring shortgrass prairie, fallow fields and crop stubble for seeds and waste grain, they often gather in massive flocks that burst into the air when disturbed.

By March, it is too mild on the Plains for these hardy birds and they begin their long journey back to the Arctic; there they consume countless insects, feeding many to their nestlings.  Slow to head south in the fall, they generally arrive on the Great Plains in November.  

An Arctic Visitor

Arriving with the latest winter storm, a rough-legged hawk was hunting on the farmlands east of Columbia yesterday morning.  Perched atop a small tree, as is typical for this open-country raptor, our visitor from the Arctic was unfazed by the cold wind.

Nesting on Arctic cliffs, these hardy hawks feed primarily on lemmings and their population waxes and wanes in concert with the availability of their prey.  Rough-legged hawks winter across the northern half of the U.S. but are most abundant on the High Plains where the topography mimics their home territory.  Indeed, I encounter dozens of these hunters on winter trips between Missouri and Colorado but generally observe only a few (at most) near Columbia throughout the colder months.

It is always reassuring to watch an Arctic native when frigid air and heavy snow invade the Heartland.  Though we retreat to our heated homes and vehicles, this hawk seems to relish the chill, even shunning the protection of dense winter forest. 

An Early Shorebird

Earlier this week, I encountered a flock of pectoral sandpipers at Eagle Bluffs Conservation Area, foraging on a mudflat along a marsh-lined channel.  They were the first migrant shorebirds that I have observed this year.

Indeed, pectoral sandpipers are among the earliest spring migrants; having wintered in South America, they are headed for the Arctic tundra of Alaska and Canada.  These medium-sized sandpipers feed primarily on insects and aquatic invertebrates and are most often seen in open wetlands or on flooded fields.  On their breeding grounds, nests are nothing more than a scrape in the tundra surface.

While we impatiently wait for the chilly, wet month of March to end, these hardy, long-distance travelers assure us that spring is already underway.  By the time we are enjoying the warmth and color of April and May, they will be settling into their Arctic digs.  

The Arctic Sparrow

This morning, while driving along a country road, I encountered a flock of American tree sparrows, scouring the gravel for seeds.  These attractive songbirds, easily identified by their rusty cap and central breast spot, are winter residents across the northern two-thirds of the Lower 48.

Despite their name, American tree sparrows breed across the Arctic tundra and adjacent scrublands; in fact, they breed farther north than any other American sparrow.  Nests are placed directly on the ground and adults forage primarily on grasslands or in thickets and shrubs.  Insects and seeds are consumed while they are in the Arctic but their diet is limited to seeds on their wintering grounds.

Indeed, these hardy sparrows migrate south rather late in the fall and are among the first songbirds to head north in the spring (often by early March).  On the other hand, they are fairly common here during the winter months; just don't look for them in trees!

Black-bellied Plovers

Black-bellied plovers are medium-sized shorebirds that breed in the High Arctic and winter on warm coasts of all Continents except Antarctica.  While their breeding plumage is striking (see photo), their winter plumage is a drab mix of gray and white.

Usually observed alone or in small groups, black-bellied plovers often mingle on beaches with larger flocks of shorebirds, including sanderlings, willets and red knots.  While their cohorts tend to be skittish, these plovers are rather tolerant of human beach-combers, tending to walk away when approached.  When left alone, they scour the sand for insects, small mollusks and various marine invertebrates.

Black-bellied plovers are usually observed in breeding plumage just before and during their migration to the Arctic.  On occasion, however, non-breeding and immature birds sport their handsome coat on southern beaches during the late spring and summer months, as we observed on Longboat Key yesterday.

Death on the Initial Journey

Tundra swans, formerly known as whistling swans, breed along the Arctic Coasts of Alaska and Western Canada.  Monogamous, adult pairs remain together throughout the year and raise up to seven cygnets each summer.  Fledged within two months, the young remain with their parents through the first winter and disperse the following spring.

Most tundra swans winter on estuaries along the Pacific Coast (from Alaska to Northern California) or along the Mid Atlantic Coast.  Smaller numbers head for wetland areas of the Desert Southwest and Southern Plains and some move south along the Colorado Front Range en route.  Over the past few weeks, a lone immature tundra swan settled on a lake at South Platte Park; clearly he/she became separated from the family or could not keep pace due to a congenital or acquired illness.  Indeed, in recent days, several birders noted that the visitor seemed to be ill and, this morning, it was dead, lying on the shore of the lake.

Tundra swans have an expected natural lifespan of 15-20 years.  Obviously, our visitor did not survive his/her initial journey from the Arctic, perhaps succumbing to a genetic defect or perhaps poisoned by the careless activity of humans.  A life cut short is always a sad event but when the victim is a beautiful and graceful long-distance migrant, the death seems especially tragic.

Cackling Geese

On my walk along the South Platte this morning, I encountered a large flock of cackling geese, resting on the river.  Prior to 2004, these "small Canada geese" were considered to be subspecies of their larger cousins.  They are now classified as a separate species though they, themselves, are represented by several subspecies.

After nesting on the Arctic tundra of Northwest Canada and Alaska, cackling geese winter in the Pacific Coast States or in the south-central U.S.; their numbers seem to be increasing along the Colorado Front Range, both during migrations and throughout the winter.  When mingling with Canada geese, cackling geese are relatively easy to identify due to their smaller size, stubby bill, shorter neck and, in some subspecies, a white collar at the base of their neck.  They also have a higher-pitched call than Canada geese and, in my experience, tend to be calmer and quieter when resting on lakes or rivers.

Cackling geese are perhaps easiest to identify when flying at a distance.  While their coloration matches that of Canadas, their small size makes them look more like ducks than geese.  Should the flock approach your location, their higher-pitched calls confirm the identification.

Migrant Black Scoters

Black scoters have been turning up in both of my primary eBird areas (Arapahoe County, Colorado, and Boone County, Missouri) in recent weeks.  These sea ducks breed along Arctic Coasts and on tundra lakes of Alaska and Northern Canada, wintering along both coasts of North America as well as the Gulf Coast.

While they occasionally turn up on reservoirs and lakes of the interior, they are not as common away from the coasts as their white-winged cousins.  Black scoters are usually encountered in flocks, bobbing in the water of coastal bays and diving for mollusks, crustaceans and other aquatic invertebrates.  When observed on lakes of the interior, they tend to be alone or in small groups; most move on to coastal areas for the winter but some stay on inland lakes if adequate food is available and the waters remain open.

Unfortunately, I have not had the opportunity to observe this year's visitors to Colorado and Missouri but I have often seen wintering black scoters off Longboat Key, Florida, where we own a condo.  Wherever they are found, one cannot help but admire these hardy migrants from the far North.

Crossing Greenland

On our flight back from Geneva, Switzerland, yesterday, the route took us over the southern tip of Greenland, the largest island on our planet.  It was our first encounter with that land of ice, rock and scenic fjords and, for twenty minutes or so, we were mesmerized by the spectacle, 34,000 feet below.

Sparsely populated by humans, this Arctic nation is an independent territory of Denmark.  Mountain ranges run along its east and west coasts while a massive ice sheet covers 80% of the island's surface.  Icebergs speckled the fjords as we passed over Greenland and the majesty of its landscape was truly inspiring.

Of course, one cannot mention Greenland without invoking the fact that its Arctic ecosystem is threatened by global warming.  The rate of melting has sharply increased and the total loss of Greenland's ice sheet would raise sea levels by 24 feet, a disaster for island and coastal communities and ecosystems across the planet.

See also:  Greenland and Iceland and The Greenland Ice Sheet

American Tree Sparrows

On this mild, breezy afternoon, my wife and I took a walk around Perry Phillips Lake, south of Columbia, Missouri.  Two pair of red-tailed hawks cavorted in the wind but the lake remained frozen and no waterfowl were observed.  However, we did come across a flock of American tree sparrows, foraging in thickets along the south shore.

Residents of Alaska and Northern Canada where they breed in the Arctic Zone, these attractive sparrows are best identified by their rusty cap, white wing bars and light gray underparts with a central breast spot.  Gregarious during the winter months, they visit northern and central latitudes of the Lower 48, favoring open country with wooded streams or wetlands; while they visit backyard feeders on occasion, these sparrows are far more common in rural areas.  And though their name suggests otherwise, they spend most of their time on the ground or in low shrubs and saplings.

By late winter, the males begin to sing, longing to return to their northern homeland before warm, humid air invades the Heartland.  There they will pair up with a female and construct a nest in willow thickets or directly on the tundra.  Feasting on both insects and seeds during the breeding season, they consume grass and wildflower seeds during the winter months.

Kudos for Wild North

A few days ago, while taking care of two grandsons, I searched Netflix for a program that we all might enjoy.  Fortunately, I came across Wild North, a three episode series on the landscape, seasons and wildlife of Norway.

Narrated in English, the program covers the Coastal, Forest and Mountain ecosystems of that far northern country, offering gorgeous scenery and close-up video of the region's many wild residents.  Unlike some modern documentaries, Wild North does not humanize or sanitize nature, providing a balanced overview of her complex web of life.

In many ways, the coverage of life in polar or sub-polar ecosystems is especially inspiring.  Creatures that inhabit those life zones must deal with challenges that go well beyond the typical predator-prey relationships.  Wild North highlights that fact and is recommended for young and veteran naturalists alike.

American Golden Plovers

Six American golden plovers fed on a mudflat at Eagle Bluffs Conservation Area this morning, having stopped to rest and feed on the Missouri River floodplain as they head for the Arctic tundra of Alaska and Canada.  These long-distance migrants leave their Arctic breeding grounds by late summer, traveling to grasslands of Patagonia (in southern South America) for the northern winter; this journey is achieved without rest stops as the plovers travel off the East Coast of the Americas.

Come spring, American golden plovers migrate northward through the heart of North America; it is then (primarily in late March or early April) that they may be encountered on fields or mudflats, often in large flocks.  After feeding on invertebrates and seeds, they continue their journey to the north and will be nesting on the tundra by late spring.

This morning's visitors had not yet molted to their summer plumage but they were nevertheless attractive birds.  Of course, their beauty is magnified by our knowledge of their stamina; seasonal residents of two Hemispheres, they grace the Heartland for but a few weeks each year.  My friend and I were fortunate to enjoy their presence.

Wintering Tundra Swans

Breeding across the Arctic tundra of Alaska and Canada, North American tundra swans are represented by two populations, each currently comprised of about 100,000 birds.  The western population, which breeds in Alaska, winters on estuaries of the Pacific Northwest and on lakes of California's Central Valley and the Great Basin.

The eastern population, which often stops to rest and feed in wetlands along the Great Lakes during migrations, winter primarily on coastal bays of the Mid-Atlantic region.  Nevertheless, small flocks may turn up anywhere between these major wintering areas, including lakes along the Front Range of Colorado and New Mexico, reservoirs of the Great Plains and riverine wetlands along the Missouri, Mississippi, Arkansas and Ohio Valleys.

Resting on open waters, these magnificent birds feed primarily on aquatic vegetation and on waste grain in nearby agricultural fields; they are also known to consume clams and other marine invertebrates.  Like snow geese, their spring migration (which peaks from February to March) is often more gradual and less direct than their autumn flights and the swans generally travel in smaller flocks.  Smaller and slimmer than trumpeter swans, tundra swans are also identified by their high-pitched calls (hence their nickname: "whistling swans") and by a small yellow patch at the base of their bill.

Red-throated Loons

Having encountered my first red-throated loons along the coast of South Carolina yesterday, I thought it might be a good time to review the nature of this bird.  This smallest member of the loon family breeds across northern Alaska, Canada and Greenland, nesting in tundra ponds and wetlands.  In winter, it is found on coastal marine waters from Alaska to the Baja and from Newfoundland to Georgia.

Red-throated loons are monogamous and both parents take part in nest building and in caring for the young.  Two eggs are generally laid in a mound of vegetation that is placed onshore or directly in shallow water; hatchlings are fed aquatic insects while the adults feed on a wide variety of fish and crustaceans.  Unlike their cousins, these smaller, thinner loons do not transport young on their backs and are able to take off from land or the water surface without a running start.

While the adults lose their distinctive red and gray markings in the non-breeding season, wintering birds are identified by the white and gray pattern on their head and neck, by their slight build and by their habit of holding both their head and bill in an upturned position (in the manner of much larger cormorants).  Indeed, it was this latter behavior that first caught my attention; as veteran birders know, common species are often quickly identified by their silhouette and mannerisms and any unusual appearance or behavior demands closer inspection.

Caving to Big Oil

Despite the ecological disaster wrought by the Deepwater Horizon explosion in the Gulf of Mexico, five years ago, the effects of which have yet to be fully determined and addressed, the Obama Administration will allow Shell Oil to drill in the pristine waters of the Arctic Ocean off the coast of Alaska.  While the leases were initially granted by the Bush Administration, permission to drill was delayed until "stringent new regulations" were in place.

Though the Obama Administration has spearheaded efforts to reduce our use of fossil fuels, promote solar and wind energy and protect threatened wilderness areas, one wonders why they are caving to Big Oil at a time when there is a worldwide glut of gas and oil and when the tragic consequences of our dependence on fossil fuels (including transportation spills, groundwater and wetland pollution and global warming, among many others) are becoming more and more evident.  To assume that strict drilling regulations will protect the fragile yet treacherous environment of the Arctic Sea is pure folly.

Unfortunately, the political influence of Big Oil trumps any perceived shift toward clean, renewable energy.  In the meantime, as we lurch from one ecological crisis to another, the welfare of our planet, with its magnificent diversity of life, is placed at risk.  The political courage to protect natural ecosystems from the gluttonous adventurism of the Oil & Gas Industry appears to be lacking in our country and across the globe.

Arctic Sinkholes

Over the past few decades, climatologists have documented a gradual reduction in both the thickness and the expanse of Arctic sea ice, a result of global warming that has been documented across the planet.  This summer, as was reported on PBS last evening, new and unexpected findings in the Arctic appear to offer additional evidence of Earth's ongoing climate change.

Several large sinkholes have been discovered on the Arctic tundra of northern Siberia; edged by loose soil, there was initial suspicion that they might represent small impact craters.  Others suggested that the holes may have resulted from the eruption of subterranean pockets of methane.  At this point, however, most of the investigators have concluded that they are true sinkholes, having developed due to melting of deeper layers within the permafrost; this process has created water channels, undermining the surface of the tundra.

While the surface of the Arctic tundra has long thawed during the summer months, the deeper permafrost has remained frozen since the last glacial period of the Pleistocene.  Apparently, the global warming that began at the peak of that glaciation (some 20,000 years ago) and has accelerated since the onset of the industrial revolution, has now reached a point where the permafrost is threatened.  As more sinkholes develop, climatologists also suspect that significant amounts of carbon dioxide and methane might be released from the Arctic subsoil, a potential massive source of the greenhouse gasses that fuel global warming.

Rough-legs on the High Plains

Winter is not the ideal season for crossing the High Plains of North America; strong winds, blizzards and dust storms may pose a challenge for travelers but monotony is the primary threat.  The flat, nearly treeless terrain becomes a brown sheet of dry grasslands and crop fields and encounters with wildlife are generally few and far between.

Yesterday morning, however, I was entertained by a large number of rough-legged hawks as I traveled along Interstate 70; at least 25-30 were encountered between Denver and Wakeeney, Kansas, perched on fenceposts or hovering above the plains, hunting for rodents.  East of Wakeeney, trees become more abundant and the topography is more varied; there, in the mid-grass and tallgrass biomes, red-tailed hawks are the dominant raptors throughout the year.

Rough-legged hawks, named for their feathered legs and feet, are circumpolar in distribution and breed on the Arctic tundra and adjacent taiga.  Before winter sets in, they head to more southerly climes and are found throughout most of the U.S. except for the Southeastern States.  Since they favor open country that mimics their homeland, they are best found on the High Plains and across the basins of the Intermountain West.  Bulky in appearance, they are easily identified by a prominent black tail band and dark wrist patches on the underside of their wings; their plumage is otherwise highly variable.  While many hawks and falcons hover when they hunt (especially on the windy plains), rough-legged hawks are especially inclined to use that technique.

Long-tailed Ducks in Colorado

Long-tailed ducks, formerly known as oldsquaws, nest along rivers, lakes and ponds of the Arctic tundra.  Most winter offshore along the Pacific and Atlantic coasts of North America or on the Great Lakes; however, a small number turn up on inland lakes and reservoirs during the colder months.

According to the Colorado Birding Society, about 15 long-tailed ducks have been observed along the Front Range this winter, from the northern Colorado border to Pueblo Reservoir; I had the good fortune to watch three of them on South Platte Reservoir, in southwest Metro Denver, this morning.. Those hoping to observe these attractive visitors must be patient since they often spend more time underwater than on the surface; using their wings for propulsion, long-tailed ducks can dive to 200 feet (more than any other species of waterfowl) and may remain underwater for two minutes (per my observation this morning).  During those dives, the ducks feed on bottom vegetation, aquatic invertebrates and small fish.

Molting three times between autumn and spring, long-tailed ducks have variable plumage in the course of a year; males, which sport the long tail for which the species is named, are more white in winter and darker in summer.  These sea ducks are also known for their varied cackles and yodeling that peak in winter, when mating displays occur; indeed, by the time they return to the Arctic, breeding pairs have been established.

The Eastern Snowy Owl Invasion

Snowy owls breed in the Arctic, where they feed primarily on lemmings.  Since the lemming population tends to crash every four years or so, snowy owls generally appear across the northern half of the U.S. in those winters.  During these irruptions, the owls feed on a variety of small mammals, waterfowl and sea birds.

This winter, a spectacular invasion of snowy owls is occurring in eastern North America; while concentrated in southeastern Canada, New England and the Great Lakes region, the beautiful raptors have been spotted southward, from Missouri and Arkansas to North Carolina and, of all places, Bermuda.  Most of the birds are heavily marked with black feather edging, indicating that they are young birds, having fledged this past summer.  This observation suggests that the invasion is primarily due to an overpopulation of snowy owls in the eastern Arctic rather than to a crash in the lemming population.

While the specific cause for this invasion is not yet certain, it has garnered a great deal of attention among birders throughout the eastern U.S.  Whether global warming is beginning to have some affect on both breeding success and irruptive behavior is an intriguing consideration.  Indeed, the ongoing disruption of the Arctic ecosystem will have a significant impact on more southern ecosystems as well; the opportunity to see more snowy owls does not balance the many negative effects that will come our way.