They were half a mile ahead when I first saw them, dressed in black and standing on the highway. Even from a distance, I could tell that they were a pompous bunch, quarrelsome and aggressive. Driving closer I could see the battered corpse, its blood splattered across the road surface, a gruesome scene amidst the fading colors of late October but somehow appropriate on this Halloween weekend.
That murder of crows would likely feast on the carcass throughout the morning before wandering off to harass raptors and annoy humans with their raucous calls. This is, after all, the beginning of their season, when there is plenty of waste grain, winter kill and highway victims to sustain them through the cold, dark months. Celebrating their good fortune, crows gather in large, noisy flocks to wander the countryside before settling down at a favored roost site.
Despised by many humans, these corvids play an important role in nature's cycle, scavenging for leftovers, removing the dead and controlling the population of insects, mice and invasive bird species. Their garrulous flocks are a classic feature of the Midwest winter and their hardiness during this season of death certainly garners my respect and admiration.
Sabtu, 29 Oktober 2011
Kamis, 27 Oktober 2011
In Praise of Old Barns
Crossing the till plains of the American Midwest, once a spectacular tallgrass prairie and now the productive Cornbelt, is not the most interesting journey on our planet. Fortunately, parcels of forest, scenic stream valleys, a large concentration of raptors and seasonal flocks of waterfowl make the drive more enjoyable. And then there are the old barns.
With all due respect to the architects of our magnificent, ornate cathedrals, old wooden barns are, in my opinion, the most inspiring of man-made structures. While the religious believe that spired churches connect man with his God, old barns surely tie us to the Earth. Farmers have long depended on these wooden buildings to protect their livestock, their harvest and their equipment; at the same time, these scenic structures have provided both food and shelter for a wide range of native creatures, from field mice to red fox to barn owls.
Cathedrals, maintained by devoted parishioners and historical societies, retain their glory through the centuries. Old barns, on the other hand, often reflect their age, a response to the death, infirmity or financial problems of their owner; nevertheless, well constructed barns remain intact for many decades before slowly crumbling under the relentless assault of natural forces. Even then they retain their dignity, providing shelter for wildlife and rustic beauty for human travelers and photographers. Though some of their lumber is recycled for interior decoration, most of these iconic structures gradually fade into the natural landscape, their components recycled by nature's saprophytes.
With all due respect to the architects of our magnificent, ornate cathedrals, old wooden barns are, in my opinion, the most inspiring of man-made structures. While the religious believe that spired churches connect man with his God, old barns surely tie us to the Earth. Farmers have long depended on these wooden buildings to protect their livestock, their harvest and their equipment; at the same time, these scenic structures have provided both food and shelter for a wide range of native creatures, from field mice to red fox to barn owls.
Cathedrals, maintained by devoted parishioners and historical societies, retain their glory through the centuries. Old barns, on the other hand, often reflect their age, a response to the death, infirmity or financial problems of their owner; nevertheless, well constructed barns remain intact for many decades before slowly crumbling under the relentless assault of natural forces. Even then they retain their dignity, providing shelter for wildlife and rustic beauty for human travelers and photographers. Though some of their lumber is recycled for interior decoration, most of these iconic structures gradually fade into the natural landscape, their components recycled by nature's saprophytes.
Selasa, 25 Oktober 2011
Summer Wind
Ahead of an approaching cold front, strong southerly winds are raking Missouri today, pushing afternoon highs into the 80s (F). Despite the colorful leaves and browning grasslands, summer has returned to the Heartland.
Our recent drought has left the woodlands tinder dry; seasonal lakes have given way to parched basins and the creeks are but chains of stagnant pools. After a less than stellar autumn display, this gusty, warm wind is accelerating the leaf fall, making it look like November but feel more like August.
Of course, this summer heat will soon be doused by Canadian air. The cold front, advancing across the Great Plains, is due this evening and is forecast to bring showers and much cooler temperatures in its wake; over the coming days, our afternoon highs will be 30 degrees cooler than they are today. Then we'll remember that winter is closing in and that snow geese will soon call from the cold night sky.
Our recent drought has left the woodlands tinder dry; seasonal lakes have given way to parched basins and the creeks are but chains of stagnant pools. After a less than stellar autumn display, this gusty, warm wind is accelerating the leaf fall, making it look like November but feel more like August.
Of course, this summer heat will soon be doused by Canadian air. The cold front, advancing across the Great Plains, is due this evening and is forecast to bring showers and much cooler temperatures in its wake; over the coming days, our afternoon highs will be 30 degrees cooler than they are today. Then we'll remember that winter is closing in and that snow geese will soon call from the cold night sky.
Senin, 24 Oktober 2011
Turkey & Earthquakes
Yesterday's tragic earthquake in eastern Turkey is just the latest in a series of tectonic events that have impacted that region over the past 50 million years. Lying at the confluence of four tectonic plates, the Eurasian, African, Arabian and Anatolian, Turkey is one of the most geologically active regions on our planet.
Most of the country sits on the Anatolian Plate, a small continental plate that is surrounded by the other three larger plates. Fifty million years ago (MYA), as the Tethys Sea began to close, the African Plate drifted northward, colliding with southern Europe and forcing up the Alps and associated ranges. Then, about 30 MYA, the Red Sea began to open, shoving the Arabian Plate toward the northeast; its collision with the Eurasian Plate, which, like that between Africa and Eurasia, continues today, has crumpled up the Zagros Mountains of Iran. In eastern Turkey, the Arabian Plate is scraping along and pressing against the Anatolian Plate, forcing the latter to rotate counterclockwise, toward the west; in concert, across northern Turkey, the Anatolian Plate scrapes past the southern edge of the Eurasian Plate. Finally, along its southern rim, the Anatolian Plate interacts with the African Plate via a complex chain of transform faults, compression points and subduction zones.
As these Plates continue to rearrange themselves, pressure builds along the intervening fault lines and, though plate movement is in the order of only 3-10 mm per year, friction eventually fails and an earthquake results. Unfortunately, this pattern will continue and, like Los Angeles and Tokyo, Istanbul awaits a geologic catastrophe.
Most of the country sits on the Anatolian Plate, a small continental plate that is surrounded by the other three larger plates. Fifty million years ago (MYA), as the Tethys Sea began to close, the African Plate drifted northward, colliding with southern Europe and forcing up the Alps and associated ranges. Then, about 30 MYA, the Red Sea began to open, shoving the Arabian Plate toward the northeast; its collision with the Eurasian Plate, which, like that between Africa and Eurasia, continues today, has crumpled up the Zagros Mountains of Iran. In eastern Turkey, the Arabian Plate is scraping along and pressing against the Anatolian Plate, forcing the latter to rotate counterclockwise, toward the west; in concert, across northern Turkey, the Anatolian Plate scrapes past the southern edge of the Eurasian Plate. Finally, along its southern rim, the Anatolian Plate interacts with the African Plate via a complex chain of transform faults, compression points and subduction zones.
As these Plates continue to rearrange themselves, pressure builds along the intervening fault lines and, though plate movement is in the order of only 3-10 mm per year, friction eventually fails and an earthquake results. Unfortunately, this pattern will continue and, like Los Angeles and Tokyo, Istanbul awaits a geologic catastrophe.
Minggu, 23 Oktober 2011
Sunday Morn at Eagle Bluffs
On this glorious October morning, I headed for Eagle Bluffs Conservation Area, my favorite haunt in central Missouri. There, on the floodplain of the Missouri River, I was greeted by flocks of horned larks along the entry road, by a lone bald eagle atop a dying shade tree and by the sound of distant shotgun blasts, a reminder that the culling season is underway.
Water birds were relatively sparse on the ponds of the refuge; while coot and pied-billed grebes were common, ducks were limited to scattered, small flocks of mallards, gadwall and blue-winged teal; a pair of ruddy ducks caught my eye and noisy killdeer rushed along the shorelines. Raptors were the highlight of this morning's visit, represented by numerous red-tailed hawks, the lone bald eagle, a few northern harriers and a red-shouldered hawk that rose from the marsh with a snake in his talons. Clouds of red-winged backyards drifted across the floodplain, a few great blue herons stalked the shallows, a quartet of barn swallows rested on a drowned sapling and small groups of yellowlegs foraged on the mudflats.
Many, if not most, Americans attend church on Sunday mornings for their weekly dose of inspiration and humility. I prefer nature, with its bounty of life and its spectacles of death.
Water birds were relatively sparse on the ponds of the refuge; while coot and pied-billed grebes were common, ducks were limited to scattered, small flocks of mallards, gadwall and blue-winged teal; a pair of ruddy ducks caught my eye and noisy killdeer rushed along the shorelines. Raptors were the highlight of this morning's visit, represented by numerous red-tailed hawks, the lone bald eagle, a few northern harriers and a red-shouldered hawk that rose from the marsh with a snake in his talons. Clouds of red-winged backyards drifted across the floodplain, a few great blue herons stalked the shallows, a quartet of barn swallows rested on a drowned sapling and small groups of yellowlegs foraged on the mudflats.
Many, if not most, Americans attend church on Sunday mornings for their weekly dose of inspiration and humility. I prefer nature, with its bounty of life and its spectacles of death.
Sabtu, 22 Oktober 2011
Tardy Snowbirds
Since filling the feeder and hanging up the suet block last week, the usual cast of characters have made their appearance. Chickadees, small yet courageous and ever-optimistic, were the first to arrive, followed closely by tufted titmice, their reliable feeding companions. Industrious white-breasted nuthatches soon stopped by, storing most of their larder in bark crevices for later consumption. Downy and red-bellied woodpeckers led the assault on the suet block while mourning doves, cardinals and white-throated sparrows have scoured the ground beneath the feeder, taking advantage of seed scattered by house finches, blue jays and house sparrows.
But one common visitor has not yet arrived in central Missouri (or at least not on our modest parcel of earth). Dark-eyed juncos, commonly known as snowbirds, usually appear by mid October, just as the last of the summer residents are departing for the south. Most abundant along country roads where they feast on the seeds of grasses, wildflowers and so-called weeds, juncos are also common in suburban areas where they forage beneath shrubs and feeders.
Perhaps the conditions in their Canadian homeland are too mild to send them southward but, unlike waterfowl and raptors, their travels are dictated by the solar cycle, not by the weather. Maybe they're already in town but have not yet visited our property; then again, migrant songbirds tend to zero in on the same wintering area each year. One thing is certain: the hardy and attractive juncos will soon join our backyard residents, take advantage of our handouts and brighten my winter.
But one common visitor has not yet arrived in central Missouri (or at least not on our modest parcel of earth). Dark-eyed juncos, commonly known as snowbirds, usually appear by mid October, just as the last of the summer residents are departing for the south. Most abundant along country roads where they feast on the seeds of grasses, wildflowers and so-called weeds, juncos are also common in suburban areas where they forage beneath shrubs and feeders.
Perhaps the conditions in their Canadian homeland are too mild to send them southward but, unlike waterfowl and raptors, their travels are dictated by the solar cycle, not by the weather. Maybe they're already in town but have not yet visited our property; then again, migrant songbirds tend to zero in on the same wintering area each year. One thing is certain: the hardy and attractive juncos will soon join our backyard residents, take advantage of our handouts and brighten my winter.
Jumat, 21 Oktober 2011
Swallowtail Butterflies
Despite the recent chilly nights, a few tiger swallowtails were still flittering about our yard on this mild, sunny, autumn afternoon. Members of the genus Papilionidae, swallowtails are represented by forty species in North America and more than 550 across the globe; though their common name reflects a deeply forked tail, not all species harbor that anatomic trait. Birdwing butterflies, the largest members of the genus (and the largest butterflies on Earth), are found in Australia.
After mating, the male swallowtail secretes a sticky substance that plugs the genital tract of the female, ensuring that his genes do not receive competition from another suitor. The female lays her eggs on a host plant (often very specific) and these hatch into caterpillars within a few days. The larvae have several defenses against predation; in their earliest stage, they resemble bird droppings (not terribly appetizing) which molt several times to become large colorful caterpillars with a variety of bright bands and spots (suggesting toxicity). Some species do feed on toxic plants and the ingestion of those larvae can cause sickness or death in some predators; over numerous generations, susceptible predators have "learned" to leave them alone. Finally, swallowtail caterpillars have a gland behind their head, known as the osmeterium, which emits a potent, noxious chemical; while this seems to be effective against other insects and spiders, larger predators (snakes, toads, birds, mammals) are apparently undeterred by its scent.
Among the common North American species are the tiger, black and zebra swallowtails. Tiger swallowtail caterpillars feed on a variety of deciduous trees, black swallowtail larvae (often called parsley worms) feed on members of the carrot family (including parsley, fennel and dill) and zebra swallowtail caterpillars feed almost exclusively on the leaves of pawpaws. Temperate zone swallowtails overwinter as pupae and the beautiful adults spend the warmer months mating and sipping on nectar; depending upon latitude, they produce 2-3 broods each year before cold weather puts an end to their one and only season in the sun.
After mating, the male swallowtail secretes a sticky substance that plugs the genital tract of the female, ensuring that his genes do not receive competition from another suitor. The female lays her eggs on a host plant (often very specific) and these hatch into caterpillars within a few days. The larvae have several defenses against predation; in their earliest stage, they resemble bird droppings (not terribly appetizing) which molt several times to become large colorful caterpillars with a variety of bright bands and spots (suggesting toxicity). Some species do feed on toxic plants and the ingestion of those larvae can cause sickness or death in some predators; over numerous generations, susceptible predators have "learned" to leave them alone. Finally, swallowtail caterpillars have a gland behind their head, known as the osmeterium, which emits a potent, noxious chemical; while this seems to be effective against other insects and spiders, larger predators (snakes, toads, birds, mammals) are apparently undeterred by its scent.
Among the common North American species are the tiger, black and zebra swallowtails. Tiger swallowtail caterpillars feed on a variety of deciduous trees, black swallowtail larvae (often called parsley worms) feed on members of the carrot family (including parsley, fennel and dill) and zebra swallowtail caterpillars feed almost exclusively on the leaves of pawpaws. Temperate zone swallowtails overwinter as pupae and the beautiful adults spend the warmer months mating and sipping on nectar; depending upon latitude, they produce 2-3 broods each year before cold weather puts an end to their one and only season in the sun.
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