We humans have been domesticating animals for the past 12,000 years and they have played a crucial role in the rise of our civilization and in the formation of our varied cultures. We have used and abused animals for food, clothing, transportation, muscle power, laboratory experimentation, pollination, recreation and companionship.
Dogs were the first animals to be domesticated, used by clans of the Middle East for protection and hunting assistance some 12,000 years ago. Goats were domesticated in the Fertile Crescent about 10,000 years ago while sheep and pigs were raised in Turkey and Syria by 9000 years ago. About 8000 years ago, cattle were domesticated in Northern Africa and India, cats joined the households of Egypt and chickens were bred for eggs and meat in Southeast Asia. As the horse was domesticated by tribes of central Asia, some 6000 years ago, the Incas were utilizing llamas in the Andes of South America and donkeys were brought under human rule in Northern Africa, soon to be joined by camel caravans. Ducks were raised in Southeast Asia by 5000 years ago, guinea pigs were domesticated in the Andes 4500 years ago and elephants were pressed into service in India about 4000 years ago. Caribou were domesticated across the Arctic about 3000 years ago, turkeys were raised in Mexico 2000 years ago, honey bees were brought under control in Europe 1500 years ago, goldfish were farmed in China 1000 years ago and rabbits were domesticated in Europe by 500 years ago.
Looking at our pampered dogs and cats, better fed than many human populations, we sometimes glorify our relationship with the other animals that share this planet. Yet, as vital as many have been to the survival of our species, we have not often treated them with the dignity that they deserve. The abuse of animals on industrialized farms and in scientific labs has been a blight on our culture and must be addressed if we are to earn our self-proclaimed title of Earth's stewards.
Tuesday, March 6, 2012
Monday, March 5, 2012
Education, Liberalism & Faith
Rick Santorum's proclamation that higher education indoctrinates students with godless, liberal ideology unleashed a political firestorm among Democrats, Independents and moderate Republicans; of course, his disrespectful style, labeling President Obama a snob, did not help his cause. Nevertheless, there is some truth to Santorum's message that he may not wish to acknowledge.
There is little doubt that education and religious faith have an inverse relationship, especially when one defines faith by the rigid dogma of most Western religions. Though some studies refute the fact that liberalism and agnosticism (or atheism) are more common in the college-educated population, I suspect that these associations do prevail in certain fields of study. As a physician, I know many medical professionals who remain devoted to their Church but the great majority do so with a liberalized view of social issues, including birth control; they and other social service professionals come to appreciate the complex nature of community health, having witnessed the effects of poverty and family dysfunction first hand. And, as a naturalist, academically trained in biology and medicine and self educated in geology and natural history, I'm confident that those persons highly trained in the natural sciences are far more likely to be agnostic or atheistic when compared to members of the general population.
Knowledge both improves our understanding of life's many mysteries and feeds our curiosity. The more we learn about any subject, the less likely we are to settle for simplistic, mystical and unproven theories of the laws that govern it; education broadens our perspective, enabling us to see the grays that exist between the blacks and whites on which religious conservatives tend to focus. Since religion evolved from a desire to define our place in the natural world, its rigid doctrines are least palatable to those who have an in-depth knowledge of the natural sciences.
There is little doubt that education and religious faith have an inverse relationship, especially when one defines faith by the rigid dogma of most Western religions. Though some studies refute the fact that liberalism and agnosticism (or atheism) are more common in the college-educated population, I suspect that these associations do prevail in certain fields of study. As a physician, I know many medical professionals who remain devoted to their Church but the great majority do so with a liberalized view of social issues, including birth control; they and other social service professionals come to appreciate the complex nature of community health, having witnessed the effects of poverty and family dysfunction first hand. And, as a naturalist, academically trained in biology and medicine and self educated in geology and natural history, I'm confident that those persons highly trained in the natural sciences are far more likely to be agnostic or atheistic when compared to members of the general population.
Knowledge both improves our understanding of life's many mysteries and feeds our curiosity. The more we learn about any subject, the less likely we are to settle for simplistic, mystical and unproven theories of the laws that govern it; education broadens our perspective, enabling us to see the grays that exist between the blacks and whites on which religious conservatives tend to focus. Since religion evolved from a desire to define our place in the natural world, its rigid doctrines are least palatable to those who have an in-depth knowledge of the natural sciences.
Sunday, March 4, 2012
Restless Locals
While most summer songbirds won't arrive until April, some of our permanent and winter residents are often best observed during March, when they are most likely to turn up in our residential areas. Restless due to the approach of their migration and/or mating season, these birds begin to roam about, leaving their more secluded and less developed winter haunts.
In my experience, permanent residents such as hairy woodpeckers, eastern bluebirds, northern mockingbirds and barred owls are more often seen in suburban areas during this month than at other times of the year. So too are winter residents such as white-crowned sparrows, fox sparrows, purple finches and yellow-bellied sapsuckers.
Perhaps this observation is purely an illusion, the product of my increasing attention to our yard and its inhabitants during the milder days of late winter. But I suspect that birds, like us, are energized by the lengthening daylight of March and I know that we, like them, become restless with the growing promise of spring.
In my experience, permanent residents such as hairy woodpeckers, eastern bluebirds, northern mockingbirds and barred owls are more often seen in suburban areas during this month than at other times of the year. So too are winter residents such as white-crowned sparrows, fox sparrows, purple finches and yellow-bellied sapsuckers.
Perhaps this observation is purely an illusion, the product of my increasing attention to our yard and its inhabitants during the milder days of late winter. But I suspect that birds, like us, are energized by the lengthening daylight of March and I know that we, like them, become restless with the growing promise of spring.
Saturday, March 3, 2012
White-Fronts at Eagle Bluffs
It was another spectacular morning at Eagle Bluffs Conservation Area today; the sky was clear, the air was cool and both raptors and waterfowl were abundant. Joining the wide variety of ducks were hundreds of American white pelicans, small groups of Canada and snow geese and a large flock of greater white-fronted geese.
Breeding across the Arctic tundra of Alaska and Canada, greater white fronted geese winter along the Gulf Coast, from Louisiana to Mexico, and along the Pacific Coast from Oregon to Mexico; a Greenland subspecies usually winters in the British Isles but may turn up along the Atlantic Coast of the U.S. Another subspecies, known as tule geese, breed in Alaska and winter in marshlands from Oregon to California.
Migrant flocks of greater white-fronted geese, often numbering in the thousands, are usually found west of the Mississippi Valley; there they stop to rest and feed on wetlands and crop fields and, from a distance, may be mistaken for Canada geese. Slimmer and more agile in flight than their Canadian cousins, white-fronts have a higher pitched call, pinkish bills, orange legs and feet and a distinctive white band at the base of their bill. Like most geese, these hardy migrants mate for life and often remain in family groups for a year or more. For some reason, much to the delight of myself and other regional birders, greater white-fronted geese and American white pelicans have become abundant migrants at Eagle Bluffs over the past few years; let's hope that trend continues!
Breeding across the Arctic tundra of Alaska and Canada, greater white fronted geese winter along the Gulf Coast, from Louisiana to Mexico, and along the Pacific Coast from Oregon to Mexico; a Greenland subspecies usually winters in the British Isles but may turn up along the Atlantic Coast of the U.S. Another subspecies, known as tule geese, breed in Alaska and winter in marshlands from Oregon to California.
Migrant flocks of greater white-fronted geese, often numbering in the thousands, are usually found west of the Mississippi Valley; there they stop to rest and feed on wetlands and crop fields and, from a distance, may be mistaken for Canada geese. Slimmer and more agile in flight than their Canadian cousins, white-fronts have a higher pitched call, pinkish bills, orange legs and feet and a distinctive white band at the base of their bill. Like most geese, these hardy migrants mate for life and often remain in family groups for a year or more. For some reason, much to the delight of myself and other regional birders, greater white-fronted geese and American white pelicans have become abundant migrants at Eagle Bluffs over the past few years; let's hope that trend continues!
Friday, March 2, 2012
The Cost of Intelligence
We humans differ from "lower" mammals in several ways: the complexity of our large brains, our upright posture, our manual dexterity and our capacity for articulate speech. Our intelligence, the product of our complex brain, affords many advantages, including our ability to reason, imagine, theorize, create, communicate and plan, among many other cognitive functions. This brain power also comes with a price.
Relative to other mammals, we humans undergo slow physical development and remain highly dependent upon our parents for a decade or more. While this provides a wealth of vital experience for our developing brains, it puts us at risk for an early death; of course, this was especially true before the era of modern technology and medicine, when children were exposed to a wide variety of natural threats. Furthermore, our slow physical development delays sexual maturity, reducing the capacity of human populations to recover from catastrophic events.
On a more personal level, intelligence produces a source of stress that is not experienced by other mammals. Humans must deal with the effects of regret, guilt, fear, criticism and anticipation. The greatest price, of course, is the knowledge that life is transient and that we, like all other creatures, will die; it is this knowledge that has molded human culture from its earliest days, spawning beliefs that serve to douse our fear.
Relative to other mammals, we humans undergo slow physical development and remain highly dependent upon our parents for a decade or more. While this provides a wealth of vital experience for our developing brains, it puts us at risk for an early death; of course, this was especially true before the era of modern technology and medicine, when children were exposed to a wide variety of natural threats. Furthermore, our slow physical development delays sexual maturity, reducing the capacity of human populations to recover from catastrophic events.
On a more personal level, intelligence produces a source of stress that is not experienced by other mammals. Humans must deal with the effects of regret, guilt, fear, criticism and anticipation. The greatest price, of course, is the knowledge that life is transient and that we, like all other creatures, will die; it is this knowledge that has molded human culture from its earliest days, spawning beliefs that serve to douse our fear.
Thursday, March 1, 2012
The Final Gauntlet
From a naturalist's point of view, the long march toward spring begins at the winter solstice as the days begin to lengthen and the amount of solar radiation gradually increases. Of course, the low sun angle precludes any significant warming effect until late in February and we must rely on southerly winds to provide respites from the winter chill.
By March, the first calendar month of spring, signs of the season unfold in earnest as bulb plants flower, lawns begin to green, buds swell, bird song intensifies, waterfowl migrate and mating rituals are seen and heard across the Heartland, from the frenzied calls of chorus frogs to the hysterical cries of flickers and the trilling of toads. Few would argue that this month offers our first significant taste of spring but, as residents of the Temperate Zone know, winter is reluctant to concede defeat.
For winter weary humans, tropical blood coursing through our veins, March represents the final gauntlet in our quest to escape the cold, dark season of despair. While outbreaks of glorious, warm weather are usually spaced through the month, they are interspersed with the raw, damp, chilly days that slow nature's recovery. March is a dose of reality, a microcosm of life's turbulent cycle of joy and sorrow, success and defeat.
By March, the first calendar month of spring, signs of the season unfold in earnest as bulb plants flower, lawns begin to green, buds swell, bird song intensifies, waterfowl migrate and mating rituals are seen and heard across the Heartland, from the frenzied calls of chorus frogs to the hysterical cries of flickers and the trilling of toads. Few would argue that this month offers our first significant taste of spring but, as residents of the Temperate Zone know, winter is reluctant to concede defeat.
For winter weary humans, tropical blood coursing through our veins, March represents the final gauntlet in our quest to escape the cold, dark season of despair. While outbreaks of glorious, warm weather are usually spaced through the month, they are interspersed with the raw, damp, chilly days that slow nature's recovery. March is a dose of reality, a microcosm of life's turbulent cycle of joy and sorrow, success and defeat.
Wednesday, February 29, 2012
Evolution of the Horse
The common ancestor of Perissodactyls (horses, rhinos, tapirs) appeared in North American during the Paleocene, about 60 million years ago (MYA). The first known member of the horse lineage was Hyracotherium, formerly known as Eohippus, a small deer-like herbivore of subtropical forests that fed on tender vegetation and fruit. Appearing in the early Eocene, some 55 MYA, this dog-sized mammal evolved through a series of early horse ancestors to Oligocene forms such as Mesohippus (37 MYA) and Epihippus (30 MYA) that began to emerge from the forest to take advantage of newly evolved and nutritious grasslands; in concert, their teeth took on traits vital to grazing and their dominant third toe would evolve toward the modern hoof.
Diversification in the early Miocene led to Parahippus, a pony-sized ancestor, and Meryhippus (17 MYA), the first true grazer and fleet, horse-sized member of the lineage. Meryhippus diverged into at least three groups, one of which, Hipparion, was the first ancestral horse to cross into Eurasia. Equus, the genus of all modern horses, first appeared in the Pliocene, about 5 MYA; some members of that genus spread into South America by 1.5 MYA while others crossed the Bering land bridge into Eurasia throughout the Pleistocene. By the end of the Wisconsin Glacial Period, 10,000 years ago, the horse had disappeared from the Americas, likely a result of changing flora and hunting pressure from humans; they would be domesticated by human tribes in Central Asia about 6000 years ago and brought back to the Americas by Spanish explorers in the 15th and 16th Centurys.
The above summary leaves out numerous intermediate and side-branch species in what is one of the most complete and well documented evolutionary trees for any mammal. Perhaps most enlightening is the gradual, physical adaptation of ancestral horses to their changing environment, progressing from small, forest dwelling creatures to large, fleet and hardy residents of our vast grasslands. What better creature, so vitally important to the advance of human culture, to fully understand and appreciate?
Diversification in the early Miocene led to Parahippus, a pony-sized ancestor, and Meryhippus (17 MYA), the first true grazer and fleet, horse-sized member of the lineage. Meryhippus diverged into at least three groups, one of which, Hipparion, was the first ancestral horse to cross into Eurasia. Equus, the genus of all modern horses, first appeared in the Pliocene, about 5 MYA; some members of that genus spread into South America by 1.5 MYA while others crossed the Bering land bridge into Eurasia throughout the Pleistocene. By the end of the Wisconsin Glacial Period, 10,000 years ago, the horse had disappeared from the Americas, likely a result of changing flora and hunting pressure from humans; they would be domesticated by human tribes in Central Asia about 6000 years ago and brought back to the Americas by Spanish explorers in the 15th and 16th Centurys.
The above summary leaves out numerous intermediate and side-branch species in what is one of the most complete and well documented evolutionary trees for any mammal. Perhaps most enlightening is the gradual, physical adaptation of ancestral horses to their changing environment, progressing from small, forest dwelling creatures to large, fleet and hardy residents of our vast grasslands. What better creature, so vitally important to the advance of human culture, to fully understand and appreciate?
Tuesday, February 28, 2012
Deadly Romance
No, this is not the title for another TV murder mystery. Rather, it is an acknowledgement that we have entered the peak roadkill season, as the carcasses of raccoons, opossums and skunks litter our scenic byways. Soon to be joined by lovesick groundhogs, these small mammals are roaming about in response to their mating instinct, following trails of pheromones across the late winter landscape. Primarily nocturnal, these determined suitors sometimes look for love in the wrong places, even on our concrete ribbons of death, and too often meet an inglorious demise.
Were it not for our roads and vehicles they might be culled by owls, fox or coyotes; in fact, fresh carcasses may be claimed by natural predators while others provide sustenance for vultures and less conspicuous scavengers. Fortunately, these small mammals are prolific and the highway slaughter has little impact on their populations.
However, it is disturbing to realize that these victims are often lured to their deaths by the chemicals of reproduction. Then again, nature sustains itself through a balance of life and death and we often take part in that process, as purposeful hunters or as night-blind motorists.
Were it not for our roads and vehicles they might be culled by owls, fox or coyotes; in fact, fresh carcasses may be claimed by natural predators while others provide sustenance for vultures and less conspicuous scavengers. Fortunately, these small mammals are prolific and the highway slaughter has little impact on their populations.
However, it is disturbing to realize that these victims are often lured to their deaths by the chemicals of reproduction. Then again, nature sustains itself through a balance of life and death and we often take part in that process, as purposeful hunters or as night-blind motorists.
Monday, February 27, 2012
Flamingos & Grebes
Watching a flamingo navigate the shallows of an ephemeral lake, one would surely conclude that it is closely related to storks, herons and ibis; yet, placing this bird on the tree of avian evolution has long been a subject of controversy. By late in the 20th Century, fossil evidence from across the globe seemed to suggest that flamingos are a hybrid between shorebirds and waterfowl; indeed, they harbor the same feather lice that are found on ducks and geese. The fossil evidence also revealed that, despite their current concentration in tropical and subtropical life zones, flamingo species were widely dispersed throughout temperate regions before the Pleistocene Ice Age.
Then, within the past decade, molecular geneticists discovered that flamingos are, in fact, most closely related to grebes. This finding sent a shock wave through the world of avian biologists, especially given the obvious differences in the appearance and behavior of those bird groups. Nevertheless, morphologic studies have since confirmed that flamingos and grebes are, indeed, sister species.
While controversy continues to smolder, this story highlights the role of science throughout human history. Originally convinced that we lived on a flat landscape around which the sun, moon and stars revolved, we later learned, through scientific investigation, that we live on a smallish globe on an outer band of a massive galaxy that is one of billions of galaxies in our Universe. Despite the constant protestations of religious groups, we have also unraveled the mysteries of evolution, plate tectonics, genetics and astrophysics, among others. Throughout this ongoing process of discovery, human assumptions and beliefs have repeatedly dissolved in the wake of scientific progress.
Then, within the past decade, molecular geneticists discovered that flamingos are, in fact, most closely related to grebes. This finding sent a shock wave through the world of avian biologists, especially given the obvious differences in the appearance and behavior of those bird groups. Nevertheless, morphologic studies have since confirmed that flamingos and grebes are, indeed, sister species.
While controversy continues to smolder, this story highlights the role of science throughout human history. Originally convinced that we lived on a flat landscape around which the sun, moon and stars revolved, we later learned, through scientific investigation, that we live on a smallish globe on an outer band of a massive galaxy that is one of billions of galaxies in our Universe. Despite the constant protestations of religious groups, we have also unraveled the mysteries of evolution, plate tectonics, genetics and astrophysics, among others. Throughout this ongoing process of discovery, human assumptions and beliefs have repeatedly dissolved in the wake of scientific progress.
Sunday, February 26, 2012
Pleistocene Plant Revival
A recent article in the New York Times reported on the successful revival of a narrow-leafed campion from deposits of the late Pleistocene. Russian paleontologists had discovered seeds and fruits of the plant in river bed sediments of eastern Siberia, apparently buried by a ground squirrel; radiocarbon dating of the seeds indicated that they were first entombed about 32,000 years ago, when humans were displacing Neanderthals in Europe and Denisovans in eastern Asia.
While efforts to germinate the seeds were unsuccessful, the scientists were able to thaw and culture placental cells from the fruit, yielding mature plants that flowered and produced new seed; these descendent seeds were then planted to yield another generation of campions. According to the article, the Russian scientists speculate that the Pleistocene plant material was buried in soil just above the permafrost layer, favoring its prolonged viability; in addition, sugars and phenols within the plant tissue served as an antifreeze, protecting cellular structure.
Though this story focuses on what appears to be a record for ancient plant revival, it says more about the nature of life itself. Rather than some mystical or spiritual property, life is a physical process, requiring just the right biochemistry and environment in which to flourish. Governed by DNA and coordinated by neurovascular networks, the stem cells of life give rise to complete organisms and, as this event revealed, may do so after long periods of dormancy. We humans are just beginning to understand the potential benefits of this knowledge and, if not derailed by the forces of religious mysticism, stem cell research will play a major role in the future of agriculture and health care.
While efforts to germinate the seeds were unsuccessful, the scientists were able to thaw and culture placental cells from the fruit, yielding mature plants that flowered and produced new seed; these descendent seeds were then planted to yield another generation of campions. According to the article, the Russian scientists speculate that the Pleistocene plant material was buried in soil just above the permafrost layer, favoring its prolonged viability; in addition, sugars and phenols within the plant tissue served as an antifreeze, protecting cellular structure.
Though this story focuses on what appears to be a record for ancient plant revival, it says more about the nature of life itself. Rather than some mystical or spiritual property, life is a physical process, requiring just the right biochemistry and environment in which to flourish. Governed by DNA and coordinated by neurovascular networks, the stem cells of life give rise to complete organisms and, as this event revealed, may do so after long periods of dormancy. We humans are just beginning to understand the potential benefits of this knowledge and, if not derailed by the forces of religious mysticism, stem cell research will play a major role in the future of agriculture and health care.
Saturday, February 25, 2012
Eastern Sandhill Cranes
Most American birdwatchers associate sandhill cranes with the Great Plains and Western U.S., having seen large flocks at staging areas, such as the Platte River in Nebraska or the San Luis Valley in Colorado, or at wintering grounds in California, New Mexico or Texas. But there is a large and growing eastern population of sandhill cranes, composed primarily of the greater sandhill crane subspecies.
These cranes breed in the vicinity of James Bay, Canada and around the Great Lakes, from Minnesota and Wisconsin to Michigan and northern Ohio. On their migrations to wintering areas from southern Georgia to central Florida, they use two primary staging areas: the Jasper-Pulaski State Fish & Wildlife Area, in northwest Indiana, and the Hiwassee Wildlife Refuge, just NNE of Chattanooga, Tennessee. Of course, migrant flocks may be seen in wetland areas and agricultural fields anywhere between their breeding and wintering areas and the cranes may shorten their travels if mild conditions persist and they encounter a plentiful food supply.
Non-migratory populations include the Florida sandhill cranes, found from the Okefenokee Swamp to the Everglades (with the greatest number on the Kissimmee Prairie, north of Lake Okeechobee) and the endangered Mississippi sandhill cranes, found on or near the Mississippi Sandhill Crane NWR, along I-10 in southern Mississippi; the latter population currently numbers about 110 cranes. Another non-migratory population of sandhill cranes inhabits Cuba. All sandhill cranes, whether found in the eastern or western U.S., are threatened primarily by habitat loss, the result of marsh drainage, stream water diversion or agricultural development.
These cranes breed in the vicinity of James Bay, Canada and around the Great Lakes, from Minnesota and Wisconsin to Michigan and northern Ohio. On their migrations to wintering areas from southern Georgia to central Florida, they use two primary staging areas: the Jasper-Pulaski State Fish & Wildlife Area, in northwest Indiana, and the Hiwassee Wildlife Refuge, just NNE of Chattanooga, Tennessee. Of course, migrant flocks may be seen in wetland areas and agricultural fields anywhere between their breeding and wintering areas and the cranes may shorten their travels if mild conditions persist and they encounter a plentiful food supply.
Non-migratory populations include the Florida sandhill cranes, found from the Okefenokee Swamp to the Everglades (with the greatest number on the Kissimmee Prairie, north of Lake Okeechobee) and the endangered Mississippi sandhill cranes, found on or near the Mississippi Sandhill Crane NWR, along I-10 in southern Mississippi; the latter population currently numbers about 110 cranes. Another non-migratory population of sandhill cranes inhabits Cuba. All sandhill cranes, whether found in the eastern or western U.S., are threatened primarily by habitat loss, the result of marsh drainage, stream water diversion or agricultural development.
Friday, February 24, 2012
Winter's Comeback
My office at the medical school commands a broad view to the west and, at noon yesterday, I looked out on an idyllic scene; bright sunshine, blue skies and a warm, southwest wind brought the look and feel of mid spring to mid Missouri. However, on closer inspection, I could see a swath of haze across the northwestern horizon and, within a few hours, a wall of clouds had taken its place.
By late afternoon, most of the sky was covered with a thick, gray overcast and a chilly, west wind had replaced the mild southerly breeze; our noontime high of 65 degrees F had dropped into the low fifties. Overnight, as the cold front passed to our east, strong, northwesterly winds rattled the windows and sent a deep, intermittent roar through the barren trees. While the snowfall will remain to our north and east, we won't get out of the forties today and a gusty north wind will make it feel much colder.
The weather gyrations of spring have begun, as winter and summer battle for the Heartland. Pacific storms will invade our region on a regular basis, preceded by a moist, balmy flow and followed by a winter wallop. This seasonal war, however uncomfortable, will provide shallow pools and flooded fields for migrant waterfowl and will set the stage for the warm, fragrant, verdant days ahead.
By late afternoon, most of the sky was covered with a thick, gray overcast and a chilly, west wind had replaced the mild southerly breeze; our noontime high of 65 degrees F had dropped into the low fifties. Overnight, as the cold front passed to our east, strong, northwesterly winds rattled the windows and sent a deep, intermittent roar through the barren trees. While the snowfall will remain to our north and east, we won't get out of the forties today and a gusty north wind will make it feel much colder.
The weather gyrations of spring have begun, as winter and summer battle for the Heartland. Pacific storms will invade our region on a regular basis, preceded by a moist, balmy flow and followed by a winter wallop. This seasonal war, however uncomfortable, will provide shallow pools and flooded fields for migrant waterfowl and will set the stage for the warm, fragrant, verdant days ahead.
Thursday, February 23, 2012
The Armadillo Army
Distantly related to sloths and anteaters, armadillos evolved in South America during the mammal explosion of the early Tertiary Period, some 50-60 million years ago. When the Isthmus of Panama formed, about 3 MYA, some species moved into Central America; today, all but 2 of the 20 modern species of armadillo inhabit South America and the nine-banded armadillo is the only one found in the United States.
Since crossing into Texas in the late 1800s, nine-banded armadillos have rapidly expanded their range; limited by dryness and poorly equipped to survive in prolonged cold, these prolific mammals can be found from western Oklahoma to the Atlantic Seaboard and from southern Kansas, southern Missouri and South Carolina to the Gulf Coast. Favoring streamside habitat, the armadillo army has spread along the Arkansas and Lower Mississippi Valleys and inward from the Gulf and Southern Atlantic Coasts via rivers and streams of the broad Coastal Plain; they have also been transplanted to some areas in the Southeast.
Armadillos mate in mid summer and, after delayed implantation and four months of pregnancy, identical quadruplets are born in early to mid spring; able to forage soon after birth, they nurse for two months and are sexually mature by the following summer. Powerful diggers, armadillos feast on earthworms, insects, grubs, fruit and carrion and excavate dens in which to sleep, give birth or to wait out periods of cold weather. Though often victims of dogs, coyotes and automobiles, armadillos may live 15 years or more and their range is expected to expand into the Mid Atlantic States over the coming decades.
Since crossing into Texas in the late 1800s, nine-banded armadillos have rapidly expanded their range; limited by dryness and poorly equipped to survive in prolonged cold, these prolific mammals can be found from western Oklahoma to the Atlantic Seaboard and from southern Kansas, southern Missouri and South Carolina to the Gulf Coast. Favoring streamside habitat, the armadillo army has spread along the Arkansas and Lower Mississippi Valleys and inward from the Gulf and Southern Atlantic Coasts via rivers and streams of the broad Coastal Plain; they have also been transplanted to some areas in the Southeast.
Armadillos mate in mid summer and, after delayed implantation and four months of pregnancy, identical quadruplets are born in early to mid spring; able to forage soon after birth, they nurse for two months and are sexually mature by the following summer. Powerful diggers, armadillos feast on earthworms, insects, grubs, fruit and carrion and excavate dens in which to sleep, give birth or to wait out periods of cold weather. Though often victims of dogs, coyotes and automobiles, armadillos may live 15 years or more and their range is expected to expand into the Mid Atlantic States over the coming decades.
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