Posts Tagged ‘grizzly bear’

The Kentucky Bluegrass Country

September 12, 2012

Some specimens excavated from the Little Kettle Creek fossil site in Wilkes County, Georgia suggest a climate phase at the time of their deposition similar to the present day climate of the Kentucky Bluegrass Country.  https://markgelbart.wordpress.com/2011/03/17/little-kettle-creek-the-only-pleistocene-fossil-site-in-the-piedmont-region-of-southeastern-north-america/       Bog lemmings reach their present day southern range limit in northern Kentucky, and red backed voles occur in cool north facing slopes of the southern Appalachians.  Yet, both of these species lived in central Georgia during some portion of the last Ice Age.  Moreover, evidence from catfish bones also implies much harsher winters than are known in Georgia today.  Rural areas of the Kentucky Bluegrass Country, particularly horse pastures with centuries old trees growing in them, are considered relics of the kind of savannah woodlands that predominated in southeastern North America during much of the Pleistocene.  Accordingly, this intriguing similarity between the present day Bluegrass Country and Pleistocene central Georgia inspired my research for this blog entry.   However, there are some important differences between the 2 regions.

Map of the Kentucky Bluegrass Country.  The present day climate here is a close analogue to some climate phases of the Ice Age in central Georgia.

The geology of the Kentucky Bluegrass Country causes a differing soil chemistry from that found in most of Georgia.  The inner bluegrass region rests on top of ancient limestone, making the soil basal while most of Georgia’s soil is acid.  The limestone orginated from Paleozoic Age coral reefs that ringed islands resembling those of the modern day Bahamas.  Over time geological processes turned all that coral into limestone.  The underlying limestone  makes the soil of the bluegrass region among the richest in the world.  The soil is high in calcium and other minerals that help plants grow and the animals that eat these nutritious plants are healthier than those from other regions, explaining why this is good land for raising horses.  Most of Georgia’s soil was never nearly this fertile, even before agriculture wore out the land.  The underling rock in the outer bluegrass region is shale.  Shale is merely fossilized mud.

Note the spectacular 400 year old bur oak in the top left photo. Bur oak is a characteristic species of the Kentucky bluegrass country.  I tried in vain to find as impressive a photo on google images, so I ripped this one off from the below referenced book.

Note the stand of giant bamboo cane in the bottom right photo.  Cane is a relic today, but at the time of European settlement it formed thickets that were as much as 20 miles long adjacent to streams and rivers.  Daniel Boone escaped from Indian captivity by running into one of these canebrakes.

The photo in the upper right corner is a typical feature of the Kentucky river with a steep bluff on one side and a floodplain on the other.  The photo in the upper left corner is of a spring that emerges above ground and seeps back underground.

The calcium rich soil fosters the growth of calciphiles–plants that grow best in this type of earth.  Pre-settlement forests consisted of sugar maple, black walnut, butternut, blue ash, white ash, Kentucky coffee tree, honey locust, black cherry, bur oak, chinquapin oak, Shumard’s oak, white oak, shellbark hickory, buckeye, hackberry, and mulberry.  Common undergrowth trees included great stands of pawpaw, crabapple, hazelnut, plum, twinleaf, blue cohosh, and slippery elm.  Many of these species are shade intolerant, and they grew in natural widely spaced groves similar to those described by William Bartram from his travels through Georgia in the 18th century.  The trees grew far enough apart to allow sunlight to reach the ground, allowing a wide variety of grasses and herbs to flourish.  A few of the common species found in the pre-settlement savannah woodlands were buffalo grass (Panicum sp.), the now endangered buffalo clover (Trifolium stoloniferum), wild rye (Elymus villosus and virginica, not the European grain), wild peavine (Amphicarpa bractenta), the edible wild bean (Phaeseolus polystachios), goldenrod (Solidago sphacelata), and many calcium-loving ferns, sedges, and wild flowers.  Giant bamboo cane (Arundinaria gigantea) grew in thick stands along streams and rivers.  One stand of bamboo was estimated to be 20 square miles in extent.

The Kentucky River washes away some of the rich soil on the floodplain, resulting in thinner, poorer soils along its margin.  This area sported a somewhat different composition of trees that included sycamore, white oak, elm, and tulip with an undergrowth of dogwood.  Red cedar, now a more common tree in second growth forests here, grew on rocky bluffs.

European settlers rapidly destroyed much of this beautiful environment.  They cut down most of the trees and converted most of the rich cane land into pasture.  They introduced species of grasses and herbs that outcompeted native plants.  They killed most of the sugar maple trees by cutting big chunks out of the trees to harvest the sap instead of carefully tapping the trees in a way that would keep them alive.  They allowed their livestock to overgraze between the trees, eliminating regenerating trees, reducing pawpaw stands, and wiping out hazlenut, so that the latter is completely absent from the region today.  However, many of the bluegrass pastures host ancient pre-settlement trees that are still standing.  A 400 year old bur oak still lives in Bourbon County.  Other pastures consist of groves of blue ash, bur oak, and Kentucky coffee trees ranging in age between 200-400 years old. The pastures are remnants of savannah woodlands.  Mowing is preventing regeneration and eventually these old trees will die.  For this reason these relics are endangered.

Botanists are uncertain whether Poa pratensis, the species of bluegrass for which this region gets its name, is a native or an introduced species.  Bluegrass is also known as English grass, and it ranges into Eurasia and select areas of the Rocky Mountains.  The first settlers reported seeing bluegrass growing in Kentucky in the mid 18th century, and there is no ship’s record of it being imported that early.  This species may have had a natural Holarctic range, meaning that millions of years ago it spread across the Bering landbridge.

Ecologists think the trampling and grazing of great herds of bison and elk  shaped the savannah woodland environment here, and that fire was rather infrequent.  The rich land and abundant mineral licks attracted unusually large numbers of ungulates to this area.  The bison, elk, deer, bear, and passenger pigeons kept tree saplings naturally thinned, fostering the growth of widely spaced trees.  Fire must have occurred only rarely because sugar maple (a fire intolerant species) was formerly common here.  This ancient savannah woodland environment originated during the Pleistocene, though the plant and animal composition varied, depending upon the climate phase.  During interstadials and interglacials when deciduous trees were abundant, mastodons, giant ground sloths, deer, and long-nosed peccary thrived.  Both honey locust and Kentucky coffee trees bear leguminous pods that mastodons would have spread across the landscape in their dung.  Perhaps their abundance here along with pawpaws is evidence that mastodons made their last stand in the bluegrass country.

There is an excellent Pleistocene age fossil site in the region–Welsh Cave.  It was excavated in 1965.  Here’s the list of fossil speciments found here.  *denotes extinct species. # denotes species no longer found in the region

*dire wolf

#grizzly bear (southeasternmost known occurrence)

#badger

least weasel

*mammoth

horse

*flat-headed peccary

water shrew

pygmy shrew

short-tailed shrew

eastern mole

#snowshoe hare

#red squirrel

#spruce vole

yellow-cheeked vole

red-backed vole

meadow vole

pine vole

#porcupine

#thirteen lined ground squirrel

#pocket gopher

brown bat

pipistrelle

The radiocarbon date from the fossils found here was ~13,000 BP which translates to ~15,000 calender years BP.  The faunal composition suggests a prairie environment with fingers of boreal forests consisting of pine, spruce, birch, and northern hardwoods.  Superficially, it would have resembled the lowlands of the present day Yellowstone National Park in appearance.  Obviously, the preponderance of species that prefer (or preferred in the case of extinct species) open spaces indicates the fossils were deposited during the Last Glacial Maximum when hardwood forests were on the wane and grasslands were expanded because of the cooler drier climate.  The Welsh Cave site is the southeasternmost known occurrence of the grizzly bear.  13-lined ground squirrels lived in Kentucky until as recently as 600 AD.  Their remains have been found in Indian middens dating to then.

Two More Interesting Notes About Pre-Settlement Northern Kentucky

–A passenger pigeon roosting site in 18th century Shelbyville, Kentucky was estimated to be 120 square miles in extent.

–The Kentucky River, a tributary of the Ohio River, once was home to a freshwater species of cod, now restricted to more northerly localities.  The American burbot, also known as the eel pout, is called the “poor man’s lobster.”  Along with 2 species of sturgeon and the paddlefish, it’s been eliminated from Kentucky’s waters.

Reference:

Wharton, Mary; and Roger Barbour

Bluegrass Land and Life

The University of Kentucky Press 1991

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Pleistocene Bears of Southeastern North America

March 10, 2011

Nothing demonstrates wilderness more than a robust population of free roaming bears.  During the Pleistocene before people were around to kill them and destroy their habitat, there must have been tens of thousands of bears living within the boundaries of what today is Georgia.  It’s possible that 5 different species could have been found here in the same time span, though we can be more sure there were at least 3 sharing the same range.  Today, only 1 species of bear resides in Georgia–an estimated 5100 black bears still roam the mountains, the Okefenokee Swamp, the Altamaha and Ocmulgee river bottoms, and Houston County.  Occasional stragglers leave these last strongholds and raid urban dumpsters and suburban bird feeders, but these occurrences are rare.  One study of Georgia bears determined that suitable habitat can support 1 bear for every 3 square kilometers.  That means ideally, Pleistocene Georgia hosted a population of 30,000-40,000 bears.  (*Georgia is about 60,000 square miles. 1.86 square miles =3 square kilimeters.  Moreover, during stadials Georgia’s land mass increased by about 10,000 square miles due to the fall in sea level.)

Here’s a review of every known bear species that lived during the Pleistocene in southeastern North America.

Black bear–Ursus americanus

Photo from google images of a black bear in the Okefenokee Swamp.

Ursus abstruscus is the probable evolutionary ancestor of American and Asian black bears which once consisted of a geographically continuous population.  Glacial ice separated the two populations at the beginning of the Pleistocene, resulting in two different species.  Bjorn Kurten notes that Pleistocene black bears grew as large as modern day grizzlies.  I believe Pleistocene black bears were larger and fiercer than their modern day descendents because they had to survive confrontations with saber-tooths, giant panthers, jaguars, and packs of dire wolves.  Cavers and scientists discovered black bear fossils at Ladds and Kingston Saltpeter Cave in Bartow County, and the Isle of Hope Site in Chatham County.  They’re also commonly found in Florida fossil sites but only a few have been recorded from South Carolina.

Florida spectacled bear–Tremarctos floridanus

Photo of a spectacled bear, Tremarctos ornatus,  from google images.  This is the only living species from the once widespread short-faced bear family.  It is a close relative of the extinct Tremarctos floridanus.  Of course, scientists have no way of knowing whether Tremarctos floridanus was also spectacled, but they call it that anyway.

Now extinct, this was likely the second most common species of bear in southeastern North America during the Pleistocene.  Only 1 specimen has ever been recovered in Georgia (at Ladds), but its fossils have commonly been found in Florida and South Carolina.  It’s thought of as primarily a vegetarian, but a recent study of Pleistocene bears concluded that all were opportunistic omnivores that would eat anything they could obtain.  Tremarctos’s range in the late Wisconsinian Ice Age seems to have been restricted to the southeast.  During warm interglacials it expanded as far north as Kentucky.  It probably just lived in the coastal plain of Georgia and South Carolina as well as Florida during colder climatic stages.

Lesser short-faced bear–Arctodus pristinus

Photo of a fossil jaw bone of Arctodus pristinus from Additions to the Pleistocene Mammal Fossils of South Carolina, North Carolina, and Georgia by Albert Sanders.

Photo of fossil bear teeth from the above mentioned publication.

It’s unclear from the fossil record whether this species co-existed with its larger cousin, the giant short-faced bear, or was simply ancestral to it.  Its fossils have only been recovered from a few eastern sites in Florida, South Carolina, Maryland, and West Virginia.  Teeth attributed to this species overlap in size with those of Arctodus simus.  Florida fossils of this species, including those from Leisey Shell Pit, indicate this animal lived from the early to mid-Pleistocene (~1.8 million-300,000 BP), whereas giant short-faced bear fossils in Florida date to the late Pleistocene (~300,000-~11,000 BP).  However, fossils of the lesser short-faced bear were found in South Carolina sediments thought to date from the Sangamonian Interglacial (~132,000-~118,000 BP) which is also considered late Pleistocene.  These South Carolina specimens haven’t been radiometrically dated, so no one knows exactly how old they are.  Perhaps this species did survive as a relic species in some geographical locations until the megafauna extinction.  Arctodus pristinus is considered more of a general feeder; Tremarctos floridanus a more herbivorous species; Arctodus simus a more carnivorous bear.

Giant short-faced bear–Arctodus simus

Dan Reed’s photo-shopped reconstruction of a giant short-faced bear.   

The giant short-faced bear ranks up there with mammoths, mastodons, ground sloths, and saber-tooths as among one of the most spectacular creatures of this era.  Studies suggest it lived by aggressive scavenging.  It’s extremely acute sense of smell detected blood from a great distance.  Then, the beast would relentlessly trot toward the source of the appetizing odor, and its sheer size would intimidate the partially satiated carnivore that actually made the kill into surrendering the carcass.  Arctodus simus fossils are more common in western fossil sites, but a few have been discovered in the southeast, proving it did occur here, at least sporadically.  An Arctodus simus skeleton rested in the Fern Cave system in Jackson County, Alabama which borders northwestern Georgia, until it was discovered by cavers in 1970.  In addition a number of teeth from this species have recently been discovered in north Florida fossil sites, and some Arctodus simus material was also discovered in Virginia.

Grizzly bear–Ursus arctos

Photo of a grizzly bear and cub from google images.

Welsh cave in Kentucky yields grizzly bear fossils dating to about 12,000 BP.  This is the easternmost known occurrence of this species.  Grizzly bears roam hundreds of miles, so it’s likely if they lived in Kentucky then that they must have entered Tennessee.  But the lack of grizzly bear fossils in other southeastern states suggests they never penentrated the region in significant numbers.  Still, I believe a few irregular stragglers may have wandered into what’s now north Georgia.  It may be that the existence of 3 or 4 other species of bears prevented grizzly bears from colonizing much of the southeast during the Pleistocene, and then man arrived, creating another obstacle blocking their migration into the region.  Grizzly bears are a relatively recent addition to North America’s mammalian fauna, but they did live on the continent prior to the LGM, 30,000 years BP.  They’re the same species as the Eurasian and Alaskan brown bears.

If I could live in the Pleistocene (part 4).

For those unfamiliar with this blog, I occasionally fantasize living during the Pleistocene but with modern conveniences, such as an adobe house with woodstoves, solar heating, electricity, and a time tunnel that connects me to the modern world.

I’ve thought of a simple way to observe bears from my abode.  Connected to my Pleistocene house is a 5 story watchtower designed in the shape of a lighthouse in which I can view the surrounding landscape.  I would take a barbecue grill to the fifth story which has a canopy but an open window stretching for 360 degrees around.  There, I would grill meats.  The aroma should attract bears and other carnivores from miles around.  A bear could potentially climb up the side of a light-housed shaped building, so I would have to have some kind of designed guards that would prevent this. 

I would avoid hunting bears, if possible.  I think modern hunters who kill bears are jerks.  I can understand why the pioneers did it.  They didn’t have grocery stores and had to eat and make use of what they could obtain.  But there is no reason to hunt bears today, unless they prove a danger to tourists.  They don’t reproduce as rapidly as deer, and it’s just not ecologically necessary to hunt them.

Bears were a valuable source of meat and fat for early settlers.  Early accounts reveal an important dish of the Indians.  The Indians frequently diced up venison (which is very lean) and fried it in bear fat.  Bear fat was also the number one source of cooking fat in New Orleans in 1800.  It was gradually replaced by lard as the settlers brought in hogs.