Scull Shoals, Greene County, Georgia

December 6, 2016

Scull Shoals is a ghost town located in Greene County, Georgia adjacent to the Oconee River.  People have lived at this site off and on for at least 8000 years and probably longer.  Archaeologists have excavated Indian artifacts, including broken pottery pieces and arrowheads, representative of the Archaic, Woodland, and Mississippian Cultures.  After the Revolutionary War the U.S. government granted this land to war veterans.  The Cherokee Indians were not too happy to have their land granted to Europeans, so they attacked the first settlements in 1788 or 1789.  In response the settlers built Fort Clark here in 1793, and the Cherokees were eventually driven away from their homeland.

Location of Greene County, Georgia

What Scull Shoals looked like during the 19th century.  Note the barren almost treeless landscape.  It was surrounded by cotton and corn fields that were muddy moonscapes during winter.

The settlement was named for the beautiful rocky shoals in this part of the Oconee River.  These shoals are no longer visible because eroded soil has covered them deep under sediment.  The entire site was a magnificent virgin forest until European settlers ruined it.  First, they built saw and paper mills, hydropowered by mill races they constructed.  After they cleared all the trees, they planted row crops of cotton, corn, and wheat to be processed in flour mills, also hydropowered.  During summer corn and cotton fields extended from horizon to horizon but winter landscapes consisted of mud as far as the eye could see.  Short-sighted agricultural practices led to complete erosion of the topsoil into the river, covering the shoals.

Alternating floods, droughts, and recessions destroyed the economy of the village.  Floods spoiled the grain and cotton waiting to be milled.  Droughts caused low water when the mills couldn’t be hydropowered and were thus idled.  By 1930 the town was abandoned.  Land speculators sold the site to the federal government in 1959, and it became part of the Oconee National Forest.  Today, a mixed forest of 2nd growth oak and pine surround the site.  Water oak, sycamore, and sweet gum dominate the actual site of the town, and there is an undergrowth of bamboo cane.  Some of the trees are quite large and may be over 80 years old.  Ecologists believe it takes 1000 years to build 1 inch of topsoil.  The original topsoil was 12 inches thick, so it will take 12,000 years of reforestation before the topsoil is as rich as it was in the 18th century.

We saw an armadillo when we visited Skull Shoals.  The population of armadillos now outnumbers people here.

The kiosk in front of the old site of Scull Shoals.

The town general store.

The mill manager’s house.

This bridge spans the millrace.  Due to the drought, there is no water in the millrace.  Droughts contributed to the decline of Scull Shoals because they couldn’t run the mills without water powering them.

During times of normal water flow this millrace is filled with running water.

Note how low the Oconee River is.  The beautiful shoals that inspired the name of the town have been covered by eroded soil and are no longer visible.

Big sycamore trunk. The federal government bought the site in 1959 and added it to the Oconee National forest.

Scull Shoals is now a nice picnic area.  Dominant trees consist of water oak, sycamore, and sweetgum.

Armadillos outnumber people as permanent residents of Scull Shoals today.

The Strange Little Star-nosed Mole (Condylura cristata)

December 2, 2016

Strange.  Cryptic.  Uncommon.  Unique.  These are all words that could be used to describe the star-nosed mole.  The alien-looking structure on the end of its nose is known as an Eimer’s organ.  All 30 species of moles have this organ, but none have one that is as developed as the star-nosed mole’s.  The Eimer’s organ is used to detect prey in underground darkness and water, but scientists aren’t sure how it works.  Some think it senses tacticle stimulation, while others believe it senses the electrical fields of prey. It may sense both.  In any case over half of a star-nosed mole’s brain is used to process information gathered by its Eimer’s organ.

The star-nosed mole is a semi-aquatic subterranean mammal, living in meadows and woods adjacent to streams, ponds, and marshes.  They also occasionally occur in drier habitats.  Their underground tunnels often lead to water.  Incredibly, they can smell underwater by blowing a bubble that sticks to the end of their nose.  They are the fastest feeder on the planet, able to detect and consume prey in .2 seconds.  Scientists believe they evolved this rapid feeding mechanism and well developed Eimer’s organ to help them survive wet muddy environments where there is a dense population of small insects.  Star-nosed moles feed upon insects, worms, mussels, snails, crustaceans, salamanders, frogs, and fish.

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Star-nosed mole.

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Range map for the star-nosed mole.  This map doesn’t include Richmond, County Georgia where I reside.  Star-nosed moles do occur in east central Georgia.  My cat killed a specimen and left it on my back porch about 10 years ago.  They likely have a more extensive range than this map indicates but are rare and haven’t been reported in many areas of their range.

As far as I know, I am the only person to report the presence of star-nosed moles in Richmond County, Georgia.  According to the scientific literature and accepted range maps, star-nosed moles don’t occur in east central Georgia.  But about 10 years ago, a cat killed a star-nosed mole in my back yard.  My lot is on a sandhill plateau approximately 1/2 mile from a creek and wetland.  All other cat-killed moles in my yard were the much more common eastern mole ( Scalopus aquaticus ).  There is no chance of misidentification–the star nose is obvious.

Star-nosed moles may have been more widespread in southeastern North America during cool Ice Ages.  Over half of their present day range was under glacial ice then, and their range shifted south.  Pleistocene-aged remains of star-nosed moles have been excavated from caves in Arkansas and Missouri–far outside their present day range.  Cool moist stages of climate with low evapotranspiration rates supported more boggy environments favored by star-nosed moles.  However, it’s possible star-nosed moles still occur in those states but exist in cryptic populations yet to be discovered (or recognized and reported) because it is an uncommon animal that lives underground and is not often seen.

Video about the star-nosed mole.

Reference:

Catania, Kenneth

“A Nose that Looks Like a Hand and Acts Like an Eye: the Unusual Mechanism of the Star-nosed Mole”

Journal of Comparative Physiology 85 (4) 1999

Pleistocene Manatees (Trichechus manatus)

November 28, 2016

Mammoths and mastodons no longer roam North America, but a relative of the elephants can still be found in Florida.  The manatee belongs to the superorder paenugulata which includes the proboscidea (elephants), the hyracoidea (hyraxes), and the sirenia (manatees and dugongs).  Strange as it may seem, these quite different looking animals are somewhat closely related.  Manatees share many anatomical characteristics with elephants.  Their incisors resemble elephant tusks, and the toenails on their flippers exactly match those found on elephant toes.  Manatees use their lips to feed on vegetation, much like elephants use their trunks when foraging for food.  And manatee teeth are replaced by horizontal forward movement– the same process of dental development that occurs in elephant mouths.  A scientist first recognized the anatomical similarities between manatees and elephants in 1945.  Recent genetic studies confirm this early cladistic analysis.

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The proboscidea, hyracoidea, and sirenia orders belong to the same clade–the paenugulata.

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All of these species of manatees are still extant except for Steller’s Sea Cow which was overhunted  to extinction in 1768.

The species of manatee still extant in Florida today ecologically replaced an extinct species of dugong during the late Pliocene or early Pleistocene.  This species is known as the West Indian manatee because it occurs along the Caribbean island coasts–also known as the West Indies.  Manatees occasionally swim as far north as Massachusetts during summer but return to waters off the coast of south Georgia and Florida before winter.  West Indian manatees can’t survive cold water temperature.  Fossil evidence shows manatees have long straggled north of their winter range–remains of manatees dating to the Pleistocene have been found near the coasts of South Carolina, Virginia, and New Jersey.  There is some evidence that manatees were extirpated from Florida during the coldest stage of the last Ice Age.  Fossils of manatees dating to before the Last Glacial Maximum in Florida resemble a subspecies no longer found in the state.  Manatees from the Caribbean recolonized Florida following the end of the last Ice Age.  Pleistocene-age manatee bones have been excavated from over 24 sites in Florida, and men hunted them as soon as Indians arrived in the region.

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Manatees in the St. Mary’s River, Georgia.  I saw manatees when I visited Wakulla Springs, Florida.

West Indian manatees feed upon over 60 kinds of aquatic plants such as eel grass and turtle grass, and they incidentally ingest snails and small fish while munching on vegetation.  The extinct Stellar’s sea cow ( Hydromalis gigas ) ate kelp.  Stellar’s sea cow was the largest species of manatee, formerly reaching lengths of 30 feet.  It was the only species of manatee adapted to live in cold water.  They evolved a layer of blubber to help them cope with the frigid temperatures of the north Pacific.  Sea cows were widespread during the Pleistocene, ranging as far south as Monterey Bay, California, but by 1747 when they were first discovered by Europeans, they were already relegated to a small relic population off Commander Island located in the remote Bering Sea.  They were overhunted to extinction by 1768.

Some archaeologists speculate Paleo-Indians first reached North America by following a route along the Pacific coast, but they have no concrete evidence.  The reduction in the population and range of Stellar’s sea cow may be indirect evidence supporting this hypothesis.  Prehistoric seafaring people likely overhunted Stellar’s sea cow and extirpated them over most of their former range.  Sea cows reproduced slowly and were easier to hunt than whales.  Kelp beds, the habitat they preferred, have remained abundant throughout their decline and extinction, so ecological change can’t be the reason they became extinct.

All extant species of manatees are in danger of extinction today precisely because of the slow reproductive rate that doomed Stellar’s sea cow.  Manatees reproduce fast enough to replace populations lost to cold snaps, red tides, and other causes of natural mortality, but the addition of deadly boat propellers to their environment may be pushing them over the edge.

Pleistocene Pecans (Carya illinoinensis)

November 20, 2016

The pecan tree is 1 of 17 species of hickory trees.  Hickories are native to North America and Asia and formerly occurred in Europe, but Ice Ages, beginning about 2.5 million years ago, wiped them out there.  European mountains have an east to west orientation, while American mountains are oriented north to south.  Hickories prefer temperate climates, and the east-west mountains blocked their retreat in Europe during glacial expansions.  This explains why hickories and so many other tree species survived Ice Ages in North America but not in Europe.

Evidence of fossil pollen grains suggests hickory trees grew alongside dinosaurs during the late Cretaceous, though the oldest fossil hickory nut dates to about 34 million years ago.  Most early hickory species had thin shells, but they evolved thicker shells about 38 million years ago in response to the evolution of tree squirrels.  Squirrels love the nutrient rich nuts, so hickories evolved nuts with thicker shells, and the squirrels in turn evolved greater gnawing power.  Evolution is a constant struggle.  However, pecans retained the thinner shells of their early ancestors.  This puzzled me because it seems as if squirrels would have eliminated all hickory species with thinner shells because they were easier to exploit.  I wondered if pecans were a recent species, cultivated and spread by Native Americans.  I’ve concluded however, based on certain lines of evidence, that pecans are an ancient species of hickory, not a recently evolved species manipulated by man.

Wild Pecan Tree

Wild pecan tree.

{The native range of Carya illinoensis}

Native range of wild pecan trees.  Man has greatly expanded this range by planting pecan orchards.  Georgia is now the leading producer of pecans, though they are not native to this state.  Pecans need longer growing seasons than other species of hickory because their nuts mature later.

Genetic studies determined pecans have a large genetic diversity within populations.  If pecans descended from human cultivation, they would have low genetic diversity because they would descend from a small population initially cultivated by man.  I was also mistaken in considering squirrels the only major predator of hickory nuts.  The pecan weevil ( Curculio caryae ) infests all species of hickories, and pecan trees growing in mixed stands with other hickory species have an advantage over their cousins.  Pecans mature later in the season than other species of hickory.  The pecan weevil hatches and emerges in August and will infest whichever hickories have developed kernels.  Because thick shelled hickories mature before thin-shelled pecans, the pecan weevil will infest them first and go through their life cycle without ever infesting the thin-shelled pecan.  Weevils will wait for pecans to mature, if no other hickory trees are available.  So though thin shelled pecans may suffer heavier squirrel predation, they are less likely to have their nuts destroyed by weevils, if they grow near other species of hickory.

Pecan weevil larvae in nut

Pecan weevil larva.  Pecans mature later than hickories.  Though squirrels favor pecans over hickories, the later maturing pecans are less likely to be attacked by pecan weevils in mixed forests, giving pecans an advantage over other hickory species.

Pecans are native to river bottomland terraces where they grow in forests dominated by sycamore, sweetgum, and elm.  Other subdominants in these terrace forests include water oak, box elder, silver maple, cottonwood, green ash, hackberry, and other hickory trees. Pawpaw, bamboo cane, pokeweed, grape vine, poison ivy, and green brier make up the thick undergrowth of bottomland forests.

Pecans hybridize with 5 other species of hickory.  The nuts produced by wild pecans and hybrids vary in quality.  Most are smaller and have somewhat thicker shells than cultivated varieties of pecans, and some even have high amounts of bitter tannins–all part of their ongoing evolutionary war with squirrels and weevils.  Human cultivation of pecans on a large scale began circa 1900.  Though Georgia isn’t part of the pecan’s native range, the state is the leading producer, and there is a large demand in China and India, resulting in high prices at the grocery store for the nuts.

Most cultivated varieties of pecans don’t mature before the first killing frost occurs in Midwestern states.  A few small early maturing varieties can produce in the Midwest as can the hican–an hybrid cross between pecan and shellbark hickory.

Hican 5-nut sample prior to cracking. US quarters shown for size comparison.

 

 

 

 

 

 

 

 

 

 

 

Hican nuts–an hybrid cross between a pecan and a hickory.  They produce earlier maturing nuts  for northern locations that have frosts before pecans can fully develop.

The southern Mississippi River Valley has long served as a refuge for pecans and other hickory trees during glacial expansion cycles.  Here, they grew in mixed Ice Age forests with spruce, beech, walnut, and oak.  Pecans expanded their range north up the Mississippi River Valley following the end of the last Ice Age.

The oldest written recipe for pecan pie dates to 1886.  It was a custard pie made with sugar, eggs, and butter.  (Sugar/custard pies originated during the Middle Ages.)  Pecan pies became more popular in the 1930s when some unnamed employee of Karo syrup invented a recipe for a pecan pie using syrup as well as sugar.  I prefer my pecan pie made with maple-flavored corn syrup.

Pecan Pie

Pecan pie with whiskey maple cream sauce.  I like my pecan pies made with maple flavored corn syrup.

 

Forest Succession and Changing Song Bird Species Composition in Central Georgia

November 13, 2016

Cotton and corn cultivation were important in central Georgia until the boll weevil struck in the 1920’s.  Then the depression bankrupted many farmers who tried to persevere, despite this agricultural pest.  This economic calamity gave ecologists the opportunity to study forest succession as fallow fields eventually were transformed into climax forests.  In less than a year bare soil becomes covered in grass and weeds 2 feet tall.  Ragweed, asters, and broomsedge (a type of bunch grass) take over in the 2nd year, and by the 3rd year broomsedge and pine saplings up to 3 feet tall predominate.  These 1st three years are known as the “grassland stage.”

If left unmodified, years 3-10 are known as the “grass and shrub stage.”  Broomsedge and pine saplings are joined by blackberry, blueberry, sumac, greenbrier, and persimmon often covered by grape vines, Virginia creeper, Carolina jessamine, and honeysuckle–all plants that thrive in the sun.  Eventually, pine trees emerge above this tangled mess.  During years 11-30 the landscape is known as a “young pine forest.”  An “old pine forest,” years 31-60, hosts tall pine trees but with a dense oak understory.  This mixed pine/oak forest is habitat for more species of birds than any other stage.  Lightning strikes, red heart disease, and pine beetles kill many pine trees during this stage, opening up the forest canopy and creating uneven-aged stands of trees beneficial for many different species of birds.  After 60 years left fallow the land becomes a climax oak/hickory forest.

Below is a chart interspersed with photos showing the association of bird species with each stage of forest succession.

Years 1-3 (Grassland Stage)–grasshopper sparrow, field sparrow, song sparrow, meadowlark, killdeer plover, quail, junco, horned lark.

Female grasshopper sparrow returning to nest with prey in beak

Grasshopper sparrows (Ammodramus summurum) are abundant in old fields.

Years 3-10 (Grass and Shrub Stage)–Add white-throated sparrow, rufus-sided towhee, cardinal, catbird, mockingbird, mourning dove, Carolina wren, and brown thrasher.

bobwhite quail covey

 

 

 

 

 

 

 

 

 

 

 

Covey of quail.  This species becomes most abundant 3-5 years after cleared land is left fallow.

Years 11-30 (Young Pine Forest)–Subtract most of the grassland species but add flicker, blue jay, chickadee, titmice, pine warbler, and white-eyed vireo.

Eastern Towhee

 

 

 

 

 

 

 

 

 

 

 

 

 

Rufus sided towhees move into young pine forests.

Years 31-60 (Old Pine Forest Stage)–Subtract mourning dove, catbird, mockingbird, brown thrasher, and white-eyed vireo, but add summer tanager, woodpeckers, yellow-throated warbler, black and white warbler, wood thrush, flycatchers, red-eyed vireo, and kinglets.

Carolina Wren Photo

Carolina wrens are abundant in old pine forests with an hardwood understory.

> 60 years (Climax Oak/Hickory Forest) Subtract towhee, pine warbler, and tanager, but add white breasted nuthatch.

White-breasted nuthatch foraging in tree

White breasted nuthatches won’t move into a forest until it is at least 50 years old.  Last time I saw this species was when I visited Marshall Forest in Rome, Georgia which is a virgin forest.

Forest succession from bare soil to climax forest has occurred in Georgia ever since Indians began cultivating the land here over 1000 years ago.  However, habitat including each successional stage is much older than this because our present day species of song birds, especially habitat specialists, have existed for over 1 million years.  Before man impacted the environment, changes in the landscape depended upon natural disturbances.  Heavy acorn consumption by megafauna along with trampling and bark-stripping suppressed tree recruitment and growth.  Lightning-ignited fires thinned forest into open woodlands.  Tornadoes and downbursts flattened wide swaths of trees.  Drought, ice storms, floods, and fluctuating climate cycles also changed forest structure and tree species composition.  Landscapes are never eternally permanent.

References:

Johnson and Odum

“Breeding Bird Populations in Relation to Plant Succession on the Piedmont of Georgia”

Ecology 37 1956

Meyers, J.M. and A.S. Johnson

“Bird Communities Associated with Succession and Management of Loblolly-Shortleaf Pine Forests”

U.S. Forest Service General Technical Report

 

Native Fish Species Composition of Piedmont Tributary Creeks of the Chattahoochee River

November 7, 2016

The many present day creeks and small rivers that flow through the piedmont region of central Georgia originated between 15,000 years BP-8,000 years BP when water tables rose as a result of melting glaciers far to the north of the state.  Before this, during the Glacial Maximum, the regional landscape was much more arid and only the largest of rivers and creeks still flowed…and those were often low flowing and clogged with sandbars.  Intermittent springs probably occurred in the lowest areas of topography along the present day courses of smaller streams.  Climatic phases with increased precipitation raised the water table enough to cause water flow between springs, and these creeks eventually emptied into the nearest river.  So much atmospheric moisture was released at the end of the last Ice Age that rivers and creeks had a larger flow than they do today.  This occurred between ~10,000 years BP-~5,000 years BP when rivers were classified as “supermeandering.”  Fish found their way from rivers into newly formed creeks during the late Pleistocene/early Holocene, though a few species may had persisted in relic Ice Age springs before water tables rose.  About 40 years ago the noted naturalist, Charles Wharton, electro-fished a small unnamed creek located 1.4 miles south of Sopa Creek, a tributary of the Chattahoochee River, and he determined the “near original” composition of fish species typical of piedmont streams that flow into this river.  These creeks flow through steep terrain often between high bluffs and where protected are still very beautiful natural areas.

Map of Georgia highlighting Cobb County

Cobb County, Georgia.  Charles Wharton electro-fished a small stream here over 40 years ago and determined the original fish species composition of piedmont Chattahoochee feeder creeks.

This is where Sopa Creek flows into the Chattahoochee River.  Sherman ordered his troops to cross over the rocks here during the Civil War.

The fish species Wharton found in his survey included band fin shiner ( Notropis zonistius ), central stoneroller ( Campostoma anomalum ), creek chubsucker ( Erimyzon oblongus ), Alabama hog sucker ( Hypentelium etowanum ), yellow bullhead catfish ( Ictalurus natalis ), bluegill ( Lepomis machrochorus ), and banded sculpin ( Collus carolinae ).  The band fin shiner is a small minnow native to the Chattahoochee River drainage, though it has been introduced to other river systems wherever fishermen dump their bait buckets.  The stoneroller is a widespread species in the Midwest.  It eats algae and may school in the hundreds.  They grow up to 8 inches long.  The creek chubsucker can grow twice as long as the stoneroller, and it eats small crustaceans and insect larva in addition to algae.

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Alabama hog sucker.

The yellow bullhead catfish is omnivorous and can grow up to 6 pounds, though it normally reaches a weight of about 2 pounds.  Bluegills also grow large enough to make a good meal.  Early settlers placed fish traps in the nearest streams and caught supper, while they were busy clearing and cultivating their land.  Bluegills and catfish living in clear moving streams with rocky  bottoms probably taste better than those taken from muddy ponds.

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Yellow bullhead catfish.

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Bluegill sunfish or bream.

The banded sculpin is a freshwater relative of a large family of saltwater species.  Banded sculpins are nocturnal ambush predators that live under stones.  They compete with crayfish for the same type of habitat.

Banded Sculpin - Cottus

Banded sculpin.

The origin of the name Sopa Creek has a disputed origin.  This stream flows for 11.6 miles through Marietta until it empties into the Chattahoochee River.  Today, the headwaters emerge from a spring under a manmade culvert, but I’m sure the original landscape was picturesque.  Now, it is surrounded by suburban sprawl.  Some say this creek gets its name from the foam caused by water rushing through rocks.  The foam resembles soap spuds, and supposedly an early mapmaker misspelled soap.  Others claim the creek is named after an old Cherokee Indian (Old Sopa) who lived nearby.  He reportedly refused to be removed when is compatriots were force marched to Oklahoma on the Trail of Tears.

Reference:

Wharton, Charles

The Natural Environments of Georgia

Georgia Department of Natural Resources 1978

 

Pleistocene Ungulates of Interstadial Oak Woodlands and Forests in Southeastern North America

November 4, 2016

I have long been curious about the wildlife I would encounter, if I could travel in a time machine to a wilderness cabin located in central Georgia 36,000 years ago.  This climatic stage was an interstadial–a relatively warm wet phase of the Ice Age.  It was likely well before people entered the region, so I could experience an ecosystem completely uninfluenced by man.  Pollen evidence from deep ocean cores suggests an expansion of oak woodlands and forests during interstadials, while pine and spruce declined.  (Botanists distinguish the difference between woodland and forest.  A woodland has 50%-80% canopy coverage; a forest has >80% canopy coverage.)  Oak woodlands were probably the most common natural community in the Georgia piedmont during interstadials.  They had an open structure with centuries-old, large diameter trees in the overstory and herbaceous and grassy understories.  Megafauna trampling and foraging along with low intensity fires and occasional windstorms maintained the open structure of the woodlands.  Areas less frequented by megafauna and protected from fire fostered thicker forests.  Oaks dominated the landscape but co-occurred with hickory, chestnut, and pine.  The warmer the climate phase, the greater the variety of trees.

Oak woodlands provided ample food for a large population of animals.  Acorns and plants growing in the understory fed herds of ungulates as well as bears, small game, and birds.  Bison, horses, and mammoths prefer(ed) prairies and meadows, and mastodons foraged alongside streams.  Although these species occasionally wandered into woodlands, they were probably less common than other species of ungulates in this environment.  Instead, ungulates that fed mostly on forest vegetation prevailed in oak woods.  Studies of bone chemistry that determined dietary preference suggest forest denizens included white-tail deer, long-nosed peccary, tapir, and paleollama.  These are the ungulates I would expect to see from a window in my imaginary wilderness cabin.  Fossil remains of paleollama ( Palaeolama mirifica) have not been found north of the coastal plain, but they may have ranged into the piedmont.  Its cousin, the large headed llama ( Hemiauchenia macrocephela ), was more widespread and isotopic studies indicate it could subsist on either prairie or forest vegetation.  The presence of at least 1 species of llama in central Georgia seems likely.  And of course herds of ungulates attracted a whole array of predators.  The woods of today seem so destitute by comparison.

DNR Camera Project

 

 

 

 

 

10 white-tail deer and a turkey.  This species of deer and its immediate ancestor have populated southeastern North America for millions of years.

Long-nosed peccary.  The success of invasive wild hogs shows that forest environments in the south can support a large population of pig-like animals.

Mountain tapir and young

Mountain tapir with a baby.  Tapirs that lived in the upper south during the Pleistocene likely were adapted to temperate climates like this species.  Isotopic studies of tapir bones indicate they preferred the thickest part of the forest.

Paleollamas of the Pleistocene Period in Florida.

Paleollamas.  They occurred in Florida and the coastal plain and may have ranged into the piedmont.  This species of llama also preferred deep forest, but its cousin, the large-headed llama, was more adaptable.

 

6 Scariest Species to have Ever Lived in Georgia

October 30, 2016

6. The Hell Pigs

Vicious entelodonts lived on earth from the late Eocene to the mid Miocene (for over 20 million years).  They were 4 feet tall and reached weights of 930 pounds.

Entelodonts are known as hell pigs because their fossil remains represent a once terrifying animal that resembled a giant pig.  They occurred across most of the Northern Hemisphere, and there were many species over time.  Entelodonts existed between 37.2 million years BP-16.3 million years BP.  Although they resembled pigs, anatomical evidence suggests they were more closely related to the common ancestor of hippos and whales.  Enteledonts were 4 feet tall and weighed up to 930 pounds.  They were fast runners, and paleontologists believe they rammed into their prey, knocking their victims down and biting them until their bones were broken, probably similar to the way hippos kill humans in Africa today.  Fossil evidence of enteledonts has been found in Twiggs and Houston Counties in Georgia.  The tooth found in Houston County compares favorably with Archaeotherium, a once widespread species of enteledont.

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Entelodont tooth found in Bonaire, Georgia.  I am not the author who took a photo of this tooth.

4. (tie) The Giant Short-faced Bear (Arctodus simus) and the Saber-toothed Cat (Smilodon fatalis)

I can’t decide which 1 of these was more frightening.  Giant short-faced bears were on average as large as Kodiak bears–the largest subspecies of brown bear ( Ursus arctos ).  However, they probably made a lot of noise and could be easily detected and avoided.  Saber-tooths were ambush predators and could sneak up on prey in the dark or in thickly vegetated habitat.  Arctodus was much larger, weighing about 1000 pounds compared to ~350 pounds for Smilodon.  But the latter was very powerful and sported fangs.  Fossil evidence of this big cat has been found in all of the states bordering Georgia.  Fossil evidence of Arctodus has turned up in an Alabama county adjacent to Georgia as well as several sites in Florida.  Both undoubtedly once ranged into Georgia.

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Giant short-faced bear and saber-toothed catThe illustration of this saber-tooth is inaccurate.  Smilodon had a bob-tail and their forelimbs were much more powerfully built than depicted here.

3. Appalachiosaurus

 

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Appalachiosaurus terrorized upstate Georgia during the late Cretaceous.

Appalachiosaurus was a species of tyrannosaur that lived on the eastern side of the Western Interior Seaway during the late Cretaceous (~80 million years BP-65 million years BP).  They were the top land predator, probably hunting hadrosaurs or anything else they could catch.  Fossil evidence of this species has been excavated from Hannahatchee Creek near Columbus, Georgia.  The type specimen, a nearly complete skeleton, was found in Alabama.

2. Deinosuchus rugosus

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Evidence suggests Deinosuchus rugosus ate tyrannosaurs.

This extinct crocodylian, a relative of alligator ancestors, grew to an estimated 36 feet long and weighed up to 17,000 pounds.  They were large and powerful enough to seize and drag a tyrannosaur into the water, and there is some fossil evidence they preyed upon them.  They likely ate dinosaurs as a significant part of their diet.  Fossil evidence of this species has also been found in Hannahatchee Creek as well as the Chattahoochee River in Georgia.

1. Man (Homo sapiens)

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Homo sapiens is clearly the scariest species to have ever walked on earth.  Here is a photo of an atomic bomb mushroom cloud.  Humans can wipe out entire cities with nuclear weapons.

Human beings construct weapons of mass destruction capable of turning livable habitat into uninhabitable wasteland.  I can’t think of anything scarier than that.

Shell Bluff, Burke County, Georgia

October 24, 2016

40  million years ago, the entire coastal plain of southeastern North America was below sea level.  In Georgia sea shore occurred along a line that roughly corresponds with the latitudes of Columbus, Macon, and Augusta.  Rich zones of zooplankton nourished near shore oyster beds populated by a species that grew up to 20 inches in length. Fossils of this extinct giant oyster ( Crassostrea gigantissima ) are exposed at many locations along the ancient shoreline wherever rivers or creeks erode into Eocene Age formations.  Perhaps the best exposure can be found at Shell Bluff in Burke County, Georgia.  This site is a 30 minute drive from my house, and I have long wanted to visit it, but alas it is private property not generally open to the public.

Map of Georgia highlighting Burke County

Location of Burke County, Georgia.  Shellbluff is located on the eastern boundary by the river.  A small local community is named after the site.

http://digitalcommons.gaacademy.org/cgi/viewcontent.cgi?article=1012&context=gjs

I couldn’t find a photo of Shellbluff that I could directly link to my blog, but the above linked Georgia Journal of Science article has a nice picture in the pdf file.

Old photo of the fossil oyster bed at Shell Bluff.

crassostrea gigantissima_griffins_landing_savannah_river_burke_co_ga_alan_cressler_2, I_AMC1300

Look at the size of the extinct Crassostrea gigantissima. A chemical analysis of these giant oyster shells determined a cool shift in climate occurred during the late Eocene.  Average winter sea surface temperatures were the same then as they are today, but summer sea surface temperatures were 3-12 degrees F cooler than those of today.

The bluff is 150 feet high and reportedly the giant oyster shell beds are 80-100 feet from the Savannah River.  The soil near the bluff consists of limestone and sandy marl, and it is rich in calcium.  Because of the unique microclimate and calcium-rich soil, there is a natural community quite different here from the surrounding fire-adapted longleaf pine/turkey oak sand hills.  This natural community is known as a bluff forest with northern affinities or as some other botanists refer to it, a mesic slope forest.  The steep slope and cooling river protect this forest from fire, and the north-northeast exposure helps keep temperatures cooler than in the surrounding terrain.  Many of the plants growing here are disjunct populations of species more commonly found in the Appalachian Mountains or the Midwest.  Species of northern affinities present at Shell Bluff include green violet, tall bellflower, wild ginger, black cohosh, ravine grass, and black walnut.  The overstory consists of white oak, beech, pignut hickory, basswood, and black walnut.  Dogwood, red buckeye, hop hornbeam, 2 species of pawpaw, beautyberry, Carolina buckthorn, and redbud comprise the midstory.  3 of these species–red buckeye, Carolina buckthorn, and red bud–are notable calciphiles (plants that prefer calcium rich soils).  Some rare plants grow here too such as the Ocmulgeee skullcap.

Ocmulgee Skullcap for sale buy Scutellaria ocmulgee

Shellbluff is home to this rare mint–Ocmulgee Skullcap (Scutellaria ocmulgee).

William Bartram found mock orange (Philadelphus inodorous) growing at Shell Bluff in 1775.

John Bartram and his son, William, visited this site in 1765, and William returned 10 years later.  They saw the forest before it was ever logged.  The virgin timber consisted of white oaks, beech, and sweetgum with trunks that were 5 feet in diameter.  Cypress trees were over 6 feet in diameter.  There are probably few, if any, trees this large at the site today.  Bartram included tupelo, tulip, and mulberry in his list of tree species here.  I’m not sure, if these species still exist on the site since it has been logged.  Other rare plants that Bartram cataloged may also be extirpated from the site including mock orange, leather wood, Carolina spice bush, and ginseng.

Bluff forests with northern affinities are relic habitats that represent natural communities formerly more widespread in the surrounding region.  Oak and beech forests with cool climate associates likely formed a more continuous range throughout the mid to deep south during cool moist interstadials.  (Though interstadials were warm phases of climate within Ice Ages, average temperatures were still cooler than those of the present day.)  But these mesic forests also waned during arid cold stadials when grasslands and scrub habitat expanded.  River bluffs have provided refuge for this type of forest during both hot and cold extreme shifts in climate, probably for millions of years.

Reference:

Edwards, Elliott

“Shell Bluff–A Fossiliferous Ridge, The Site of the Extinct Oyster Crassostrea gigantissima and History of its Identification”

Georgia Journal of Science 74 (2) 2016

 

 

Sisters Eating Each Other’s Babies

October 18, 2016

Animals are not people too, contrary to the emotional assertion of some humans who weigh the rights of animals as greater or equal to that of men.  Almost all vertebrates exhibit some behavior patterns that if they were human would get them incarcerated in prison or a mental hospital.  Imagine a mother, usually a vegetarian, who regularly attempted to break into her sister’s house to feed upon her babies.  A case such as this would horrify everybody, and it would attract national attention.  But it is normal behavior for the black-tailed prairie dog ( Cynomys ludovicianus ).

Image result for prairie dog cannibalism

39% of prairie dog litters are cannibalized by lactating sisters.

Prairie dogs are primarily vegetarian; feeding upon wheat grass, buffalo grass, scarlet globemallow, rabbit brush, thistle, prickly pear cactus, and roots.  They occasionally eat insects and bison manure as well.  However, lactating females regularly seek out and cannibalize their sister’s pups.  Prairie dog cannibalism is the leading cause of mortality among pups–39% of baby prairie dogs are killed by their aunts.  Cannibalism occurs among other species of squirrels but at a much lower rate, and the act is executed by unrelated squirrels.

John Hoogland, the scientist who first studied prairie dog cannibalism, believes this cannibalistic behavior evolved for 5 reasons.

  1. Removal of future competition.
  2. Extra nutrition for lactating females.
  3. Less competition for foraging.  After a prairie dog loses her pups she will stop defending her territory and range farther for food.
  4. Females without pups spend more time scanning the landscape for predators, thus helping the security of the entire prairie dog town.
  5. Lactating females who lose their pups are less likely to prey on other prairie dog pups

Prairie dogs are a keystone species that co-existed with bison in the North American short grass prairie region for millions of years.  Studies show prairie dog activity greatly benefits the environment.  Their burrows help drain the soil preventing erosion.  They churn up soil, increasing fertility, and prairie dog towns host a variety of plants that are more nutritious for grazers than areas without prairie dogs.  Yet, most local governments consider prairie dogs a pest and have mandatory eradication programs.  Prairie dogs wrongly get blamed for denuded ranges that have been overgrazed by livestock.  There is also a myth that cows and horses can break their legs in prairie dog holes, though an example of this has never been documented.

The late Larry Haverfield protected prairie dogs on his 7000 acre ranch because he recognized the benefits they provided.  In 2006 the Kansas authorities ordered him to poison the prairie dogs on his land and when he refused, they threw him in jail.  A court injunction stopped the local county in Kansas from eradicating the prairie dogs on his property, and now his land serves as an environmentally friendly refuge where once common but now rare prairie wildlife still thrives.  The endangered black-footed ferret, a predator of prairie dogs, was re-introduced here.  Hopefully, science will some day overcome the myths and misinformation so many ranchers have about this important beneficial species.

Reference:

Hoogland, John

The Black-tailed Prairie Dog: Social Life of a Burrowing Mammal

University of Chicago Press 1995