Archive for May, 2014

Southeastern Grasslands are of Great Antiquity

May 29, 2014

I enjoy watching a summer thunderstorm.  Lightning strikes offer a natural fireworks show that sometimes surpasses the manmade kind.  The furious wind and roaring thunder show the excited side of mother nature.  It’s the dangerous side of nature–a human could be vacuumed into the sky by a tornado, electrocuted by lightning, or clobbered by a hailstone or wind-strewn debris.  Nobody, not a king nor a baby, is immune to these hazards.

Natural fireworks.

Some anthropologists and a few old school ecologists wrongly believe most of the grasslands that occurred in southeastern North America when Columbus accidentally sailed into the Caribbean were the result of manmade fires.  Reed Noss dispels this notion in his book, Forgotten Grasslands of the South. The map below shows the frequency of lightning strikes in North America.  The south, and especially Florida, has more lightning strikes than any other region of the continent.  Dr. Noss believes the high frequency of lightning strikes can spark enough wild fires to maintain abundant grasslands without any human activity.

Map of average annual lighting strikes in North America between 1989-1999.  Lighting strikes were naturally common enough to have sparked grassland-creating wild fires long before humans arrived in North America.

Long Distance Controlled Burn

A longleaf pine savannah on fire.  Longleaf pines are one of the few species of tree whose seedlings can survive fire.

Several lines of evidence support Dr. Noss’s conclusion that anthropogenic activity was not necessary to maintain grasslands.  Formerly, longleaf pine savannah covered most of the coastal plain region of the south.  There were even patches of pine savannah in the piedmont region, though oak and hickory dominated that area.  There are over 900 species of plants endemic (meaning they live nowhere else) to longleaf pine savannah compared to just 80 endemic species found on the grasslands of the Great Plains.  A high number of endemic species suggests an ecosystem of great antiquity and stability.  Because evolution is usually a slow process, it’s not likely that all of these endemic fire-dependent species could have evolved in just the last 12,000 years.  Longleaf pines require fire intervals of 1-10 years or hardwoods will crowd them out.  Longleaf pines grow slowly, taking decades to reach reproductive age.  A species that reproduces this slowly would have never been able to adapt quickly enough to survive a sudden change in fire regime caused by man.  These fire dependent species must have already been present before man colonized the region.

Many species of animals are also endemic to pine savannahs.  The gopher tortoise and the red cockaded woodpecker are perhaps the 2 most well known vertebrates dependent on this fire-influenced environment. Gopher tortoise fossils have been found that date to millions of years ago, while red cockaded woodpecker fossils come from deposits in the vicinity of 200,000 years old.  The presence of these species and many others in the fossil record long predate man’s entrance into the region.  This is obvious evidence that southern grasslands preceded man.

There was a lower frequency of lightning strikes during the coldest stages of the Ice Ages.  Evidence from most fossil sedimentary sites show little, if any charcoal, indicating reduced fire activity.  However, less precipitation combined with megafaunal grazing created grasslands during the colder climatic phases.  Following the megafaunal extinctions, fire activity spiked because so much vegetation was no longer being eaten and instead it became dry tinder.

During the Last Glacial Maximum, longleaf pine savannahs still occurred in refugium located in Florida, Louisiana, Texas, and probably along the continental shelf where sea levels regressed.  Paradoxically, these areas were warmer and wetter during Ice Ages because the Gulf Stream shut down and warm water that normally circulated north pooled around these lower latitudes.  Oak scrub and prairie, the result of aridity and megafauna foraging, predominated in the upper coastal plain.  Longleaf pine savannah didn’t recolonize the upper coastal plain until about 6,000 years ago, but the pollen record suggests this type of environment has waxed and waned cyclically for millions of years, becoming common and widespread during warm and wet climatic phases.

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Some Plants and Birds that Favor Overgrazed Landscapes

May 25, 2014

Herds of Pleistocene megafauna were mobile and could never stay in one location for long or they would outstrip their food supply.  They seasonally traveled along the same corridors for decades or even centuries, until varying climatic changes altered their migration patterns.  During interstadials when forested conditions prevailed, grazers were forced to travel far and wide to satisfy their nutritional requirements, and during stadials when grassy environments were more common, the browsers had to migrate greater distances.  Many megafauna game trails led to valuable resources such as salt licks and water holes.  The megafauna greatly influenced the composition of plants, insects, and birds along these game trails, creating unique ecological associations and natural environments.  They trampled the ground, overgrazed and overbrowsed vegetation, debarked and killed trees, and unleashed large quantities of manure.

Most of the unique ecological associations formerly found on megafauna game trails no longer exist in North America, but the buffalo traces that early settlers encountered were a final relic.    Many buffalo traces led to the Blue Licks in Kentucky–a freshwater spring and salt lick.  The “immense” herds of buffalo had eroded the land everywhere here from up to 4-5 miles away.  Tree roots were visible due to this erosion.  Two species of now rare plants are thought to have been more abundant then because they depended upon habitat created by buffalo herds traveling along these traces.

Short’s goldenrod–a rare species known from only 3 sites.  These sites were formerly connected by a buffalo trace.

Goldenrod Soldier Beetle - Chauliognathus pensylvanicus

Goldenrod soldier beetle.  This is an important pollinator of Short’s goldenrod.

Short’s goldenrod (Solidago shortii) was discovered on Rock Island–a limestone outcrop located in the middle of the Ohio River Falls.  This was a former crossing spot for bison herds.  The Macalpine Lock and Dam later flooded this location, extirpating this population.  This species was later found growing on Blue Licks Battlefield Park in northern Kentucky and Harrison-Crawford State Park in Indiana.  All 3 known localities have 1 thing in common–they were formerly connected by the same buffalo trace.  Apparently, this species of goldenrod requires overgrazed trails, and they spread along this corridor, thanks to the bison.  It’s possible the goldenrod seeds were transported in bison dung.  Without trampling, grazing, and erosion, other species of plants outcompete and exclude this species of goldenrod.

Running Buffalo Clover–another rare plant that used to commonly grow on the buffalo traces.

Running buffalo clover (Trifolium stoloniferum) is another species now more restricted in range than in the past.  This is the only species of clover that does not have a rhizobial association.  All other species of clover and legumes have colonies of bacteria growing in their root nodules that help them absorb nitrogen.  However, running buffalo clover grew in patches frequently fertilized with nitrogen-rich bison dung, precluding their need for a rhizobial association.

Megafaunal trails likely had groves of wild fruit trees originating from seed-filled dung.  Persimmon, paw paw, plum, crabapple, wild squash, and passion fruit (maypop) probably were abundant on the sunny trails where large shade trees suffered high rates of mortality due to damage suffered from megafauna activity.  Dung beetles, scavenging birds, and predators all followed the mobile herds.  Thickets of shrubs and brier patches colonized abandoned megafauna trails and pastures, providing ideal habitat for rabbits.

Burrowing Owls

 

 

 

 

 

 

Burrowing owls prefer overgrazed cow pastures or frequently mowed golf courses and airports.

The burrowing owl (Athene cunicularia) has an odd present day range.  It mostly occurs in western North America, but a relic population lives in Florida.  Recent studies determined the relic Floridian population prefers overgrazed pasture land.  They like short grass with few trees, so they can have a good view of approaching predators.  They’ve actually expanded their range in the past century to include land cleared by humans such as golf courses, cemeteries, and airports.  However, they are considered threatened by increasing development that converts cow pasture to suburbs.  Burrowing owls must have occurred throughout much of eastern North America during the Pleistocene when game trails provided a network of suitable habitat.

Audubon’s Crested Caracara also requires overgrazed grasslands.

The crested caracara (Caracara cheriway) also occurs as a relic in south central Florida.  The rest of its range includes South America north to Texas.  Formerly, a coastal grassland habitat connected Florida with Texas, but during the Holocene forested habitat, unsuitable for this species, replaced this coastal grassland environment.  This is a scavenging bird that eats carrion, bird nestlings, disabled small animals, and insects.  They inhabit open ground where they search for food under woody debris and even cow dung.  Caracaras were also more widespread during the Pleistocene, but are more limited than burrowing owls because they are less cold tolerant.

Refererences:

Morrison, Joan

“The Crested Caracara in the Changing Grasslands of Florida”

Proceedings of the Florida Dry Prairie Conference 2004

Noss, Reed

Forgotten Grasslands of the South

Island Press 2013

The Nature of 12 Years a Slave

May 21, 2014

Some past Oscar winners are so bad they’re unwatchable, but 12 Years a Slave is a great movie that topped a lot of other really good movies released in 2013.  The setting of the movie is primarily in Louisiana between 1841-1853.  Because this region was frontier wilderness then, the movie inspired me to read the book for insight into the area’s natural history.  Most of this essay will focus on this natural history, but first I want to comment on the literary quality of the book, and an odd misconception of slavery I found while researching this topic.

12 Years a Slave is the true story of Solomon Northrup, a freed black man, who was kidnapped and forced into slavery for 12 years until he was rescued by his white friend from New York.  Solomon Northrup is credited with authoring the book–it is his story.  But he had an excellent ghost writer by the name of David Wilson.  Though Northrup was not illiterate, he had been forbidden to read or write for 12 years, and there is no way such an unpracticed individual could have produced such a well written book without professional writing help.  Some of the best books I’ve ever read were written by ghost writers.  Ozzie Osboure had an amazing ghost writer for his biography.  Ozzie is admittedly illiterate due to a learning disability.  Moreover, it’s difficult to understand his mumbling speech.  Nevertheless, Ozzie’s ghost writer did a fantastic job capturing his voice, just as Wilson captured Solomon’s voice.

Northrup

Portrait of Solomon Northrup.  When one of his psychopathic slave-owners attacked him with an axe, he fled into a virgin bottomland forest and saw dozens of alligators and hundreds of cottonmouth water moccasins in just 24 hours.

While researching this topic, I came across a stupid blogger who claimed slaves were well off because they had room and board.   This is a surprisingly prevalent revisionist view among some right-wingers. I wonder if any of these right-wingers would be willing to trade room and board for whippings, forced labor, rape, and being separated from their children forever.  What kind of cuckoo land propaganda brainwashes these delusional dumb asses?

Solomon Northrup endured 4 “masters.”  One was a nice guy, though, of course, misguided; two were greedy sadists, and another was an homicidal maniac.  One day, the homicidal maniac tried to kill Solomon with an axe.  Fortunately, Solomon was able to overpower this crazy little dude and choke him unconcious, giving him time to flee into a virgin bottomland swamp. (This scene was not depicted in the movie.) When Tibeats, the name of this psycho, revived, he jumped on his horse and sought the help of professional slave trackers who used a pack of a vicious type of mutt to hunt down slaves.

Virgin bottomland forest of cottonwood and hackberry in Louisiana.  The forest Solomon fled through was swampier than this and had cypress and tupelo giants growing in it.

This  dog is known (if you’ll excuse the ugly adjective) as a nigger hound.  It isn’t actually a hound but rather a cross between an old fashioned working bulldog and a mastiff.  Slave-owners used them to hunt down escaped slaves.

The standard slave hunting dog, known variously as a Cuban bloodhound or nigger hound, was not an hound at all but rather a cross between an old fashioned  American bulldog and a mastiff.  In Louisiana most slaves were easily captured because few knew how to swim, and eventually they’d reach a bayou they could not cross.  The dogs would either tree the slave or trap them against the watery barrier.  Dogs often seriously injured or killed slaves before the trackers could catch up to them. Solomon knew how to swim and successfully escaped the dogs by fleeing deep into the swamp and losing his scent in the numerous watercourses.  He found himself inside a virgin bottomland forest of immense trees consisting of cypress, tupelo, oak, and sycamore.  Tree frogs croaked constantly as Solomon navigated around alligators and cottonmouth water moccasins.  He claimed to have seen over 100 of the latter during 12 hours of daylight.  He traveled all night and eventually found his way back to his old “master” who still owned the deed on him, though he had mortgaged him to Tibeats.  (Slaves were traded in lieu of cash for debts.)  Ford, the nicer “master,” convinced Tibeats to rent Solomon to another plantation-owner instead of punishing him for fending off the axe attack.  Tibeats later sold Solomon to a greedy sadist who whipped slaves almost daily.

Solomon later learned of a trick slaves could use to keep nigger hounds from tracking them, though he never again dared attempt a direct escape.  He knew of an escaped slave that built an hut in the wilderness and lived there for a year before she returned to the plantation.  The plantation dogs refused to track her because when no one was looking, she had intimidated the dogs and showed the dogs she was dominant over them.  Solomon often had to supplement his diet with raccoon or oppossum, and he used a club and the plantation dogs to hunt these critters.  When he was in the woods with the dogs, he’d become dominant over them, so that if he ever tried to escape again, they’d refuse to track him.

The ration Solomon received was miserable–cornmeal, maggoty bacon, and the occasional sweet potato.  With no cooking utensils he had to subsist on unleavened cornbread baked in ashes–in other words…a dog biscuit.  The bacon was often so infested with fly spawn it was not edible.  He built a box fish trap and baited it with corn dough, and this supplied him with most of his daily protein.  He didn’t write what kind of fish he caught, other than they tasted good.  The nearby Allemande Lake is known as the “catfish capitol of the world.”  Solomon likely caught channel, flathead, and blue catfish in his trap.

The area where Solomon slaved for most of his days in captivity is known as Bayou Beouf, named for all the feral longhorn cattle that formerly abounded in this neighborhood. These longhorn cattle were wild descendents of cows the Spanish brought from Europe.  This is a dangerous breed capable of fending off large predators.  There were also planty of feral hogs here.

La Bayou Boeuf was named after all the feral and semi-tame cattle that roamed the region when Americans first settled in this wilderness.  The cattle descended from those brought to Texas from Spain.

When Solomon was first brought to Louisiana he stayed at Ford’s plantation in “The Big Piney Woods.”  This plantation was located in the middle of a longleaf pine savannah–a now rare type of environment that formerly covered most of the southeast’s coastal plain.  While working for Ford, he also encountered Chickasaw Indians, still living in the region.

Tibeats rented Solomon to a man in the process of clearing a forest on his plantation.  To reach this territory, Solomon’s party traveled through a massive canebrake–a huge monotypical stand of bamboo cane, also a now rare environment that formerly was commonplace.  This is how he describes it:

“After passing through Baton Rouge swamp, and just at sunset, turning from the highway, we struck into the “Big Cane Brake.”  We followed an unbeaten track, scarcely wide enough to admit the wagon.  The cane, such as are used for fishing rods, were as thick as they could stand.  A person could not be seen through them the distance of a rod.  The paths of the wild beasts run through them in various directions–the bear and the American tiger abounding in these brakes, and wherever there is a basin of stagnant water, it is full of alligators.”–Solomon Northrup 1853

Apparently, jaguars occurred as far east as Louisiana until as late as 1887 (See: https://markgelbart.wordpress.com/2012/09/26/how-recently-did-the-jaguar-panthera-onca-roam-eastern-north-america/)  Early colonists referred to them as “the American tiger” to distinguish them from a cougar which they called “panther.”

Brutal: The 20-stone cat sunk its teeth into the eight-foot reptile before dragging it back across the water and into the jungle

Jaguar killing a caiman.  Solomon Northrup and the early Louisiana settlers referred to jaguars as the “American tiger.”  They abounded in an area known as the “Big Canebrake.”

Solomon didn’t mind the hard work of cutting down trees, but the mosquitoes and gnats were intolerable in this virgin swamp forest on the other side of the Big Cane Brake.

We may consider outselves more enlightened than people were in the 19th century, but I’m certain there are just as many greedy sadists and violent psychopaths now as there were then.  The wilderness, however, is gone.  I prefer the wildernes over humanity.

Primeval Monster Gators (Alligator mississippiensis)

May 16, 2014

How big can an American alligator get?  Early Colonial explorers and naturalists claimed these reptiles could grow to as large as 20-25 feet long.  William Bartram wrote that he saw individuals of this length during his trip through Florida in 1774, but he’s notorious for miscalculating distances.  I believe Bartram had poor eyesight even before he was struck with scarlet fever a few years later.  The largest alligator on record was a specimen killed on Marsh Island, Louisiana in 1890.  It measured 19 feet, however, this record was never verified because the beast was too heavy to drag away from shore.  It would have weighed an estimated 2200 pounds.  The largest verified alligator was a specimen measuring 17.5 feet, killed in Everglades National Park.  Modern day state records have recently been set in Arkansas, Mississippi, and Texas, but these all measured slightly under 14 feet.  Large alligators of this size are rarer today than during the pre-European settlement era because hunters kill most gators that exceed 6-8 feet.

lufkin record alligator

A nearly 14 foot long alligator killed in Texas.  A fossil of a Pleistocene-aged alligator was from an animal estimated to be 7 feet longer than this one.

If alligators formerly did reach over 20 feet in length as Bartram and others claimed, it occurred to me there might be some fossil evidence of this.  Alligators are one of the most common large vertebrate species found in Florida fossil sites.  Data from the University of Florida Museum indicates alligator fossils have turned up in probably over 100 fossil sites in Florida, and this doesn’t even include the many found by hobbyists.  Alligators have been a common component of Florida’s fauna for millions of years.  The American alligator has undergone little morphological change for nearly 5 million years.  Its evolutionary predecessor, Olsen’s alligator, was smaller and did differ in skull morphology enough to be considered a separate species.  One alligator specimen found at Haile, an early Pleistocene fossil site (~2 million BP),  represented an animal estimated to be 21 feet long when it was alive.  A gator this size likely weighed 2500 pounds.  This specimen certainly supports the veracity of early explorer’s claims of seeing alligators that were 20-25 feet long. 

maxilla of Alligator mississippiensis

Fossil alligator maxilla from Sarasota, Florida.  This specimen dates to the late Pleistocene.

Pleistocene alligators did not necessarily top the food chain.  During droughts, big gators often travel overland looking for deeper water holes.  When in this vulnerable situation, even large gators could have fallen prey to big cats such as jaguars or saber-tooths.  In some areas of South America, the alligator-like caiman is an important item of a jaguar’s diet.

Zombie Gators

Some Florida lakes have become so polluted from fertilizer run-off that large algal blooms occur.  Gizzard shad thrive in these polluted waters, while populations of other species of fish decline.  Alligators can safely eat gizzard shad as long as there are other species of fish in the water.  However, when alligators are forced to subsist on just gizzard shad they enter a zombie-like state known as ataxic neuropathy.  This is a fancy name for becoming paralyzed.  Gizzard shad flesh has thiaminase–an enzyme that breaks down thiamine, an important B vitamin.  This prevents gators from digesting thiamine without which their nervous system ceases functioning.  The zombie-like state is followed by death, unless the gator is given thiamine.

Zombie Alligators

A zombie gator.  Alligators fed on a diet of nothing but gizzard shad suffer a nutritional deficiency that paralyzes them.  They can be revived with thiamine, a B vitamin.

gizzard shad fish

Gizzard shad (Dorosoma cepedianum).  Gators can safely eat this fish as long as they have other species of fish in their diet as well.  A diet of just gizzard shad will poison them.

Bartram’s Battle Lagoon

In 1774 William Bartram traveled on the St. Johns River, Florida.  He witnessed an incredible fish migration that attracted hundreds of large alligators.  A fish migration as he described no longer occurs on this scale at this geographic locality.  Few, if any places left on earth, provide such a spectacle.  It was probably a migration of gizzard shad.  This migration attracted largemouth bass which fed upon the shad, while gars preyed on the bass.  Alligators ambushed them all.  Bartram saw this migration on the part of the St. John’s River that flows between Lake George and Lake Dexter.  (There are 2 Lake Dexters in Florida.  This is the one located in Ocala National Forest.)  Below the next image is Bartram’s account.  (Incidentally, Bartram refers to largemouth bass as trout.  Old timers still refer to bass caught in brackish waters as “green trout.”)

Click to view larger image

Lake Dexter is the middle lake.  The part of the St. John’s River between Lake George in the distance and Lake Dexter in the middle is where Bartram witnessed a massive fish migration that attracted hundreds of gators.

It was by this time dusk, and the alligators had nearly ceased their roar, when I was again alarmed by a tumultuous noise that seemed to be in my harbour, and therefore engaged my immediate attention.  Returning to my camp, I found it undisturbed, and then continued on to the extreme point of the promontory, where I saw a scene, new and surprising, which at first threw my senses into such a tumult, that it was some time before I could comprehend what was the matter; however, I soon accounted for the prodigious assemblage of crocodiles at this place, which exceeded every thing of the kind I had ever heard of.

How shall I express myself to convey an adequate idea of it to the reader, and at the same time avoid raising suspicions of my want of veracity.  Should I say, that the river in this place from shore to shore and perhaps near a half a mile above and below me, appeared to be one solid bank of fish, of various kinds, pushing through this narrow pass of St. Juans into the little lake, on their return down the river, and that alligators were in such incredible numbers, and so close together from shore to shore, that it would have been easy to have walked across on their heads, had the animals been harmless.  What expressions can sufficiently declare the shocking scene that for some minutes continued, whilst this mighty army of fish were forcing the pass?  During this attempt, thousands, I may say hundreds of thousands of them were caught and swallowed by the devouring alligators.  I have seen an alligator take up out of the water several great fish at a time, and just squeeze them betwixt his jaws while the tails of the great trout flapped about his eyes and lips, ere he had swallowed them.  The horrid noise of their closing jaws, their plunging amidst the broken banks of fish, and rising with their prey some feet upright above the water, the floods of water and blood rushing out of their mouths, and the clouds of vapour issuing from their wide nostrils, were truly frightful.  This scene continued at intervals during the night, as the fish came to pass.  After this sight, shocking and tremendous as it was, I found myself somewhat easier and more reconciled to my situation, being convinced that their extraordinary assemblage here was owing to this annual feast of fish, and that they were so well employed in their own element, that I had little occasion to fear their paying me a visit.”–William Bartram, 1774

References:

Ross, J.P. et. al.

“Gizzard Shad Thiaminase Activity and its Effect on the Thiamine Status of Captive American Alligators (Alligator mississippiensis)”

Journal of Aquatic Animal Health 2009

http://www.flmnh.ufl.edu/vertpaleo/fossilspeciesAlligatormississippiensis.htm

The Land Walt Disney Ruined

May 12, 2014

1,145,956 people live in Orange County, Florida today, making it one of the most crowded colonies of Homo sapiens in the United States.  A satellite view of this county reveals a densely packed network of suburbs surrounding the many lakes that dot this once beautiful piece of real estate.  It appears as if green space has been entirely extinguished here.  Walt Disney is responsible for much of the ungodly mess Orange County has become.  He created Disney world, a shitty tourist trap constructed between 1965-1972.  In my opinion the entertainment value of Disney World is nil, and a blank television screen is preferable to 95% of the series presently aired on Disney-owned ABC network.  I can’t understand how even small children are entertained by the imbecilic cartoon characters created by Disney’s company.  Ironically, the man behind Bambi destroyed more deer habitat than any other business criminal in history.  It disgusts me how the real interesting fauna of Florida has been replaced by artificial anthropomorphized animals.

Map of Florida highlighting Orange County

Orange County, Florida.

Walt Disney with one of his imbecilic cartoon characters.  Real animals are far more interesting than Mickey Mouse.

There were at least 7 different types of natural communities that formerly made up the landscape of Orange County.  In 1774 William Bartram found hardwood hammocks growing on the lake shores and islands within the lakes in north central Florida.  The tree composition consisted of live oak, palm, magnolia, orange, and many other temperate and subtropical species.  Orange trees were not native to Florida but Indians widely planted this fruit from seeds they obtained from early Spanish colonists 200 years earlier.  Large orange groves, abandoned by declining Indian populations, were being invaded by native trees in some places.  Other wild fruit trees included papaya (Carica papaya), tallow plum (Ximenia americana), coco plum (Chrysohailaanos icaco), and pawpaw (Asimina triloba).  Ivy and grape vines covered the hammocks and spectacular flowers such as hibiscus grew in the understory.

Hibiscus coccineus.  Bartram found stalks of this flower growing 12 feet tall.

Silver Glen Springs in Ocala National Forest.  The numerous springs and lakes of Orange County acted as firebreaks protecting hardwood hammocks that would have otherwise been converted to longleaf pine savannah.

Florida has more thunderstorms and lighting strikes than any other region of North America.  Accordingly, lighting ignited wildfires shaped the most common type of environment found in Orange County.  Lakes acted as firebreaks that protected hardwood hammocks, but longleaf pine savannahs predominated on uplands away from water.  Widely spaced pines with grassy understories supported lots of wildlife.  Great herds of bison, feral longhorn cattle, horses, and deer used to roam the savannah along with mighty flocks of cranes and turkeys.  Burrowing owls and caracaras preferred the heavily grazed grasslands where they had a good view of potential threats.  By contrast the now nearly extinct grasshopper sparrow preferred to nest in tufts of bunchgrass perchance left ungrazed.  This species requires large ranges because the type of habitat they need is ephemeral, annually disappearing in some areas and appearing in others.  A slight dip in elevation of only a few inches differentiated 2 similar but distinct natural communites–dry longleaf pine savannah and wet pond pine savannah.  They shared some species of flora and fauna but carried many different species as well.  Crayfish for example preferred the latter.

Sand scrub habitat hosted gopher tortoises, a species Bartram referred to as abundant in 1774 but has probably been extirpated from modern day Orange County.  There are many commensal species that co-occur with the gopher tortoises, including the spectacular indigo snake.

Gopher Tortoise Burrow

Gopher tortoises, now endangered, were formerly abundant on all areas of Florida with sandy soils.

Cypress swamps with 1000 year old specimens grew in low lying areas.  Drought or storm-killed trees attracted the now extinct ivory-billed woodpecker.  This bird required freshly killed trees infested with beetle larva.  Some cypress trees were exceptionally large, and they were covered with Spanish moss.  The myriads of mosquitoes made these swamps a paradise for several species of bats that nested in cypress snags.  Mosquito county was the original name of Orange County.

An 1000 year old, 90 foot tall cypress tree in Louisiana.  Trees this age used to be common in Orange County.

Some low lying areas were treeless marshes where grasses and sedges grew.  This was the habitat of the marsh rabbit and many species also found on the savannahs.

Swamprabbit

Marsh rabbit.  The artificial Mickey Mouse and Donald Duck replaced this real living and breathing animal in Orange County.  Walt Disney, a so-called animal lover, hypocritically destroyed most of the marsh rabbit habitat here.

Modern lakes in Orange County are often polluted from fertilizer runoff.  Gizzard shad are the only species of fish to thrive in these algal blooms.  Formerly, these lakes supported much higher largemouth bass populations that fed alligators and wading birds.  Wintering ducks and geese used to be much more abundant.

Bartram wrote that the most common songbirds in Florida were green jays, loggerhead shrikes, and rufous-sided towhees.  I’m sure the jays he saw were the Florida scrub jay (Aphelocoma coerulescens); rare now but still present in Florida.  Bartram must have been color blind because there is no green on this bird.  Green jays occur no farther north than the Rio Grande, but there was a species of green jay that lived in Florida during warm stages of the Pleistocene.  Bartram is the only person to record the king vulture in Florida–a bird that today is restricted to tropical regions of South America.  He saw them scavenging reptiles unable to escape wild fires.

Bartram saw bears, wolves, and bobcats in Florida.  Bears fed on oranges and wild fruits.  The Florida black bear is the largest subspecies of Ursus americanus, thanks to the year round foraging opportunities that preclude the need for hibernation here.

Rock Springs is a Pleistocene fossil site located in Orange County, Florida.  It yielded a typical Rancholabrean large mammal fauna.  For a list of species found at the site here’s a link to a wikipedia article. (http://en.wikipedia.org/wiki/Orange_County,_Florida_paleontological_sites).  Rock Springs is a good avifossil site.  The abundant fossils of ducks and wading birds show that wetlands have often been common here.

Orange County was still a sportsman’s paradise in the first half of the 20th century.  Though many of the natural communities had been transformed into citrus orchards and cow pastures, there was still enough green space to make for superior deer and quail hunting, while the black bass fishing remained outstanding.  But the citrus business shifted south following a killing freeze, and pastureland has transmogrified into unending suburbs, and now the land is ruined.

The late George Leonard Herter lamented this ruination.  He enjoyed dining at a long gone local restaurant owned by Peter Miller.  Miller served largemouth bass, dressed, skinned, and boiled whole and covered with dill-flavored mayonaise and a side of garlic-infused sourkraut.  None of the chain restaurants that currently add to the congestion of this suburban nightmare serve a dish this unique.  The unique natural beauty of Orange County is as forlorn a thing as a locally-owned restaurant.

 

The Early Holocene Survival of Late Pleistocene Megafauna in the Americas

May 6, 2014

Most Pleistocene species of North American megafauna stopped occurring in the fossil record about 12,000 calender years ago.  It is remarkable how consistently the latest terminal radiocarbon dates of Pleistocene megafauna cluster around this time boundary.  Specimens that date to younger than this boundary are always questioned and resubmitted for another round of radiocarbon dating till a more believable result is attained, or they are dismissed as “contaminated” samples.  One notable exception to this rule was the discovery that mammoths survived on the Pribiloff Islands, located between Siberia and Alaska, until about 4000 calender years ago.  (See:https://markgelbart.wordpress.com/2013/09/15/the-late-extinction-of-the-pribiloff-island-mammoths/).  Another accepted exception are some of the fossils of dwarf ground sloths found on Carribean islands.  They also date to just a few thousand years ago.  However, these late survival sites are considered special cases explained by the isolation of islands.  The consistent terminal radiocarbon dates on the mainland suggested to scientists a fairly rapid extinction event.  Explanations include sudden climate change, a “blitzkrieg” human hunting overkill scenario, or a comet impact.  Any evidence that Pleistocene megafauna survived for thousands of years past the boundary of 12,000 BP  destroys all 3 of these explanations.

The fossil record is reliably incomplete because over 99% of animals that ever lived never became fossilized or preserved.  I hypothesize the final radiocarbon dates cluster around 12,000 BP because this is the last time these species were common enough in the environment to be preserved.  After this date, many of these species still existed but in isolated populations in areas with low human density and therefore were less likely to become preserved.  My hypothesis is supported by studies of sedaDNA in Alaska permafrost that show mammoths lived for 2200 years later than the last dated bone for this species, and horses were present here for 3700 years past the commonly accepted extinction date for this species in America. (See:https://markgelbart.wordpress.com/2011/02/24/csi-pleistocene-alaska/).

The Devil’s Den site in Florida also yielded early Holocene radiocarbon dates on megafauna bones. (See:https://markgelbart.wordpress.com/2012/07/08/the-devils-den-fossil-site-may-have-been-located-in-one-of-the-last-refuges-of-the-megafauna/).  These dates were obtained during the early 1970’s before improvements in radiocarbon dating were developed.  As far as I can determine, these specimens have not been redated.  If they haven’t, they should be.

Fossil remains of now extinct megafauna from 2 sites in South America also date to the early Holocene.  At the La Moderna site in Argentina, scientists excavated the remains of guanacos, paleollama, Amerihippus (an extinct species of horse), onohippus (a half-ass), deer, macrauchenia, toxodon, armadillo, glyptodont,  megatherium, and glossotherium.  Humans butchered many guanacos at this site as well as horse,  ground sloth, and glyptodont.  I think this is the only site where evidence of a human-butchered glyptodont has ever been found.  Only the bones of the most edible parts of the ground sloth were found here–evidence the beast was killed elsewhere, and the choice cuts carried to this site.  The calender year dates at this site average to between 7800 BP-8300 BP.

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Evidence humans butchered a glyptodont was found at the La Moderna site in Argentina.

At the Camp Laborde site also in Argentina, scientists excavated rhea (an ostrich like bird), the fossil remains of 2 species of glyptodont, a megatherium associated with 2 quartz tools, peccary, llama, cavy, viscacha, and a canid closely related to the extinct Falkland’s wolf.  Humans evidentally butchered the megatherium ground sloth here too.  The average calender year dates found here range between 8500 BP-9000 BP. 

The Falkland Island’s wolf became extinct in 1876.  Fossils of a closely related species were found at the Camp Laborde site.

The cavy or Patagonian mara (Dolichotis patagonus).  Fossils of this species were also found at the Camp Laborde site.  Although it looks like a hare, it is actually in the rodent family.  An example of convergent evolution. 

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The plains viscacha (Lagostomus maximus).  It is closely related to the chinchilla.  Fossils of this species were found at Camp Laborde.

The Falkland Island’s Wolf was hunted to extinction on the island by 1876.  A close relative lived on the mainland of South America until about 1600 years ago.  The species was nicknamed “the foolish dog” because it showed no fear of humans.  This canid was the only native terrestrial mammal on the Falkland Islands.  DNA evidence suggests it colonized the Falklands by traversing a narrow landbridge that must have existed 16,000 years ago.

The authors of the below referenced study use evidence from Camp Laborde  to reject the “blitzkrieg” overkill model of extinction.  (It’s kind of ironic that they use evidence of humans exploiting megafauna as evidence against overkill.)  They believe humans didn’t rapidly overkill megafauna because many of these species still existed in areas of South America with low human density until well into the Holocene.  However, they do believe a combination of climatic and anthropogenic change doomed South American megafauna.  I disagree with their reasoning and believe that if humans never colonized South America, most of these species would still be extant. Humans were ultimately responsible for megafaunal extinctions, but it took thousands of years rather than hundreds to completely wipe them out.  Pollen evidence from this study does not support climate change as a cause of extinction.  This site was a humid grassland during the early Holocene…just like the pampas of modern day Argentina.

Reference:

Politis, Gustavo; Pablo Messeneo

“The Camp Laborde Site: New Evidence for the Holocene Survival of Pleistocene Megafauna in the Argentine Pampas.”

Quaternary International 191 2008

Giant Ground Sloths Used Bipedal Locomotion

May 2, 2014

Artists often depict giant ground sloths standing on their hind legs while reaching into trees to eat leaves, but rare preserved tracks in Argentina show they occasionally walked for considerable distances using just their hind legs.  (Not unlike the bear in this youtube video https://www.youtube.com/watch?v=m3_tch2HTEY).  Other tracks show they also walked on all 4 limbs, so they had diverse methods of locomotion.  Ground sloths were able to observe their environment for greater distances when they walked upright, giving them an evolutionary advantage they shared with man.  It would have been hard for a predator to ambush them, and when prepared, this powerful mammal, protected with armor under its thick fur and armed with long claws, was more than a match for any other beast till men with spears came along.  Ground sloths were one of the few South American mammals that were able to successfully colonize North America in the Great American Biotic Interchange that took place  when a landbridge formed between the 2 continents.  Their ability to dig deep underground burrows enabled some species to colonize Alaska and Canada (See:https://markgelbart.wordpress.com/2012/10/10/some-giant-ground-sloths-dug-long-burrows/ )  I think ground sloths were so unique, that if I was able to bring just 1 species of extinct Pleistocene mammal back to life, I would choose a species of ground sloth.

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Location of fossil sites where ground sloth tracks have been found.

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A megatherium once walked here.  The Atlantic Ocean was probably about 50 miles to the east of this site when this ground sloth treaded this ground.

Shasta ground sloths in woodland

Like tree sloths, ground sloths browsed on leaves.  Some species ate forbs growing in grasslands.

The fossil sites where preserved tracks of ground sloths have been found are located near the coast of Argentina.  Collectively, they are known as Monte Hermoso cliffs, first studied by the Charles Darwin.  His discovery here of fossils of extinct species similar to existing species probably sparked his conception of the Theory of Evolution.  Most of the sites in this region include both fossil remains and fossil tracks, also known as ichnofossils.  Like on the coastal plain of southeastern North America, geologically older fossil sites are located farther inland than younger sites because high sea levels destroy the latter.  The oldest fossil site at Monte Hermoso dates to the late Miocene/early Pliocene before the Great American Biotic Interchange.  All the fossils at this more ancient site are from species that evolved in isolation when South America was an island continent.  A South American land mammal age was named after this site–Monthermosan.  Fossils of boryhianid, a 300 lb marsupial carnivore, were found here along with many species of archaic ungulates and rodents that evolved in South America such as cavies and capybaras.

Macrauchenia–an archaic South American ungulate.  One genus did survive to the late Pleistocene.

 

 

 

Toxodon–another archaic South American ungulate.  One genus of toxodon also survived till the late Pleistocene.

The Playa del Blanco site, also in this region, dates to about 16,000 BP and includes fossils of endemic species that originally evolved in South America along with the more recent North American invaders.  Scientists excavated 5 species of ground sloths, 2 species of glyptodonts, armadillos, mastodon, horses, llamas, deer, and sabertooths.  Trackways of many of these species have also been preserved.  Only 2 genuses of endemic ungulates still occurred here by then–toxodons and macrauchenia.  At nearby Pehuen Co, fossils and ichnofossils are estimated to date to about 12,000 BP.  Scientists have discovered the fossil tracks of flamingos and 30 other species of birds, cougar, bear, deer, llama, stegomastodon, horse, macrauchenia, megatherium, and a human that evidentally wore shoes or sandals.

The geological process that preserved these ichnofossils is interesting.  During the Ice Age, much of earth’s atmosphere became locked in glacial ice.  As a result, the Atlantic Ocean receded many miles to the east and rivers dried up.  Precipitation, that today drains through rivers, instead flowed into low areas of the terrain, forming temporary pools and ponds.  Animals attracted to the water left tracks in the mud.  Eolian sandstorms, common in this arid environment, covered the tracks.  Eventually, these sand dunes transformed into sandstone.  Today, ocean waves are eroding into this sandstone, revealing the ancient trackways.  Give the Argentinean government credit for protecting these rare and fascinating fossil sites.

Reference:

Buyan, Cristana; Teresa Manera, Gustavo Politis, Silvia Annayo

“Following the Tracks of the First South Americans”

http://link.springer.com/article/10.1007%2Fs12052-011-0335-4/fulltext.html