The Lack of Pleistocene Crocodylus acutus Fossils in Southeastern North America and its Climatic Implications

The American crocodile (Crocodylus acutus) has a range limited to the tropics.  The American alligator (Alligator mississippiensis) can survive subfreezing air temperatures by  finding refuge in deep water holes, and they can even remain active in water as cold as 45 degrees Fahrenheit, but these temperatures kill crocodiles.  The unusual freezing temperatures that struck south Florida in 2009 killed 150 crocodiles–roughly 8% of the population there.  Freezing temperatures are the main limiting factor on the American crocodile’s range.  Scientists refer to this as the “winter air isotherm.”

Range of  Crocodylus acutus.

The American crocodile is an ancient species.  The oldest known fossils of this species were found in the Rio Tomayate River, El Salvador, and they date to about 1.5 million years BP.  It is an adaptable animal capable of swimming from Cuba to Florida.  Although most females have strict nesting ranges, some males are capable of impressive long distance dispersal.  One individual was tracked, captured repeatedly, and released from various locations after it traveled over 60 miles following each release.  Another straggler made its way as far north as Isle of Palms, South Carolina one summer.  So it’s clear that if it were not for sub-freezing winters, the American crocodile would have a much greater range.  Yet, as far as I can determine, it is absent from the Pleistocene fossil record of southeastern North America.  There are only 2 Pleistocene-aged specimens in the University of Florida Museum database, and these originated in Jamaica. 

Fossils of the extinct giant tortoise (Hesperotestudo crassicutata) have been found as far north as northwestern Georgia, and it apparently was common on the coastal plain of southeastern North America.  Many paleoecologists cite the presence of the giant land tortoise as evidence that there were no freezing temperatures in this region during the time the chelonians roamed the south.  They assume this species couldn’t survive subfreezing temperatures.  However, I’ve proposed that this close relative of the extant gopher tortoise (Gopherus polypherus), a burrow dweller, also dug burrows where they could escape frosts.  (See:https://markgelbart.wordpress.com/2011/04/15/the-extinct-pleistocene-giant-tortoise-hesperotestudo-crassicutata-must-have-been-able-to-survive-light-frosts/)  Or they utilized burrows dug by giant ground sloths. (See also:https://markgelbart.wordpress.com/2012/10/10/some-giant-ground-sloths-dug-long-burrows/)  If there were no freezing temperatures on the Atlantic coastal plain during the Ice Ages, American crocodile fossils should be at least occasionally found alongside the giant tortoise remains, but instead they are completely absent–evidence the region was never frost free during any climate phase of the Pleistocene.

American crocodiles may be maladapted for cold climates, but they are well adapted to live in saline environments.  They can survive on islands that are completely devoid of fresh water.  They prefer coastal swamps where they can nest on the borders of brackish canals.  They formerly nested on Miami Beach and the Florida Keys, but man rubbed out all the crocodiles on those prime real estate locations.  By 1970 there were fewer than 300 left in south Florida, but since they’ve been protected, the population here has bounced back to 2000.  They primarily inhabit the waters of the Turkey Point nuclear plant, and the numerous small islands in the southern part of the Everglades National Park.  They can grow up to 20 feet long but mostly feed on fish and birds.  They rarely attack large mammals.  American crocodiles hybridize with Cuban crocodiles in areas where their ranges overlap. 

Visual comparison between an alligator and an American crocodile.  Note the more narrow snout of the crocodile.

The Rio Tomayate Fossil Site

Paleontologists are especially interested in the Rio Tomayate fossil site because it is located in Central America where the Great American Faunal Interchange took place about 3 million years ago when a landbridge formed between North and South America.  There’s no shortage of potential fossil sites in the region but due to political instability the area has been understudied.  But in 2002 Juan Cisneros was able to collect fossils that emerged above water level in the Rio Tomayate, El Salvador.  The fossil bones were embedded in claystone that emerges above water level during the dry season.  The city of San Salvador uses the river as a sewer, so Dr. Cisneros had to make sure and wash his hands frequently during excavation.

The most common fossils were large bones of gompotheres (Cuvieronius tropicalis) and Ermeotheriums.  The former were close relatives of mastodons; the latter were  enormous ground sloths as big as elephants.  Both ranged as far north as South Carolina’s coastal plain during warm climate phases of the Pleistocene.

Mixotoxodon.

Gompothere.

Dr. Cisneros also found fossils of a mixotoxodon, an extinct notoungulate that ranged no farther north than Mexico.  It was a forest dweller about the size and build of a large rhino.  Fossils of other large species found at this site include a Megalonyx type of ground sloth, glyptodont, horse, 2 species of llamas, red brocket deer, white-tail deer, an unidentified large canid, giant tortoise, and American crocodile.  Llamas originally evolved in North America, then colonized South America during the Great American Faunal Interchange before becoming extinct in their land of origin.  This is the only site in Central America where fossil llamas have been found.  They also became extinct here.  The unidentified canid fossil consisted of a cheek bone with teeth.  Based on the size of the tooth, it was larger than a timber wolf.  It may belong to an unknown species or it could be from a Theriodictis platansis–an extinct, heavy-bodied dog known from South American fossil sites.

Not many fossils of small animals were found at this site.  The deposition favored the accumulation of large bones.  Water currents washed away most of the smaller bones.  However, Dr. Cisneros did find remains of mud turtles, a duck, and a rabbit hip bone.

Reference

Cisneros, J.C.

“New Pleistocene Vertebrate Fauna from El Salvador”

Revista Brasiliena de Paleontologica 8 (3) 2005

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My Pawpaw Seeds Germinated

The pawpaw (Asimina triloba) is a wild fruit from a family of mostly tropical species. Asimina triloba  evolved the ability to survive in temperate climates, while the rest of its relatives were forced to retreat to tropical regions some 5 million years ago when frosts began occurring in North America.  Mastodons and ground sloths used to distribute the seeds of this fruit all over the landscape in their dung, but today wild pawpaws are limited to river and creek bottoms where occasional floods can carry the seeds of future colonies.  The fruit is being cultivated, though they are impossible to find in grocery stores due to the fruit’s limited shelf life.

I’ve been curious about this fruit for decades, and last year a nice lady from Indiana kindly sent me some pawpaws in the mail.  I planted 8 pawpaw seeds in pots and 32 directly in the ground.  Unfortunately, I had to have a new drainfield for my septic tank installed in my backyard last January, and this probably led to the demise of my directly planted seeds..  I checked the pots in April and May and saw no pawpaw seedlings.  A couple of peach trees germinated in the compost I mixed in with the potting soil, but there was no sign of the pawpaws.  I gave up and stopped looking for them.  In late July I happened to walk by the pots and saw they were full of weeds.  I started to pull the weeds and found 5 pawpaw seedlings.  Luckily, I didn’t accidentally pull any up  when I was yanking out the crabgrass.  Now, 2 months later, 2 of the saplings still look great, 1 looks fair, 1 looks kind of diseased, and 1 got totally chewed up by something, but I’m hoping it grows back from the stem or roots.  Supposedly, pawpaws have few insect pests, but I know this is not true.

Photo of 5 pawpaw saplings and 2 peach tree saplings that germinated  early this summer.  The tall saplings are the peach trees.

I don’t know how long it will take for the pawpaws to bear fruit (if ever).  I’m also growing a dozen or so peach trees from seeds that germinated in compost.  They can produce fruit in as little as 3 years, but I’m guessing the pawpaws will take quite a bit longer.

See also https://markgelbart.wordpress.com/2010/10/01/the-paw-paw-a-favored-fruit-of-the-mastodon/

and

https://markgelbart.wordpress.com/2012/09/07/pawpaws-favored-fruit-of-the-mastodons-part-ii/

Another Excerpt from Frances Harper’s Mammals of the Okefinokee Swamp–The Florida Bear

Okefenokee black bear headed for a den in a hollow log.

I’ve been periodically posting excerpts from an obscure book published almost 100 years ago by Frances Harper, an accomplished naturalist.  In his account of the black bear he gives the incorrect scientific name, Euarctos floridanus.  The modern accepted scientific name for the black bear is Ursus americanus.  His collection of accounts of the black bear is the longest of any animal in the book, indicating this was an important large animal for the settlers living here.  Due to the length, I’m skipping some parts of this chapter.  I’m leaving out the debate over whether there were 1 or 2 species of bears living in the Okefenokee.  The majority opinion among the settlers then held that there were 2 species, but the scientific community is now certain there is just 1 species.  The confusion stemmed from the wide variation in coat color and size among different individual bears, leading most to think there was more than 1 species living in the swamp.  I’m also skipping over the last 6 pages of the account which focuses on the experiences of humans hunting bears.  But I will here mention some of the more interesting accounts from that section.  Harper notes that there were no known unprovoked attacks on humans by black bears, but they were dangerous to hunt.  Hunters generally used shotguns filled with buck shot, and they hunted in early summer when the bears were easy to find while they foraged for turtle eggs.  On one occasion some bear hounds chased a bear up a tree.  The men weren’t around so 2 woman shot the bear and it fell to the ground.  However,  the women were too timid to get up close for a killing shot, like the men would have done, and the bear killed every last bear hound.  On another occasion a man took his 10 year old son with him on a bear hunt.  They both shot the bear, but the bear charged the boy and the man shot the bruin in the jaw, just barely saving his son from a severe mauling and possibly death.  Some of the old timer hunters tallied a large number of lifetime bear kills.  Obadiah Barber killed the most with a lifetime tally of 150.  Below is the excerpt from Frances Harper’s book.

Florida Bear

Habitat–There is apparently no type of habitat in the Okefinokee which the bear does not frequent.  The hammocks and the prairie ‘houses’ are perhaps its favorite feeding grounds, though it wanders freely over the piney woods and the prairies, and makes nocturnal forays for hogs to the very dooryards of the island dwellers.  But the cypress bays are its breeding haunt and its almost invariable refuge in time of danger.  In the tangled fastnesses of the bays and the sphagnous bogs it can fairly defy the hunter’s pursuit, unless pressed close and brought to bay by some well trained and courageous hounds.  John Hopkins once saw a Bear swimming across Billy’s Lake, and one may frequently ascertain, by the trail through the bordering vegetation, where one has crossed the canal.

Individual Range–Regarding the range of the individuals, Allen Chesser offered the following testimony.  About 20 years ago there was a Bear about Chesser’s Island that had killed altogether 50 or 75 hogs.  One day it was pursued but made its escape.  About the next day William Barnett, while fishing in one of the lakes on the western side of the swamp, shot the fattest Bear he had ever killed.  Its fatness indicated that it had been eating hogs; and it was considered the marauder from Chesser’s Island, for it molested the hogs no more.

Numbers–There is a general and apparently well-founded opinion to the effect that Bears have been getting much scarcer during the past few years, though some of the estimates are still surprisingly high.  In 1917 Jackson Lee said that it sometimes appears, from the abundance of ‘sign,’ as if there must be 200 or 300 bears in the swamp, but at other times they seem very scarce.  More recently, Walter Davis has said, ‘There must be a thousand.’  Sam Mizell, who in his surveying work has covered perhaps more territory in the Okefinokee than any other man, estimates one Bear per square mile, making a total of over 600 for the swamp.  In some years he sees none; in other years, three or four.  He sees the ‘sign’ nearly every day, wherever it is not too thick, too open, or too boggy.  He can not account for the discrepency between the probable annual increase accruing from 600 bears, and the dozen or so that are killed each year on the average, but he suggests slow breeding and occasional death from natural causes.  Julian Godwin estimates the number present at a thousand, and the average number killed during the course of a year at ten, suggesting that the normal annual increase is offset by ‘migration to Florida.’  As a matter of fact, it is difficult to account for the presence of even 200 Bears in the swamp. Of this number probably at least one-half would be breeding age, or more than three and one-half years old.  If each breeding female averages two young every other year, the average annual increase would be about 50.  The same number must be lost each year if accured by hunters, while another dozen die of wounds, leaving about 25 others accounted for by accident, snake bite, disease, possible migration, or other natural causes.  In the summer of 1922 we could learn of only three or four that had been taken by hunters in the entire region during the previous twelve months.  The extension of lumbering operations to the heart of the swamp and the enormous increase in the human population during the late years have undoubtedly had their effect.

Size–The size attained by individuals is indicated in some hunter’s accounts.  Allen Chesser spoke of having killed an extra fat Bear that must have weighed 400 pounds.  J.D. Hendrix spoke of another 400-pounder.  David Lee estimated the weight of the largest dead Bear he had ever seen at 500-600 pounds.  Hamp Mizell also referred to Bears of equally great weight.

Encounters and Observations–Various details in regard to the Bear’s haunts and habits will be brought out in the following chronological account of observations and experiences relating to the species.

On May 10, 1913, two of the swamp hunters were harnessed up to a boat which they were hauling on a set of wooden wheels through the low pine lands of Honey Island.  Meanwhile their dogs started up a Bear, which happened to take a course in their direction.  One of the hunters began to extricate himself from the harness in order to reach the guns on the boat.  The other, however, plunged away in panic without pausing to unharness himself, and dragged the large boat after him at such a rate that when it collided with a pine trunk the bow was so badly smashed as to necessitate the rebuilding of the entire boat.  At about the same time the Bear, in perhaps equal alarm and haste, passed directly by them.  Several days later, at this spot, I saw for myself the wrecked boat.

Early on the morning of May 18, 1912, David Lee, while paddling along the north fork of the canal, noted the fresh trail of a Bear engaged in digging up turtle eggs on the banks, and presently obtained a clear view of the animal at a distance of about 15 yards.  When he began emptying the contents of a revolver into the Bear, it jumped into the canal, but scrambled on to the bank again, and made off into the swamp, but not before most of the six shots had reached their mark.  A little later several of us followed the trail for some distance where it tore through the thick bushes of the swamp, but desisted when it gave no evidence of coming to an end.

In january, 1917, Harrison Lee and I followed a well-used Bear trail for a considerable distance through a canebrake near the south end of Floyd’s Island.  Certain trees beside the trail had been much gnawed and scratched by the animals.  I also noticed a rotten log in Floyd’s Island hammock that had been torn to pieces by a Bear.  During the same month, along the run through Billy’s Bay and also on the west fork of the canal, Jackson Lee pointed out a trail coming to the edge of the watercourse, and perhaps crossing it.  Along the banks of the canal he called attention to the dead tops of numerous sweet bays (Persea pubescens) that had been broken off by Bears while climbing the trees to feed upon the berries.

In 1921 Floyd and Black Jack Islands and the banks of the canal appeared to be particularly favorable places.  Along the canal in early June we saw their tracks and paths on the banks, noted where they had left a trail in the bordering aquatic vegetation in crossing from one side to the other, and found numerous places where they had scooped turtle eggs out of the soft earth.  While paddling along the canal late in the afternoon of June 1, several of us, hearing a sound on the bank, dimly made out the form of a Bear as it moved about and stirred the bushes, in dense thicket about 60 feet away.  Probably the animal took alarm at about this time, for complete silence ensued, and a little later we located the trail where it had leisurely set off across the prairie for a neighboring cypress ‘head.”

On June 10 Jackson Lee pointed out Bear Trails among maiden cane on Floyd’s Island Prairie.  During the next few days we found numerous signs on Floyd’s Island–trails, gnawed trees, scratchings on the ground, logs torn apart, grass pressed down where the animals had lain or rolled, broken tops of huckleberry bushes, and excrement that was purple with these berries.  These signs were especially noticeable among magnolias and canebrakes in the hammock part of the island, but some were found in the pine barrens as well.  Twice within a few days some of the Lees heard a Bear at close range as it tramped through the brush in the hammock. 

On July 28, in walking through the pine barrens of Black Jack Island, we came across a recent Bear trail every now and then. On July 7, 1922, in company with Ben and Tom Chesser, we gained an idea of the Bear’s manner of living on the Grand Prairie.  At this season it was still in search of turtle eggs, and was wandering from ‘house’ to ‘house’ across the the prairie for that purpose.  When either a boat or a Bear passes over a watery prairie, the ‘bonnet’ (Castalia) leaves in the trail remain upturned on one side for hours afterward.  The upturned side of the leaf indicates the direction from which the boar or animal has come.  One such trail that we came across had evidently been made within a couple hours.  On one of the small prairie houses the ground had been much torn up by excavations of turtle eggs.  A little to one side, in a fairly thick, brushy place on high, dry ground, was the Bear’s bed, with the dead leaves pressed down.  In another ‘house’ were gnawings on sweet bay, some of them were fresh. 

On August 29, in the edge of the prairie near Chesser’s Island, Tom Chesser followed a trail to an ants’ nest, which had been robbed so recently that the ants were still scurrying about.  During the ensuing week, which I spent in the midst of Grand Prairie, I noticed no fresh Bear signs.  By this time the turtle-egg season was probably largely past, and the animals may have been resorting more to the islands than in the prairies.

Meanwhile a couple of bears began making depredations on the hogs on Chesser’s Island, killing several within a few days.  At first a Bear came at night into the hammock close to one of the dwellings, caught a 60 pound hog, and dragged it off into the nearby cypress bay, while the victim kept squealing and bracing its feet to hold back as the marks in the ground revealed the next morning.  Some of the men were aroused by the outcry, and had reached the edge of the bay in pursuit, when they heard the Bear finally dispatch the hog about 75 yards within the bay.  Though several hunts were organized during the next few days, the Bears not only escaped, but boldly continued their nocturnal forays at intervals for weeks thereafter, and inflicted considerable losses among the hogs.

Tree-gnawing–One may find in the Okefinokee plentiful evidence of the Bear’s habit of gnawing and clawing trees.  Along the canal pine saplings were noticed that had been so maltreated as to have grown very crooked or to have been nearly killed.  Along a Bear trail near the south end of Floyd’s Island certain trees, including ‘red bay” (Gordonia lasianthus) and a magnolia, were much gnawed and scratched.  In a ‘house’ on Grand Prairie, on July 7, there were gnawings on a ‘sweet bay’ some of them thought by Tom and Ben Chesser to have been made that very day.  These marks were generally about 5 feet above the ground, and in one case perhaps a foot still higher.  Some of the old hunters are reported to have seen  the bear do the gnawing by reaching over its shoulder while rubbing its back against the tree.  Jackson Lee remarked concerning a ‘blazed’ pine on Floyd’s Island that a Bear would soon be scratching there.  This is in line with my observations in northern Alberta, where trees that had been ‘blazed’ seemed especially apt to be scratched by  Bears.

Food–Various notes wree secured on the food of these animals.  Mention has already been made of their digging in the ground for buried eggs of turtles or ‘cooters.’  They resort to the banks of the canal and to the prairie ‘houses’ more particularly in May, June, and July because of the abundance of eggs to be found there at that season.  In June we also noticed scratchings in the ground in the pine barrens of Floyd’s Island.  Though at a considerable distance from water, these were made in search of turtle eggs, according to David Lee.  He added that where a Bear once scratches for these eggs, other ‘cooters’ come to lay in the loosened earth.  Harry Chesser told of a way in which to distinguish the work of a Coon from that of a Bear digging up eggs.  The former makes only a little hole, two or three inches in diameter, whereas the latter makes a broad scoop with its paw to uncover the whole complement.

Allen Chesser states that the Bear eats Alligator eggs and also ants, such as are found plentifully in the tussocks of vegetation on the prairies.  Another source of food supply is indicated in his finding the stings of yellow jackets within the Bear’s nostrils.  Harrison Lee once found evidence that a Bear had dug out a yellow jacket’s nest at the base of a dead live oak on Floyd’s Island.

David Lee lists the following items in the Bear’s diet; white ants or wood lice; all kinds of bugs living in rotten wood (he once found two quarts of adventitious wood in a Bear’s stomach); turtle eggs, wild bees’ honey, the larvae and honey of ground nesting bumblebees; bullaces (muscadine grapes); berries of Smilax, saw palmetto, sweet tops of sweet Bays which he noticed along the canal in the winter of 1916-1917, he said that the Bear breaks the branches sometimes with its mere weight, and sometiimes by pulling on them.  Along the canal as well as on Floyd ‘sI sland we found the tops of huckleberry bushes broken off by Bears.  Ben Chesser speaks of high bush gallberries (Ilex coriaca) as a favorite food of the bear.  In August, when the bullace ripens, the animals are found feeding on this luscious fruit in favored situations, such as the banks of canals.

The swamp residents always figure on a certain loss of hogs from the depredations of Bears, and relate numerous tales in this connection.  In the old days, however, according to jackson Lee, Bears did not molest Hogs nearly as much as present.  Newton Roddenberry has known them to take Hogs out of a pen.  He once killed in 0 Bay a Bear which had carried a (~300 pound) hog about half a mile.  Allen Chesser spoke of having sat up many a night about his fields , waiting for a certain marauding Bear to catch a hog.

In 1912 all the Lee’s hogs were of the ‘piney woods’ or ‘razor back’ variety.  Within the next four years, however, they gave these up in favor of the black Essex breed.  One advanatage of the change, they said, was that, whereas the razorbacks would spend the night out in the woods where they fed during the day, the others were in the habit of returning from the woods to spend the night in the vicinity of the house, where they were less liable to attack from Bears.  On Chesser’s Island, on the other hand, the razorbacks are accustomed to pass the night near the house, but are not safe from the Bears even there.

Enemies–The species apparently has few formidable enemies save man.  Yet an occasional hog may prove no mean antagonist.  Once John Hopkins found a dead Bear and a large dead hog within 30 feet of each other near Bugaboo Island, and the possibility of the two animals having engaged in a mortal combat suggested itself to him.  Many years ago, along the Altamaha River, a vicious old hog belonging to his grandfather came in one day all bloody and torn.  When dogs were put on its back trail, they came to a dead Bear, which the hog had ‘tushed’ and disembowled.  But the hog died too.

Since the Otters are considered to be in fear of alligators, it seems that Bear cubs, in crossing the prairies or watercourses, might  likewise be in danger from this source.  The numbers of deadly snakes in the swamp might constitute another dangers, provided the Bear is not immune to their poison, or unless its keen senses enabled it to avoid them.  Yet I have heard no reports concerning any of these potential enemies.

Hibernation–So far as known, there is no hibernation in this region.  David Lee has noticed places grown with gallberries where Bears have fed throughout the winter.

The Late Extinction of the Pribiloff Island Mammoths

The Pribiloff Islands are located above the Arctic Circle between Russia and Alaska.  Some are owned by the former and a few are American owned.  Russia owns Wrangel Island, the largest of the Pribiloffs, encompassing 2900 square miles of dry land.

Map of Pribiloff Islands located between Siberia and Alaska above the Arctic Circle.

Despite its location above the Arctic Circle, Wrangel Island is home to a diverse flora and fauna.  Most of the Pleistocene fossils were found in the rivers.

During the last Ice Age a landbridge known as Beringia connected Asia with North America.  Sea level rose following the end of the Ice Age, isolating the Pribiloff Islands from the rest of the mainlands.  Although the growing season averages 25 days, Wrangel Island hosts a remarkable diversity of plant species and communities.  There are 449 species of vascular plants, 330 species of moss, and over 300 species of lichen.  This is roughly double the number of species found on the mainland of Alaska.  Many of these unique species are found nowhere else in the world.  The high number of endemic species is evidence Wrangel Island was never glaciated.  Glaciers wipe out all plant species from any location they expand over.  Steppe grasses, dwarf willows, and low growing saxifragas cover much of the island.  Common plant communities include meadow grass-low shrub, sedge and rush marshes, steppe sedges similar to those found in Mongolia, willow shrub and xeric herb, and rocky saxifragas zones.  Amazingly, several species of endemic poppy flowers grow in the low meadow communities.

Arthropod diversity is also higher on the island than the nearby mainlands.  There are 31 species of spiders, 58 species of beetles, and 42 species of butterflies; again roughly double to what’s found on mainland Alaska.    But unlike in Alaska (and the Apure River–the subject of last week’s blog entry) there is not a single species of mosquito.

Wrangel Island has been a protected nature reserve since 1976.  Over 80,000 walruses live on this island–the largest population of walruses in the world.  Ringed seals and bearded seals also live on the island and gray whales feed offshore.  The concentration of pinnipeds and the occasional whale carcass attract hundreds of polar bears.  Caribou and musk-oxen have been re-introduced,  and wolves and wolverines roam the island.  Arctic foxes and snowy owls prey on lemmings.

Polar bears on Wrangel Island.

Arctic foxes and snowy owls control lemming numbers.  Thousands of empty and half-full fuel barrels litter Wrangel island from failed attempts at human settlement.  Some naturalists want these barrels removed, but I think there is a beauty in forlorn evidence of  abandoned human habitation.

Snow geese are year round residents while Brant geese nest on the island during summer.  Hundreds of thousands of sea birds, including thick-billed guillemots, kittiwakes, several species of sea gulls, and gray plovers nest on the island.  Arctic and peregrine falcons prey on the sea birds.  Lapland longspurs and arctic willow warblers are common inland birds.

Wrangel Island is famous for being the last known place on earth where woolly mammoths (Mammuthus primigenius) lived.  S.L Vartanyan shocked the scientific community in 1995 when his radio-carbon dates on mammoth tusks found in the Neozhydomaya River were found to be just 4000 calender years old.  This is 9,000 years later than the most recent woolly mammoth fossil found on the mainland, though recent studies of mammoth DNA in permafrost suggest mammoths still occurred in Alaska until about 10,500 years ago.  Wrangel island has been isolated from the mainland by sea level rise for approximately 10,000 years.  Apparently, this isolation protected the mammoths from human hunters for 6,000 years until Inuit hunters discovered the island and shortly thereafter rubbed out the world’s last mammoths along with the woolly rhinos (easternmost known occurrence), bison, musk-oxen, horses, and caribou that also lived on the island then.  All the large land herbivores disappeared from the island about 4000 years ago.  Not coincidentally, archaeological evidence of man has been found on the island dating to 3700 BP–roughly the same time all the large ungulates vanish from the fossil record.  No direct evidence of human hunting megafauna on Wrangel Island has been found, but I believe it can be safely assumed.

It didn’t take long for Inuit Indians to wipe out all the large land ungulates on Wrangel Island.

The late extinction of the woolly mammoth on Wrangel Island blows a big gaping hole in climate change models of  Pleistocene extinctions.  No discernible change in climate and plant composition occurred 4000 years ago.  However, man does show up in the archaeological record here at this time.  Proponents of climate change models of extinction in boreal regions believe the increase in precipitation at the end of the Ice Age changed the environment in this part of the world from dry grassy steppe to spruce forest and wet tundra.  Supposedly, these environments were unsuitable for grass-eating species such as woolly mammoths, woolly rhinos, bison, and horses.  However, these species survived the Sangamonian Interglacial which was an even warmer and wetter phase of climate than the one that allegedly caused the extinction of the above-mentioned species.  I doubt these species all of a sudden lost their ability to adapt to fluctuating climate. 

A recent study of woolly mammoth DNA determined that mammoth populations fluctuated with climate fluctuations, and the authors of the study concluded climate change caused the extinction of woolly mammoths.  This conclusion is an overreach–fluctuating populations does not equal extinction.  I’m sure there were refuges for grass-eating megafauna in boreal regions–none of the plants they ate ever became rare.  There seems to be a compromise consensus among many scientists who believe it was a combination of climate change and human hunting that caused the extinction of Pleistocene megafauna.  While it’s true that climate change may have affected the geographical distributions and populations of Pleistocene megafauna in a way that made them more vulnerable to human hunting, if man could have been theoretically removed from this equation, most, if not all, of these species would still exist on earth.  Therefore, man, not climate change, is the single cause of most end Pleistocene extinctions.

There is a misconception that the Wrangel Island mammoth was a dwarf species, but a Russian study determined they were full-sized woolly mammoths.  I don’t think this study has ever been translated into English, perhaps explaining the persistence of this misconception.  Scientists estimate Wrangel Island was big enough to host a population of 500-1000 mammoths.  Dwarf elephants are known to have occurred on Malta Island in the Mediterranean, and dwarf Columbian mammoths (Mammuthus colombi) lived on the Channel Islands off the coast of California.  There were dwarf woolly mammoths living on another Pribiloff Island.  St. Paul’s Island, property of the U.S., was also home to a late population of woolly mammoths,  They survived until 7500 BP.  However, sea level rise rather than human hunting doomed this population.  Sea level rise shrank the island to just 34 square miles which was not large enough to sustain a viable breeding population of mammoths.  The last mammoths on St. Paul showed evidence of starvation and were forced to eat lots of sea weed, a food that would normally have been just an occasional dietary supplement.

Alexander Von Humboldt’s Journey on the Apure River

I wish I could time travel to the Pleistocene and take a boat ride on one of Georgia’s major rivers, such as the Savannah, Altamaha, or Chattahoochee.  I would love to write an account of that experience.    Most people don’t realize how utterly devoid of wildlife the modern world is compared to the time before man decimated nature.  Alexander von Humboldt’s boat ride on the Apure River in 1800 may be the closest real life experience anyone has ever recorded that might be comparable to my wishful journey.  Humboldt traveled throughout the Spanish-claimed colonies of South America between 1799-1804.  For over 50 years after this, he was the sole scientific source of knowledge on the nature of South America.  The Spanish government granted permission to this German scientist to make a scientific expedition through their colonial territories.  This was unusual because the rulers of Spain were influenced by the Catholic Church and didn’t understand the value of science.  Paranoid authorities there assumed foreigners who wanted to travel in their colonies were spies working for enemy governments interested in fomenting revolutions that would result in Spain losing their New World territories. 

The Apure River is located in what today is Venezuela.  At the time of Humboldt’s journey it flowed through one of the more remote regions where few missionary settlements had been established.  The wildlife present then was rich in numbers and diversity.  Many of the same or similar species lived in Georgia during the Pleistocene.  This explains why this part of his journey holds such a fascination for me.

Map of Alexander Humboldt’s scientific expedition from 1799-1804.  This journey provided most of the scientific knowledge in Europe of South America’s natural history for over 50 years because the Spanish and Portuguese governments normally forbade scientific explorations of their colonies.

The Apure River flows through the Apure State in Venezuela.  It empties into the Orinico River.  Alexander Von Humboldt journeyed on this river circa 1800.

Humboldt, and his companion, Bonpland, made the journey with the governor’s brother-in-law, a pilot, and 4 Indian oarsmen.  They used a pirogue made from oxhides stretched over a wooden frame.  The cabin on the boat had a thatched roof.  For food and drink they carried chickens, eggs, cassava, chocolate, oranges, tamarinds, sherry, and brandy.  But the majority of their diet came from animals they hunted including manatees, capybaras, turtles (and their eggs), chacalacas, and currasows–the latter 2 being chicken-like birds.  (Humboldt pronounced manatee as delicious.) They also ate fish both fresh and dried and made into meal.  They used lances more than firearms because the latter often didn’t work in the humid climate.

They suffered from mosquitoes, gnats, and a type of insect that burrowed under their toe and finger nails.  The mosquitoes are so bad in this part of the world that the customary salutation is “How bad were the mosquitoes last night?” instead of “hello” and “goodbye.”  Nevertheless, Humboldt thought the trip was worth the torment just to see all the wildlife.

Humboldt wrote that 4 or 5 caimans, which he referred to as crocodiles, were always in view of the pirogue.  Thick hedges grew alongside the river, interrupted by passages made by peccaries and tapirs that used the same paths daily to access the drinking water.  Neither showed any fear of man.  Both were spotted by Humboldt’s party frequently along with the occasional deer.  Manatees and pink dolphins, known as toninas by the Spanish, swam in the main river channel and in the flooded plains and forests.  Manatees were so abundant that 1 region of the river was called Cano de Manatee.  Clouds of birds flew in the sky, and Humboldt noted the cries of herons, spoonbills, and flamingos were constant.  The presence of pirhanas annoyed Humboldt who wanted to bathe his itchy mosquito bites but feared the vicious “caribe” fish.  When they camped at night, the jungle was alive with the sounds of monkeys, sloths, and jaguars.  Vampire bats fluttered around their camp, and even fed on the blood from Humboldt’s dog.

During the rainy season the Apure River flooded the nearby grasslands turning it into a massive lake.  The floodwaters often rose so fast that horses drowned, attracting caimans and huge flocks of vultures.  Caimans occasionally attacked swimming horses that hadn’t drowned yet.  After the waters receded, some caimans dug holes in the savannahs and hibernated til the floods returned.  One time. Humboldt’s party was startled when a caiman emerged from the ground under a tent where they’d spent the night.  The reptile sprinted through the tent toward the river.  The floods caused some river banks to be covered in sand and silt rather than hedges.  Ten or more caimans often sunned themselves on these beaches.

Herds of 50-60 capybaras could be found everywhere on the Apure.  They were the main food of the surprisingly common jaguars.  Humboldt’s party had numerous encounters with the big cats.  His party saw a very large jaguar that Humboldt said was bigger than any tiger he’d ever seen in a European zoo.  Humboldt said the jaguars here were no danger to man because they had plenty of capybaras to prey upon, though on another river later in his expedition he lost his dog, a mastiff, to a jaguar.  Mastiffs are large dogs, sometimes weighing in excess of 100 lbs.  Nevertheless, 1 particular jaguar viewed it as food.

Capybaras were extremely abundant along the Apure River during Humboldt’s journey, and they helped support very large jaguar and caiman populations.  Two species of capybaras lived along Georgia’s coastal plain rivers during the Pleistocene.

Humboldt walked right by a large jaguar while collecting plants.  It scared the shit out of him, but he walked slowly back to camp, so the jaguar wouldn’t be incited by his flight to attack.  Jaguars were one of the most common large predators in southeastern North America during the Pleistocene.

Humboldt feared that he would become a jaguar’s dinner as he relates in the following account.

“I left my companions while they beached the boat and prepared the meal.  I walked along the beach to observe a group of crocodiles asleep in the sun, their tails, covered with broad scaly plates, resting on each other.  Small herons, white as snow, walked on their backs, even on their heads, as if they were tree trunks.  The crocodiles were grey-green, their bodies were half covered in dried mud.  From their color and immobility they looked like bronze statues.  However, my stroll almost cost me my life.  I had been constantly looking towards the river, and then, on seeing a flash of mica in the sand, I also spotted fresh jaguar tracks, easily recognizable by their shape.  The animal had gone off into the jungle, and as I looked in that direction I saw it lying down under the thick foilage of a ceiba, eighty steps away from me.  Never has a tiger seemed so enormous.

“There are moments in life when it is useless to call on reason.  I was very scared.  However, I was sufficiently in control of myself to remember what the Indians had advised us to do in such circumstances.  I carried on walking, without breaking into a run or moving my arms, and I thought I noted the wild beast had its eye on a herd of capybaras swimming in the river.  The further away I got the more I quickened my pace.  I was so tempted to turn around and see if  the cat was chasing me!  Luckily, I resisted this impulse, and the tiger remained lying down.  These enormous cats with spotted skins are so well fed in this country well stocked with capybara, peccary, and deer that they rarely attack humans.  I reached the launch panting and told my adventure story to the Indians, who did not give it much importance.”

Reference:

Alexander Von Humboldt: Personal Narrative of a Journey to the Equinoctial Regions of the New Continent

Penguin Books 1995

Pigeon Mountain and a Second Excursion to Lavender Mountain

Pigeon Mountain is located in northwest Georgia, just west of Lafayette.  This area of the state is known geologically as the ridge and valley region.  The Pigeon Mountain Ridge is parallel to Lookout Mountain with a valley in between them.  Shamble Ridge, a spur of Pigeon Mountain, forms a cove where it connects with Lookout Mountain.  Most of Pigeon Mountain is protected by the state as a Wildlife Management Area.  

By the time I thought of taking a photo of Pigeon Mountain from a distance, we were late for lunch and tired from hiking, so I had my daughter take this drive-by photo from the car.  It turned out ok.

Pigeon Mountain was formerly a major passenger pigeon roosting site.  Passenger Pigeons roosted in the forest here from late August to early March.  While they were migrating from their summer breeding grounds in the midwest, the flocks were so large they caused solar eclipses that lasted for as long as 6 hours. (See: https://markgelbart.wordpress.com/2010/08/27/pleistocene-passenger-pigeon-populations/: )  Imagine the din from billions of birds flying overhead.  The dung and feathers dropping from the sky resembled snowflakes.  The ground underneath their roosting sites became white from excrement, and the weight of the birds broke tree limbs and even tree trunks in half.  The trees in their roosting sites usually died from overfertilization, opening up the forest canopy.  Plants, such as pokeweed and ginseng, grew in the sunny, nitrogen-rich spaces.  Passenger pigeons have been gone from Pigeon Mountain for over 100 years because they were market-hunted to extinction in the late 19th century.  Who knows how many plant species have suffered due to the bird’s absence.

Pigeon Mountain is covered by a nice second growth forest.  White oak is the second most common oak behind rock chestnut oak.

We walked up a ravine where a lot of beech trees grew.  The abundance of beech is evidence that passenger pigeons once nested en masse here.

I walked on a horseback trail that led up a ravine to a gravel road.  The trail was eroded and muddy.  The abundance of beech and black walnut trees here is relic evidence that passenger pigeons used to forage for mast on the mountain.  Beech trees can grow from sucker roots thereby insuring their survival, even if a flock of passenger pigeons ate every last seed every year.  Black walnuts have too thick a shell for a bird like a passenger pigeon to crack.  Since the passenger pigeon’s extinction, forests that used to be composed primarily of beech are being replaced by oaks because the acorns are no longer vacuumed up by flocks of pigeons.

Other common trees in this area of Pigeon Mountain include rock chestnut oak, white oak, black oak, hickory, tulip, white pine, Virginia pine, and loblolly pine.  I found some ripe wild muscadines that were as sweet as cultivated grapes.  I heard pileated woodpeckers, chickadees, and crows.

The Shirley Miller Wildflower Trail is located within Pigeon Mountain WMA.  I couldn’t find good directions online, but my brother-in-law showed us where it is.  (Take Highway 193 to Mclemore Cove Road and turn left.  Then turn left on Pocket Road.  This turns into a long gravel road that leads to the Wild Flower Trail and Estelle Mines.)  The Wildflower Trail is a wheelchair accessible boardwalk built in a swamp dominated by large sweetgum trees.  It’s surprising to see a swamp like this in north Georgia, though there are no cypress trees.  There are some sycamore, hickory, and red maple trees growing with the sweetgum.

The Shirley Miller Wildflower Trail is a boardwalk that was built over a swamp dominated by sweetgum.  Reminds me of the Congaree National Park.  There were few wildlflowers this time of year, but the sweetgum trees looked like they might be about 100 years old.

A rugged trail off the boardwalk leads to a cave.  Water springs from this cave and forms the creek that feeds the sweetgum swamp.  Edible-sized bream swim in the clear waters of the creek.

This time of year there are no flowers blooming on the wildflower trail.  However, on the side of the gravel road that led to it I saw blueish-purple bull thistle blooming, and lots of yellow flowers that I narrowed down to camphorweed, golden ragwort, golden aster, or blackeyed susans.  I can’t remember if the disks of the flowers were yellow or black.  If they were black, they were of the latter species, but if yellow they could be any of the first 3 I mentioned.  Many black swallowtailed butterflies were fluttering about.  We didn’t have time to see Estelle Mines, but we’ll come back next month.

The spring that flows into the sweetgum swamp originates from this cave.

I’m sure bats use this cave for roosting.

Inside one of the caverns.

Lavender Mountain

Last time I visited Lavender Mountain located on Berry College campus, I didn’t see any deer, but this time I saw them every time I turned around.

I saw lots of deer and other wildlife on the Berry College campus adjacent to Lavender Mountain.

Berry College campus is almost like a zoo.  The deer are tame and don’t run away from cars.  I also saw turkeys, over 60 Canadian geese grazing in an unmowed field, and dozens of killdeer plovers in a mowed field.  I’ve seen killdeer plover before, especially around golf courses, but never this many.  On Highway 27 a few miles from Berry College I saw a peregrine falcon perched on a telephone wire not far from a flock of blackbirds.  On a trail next to Lavender Mountain I smelled the distinct odor of a skunk that must have crossed the path that morning.

There is a trail at the bottom of a creek that bisects Lavender Mountain.  An open pine savannah grows on 1 side, but a mostly hardwood forest consisting of white oak, overcup oak, shagbark hickory, and tulip grows on the other.  I’m definitely coming back next month, and I’m going to walk to the top of Lavender Mountain.

Lavender Mountain.  It is so open there’s no need to follow a trail.  I think next time I’m going to walk to the top.

A trail follows a creek bed in a ravine that cuts through lavender mountain.  The other side of the mountain is composed of mostly hardwoods.

The trail through Lavender Mountain follows this creek bed.  You can see where the rest of the trail resumes, but I didn’t have time to walk any farther that day.

Jesus’s Ass

Jesus entered Jerusalem on the back of a baby donkey the week before his alleged execution and resurrection, according to  the book of Matthew in the New Testament.  The donkey symbolizes peace whereas the horse represents war.  Obviously, the Romans didn’t view Jesus as the leader of a peaceful movement.  The Romans only crucified people who rebelled against the empire.  The New Testament likely gives a wildly inaccurate account of what really happened.  Somehow, the Jews get blamed for Jesus’s crucifixion, as if the brutal Roman military leaders would succomb to the wishes of a mob.  Just a few days prior to when the Jews allegedly urged Jesus’s execution, they gave him an honorable reception upon his entry into Jerusalem.  The whole story doesn’t make sense and is full of logical contradictions, but this is not surprising because the bible is a clumsy compilation of stories written by many different men with differing agendas, and furthermore, passages have frequently been rewritten, mistranslated, and interpolated thousands of times by various scribes who also had differing agendas.

According to legend, Jesus rode into Jerusalem on an ass a week before he was executed and resurrected. 

The scientific name for Jesus’s ass is Equus africanus, also known as the domesticated donkey.  Originally, it ranged from North Africa through the Middle East.  The Spanish brought donkeys to North America in the 1500’s and some of them went wild and still live in the American southwest where they are called burros.  They are tough animals well adapted to living in desert environments.  They will attack predators and stomp them to death.  Some people keep donkeys to protect their other farm animals.  Here’s a delightful video of a donkey playing with a dog. http://www.youtube.com/watch?v=txfVhMFYnxU  It almost makes me want to buy one and keep it in my backyard.

Two other species of asses live in Asia.  Unlike the donkey, the Asian wild ass (Equus hemionus), and the Tibetan wild ass (Equus kiang) are considered untameable.  Hemionus means half-ass.  These wild asses are larger than a donkey and have some features that are more horse-like, hence the name, half-ass.  Formerly, vertebrate paleontologists thought Asian wild asses were sister species to the half-asses that lived in North America until the late Pleistocene about 11,000 years ago.  However, a study of Equus genetics suggests the North American half-asses did not share a close evolutionary lineage with Asian asses. Instead, their similar morphology was due to convergent evolution.

A herd of Equus kiang–the Tibetan wild ass.  Vertebrate paleontologists used to think they were closely related to the Pleistocene half-asses that formerly lived in North America because they  have similar physical characteristics.  However, genetic studies suggest this similar morphology is due to convergence and the North American half-asses have a different evolutionary lineage and are not closely related.

American half-asses lived from Alaska to Florida during the Pleistocene, but they never crossed the Bering landbridge.  Asian asses evolved from an earlier Equus species that did originate in North America but crossed the Bering landbridge before the Pleistocene.  The horse (Equus caballus) did live on both sides of the Bering landbridge from Western Europe to Florida during the Pleistocene.  Genetic evidence suggests the Pleistocene horse is the same animal as the modern day horse.  One clade of this species was restricted to North America, and it became extinct before the horse was domesticated.

Vertebrate paleontologists named over 50 species of Equus from Pleistocene-aged fossils found in North America, but genetic evidence suggests there were just 2–the horse and the North American half-ass.  A 3rd species of Pleistocene horse, the hippidion, lived in South America.

Reference:

Weinstock, Jaco; et. al.

“Evolution, Systematics, and Phylogeography of Pleistocene Horses in the New World: A Molecular Perspective”

PLOS Biology 3 (8) 2005