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Two Pleistocene Carnivore Dens Near Miami, Florida (Part 2)

October 18, 2013

Scientists unearthed thousands of bones from the Cutler Hammock site during the mid-1980’s.  The fossils were identified, catalogued, and sent to the University of Florida Museum.  Many of the specimens remain unstudied in detail, and this rich assortment offers an opportunity for paleontologists looking for research material.  The site itself was not completely excavated and is potentially available for future study.  Originally, it was a cone-shaped sinkhole cave filled with sediment, rocks, and fossils. The lower half was below the water table.  The suface was 5 meters by 6 meters wide and from 3 meters to 5 meters deep in various places.  Workers bulldozed sand over the unexcavated section, making it easy for future scientists to re-dig but protecting it from unauthorized fossil hunters.    It’s located on land that is part of Deering Estate Park–a protected environmental, historical, and archaeological preserve of 444 acres in extent.  The preserve is a rare natural area within the suburban sprawl of Miami, Florida and includes endangered pine rocklands, tropical hardwood hammock, mangrove woods, and salt marsh.

The Deering Estate.  Deering was an industrialist who decided to protect his estate from development in perpetuity.  The Cutler Hammock fossil site is located on this property.

Gary Morgan and Steve Emslie studied many of the large vertebrate bones found at Cutler Hammock, and they wrote the paper from which I mined most of the information I used for this blog entry.  They noticed a high number of bones here had gnaw marks on them and concluded this former cave served as a carnivore den during the Pleistocene.  The most common large carnivore fossils found at this site were from dire wolves (Canis dirus), totaling 42 individuals.  This is the third largest dire wolf assemblage in the world behind the La Brea Tar Pits and San Josecito Cave in Mexico.  They also found bones from 9 spectacled bears (the extinct Tremarctos floridanus), 5 coyotes (Canis latrans), 4 jaguars (Panthera onca), 3 bobcats (Lynx rufus), 1 sabertooth (Smilodon fatalis), 1 American lion (Panthera atrox), 1 cougar (Puma concolor), and 1 black bear (Ursus americanus).   The authors of the study suggest the cave was a rendezvous site for packs of dire wolves and not a place where pups were birthed.  They speculate the cave was near a source of water that attracted various prey species.  In another paper Gary Morgan mentioned that the coyote fossils found at Cutler Hammock were unusually small.  Some think they may actually belong to dogs (Canis familiaris) brought by man.  If so, it’s possible the bones may be from yellow dogs, the American dingos, which readily revert to the wild state and are capable of surviving without humans.

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Photos of deer and peccary bones gnawed by dire wolves at the Cutler Hammock site.  Click to enlarge. From the below referenced paper.

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Photo of dire wolf lower jaw and dire wolf teeth found at the Cutler Hammock site.  Click to enlarge.  Also from the below referenced paper.

Most of the bones from prey species have puncture marks–a telltale characteristic of canid gnawing.  The extinct long-nosed peccary (Mylohyus nasatus) was the most common victim of dire wolves, numbering 75 individuals of which one-third were juveniles.  Horses were the next most common dire wolf victim, though 17 of the 19 individuals were juveniles.  Next in descending order of abundance were white-tailed deer, bison, llamas, and 1 mammoth that was probably scavenged.

Tremarctos floridanus was a close relative of the extant spectacled bear (Tremarctos ornatus) of South America.  Spectacled bears are primarily vegetarian but occasionally eat meat.  Bones scavenged by bears show recognizable differences from bones scavenged by canids.  None of the Cutler Hammock bones show evidence of bear gnawing.  (Hint to professional paleontologists: the authors of this study didn’t examine the bones for evidence of big cat gnawing.  It’s a potential topic for future research.)  Scientists also found bones from mastodon, Harlan’s ground sloth, and the pampathere (a 300 pound grass-eating armadillo) at Cutler Hammock but these showed no evidence of being gnawed upon.

A hearth and bones from 3 adult and 2 juvenile humans (Homo sapiens) were found just above the level where Pleistocene fossils were found.  This material dates to ~11,100 calender years BP.  A human bone found associated with dire wolf bones (in situ) was found as well.  The radiocarbon dating on this bone is considered unreliable.  It’s possible this human bone is as old as the dire wolf bones.  However, there has been much bioturbation at this site.  Land crabs dig holes in this locality, and their actions can mix bones of different ages together.  Or humans may have buried the corpse into the fossil deposit.  Nevertheless, this human bone has dire wolf gnawmarks on it–evidence this person was scavenged (or even killed) by dire wolves.

The below referenced article lists all the vertebrate species identified from Cutler Hammock, and as I read through the list, I noticed a few interesting bird species I neglected to mention in my discussion from part 1 of this blog entry.  The extinct hawk-eagle (Spizaetus grinnelli) flew the skies of Pleistocene south Florida.  It was larger than its closest living relative, Spizaetus ornata.

Spizaetus ornatus

South American hawk-eagle.  It some times takes prey 5 times its size.  A bird like this lived in Ice Age Florida.

An extinct species of caracara (Milvago reidei), closely related to the living yellow crested caracara, also of South America, lived on the open plains of Florida then.  Passenger pigeons (Ectopistes migratorius) must have occasionally darkened the skies.

The Monkey Jungle Hammock site is thought to have been a carnivore den site as well but as far as I know no study has been conducted on the morphology of bones found there (Another hint to paleontologists.)

Reference:

Emslie, Steve; and Gary Morgan

“Taphonomy of a Late Pleistocene Carnivore Den in Dade County, Florida”

Late Quaternary Environments and Deep History: Tributes to the Career of Paul Martin

Edited by David Steadman and Jim Mead

Hot Springs South Dakota Inc. Reasearch Papers Volume 3 1995

Two Pleistocene Carnivore Den Sites near Miami, Florida (Part 1)

October 15, 2013

Many tropical hardwood hammocks dot the low lying Everglades, southwest of Miami, Florida.  Two of them have sinkholes where scientists unearthed Pleistocene-aged fossils. Monkey Jungle Hammock and Cutler Hammock along with a West Palm Beach site are the southeasternmost Pleistocene fossil localities in North America.

The Monkey Jungle fossil site is named after an adjacent tourist attraction which is kind of a monkey zoo.

The bedrock in south Florida is known as Miami limestone, built from eons of buried sea shells and coral that transformed into rock.  Rain water dissolved caverns within the limestone, and these caves attracted bats, owls, and large carnivores, and they also contain everything the meat-eaters dragged inside.  Scientists can’t use radiocarbon dating on the fossils found at these localities because the conditions have leached too much organic material from the bones.  Nevertheless, they can safely assume the fossils accumulated during the Last Glacial Maximum between ~28,000 BP- ~15,000 BP. These caves are flooded today due to the rise in sea level following the end of the last Ice Age, but they were well above the water table then.

The sinkhole in Monkey Jungle Hammock was discovered in 1969; the one in Cutler Hammock was found in 1985.  The West Palm Beach site, also discovered in 1969, is probably not a sinkhole.  Cutler Hammock is the richest of the 3 sites, yielding the abundant remains of 47 species of mammals, 51 of birds, 9 of reptiles, 7 of amphibians, and 5 of fish.  Remains of dire wolves, spectacled bears, and jaguars were the most common large carnivore bones found here.   Horses, upland bison (Bison antiquus), and long nosed peccary (Mylohyus nasatus) were apparently the most common prey animals dragged into the cave, and most of the bones were from juveniles.  Many of the bones have been gnawed upon–evidence the cave served as a carnivore den site.  Cottontail rabbits, cotton rats, and wood rats, were the most common small mammals.  Monkey Jungle Hammock is also thought to have been a carnivore den site as well as an owl and bat roost.  41 species of mammals were found here.  Only 17 species of mammals were found at the West Palm Beach site, and most of the fossils–capybaras, tapirs, alligators, turtles, and fish–indicate it was an aquatic environment rather than a cave.

The abundance of several species at these fossil sites suggests Ice Age south Florida consisted of dry longleaf pine savannah instead of the sawgrass wetlands of today.  Fossils of indigo snakes and gopher tortoises, denizens of pine savannah, are especially common.  Fossils of Hesperotestudo incisa, a dwarf version of the extinct giant tortoise (Hesperotestudo crassicutata) have been found as well.  It likely was a dry upland dweller.  Pine voles and pocket gophers inhabited south Florida then but are absent today due to the expansion of wetland environments.  Pine savannahs were maintained by occasional hurricanes and lightning-induced wildfires that kept the environment open and grassy, but the climate was more arid than it is today, and there were far fewer wetlands.

There are no above ground caves in south Florida and the West Indies today, but during the Ice Age, all of the caverns presently inundated with fresh and saltwater served as roosts for enormous bat colonies.  The extinct mustached bat (Pteronotus pristinus), the ghost-faced bat (Mormoops megalphylla), the big brown bat (Eptesicus fuscus), and the southeastern myotis (Myotis austrarpririus) all formerly hunted flying insects in the skies of Ice Age south Florida and the Caribbean Islands.  Sea level rise caused the extinction of the mustached bat, and the extirpation of the other 3 species because the cave roosts became flooded. 

An upside down flying Ghost-faced Bat (Mormoops megalphylla).  The feed on large nocturnal moths.

Distribution of Mormoops megalophylla

Present day range of the ghost-faced bat.  During the Ice Age they also lived in south Florida and the West Indies and nested in caves.  Following the end of the Ice Age and the corresponding rise in sea level, those caves were flooded, thus eliminating their roosting sites.

Mexican free-tailed bats (Tadarida brasiliensis), evening bats (Nycticius humeralis), Seminole bats, (Lasiurius sp.?) and Wagner’s mastiff bats (Eumops glaucinus) still live in south Florida.  The former is the most abundant in the region today.  They survived sea level rise because they roosted in trees, but today they almost exclusively make use of man-made structures.

Barn owl.  What a ghostly colored creature.  Here’s a link to an excellent documentary about them. http://www.youtube.com/watch?v=5NLFLO8LN78

Barn owls (Tyto alba) were common in south Florida and the West Indies during the Ice Age, thanks to the caves that provided them with roosing sites.  Other notable birds that lived in south Florida then include the terratorn, California condors, an extinct stork (Ciconia malthus), the extinct hawk-eagle (Spizatus sp.), and the whooping crane (now absent from the region.)

The reason I’m splitting this essay into 2 parts is because I’m waiting for the mailman to deliver an obscure scientific article about these 2 sites that is not available on the internet.  That article should have more information on the morphology of the gnawed and broken bones found at these sites.  4 of the 5 species of big Pleistocene cats as well as dire wolves, bears, and a small canid utilized these caves as den sites over the millenia.  I should get the article anyday now.

See also: http://markgelbart.wordpress.com/2011/11/11/banana-hole-fossil-sites/

Reference:

Morgan, Gary

“Late Rancholabrean Mammals from Southeastern Florida and the Neotropical influence in Florida’s Pleistocene Fauna”

Cenozoic Mammals of Land and Sea: Tributes to the Career of Clayton Ray

Smithsonian Press 2002

Up and Down Lavender Mountain

October 10, 2013

I visited Berry College Wildlife Management Area for the 3rd time a few days ago.  I saw deer sunning themselves in the open places behind the campus, and I encountered them bounding in the woods.   I’d already photographed Berry College deer on a previous visit and was going to forgo taking any more pictures of them.  But on the way out, we drove adjacent to a complacent herd of a dozen laying so close to the road that I couldn’t resist.  However, by then the camera batteries had lost their juice.  Nevertheless, I did satisfy my urge to climb to the top of Lavender Mountain and take photographs from there

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View from the top of Lavender Mountain

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Another view from the top of Lavender Mountain.

I didn’t know the Longleaf Pine Trail leads to the top of Lavender Mountain.  The Longleaf Pine Trail is an uphill climb, but in my ignorance I chose an even more rigorous route straight up a steep slope.  The rocky soils support an open forest of shortleaf pine and black oak with longleaf pine saplings on the lower part of the slope.  It looked so open that I didn’t think I would have any problem finding my way back.

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I found this potential rattlesnake den on the way up the mountain.  A tree had fallen, and its roots left a convenient cavern for serpents.  Many of the tree trunks on the mountain have burn marks from prescribed fire.

I reached the top of the mountain and a large hawk flew over my head.  The sight of the raptor seemed like a reward for my effort.  But the open nature of the terrain had deceived me–I looked down the steep mountain and couldn’t see my vehicle where my wife and daughter awaited.  In my haste to return I fell on my tukous 3 times and shredded my legs negotiating through a blackberry thorn patch.  A deer bounced about 10 yards in front of me, clearing the infernal thorns with ease, and in my paranoid imagination I thought of the deer attacking me in vengeance for all its brethren slain by hunters.  I pictured myself using boxing skills to ward off slashing hooves.  I avoided the potential rattlesnake den and discovered the trail that an educated hiker would’ve taken.  It was easier to descend than my chosen route.  After a brief period of directional confusion I was reunited with my family.

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Sign marking the Longleaf Trail–the route I should have taken instead of straight up a briar-choked steep slope.

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This is me at the base of a forked chestnut oak (Quercus montana) before my adventure up the mountain.  I was still excited about Georgia beating Tennessee thus stepping on their face with a hobnailed boot and breaking their nose…again!

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They have a longleaf pine restoration project at Berry College WMA.  A pine bark beetle infestation took out a number of shortleaf and loblolly pines, and managers burned and logged the area and planted longleaf pine saplings.  Longleaf pine is more resistant to pine bark beetles than other types of southern pines.  Lavender Mountain originally hosted an unusual disjunct population of longleaf pine which is normally a species found on the coastal plain rather than the mountains.

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Another view of Lavender Mountain through a firebreak.  The firebreak serves the purpose of isolating experimental populations of longleaf pine.

Mark Gelbart’s Scratched up Legs

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Look.  I’ve got a birthmark on my left leg that’s shaped like the state of Georgia.  My legs got scratched up while descending through a Lavender Mountain brier patch.

A long time ago, when I was about 20, an older woman, whose husband was serving overseas in the U.S. Army, told me I had ugly legs.  A few days after she uttered this unkind remark, she made a pass at me.  I didn’t respond.  At that age my social ability with the opposite sex was about as sophisticated as that of a mud turtle.  Being a dullard with thick skin had its advantages–I didn’t mull over her contradictory strategy of hurting someone’s feelings, then making them feel better through sex.  (The above photograph reminded me of that long forgotten incident.)  Now, after half a century of life experience, I’m sophisticated enough to know she was a bitch.  Shame on those people who use her strategy.  I’m sure there are plenty of relationships that consist of jerks who play with their partner’s low self-esteem to manipulate them emotionally.  They take advantage of vulnerability.  I’ve got no use for them.  Luckily for me, I didn’t take the bait.  Who knows what kind of trouble that would have brought me?  I had 1 friend who had an affair with a married woman.  He was murdered, allegedly by a drug fiend bribed with a line of coke.

The Estelle Mine Trail

A century ago, miners dug iron ore from an area on Pigeon Mountain.  Today, there’s a 2.9 mile trail leading to the abandoned mines.  I only hiked about a mile on the trail because I didn’t want to leave my wife alone in the car for more than 40 minutes.  My daughter and I saw some evidence of mining but didn’t reach the big tunnels in the rock that are probably located near the end of the trail.

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Side of a ravine where iron ore may have been extracted.

The trail is easy to follow.  Its eroded in places from horseback riders, and it tends to follow through ravines.  It’s hard to tell which ravines are natural and which are the result of mining.  A 2nd growth forest of white oak, chestnut oak, shorleaf pine, maple, sweetgum, sycamore, and black walnut has reclaimed the area around the mines.  I’m sure it was a barren clear cut a hundred years ago.  I kept hearing a pileated woodpecker and found the tree upon which it was roosting deep inside the forest.  I also saw a red-headed woodpecker.

We didn’t get this far on the Estelle Mines Trail, but I found this picture on google images.

Another Excerpt from Frances Harper’s Mammals of the Okefinokee Swamp–The River Otter (Lutra canadensis)

October 6, 2013

I’ve been periodically posting excerpts from an obscure book published in 1925.  Below is Frances Harper’s collection of accounts about the river otter.  I’ve only seen a live wild otter once in my entire life when I accidentally drove my car  over an unfortunate otter’s paw on my honeymoon.  It was crossing a raised highway over a salt marsh in South Carolina. I tried to swerve to avoid it, but I should have kept going straight and I would have probably missed it.  Kind of ruined the whole evening for me.  I have seen otter scat on exposed river rocks, and there was an otter slide by a creek in the woods behind a house where I lived in Athens, Georgia 37 years ago.  My closest encounter came when a tame otter escaped its pen at the Okefenokee Swamp Zoo and sniffed my shoe.

Cruelty toward animals is evident in the below excerpt.  The locals acknowledged that otters made great pets, yet they  expressed no remorse about killing  them with  steel jaw traps.  Here’s the excerpt:

River Otter–Lutra canadensis vega

The Otter is generally distributed along the waterways of the swamp, such as Billy’s Lake, the Big Water, the canal, the numerous runs through the cypress bays, and the open water of the prairies.  It is also found on the Suwannee and St. Mary’s Rivers.  It is a rather shy animal, and I have not met with it in life in the swamp.  It is still fairly common, though its present numbers evidentally do not equal those of former years.

The distribution is said to vary somewhat with the season, and various theories are advanced on the subject.  David Lee says that during the winter the Otters follow the deeper waterways for the most part.  Their occurrences on the prairies (especially in the gator holes) seems more or less limited to the season of the year, when the Alligators are generally inactive.  In the summer they are hardly found in deep water, but out in the cypress bays.  For example, there are more of them along the shallow run through Billy’s Bay in the summer than at any other season.  He supposes this is on account of their fear of Alligators (which stay mostly in the deeper water of the swamp).

According to Sam Mizell, the Otters stay in the cypress bays especially in summer.  Some foiks think they are afraid of Gators out in the prairies.  They are commoner on the prairies in winter than summer.  For one thing, this is the rutting season, and they are disposed then to travel around more.

Allen Chesser expresses the opinion that they avoid the prairies in summer because it is too warm for them there at that season.  Yet he also considers it likely that Alligators prey upon them. 

In the Okefinokee parlance, an Otter slide is practically any place where the animals defecate.  This may be merely a log beside a watercourse, the sign being frequently noted in such a situation.  More commonly, according to Jackson Lee, it is some muddy spot, where the animals leave marks of scratching and wallowing, as well as faeces.  While such spots may not be exactly comparable to the regular Otter slides on sloping banks in other parts of the continent, yet they likely serve somewhat the same purpose.  Stream banks with any appreciable slope are quite lacking in the natural topography of the swamp, though they occur here and there along the canal.  David Lee has seen, in the winter time, tussocks in the cypress bays that were perforated with a number of holes or runways, and were littered with faeces; it also appeared as if the Otters had wallowed around there on top of the ground.

In addition to its diet of fish, the species feeds upon snakes, according to Allen Chesser.  In David Lee’s opinion, it may take crawfish occasionally, but only when pressed for hunger.  Harrison Lee states that in former years the Otters used to get corn in the field at the north end of Billy’s Island, and carry it off in the swamp.  This is the less surprising when one consders the highly varied diet of a tame Otter.  Such a one, which was once kept on Billy’s Island would “eat anything,” according to David Lee.  “It had to be shut up at mealtimes, or it would come right on the table.”

Regarding the Otter’s voice, Jackson Lee said, “I heard a Auter hollerin’ one time, an’ it hollered somep’n like a Redbird (the q-note of a Cardinal. Down on Billy’s Lake he was mighty busy; he was swimmin’ about in the lake, an’ done like he was a-trailin’ another Auter.  He wuz a might big un.  I watched ‘im for a while.  The other one might ‘a’ been in heat.  Must ‘a” been some’ere abut December, about 10 yearas ago.  I was huntin’ Auter at the time.”

Harrison and Farley Lee once killed an Otter on Minne’s Lake, and its mate, after being frightened off, came back, whistling for it–‘a little sort er like a Redbird.’

In regard to the mating season and the birth of the young, Allen Chesser said, “They hunt one ernother erlong in November.  I once found two matin’ out on the perairie.  I think they have their young about the last of February or the first er March.”  According to Bryant Lee, a female taken about the middle of December, 1916, contained three or four embryos about half an inch long.  David Lee recalls four embryos in one case; perhaps three in others.

Jackson Lee thinks the young come about February or March.  He gave the following account of once finding some young ones.  “It was February, the best I can remember, about 22 years ago, right down yonder against Scrub Island.  We had a ol’ dog that would go off an’ tree, an’ stay with it till we’d come; an’ Gip was a young dog we had with us.  As we wuz goin’ to this ol’ dog that had somep’n treed, Gip treed the Auter in a hollow cypress, an’ he got it out.  Then we heard a growlin’ in there, an’ saw three young Auters, an’ took ‘em out.  We kep’ ‘em fer two weeks, an’ their eyes never did open.  Fed ‘em on milk, but they finally died.  The growlin’ we had heard wuz probably another ol’ Auter left in the stump.  We thought at the time it was the young uns, but they never growled any aft they wuz taken out.  The Cypress wuz out in the swamp, a good piece from any run, an’ it was kind er dry aroun’ there.”

About the middle of April, 1922, a young Otter was caught by an old colored man on Hull’s Creek, near the St. Mary’s River above Camp Pinckney.  It was said to have become gentle within a few moments.  It was soon made a household pet at the home of I.B. Loyd, near Folkston, where we had the good fortune to see it on July 8.  It was the particular favorite of two children, and the intimate playmate of  a cat.  It slid about on its stomach over the dirt in the yard, in a playful manner perhaps like that of wild Otters disporting themselves on their slides.  Altogether it was a most engaging little creature.  It ate greedily of watermelon, and was also said to feed upon tomatoes, dead birds, rats, and any kind of fresh meat.  A flea was seen on it.

Specimens from the swamp exhibit two types of coloration, which are well recognized by the residents, but are not considered due to differences of sex, age or season.  One is light brown; the other, dark brown, or occasionally almost black.

As the most valuable fur-bearing animal of the swamp, the Otter is much sought by the trappers, and its diminishing numbers indicate the urgent need of conservation.  It has long been without any protection whatever under the laws of Georgia.  In 1916 local hides were bringing 9 or 10 dollars,, and in 1922, twice as much.  In the winter of 1920–21, however, prices had dropped temporarily, and comparatively little hunting seems to have been carried on.  In the season of 1916 three of the Lees had taken about 20 Otters by December 22.  It seems quite likely that the Otters in the Okefinokee still number several hundred individuals.

The Otter traps, armed with teeth, are placed on the so-called slides without bait.  Sometimes a slight hollow is chopped out of the top of a log, so that when the trap is placed there, it will not form a conspicuous projection.  The trap is lightly covreed with trash such as moss, earth, or leaves.

Trapping is by no means the only method of capture.  In 1916 David Lee had trained one of his hounds to hunt Otters, and with its help he secured far more specimens than by trapping.  The hound would sit in the bow of the little boat in which the hunter navigated the swamp, and on scenting the Otter, would jump overboard to pursue it in its natural element.  If the Otter had a clear run of deep water, it would outdistance and escape the dog.  If it had as much as 10 inches of water , it would elude the dog indefinitely, just sticking its nose above the surface, and not being seen by its pursuer.  If it took refuge in a tussock, the hunter would cut a stick and thrust down into the tussock with it.  If he succeeded thus in striking the Otter, it would clear out, giving him a chance to shoot it if not caught by the dog.  The latter would, if possible, seize it by the head, and in the ensuing struggle both animals might disappear for a time beneath the surface….

The American Hyena (Chasmaporthetes ossifragus)

October 1, 2013

In 1921 Oliver Hays was the curator of a museum that eventually became the Smithsonian.  One day, he was examining fossils that had been collected from the Val Verde Copper Mine in Anita, Arizona 20 years earlier.  Barnum Brown, a world renowned fossil collector at a time when fossil hunters were celebrities, had labeled 1 specimen as “cat.”  This curious specimen consisted of just a lower jaw. After much pain-staking comparisons with other specimens, Oliver Hay concluded the jaw belonged to an extinct species of hyena that he named Chasmaporthetes ossifragus.  The paleontological community doubted Hay had correctly identified the specimen.  It was nearly 50 years before enough evidence had accumulated to verify Hay’s conclusion that hyenas once roamed North America.

Artist’s depiction of Chasmaporthetes–the hunting hyena.  It was a fast runner and an important carnivore on 4 continents during the Pliocene.

Chasmaporthetes ossifragus, known as the hunting hyena, lived in North America from about 4.9 million years BP to ~780,000 BP, making it an important large carnivore of the Pliocene and early Pleistocene.    It had long strong legs and is thought to have been an active hunting animal that chased its prey down, possibly in packs.  Although it possessed a powerful bite and did eat some bone, it didn’t eat as much bone as the modern extant spotted hyena (Crocuta crocuta).  It lived alongside other large predators such as the bone eating dog (Borophagus diversidens), the giant cheetah (Acinonyx), the scimitar-toothed cat (Dinobastis), and the dirk-toothed cat (Megantereon).  It likely preyed upon horses, llamas, camels, peccaries, deer, pronghorn, marmots, and other small mammals.

Fossil remains of Chamaporthetes have been found at 4 sites in Florida, 3 sites in Arizona, 2 sites in north Texas, 2 sites in Mexico, and 1 site in New Mexico.  It is the only species of hyena known to have crossed the Bering landbridge to North America where it was likely more widespread than its fossil record would indicate–there just aren’t many Pliocene-aged fossil sites in the midwest and northeast.  A similar species, Chasmaporthetes lunensis, lived in Europe, Asia, and Africa during the same time period, and it may actually be the same species.  This means the hunting hyena was 1 of the most wide ranging and successful large carnivores ever.  The reason for its extinction is unknown, but it disappeared at a time when forests were replacing grassland and desert habitats.  Archaic species of wolves ecologically replaced American hyenas, but it’s not known whether they outcompeted them or simply took advantage of an extinction that occurred due to other causes.

Despite their appearance, hyenas are more closely related to cats than dogs.  The order Carnivora is split into 2 suborders–feliforms and caniforms.  Feliforms include cats, civets, mongoose, and hyenas while caniforms include dogs, bears, weasels, skunks, pandas, raccoons, and seals.  There are 4 extant species of hyena.  The odd little aardwolf (Proteles cristata) is a nocturnal solitary animal that primarily feeds upon termites.  The brown hyena (Hyeaena brunnei) is a solitary scavenger that lives in South Africa.  The striped hyena (Hyeaena hyeaena)  is also a solitary scavenger, but it lives in North Africa, the Middle East, and India.  The spotted hyena ranges all across Africa and is more of an active pack hunter than the striped and brown hyenas.  It’s the species most commonly filmed for nature documentaries.  During the Pleistocene, spotted hyenas lived across Europe and Asia, and they occasionally fed upon humans.  Once in a while, archaeologists find hyena dung in caves that contains human hair and bones.

Most Homo erectus bones found in Asian caves were dragged inside by hyenas.

Oldest human hair known.  It was found in hyena dung, dating to between 250,000 BP- 195,000 BP.

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

September 27, 2013

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:http://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:http://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

My Pawpaw Seeds Germinated

September 24, 2013

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.

Shorter 001

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

and

http://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

September 20, 2013

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

September 15, 2013

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

September 10, 2013

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


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