Archive for July, 2010

Panthera atrox! What Kind of Cat was it?

July 28, 2010

One of the biggest cats to ever stalk the world roamed across North America during the Pleistocene.  Panthera atrox, weighing up to 500 pounds and possibly more, was a giant in the genus that includes lions, tigers, jaguars, and leopards.  It fed upon the bison and horses and camels that grazed the Ice Age grasslands and woodlands.  Atrox is a Latin word, meaning cruel, though it’s an error for humans to attach our emotions to an animal that merely did what it needed to do to survive.  Nevertheless, I pity any poor animal caught in the clutches of this powerful predator.

The first fossil specimen of this species was discovered in Mississippi in 1850, and its discovery immediately caused scientific controversy.  Some thought the skull resembled that of a tiger; others thought it was a lion’s skull.  By 1930 scientists had learned how to determine the difference between lion and tiger skulls.  It seems the sutures on the foreheads of the two species are quite different.  Moreover, tigers have noticeably longer nasals.  And from a view of the top of the skull, lion nostrils are visible because their skulls are more elongated, whereas those of the tiger can’t be seen from that angle.  Because Panthera atrox‘s skull closely resembled that of the lion, scientists determined that’s what it was.  Now, a new study using statistics based on data from detailed measurements of lion, tiger, jaguar, and atrox skulls and jaws, has upended the line of reasoning that assumed Panthera atrox was a lion.

The jaw bone of Panthera atrox most closely matches that of the jaguar, though it’s not an exact match, just like the skull of atrox most closely resembles that of the lion but is larger and more elongate in shape, and so is not an exact match of that species either.  So what was it?  The authors of the study referenced below measured every part of the skulls and jaws from 23 atrox fossils, 78 tigers, 126 lions, and 57 jaguars.  They then did a statistical analysis of the results and found that despite deviations between individual specimens of each species, all the measurements clustered into 4 groups, corresponding to each of the 4 species–strong evidence that Panthera atrox was indeed a distinct species.

Though this study surprises me, it makes sense because fossils of Panthera atrox are on average consistently 25% larger than anatomical specimens from extant lions.

Fossils of Panthera atrox are relatively common in western fossil sites, but they’ve also been found in Florida, and South Carolina in addition to the original type specimen discovered in Mississippi.  Undoubtedly, it occurred in Georgia.  True lions did live north of the ice sheet in what today is Alaska, but jaguars and Panthera atrox never advanced above the Cordilleran and Laurentide glaciers that covered what is now Canada.

The scientists who authored this recent study conclude that both Panthera atrox and jaguars descended from a Pliocene-age cat known as Panthera gombaszoengis which is sometimes referred to as a Eurasian jaguar.  This species colonized North America at the beginning of the Pliocene and different populations split into different species: some inhabiting forests evolved into jaguars, same living in open prairies evolved into Panthera atrox, which heretofore on this blog, I’ll refer to as the giant panther.

I believe genetic studies will eventually support this study.

The giant panther had a larger brain than lions and probably was more intelligent, making them a successful large predator, able to kill large game without the help of others of their species.

Because the giant panther is not as closely related to lions as formerly thought, it’s unlikely to have lived in prides.  Instead, like the vast majority of cat species, it survived as a solitary predator and competed with dire wolves and saber-tooths over the many large ungulate species then extant.  Throw in the mighty scavenging short-faced bear (Arctodus simus) and battles galore must have been the norm during Pleistocene dinnertimes.

Reference:

Christiansen, Per; and John Harris

“Craniomandibular morphology and phylogenetic affinities of Panthera atrox: Implications for evolution and paliobiology of the lion lineage.”

Journal of Vertebrate Zoology 29 (3) 934-945 September 2009

Note: Perhaps the giant panther looked like these jaguar/lion hybrids, though I guess they had a tawny coat, possibly lightly spotted.

www.bearcreeksanctuary.com/jaglions.htm

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Foxglove: Another Pleistocene Survivor

July 23, 2010

Poison lurks around the corner.  A half acre stand of yellow foxglove grows on land two lots down from my house where an abandoned trailer sits behind hundred year old laurel oaks.  The trailer was owned by a bachelor  before he died of a heart attack on a trip to Vegas a few years ago.  Yellow foxglove (Digitalis grandiflora) is poisonous to people and animals, including both carnivores and herbivores.   Ingestion causes loss of appetite, nausea, and a dangerously lowered heart rate that can cause death.  Drug-makers manufacture medicine from this plant, and it’s used to control the irregular hearbeats suffered by patients in congestive heart failure.

Up close views of foxglove plants.

Part of a stand of foxglove.

Foxglove was probably a common plant during the Pleistocene.  It thrives in open oak glades and prefers disturbed and burned over areas.  An old pine tree in my yard exhibits evidence of a light brush fire in my neighborhood, perhaps 30-40 years ago before houses were built here.  Foxglove also grows well in acidic soils as does low bush blueberry which grows within this patch as an associate and also likes burned over areas.

Lowbush blueberry plant growing in association with foxglove.  Both like burned over areas with acidic soil.

During the Pleistocene light brush fires, frequent in both arid and rainy climate phases, shaped the environment along with the large herds of herbivores which consumed and destroyed many succulent plants but avoided poisonous foxglove.  Foxglove would have grown with grass, which can survive grazing because their taproots remain safe underground, and blueberry which also can resprout from suckers.  All three are tough plants, surviving on this lot, despite sandy acidic soils and extreme drought and heat.  Many a Pleistocene landscape would have been dominated by these three.

Foxglove should please flower gardeners–with no maintenance, this patch in the abovementioned lot has been continuously blooming for three months, since May.

Foxglove does require the presence of oak trees, and they are restricted to forest edges and open woodlands.  They are parasitic feeders; their roots latch on to the roots of oaks and that’s how they absorb nutrients.  False foxgloves, members of the figwort family, are close relatives of the true foxgloves, and they too are parasitic feeders.  In my opinion, though the flowers are similar to those of true foxgloves, the leaves are not.

Eolian sand dunes, formed throughout the southeast during Ice Age droughts when windborne river sand accumulated, were another ideal habitat for foxglove which could grow with scrub oaks and grass on these sparsely vegetated areas.

Pleistocene Georgia’s Javelinas

July 17, 2010

Hernando De Soto brought the first pigs (Sus scrofa)  to Georgia in 1540, releasing them in the wild where they could feed on the mast and provide a ready food source.  He also offered them as gifts to Indians on a line from the southwestern corner of the state to the area of what’s now Augusta.  Diseases from pigs, such as influenza and trichinosis, may have wiped out many Indian tribes.  Feral pigs from hunters introducing wild boars and escaped farm-raised individuals interbred and now are overrunning much of Georgia.

Map from the Georgia Department of Natural Resources

Feral hogs

This is evidence that an ecological niche for a pig-like animal still exists in Georgia, and it suggests that some time late in the Pleistocene, Indians must have overhunted peccaries into extinction.  Otherwise, they would still be here because feral hogs sure thrive in state today.

Georgia’s Pleistocene Peccaries

Illustration of long-nosed peccary (top) is from the Illinois State Museum.  The replica of the flat-headed peccary (bottom) is from the Cincinnati Museum.

There were at least three kinds of peccaries (or javelinas) living in what’s now Georgia during the Pleistocene.  By far, the most common species was the long-nosed peccary (Mylohyus nasatus).  Fossils of this animal have been excavated in Bartow County from three different caves and from the Isle of Hope site along the coast.  In Georgia fossil specimens of Mylohyus are almost as common as those of white-tail deer and in fossil sites from south Florida and Arkansas it even outnumbers deer.  They inhabited forested areas, feeding on acorns, roots, and other forest mast.  They probably fed on deer fawns and turkey eggs, like modern feral hogs do.  It exhibited an odd body shape for a pig-like animal, resembling a deer more than a javelina.

A second species of peccary from Georgia’s Pleistocene was the flat-headed kind (Platygonus compressus).  Shaped more like what would expect of a javelina, it preferred dry brushy habitat, similar to that inhabited by a closely related extant species, the Chacoan peccary (Catygonus wagneri), now found in a small area along the border of Paraguay, Bolivia, and Argentina.  Flat-headed peccaries occupied Georgia’s sandhills and dry forests, habitat which expanded during the frequent dry climate cycles that struck the southeast during the Ice Age.  Though far less common here than the long-nosed peccary, their fossils are consistently found in Georgia, South Carolina, and Florida fossil sites.

A third, still extant species, the collared peccary (Pecari tajacu) probably lived in south Georgia during warm climate phases.  Their fossils are exceedingly rare in Florida’s abundant sites and are associated with species of mammals that required frost-free climate, such as Eremotherium and glyptodonts.  Only three sites in Florida yielded remains of this species, including one in the Suwanee River only about 50 miles from the Georgia border.  During warm interglacials collared peccaries expanded their range throughout the south but were never as common as the other two.

Why do feral hogs thrive now where Pleistocene peccaries became extinct?

The answer is simple: litter size.  Collared peccaries have only 1-4 young.  Until protected by game laws, they were in danger of extinction in some regions.  Chacoan peccaries have an average of 2.4 young per litter.  Pleistocene peccaries probably had the same small litter sizes.  By contrast, feral hogs can have up to 13 piglets in a litter.  Wild boars evolved on the same continent as man.  To survive human hunting pressure, individuals that produced greater young had a better chance of passing on their genes–a kind of evolutionary selection.  Moreover, after humans domesticated pigs, for obvious economic reasons, we artificially selected individuals that produced more young–in a way, creating a Frankenstein-like monster.  Once they escaped back into the wild, wild hogs were able to overcome human hunting pressure by reproducing rapidly.

The differences between true pigs and peccaries.

This is from the National Park Service site devoted to Big Bend National Park where a good population of collared peccaries lives.

……………………Peccaries…………………………..Pigs…………………………………..

Has 3 toes on hind foot……………………………..Has 4 toes on hind foot……….

bones fused in the foot………………………………Bones in foot not fused……….

lower arm bones are fused…………………………lower arm bones not fused….

38 teeth………………………………………………….34-44 teeth………………………

canine teeth are straight……………………………canine teeth are curved………

have scent glands……………………………………..lack scent glands………………

have a complex stomach……………………………have a simple stomach………

lack a gall bladder……………………………………..have a gall bladder……………

have a short tail…………………………………………have a long tail………………..

lack sweat glands………………………………………..have sweat glands…………..

References

Hulbert, Richard C.; Gary Morgan and Andrea Kervin

“Collared Peccary (Mammalia, Artidodactyla, Tayassuidae, Pecari) from the late Pleistocene of Florida”

Museum of Northern Arizona Bulletin 65

www.nps.gov/bibe/naturescience/javelina.htm

www.wildlifemanagementinfo/files/wild_hogs_4.pdf

Yahnke, Christopher; et. al.

“The Specific Fecundity, litter size, and sex ration in the Chacoan Peccary (Catagonus wagneri)”

Zoobiology  16: 301-307 1997

Cougars vs. Jaguars

July 8, 2010

Cougars and jaguars co-existed for at least 500,000 years throughout North America, and today still co-exist in many areas of South America and Mexico.  Both species are adaptable enough to occupy a wide variety of environments, including deserts, lightly wooded savannah, flooded swamps, and tropical rain forests.  They also feed upon many of the same prey species.  This spawns two questions: what ecological differentiation allows two big cat species to co-occur on the same range, and what factors allowed cougars to remain in much of North America where jaguars were extirpated?  A number of scientific studies help solve these ecological mysteries.

Comparison of cougar and jaguar diets

Studies of jaguar and cougar diets consistently show significant differentiation.  Although cougars and jaguars tackle many of the same species, the latter selects for larger sized individuals.  One study of co-occurring jaguar and cougar populations in Venezuala–a region consisting of woodland, savannah, and swamp–found the following differences in prey size selection between the two species.

…………………………………….Cougars……………………………Jaguars………………

Small size prey…………………17%……………………………………1%……………….

Medium size prey……………..31%……………………………………14%……………..

Large prey……………………….52%……………………………………85%…………….

For example in this region collared peccaries are an important diet item for both species, but cougars exclusively take small juveniles, while jaguars take mostly adults and sub-adults.  Both big cats took a wide range of prey species with cougars taking 12 different kinds of animals and jaguars taking 10.  Jaguars preyed more heavily upon capybaras here than cougars did.  Jaguars also preyed upon white-lipped peccaries–an aggressive species that cougars completely avoided.  White-lipped peccaries live in large groups and frequently come to the aid of their comrades and attack predators.  They’ve been known to kill jaguars and even humans.

Illustration by John James Audubon

Another study of jaguar diet, this one in southern Brazil where flooded plains are the predominant habitat, found that the jaguar diet there included 31% cattle, 24% caiman, 21% peccary, 4% feral hog, 3.0% marsh deer, 3.2% giant anteater, 2% capybara, 1.6% brocket deer, and about 10% other.  438 prey items were recorded, showing that jaguars will take what’s generally available.  Incidentally, both jaguars and cougars are capable of killing the alligator-like caiman, but take them less than would be expected based on their abundance.

Illustration by John James Audubon

A third study, this one in Mexico where both jaguars and cougars mostly prey on deer, peccary, and armadillo, also found that jaguars select for larger prey items.  This study concludes that the “cougar’s ability to exploit smaller prey gives them an advantage over jaguars when faced with human-induced habitat changes.”  This conclusion brings to obvious light one of the reasons why cougars survived throughout much of North America where jaguars didn’t.  After Indians overhunted much of North America’s megafauna, jaguars had difficulty finding the larger prey they preferred.  The extinction of two Pleistocene species of peccary in North America was probably devastating.  Indians even overhunted white tail deer into scarcity as John Lawson, an early European explorer (circa 1704) noted when he pointed out that deer were rare around large Indian settlements in South Carolina.  But cougars could survive in these areas on rabbits, possums, raccoons, and turkeys.

I agree that the preference for larger game that no longer exists is one factor that’s limited the jaguar’s range in North America, but I think there are other factors.

Evolution of size, coat color, adaptability to cold, and personality traits

The fossil record suggest jaguars, along with dire wolves, were the most common large carnivores (excluding omnivorous bears) in southeastern North America during the Pleistocene.  Yet, cougars found their niche here too.  During the Pleistocene both species were somewhat larger than the present day versions of these species.  Rancho La Brean specimens of cougars show that on average they were 5% larger than those of today, while Pleistocene jaguars approached modern day tigers in size.  I think this is due to the larger size and quality of prey available, particularly horses and the larger sized species of peccaries, and it’s clear these two big cats not only had a better diet, but further impetus to evolve to a greater size, so they could successfully exploit this larger prey.  One study reported that modern jaguars living in areas where cattle were introduced tend to approach the size of the larger Pleistocene jaguars, and it’s believed that jaguar populations increased following the introduction of European livestock to South America.

I theorize the spotted coat of the jaguar is another factor in its range reduction.  Indians valued the beauty of its fur and hunted them unmercifully.  There’s a possibility that Pleistocene cougars had spotted coats.  Scientists believe that cougars evolved from a kind of spotted cheetah.  Cougar kittens retain these cheetah-like spots–evidence of this evolution.  But I think many adult cougars may have been spotted until very late in the Pleistocene when man colonized the continent and hunted the spotted cougars for their coats, leaving only the dull tawny and gray coated individuals to breed, which in turn genetically swamped the spotted ones.

It has been suggested that spotted cats are more vulnerable to cold climate–another factor which may limit the jaguar’s range, but I disagree with this hypothesis.  The snow leopard of the Himalayas is an example of a spotted cat that lives in a cold region.  Moreover, jaguar fossils have been excavated from as far north as Oregon and Pennsylvania when even during the warmest interglacials, subfreezing temperatures occurred during winter. 

Jaguar fossils in Georgia have been excavated from Ladds Quarry and Kingston Saltpeter Cave.  A nearly complete skull was recovered from the former location along with giant tortoise and armadillo bones that have jaguar gnaw marks on them.  Fossils from this period probably date to a warm climate phase, but the jaguar remains from KSC are associated with the kinds of animals that live in cold and temperate climates, indicating jaguars survived colder conditions than any endured by extant populations.  Cougar fossils also were found at Ladds and in Yarbrough Cave which dates to the last glacial maximum.

One more factor in the cougar’s survival where jaguars didn’t may be evolutionary selection towards more timid individuals.  Those members of the cougar population that learned to avoid man were more likely to survive.  Timidity possibly occurred less frequently in prehistoric jaguar populations.

Cougars vs. Jaguars, wolves, and bears

So which would win in a battle between a jaguar and a cougar?  According to scientific studies, cougar and jaguar ranges frequently overlap, but they tend to avoid each other.  Certainly, a jaguar wouldn’t think it worth the effort to battle a raging mother cougar defending her kittens.  Conversely, a cougar would be out of its mind to engage in a battle with a larger, more powerful cat that bites harder than any other kind of cat in the world.  However, in one paper, international big cat expert, Howard Quigley, did cite a case of a jaguar attacking and killing a cougar.

Packs of wolves also dominate cougars in the Rocky Mountains.  Wolves occasionally kill cougar kittens, sub-adults, and even adults.  The average biomass of wolves in packs that attack a cougar outweighs the cat by a 13:1 ratio.  Rarely, cougars have been reported to kill wolves (sub-adults and adults, but not pups), but in these cases it was one-on-one and the biomass was a 1:1 ratio.  A certain percentage of cougar kills are lost to wolves and bears in areas where their ranges overlap.

References

Carvolcanti, Sandra; and Eric Gese

“Kill rates and predation patterns of jaguars (Panthera onca) in the southern pantanal of Brazil”

Journal of Mammalogy 91 (3) 722-736 2010

Hoogesteyn, Rafael; and Edgardo Mondolfi

“Body mass and skull measurements in four jaguar populations and observations on their prey base”

Bulletin of the Florida Museum of Natural History V. 39 (6) pg. 195-219 1996

Hornocker, Maurice; Sharon Negri, and Alan Rabinowitz

Cougar: Ecology and Conservation

University of Chicago Press 2002

Nunez, Rodrigo; Brian Miller, and Fred Ludjey

“Food habits of jaguars and cougars in Jalisco, Mexico”

Journal of Zoology 252 (3) 373-379

Scognamillo, Daniel; et. al.

“Co-existence of jaguar (Panthera onca) and puma (Puma concolor) in a mosaic landscape in the Venezualan llanos”

J. Zoological Society of London 259 269-277 2003

Pleistocene Survivors–The Corvids

July 2, 2010

As I noted in the very first blog entry I wrote for this website, every animal and plant speciess alive today survived and had an ecological niche during the Pleistocene.   Perhaps one of the most remarkable and successful families of Pleistocene survivors are the corvids–a bird family that includes crows, ravens, jays, magpies, and nutcrackers.  Today, only three species of corvids inhabit Georgia regularly.  In addition to those,  ravens may occasionally appear in the mountains of the northern part of the state, but their numbers have drastically declined in the region for reasons I discuss later.  But during the Pleistocene, there were seven species of corvids that lived within what’s now the state boundaries, though not necessarily simultaneously.  Here’s a look at each.

Illustration by Louis Agassiz Fuertes

Northern Raven–Corvus corvax

This is a bird of the deep wilderness.  Because Georgia Before People was nothing but wilderness, they were a common species in the northern half of the state and probably in the southern half too.  They are large–about the size of a small hawk.  I’ve never seen one in the wild but was impressed with the size of a mounted specimen I saw at a nature center in the Nantahala National Forest.  Some large crows fall within the size range of ravens, but there are some other features that can help one discern the difference between the two–ravens have a kind of beard under their chin, a more rounded tail, and a different call.  Though they’re omnivorous, they favor meat more than common crows.  Whereas this species thrived scavenging from the Pleistocene megafauna carrion and later from the herds of bison that once roamed across the Great Plains, they were unable to adapt when man converted grassland to fields of grain, nor did they like forests converted to suburbs, and therefore their range has contracted to remote wilderness areas.  Raven fossils have been recovered from Kingston Saltpeter Cave in Georgia (Bartow County) and Bell Cave in northern Alabama, suggesting they were once even more widespread in the southeast than they were when Columbus discovered America.

Common Crows–Corvus brachyrhyncos

The range of these intelligent, adaptable birds has expanded, while that of the raven has contracted.  They’re more omnivorous than ravens and actually prefer the company of man, thriving on our grain fields and garbage dumps.  They love nesting in suburbs which provide the perfect habitat for them, and they require much smaller nesting territories than ravens.  But they did live during the Pleistocene too.  Genetic tests show they diverged from European carrion crows 2 million years ago, about when they colonized North America.  Specimens of crows are also common in the fossil record.

Fish Crows–Corvus ossifragus

Scientists debate whether this is even a different species than the common crow.  Genetic tests show common crows are ancestral to this one.  They live along waterways, eating fish, shellfish, and sea bird eggs.  They also have a different call than the common crow.

Illustration by Louis Agassiz Fuertes

Blue Jay–Cyanocitta cristata

These common, noisy jays prefer oak forests and suburbs.  Oak forests existed throughout the Pleistocene, though their extent fluctuated with climatic conditions.  Fossils of blue jays were discovered at Kingston Saltpeter Cave, dating to about 13,000 years ago.

Florida Scrub Jay–Aphelocoma coerulescens

This species no longer lives in Georgia, but it must have inhabited this area sometime during the Pleistocene.  Currently, this bird’s range is a discontinous one with a population from Nebraska west to California, and another in central Florida where it inhabits scrubby prairie, alongside the burrowing owl.  During some climatic fluctuation of the Pleistocene, this scrubby habitat was more widespread across the continent, as I discussed in my blog entry entitled, “The Disjunct Range of the Burrowing Owl.”  When the climatic phase favorable to the development of scrubby prairie maximized across the region, scrub jays lived in south Georgia.

Gray Jay or Canada Jay–Perioreus canadensis

This species no longer lives anywhere near Georgia, but during the Pleistocene its current range was under miles of glacial ice, rendering that area uninhabitable.  Today, it lives in Canada and the Rocky Mountains, preferring deep wilderness areas, consisting of coniferous forests, where they’re known as “camp robbers,” because they frequent logging camps and are so tame, being unaccostomed to people, they scavenge human food and miscellaneous items without fear.  During the Ice Age the Laurentide Glacier depressed this species range south.  Fossils of gray jays were discovered in Cheek Bend Cave in Tennessee, and I’m certain this species inhabited north Georgia during the last glacial maximum.

Magpie–Pica pica

Today this species inhabits the far west; its range is nowhere close to Georgia.  It’s a scavenging bird, heavily dependent upon carrion.  Large carcasses of dead megafauna supported populations of magpies in Pleistocene Georgia.  Magpie fossils were discovered in Georgia’s Kingston Saltpeter Cave and in Bell Cave in northern Alabama.

Interesting Facts about Crows

–Besides parrots and macaws, crows and other corvids are the most intelligent birds.  Their skull to body ratio is similar to that of mammals rather than birds.  Their intelligence rivals small monkeys.

–Crows build fake nests to fool predators.

–Experiments prove crows can count to six.

–Crows use tools.  They use splinters to impale insects hidden in crevices.  They drop nuts, clams, and small turtles on hard surfaces.  Some crows even place nuts under rolling car tires.  In experiments they learned to bend wire into hooks which they use to draw small containers of water.

–Crows crush ants and rub them on themselves to ward off parasites.

–Pet crows give their owners names.

–Crows can mimic humans, other animals, and machine noises.  They have dozens of calls, denoting predators, food, and family members.

–Crows living within 3 miles of human beings have a 2.3% annual mortality rate.  Crows living more than 3 miles from people have a 38.9% annual mortality rate.

–Wild crows can live 14-20 years.  Captive crows can live 40-80 years.

–Crows mate for life, but males will cheat.

–Male crows have no penis.  Their sperm is transferred from their cloaca to the female cloaca.  Copulation lasts 15 seconds.

–Crows living in suburban areas require only 10% of the nesting area of crows living in wilderness areas, and they’re more tolerate of range overlap.

–Crows have been reported to eat over 1000 food items, including insects, worms, berries, birds eggs and nestlings, small mammals, bats, fish, snakes, frogs, salamanders, animal dung, grain, nuts, carrion, fried chicken, hamburgers, Chinese food, french fries, and human vomit.

–Crows chase sparrows into buildings, stunning and eating them.

–An experiment showed crows prefer French fries in a McDonalds bag over those in a brown paper bag.

–A nestling can eat 100 grasshoppers in 3 hours.

–Crows sunbathe for Vitamin D.

–Mobbing crows can seriously injure hawks.  Scientists suspect one eagle was even killed by mobbing crows.

–Healthy crows help crippled crows.

–Crows occasionally murder each other for reasons that mystify scientists.

–Crows can learn to distinguish between different people.  On the campus of the University of Washington with 40,000 students and professors, crows learned to specifically avoid the few scientists who had captured them.

Cheek Bend Cave

Northern ravens, magpies, and gray jays weren’t the only northern and western fauna that lived in the southeast during the last Ice Age.  In the late 1970’s scientists excavated Cheek Bend Cave in Tennessee before it was flooded by the Columbia Dam Reservoir.  They found many fossils of species with affinities for cooler climate, including 13-lined ground squirrels, pocket gophers, arctic shrews, water shrews, red-backed voles, yellow cheeked voles, red squirrels, northern flying squirrels, heather voles, wood turtles, hawk owls, boreal owls, saw whet owls, gray jays, pine grosbeaks, prairie chickens, pine siskins, and red-breasted nuthatches.  All of these today are normally found in boreal forests of Canada or western grasslands.  Fossils of some of these species have been recovered from caves in north Georgia as well, providing interesting evidence of cooler climates in the south where a patchwork of open woodland and prairies wilderness existed.  These species lived side by side with those that prefer more temperate conditions.

References

Forbush, Edward

A Natural History of American Birds of eastern and central North America

Houghton Mifflin 1939

Marzluff, John; and Tony Angell

In the Company of Crows and Ravens

Yale University Press 2005

Parmalee, Paul; and Walter Kleppel

“Evidence of Boreal Fauna in Middle Tennessee during the late Pleistocene”

The Auk V. 99 1981