Archive for the ‘Uncategorized’ Category

Pliocene and Pleistocene Gulls (Laridae) of the North Atlantic

February 2, 2015

Ring-billed gulls (Larus delawarensis) often hover over grocery store parking lots in Augusta, Georgia.  The wide open spaces and spilled junk food attract them to these man-made habitats.  They appreciate all the obese Americans who can’t wait to get home to stuff their faces.   The gulls scavenge smashed corn chips and cheese crackers off the pavement.  Gulls perform a valuable service by cleaning up schools of dead fish and mountains of human garbage.  This helps reduce the spread of toxic bacteria in the environment.

Most people think of sea gulls as shore birds, but ring-billed gulls are quite common inland and some may never see the ocean.  Other species of gulls, such as Bonaparte’s (L. philadelphia), follow rivers upstream and can also be found inland.

Ring-billed Gull Photo

Ring-billed gulls are commonly found in parking lots and landfills during winter time in Georgia.

Several species of gulls, including the laughing (L. atricilla) and Franklin’s (L. pipiyan), are primarily shore dwellers and do nest off the coast of southeastern states.  The laughing gull prefers to nest in beach thickets, though many species of gulls and terns will lay their eggs in the open.  Sea gull nestlings are mobile shortly after hatching, so they can avoid predation at an early age.

There are at least 5 species of gulls that have a polar distribution.  I hypothesize some or all of these species ranged as far south as what today is South Carolina and Georgia during the Ice Ages.  Glaucous gulls (L. hyperboreus) are a polar species that prefers nesting on rocky sea cliffs where they can feast upon nestlings of other cliff-nesting sea birds.  Today, there are no sea cliffs off the coast of southern states.  But for about 40,000 years, there was an enormous sea cliff, known as Bulls Scarp, off the coast of South Carolina where glaucous gulls could have nested. (See: https://markgelbart.wordpress.com/2014/08/14/bulls-scarp/)  About 13,000 years ago, rising sea level submerged these cliffs, and glaucous gulls likely left the region then.

Adult breeding

Glaucous gull.  This is a polar species occasionally found as far south as Virginia.  During the Ice Age it likely ranged much farther south than it does today and it probably nested on Bulls Scarp, a now submerged sea cliff.

Some paleontologists puzzle over how rare gulls are in Pleistocene fossil sites.  The La Brea tar pits preserved the bones of more than an hundred species of birds but have yielded just 1 gull specimen.  I think I know why gull remains appear so rarely in Pleistocene fossil sites.  Pleistocene shorelines are submerged today. Most fossil evidence of gulls is deep beneath the surface of the ocean.

I am unaware of any extinct species of Pleistocene gulls.  The species that are alive today are the same as the ones that lived during the Pleistocene.  However, there were 2 species of Pliocene gulls that are now extinct.  Fossils of L. lacus and L. perpetis were among bird fossils found at a site on the Florida gulf coast.  The fossils are estimated to be between 2 and 2.4 million years old.  Apparently, all the birds found at this site were killed by a toxic red tide.  (I may do a blog article about this site, if I can ever obtain a reasonably priced copy of the scientific paper documenting it.)

The Larus genus originated in the North Atlantic polar region about 20 million years ago.  Sea gulls have dispersed and have an almost worldwide distribution today.

Pleistocene Storks of North America

January 29, 2015

At least 4 species of storks lived in North America during the Pleistocene.  The wood stork (Mycteria americana), the only surviving species, is nearly absent from the fossil record.  It is known from just 1 fossil site–a tar seep in Cuba.  This fossil specimen was found associated with fossils from 2 other species of stork including Wetmore’s (M. wetmori), a similar species but distinctly larger.  Fossil evidence of Wetmore’s stork has also been excavated from sites in Florida and California, indicating it was a widespread species.  Prior to the discovery that wood storks co-existed with Wetmore’s storks on Cuba, scientists assumed the former didn’t colonize North America until the extinction of the latter at the end of the Pleistocene.  But this discovery casts doubt on that assumption.  Wood storks may have lived in parts of North America where the process of fossilization was uncommon.  There is evidence that 2 species of large owls lived in Georgia during the Pleistocene, but the fossil material is so scant scientists are unable to as yet describe the species.  This demonstrates how incomplete the fossil record can be.

The other species of stork that lived in Cuba then was an unknown and undescribed species in the Ciconia genus.  There are 7 extant species of storks in the Ciconia genus including the well known white stork (Ciconia ciconia), a bird that winters in Africa, summers in Europe, and according to legend, brings babies to awaiting parents.  The maguari stork (C. maguari) ranges throughout South America where flooded grasslands predominate. It’s the only extant American stork in the Ciconia genus.  The extinct asphalt stork (C. maltha) was a North American bird, named for specimens found in the asphalt-like tar pits of California. Fossils of this species have been excavated from 34 sites in Florida, 2 sites in California, 1 site in Idaho, and 1 site in Mexico.  (The Mexican specimen was not conclusively identified.) The sites in Florida date from the early Pliocene to the late Pleistocene.  The asphalt stork, as a species, existed for at least 5 million years and likely occurred over a wide continental range for most of that timespan. Though it was closely related to the white stork, the asphalt stork probably occupied an ecological niche similar to that of the marabou stork (Leptoptilos crumeriferus).

Maguari stork  (Ciconia maguari) of South America

Video of marabou storks sharing a carcass with African vultures. Note the featherless head and neck.  This prevents contamination from toxic bacteria on the rotting meat they eat.

Video of marabou storks vs. a pack of mongoose.

The marabou stork scavenges and hunts the African plains but nests in woodlands.  They catch and eat small mammals, bird nestlings, reptiles and amphibians, and insects.  They also rely on carrion, garbage, and even feces.  They often follow vultures, waiting for them to tear open the carcasses before taking advantage of the meal. Stork bills are incapable of opening tough hides.  Species closely related to Old World vultures lived in North America during the Pleistocene.  The asphalt stork likely followed vultures and scavenged in  much the same manner as the marabou stork.  The extinction of North America’s megafauna led to the extinction of avian scavengers including teratorns, Old World vultures, and asphalt storks.

The asphalt stork was a big bird, reaching 4.5 feet tall.  It would have been entertaining to watch scavengers make carcasses disappear during the Pleistocene.  Giant short-faced bears ruled, but if they weren’t around, there would have been battles between coyotes and storks.  With their big bills, storks probably held their own against the smaller canids.

Reference:

Saurez, William

“The Records of Storks (Ciconidae) from Quaternary Asphalt Deposit in Cuba”

The Condor 2003

 

The Odd Disjunct Range of the Sand Myrtle (Kalmia buxifolia)

January 25, 2015

Organisms with disjunct range distributions fascinate me because they provide clues about past natural environments.  Direct evidence of past landscapes is rare–over 99% of potential fossil evidence has vanished without being preserved in any way.  The existence of extant species with odd distributions helps fill in gaps in our knowledge of natural history, though it requires some uncertain speculation. The sand myrtle is 1 of many species with an interesting disjunct  range distribution.  This member of the heath family (rhododendrons and blueberries) is found in the sandhills of southern New Jersey; the mountains of northeastern Georgia, eastern Tennessee, and western North Carolina; the sandhills of North Carolina’s coastal plain, and some isolated monadnocks in the upper South Carolina piedmont.

Caesar’s Head State Park in South Carolina.  Sand myrtles grow on isolated rocky hills such as this.

Sand Myrtle (Kalmia buxifolia) at Garden Supply Company

A sand myrtle in full bloom.  They are a short plant, growing to just 20 inches in height.  They can’t grow under tree canopies.

Range map of Kalmia buxifolia shaded in  light green.  The populations are more isolated than this map indicates.

One is left to wonder why the sand myrtle disappeared from or doesn’t occur in the areas between its disjunct populations.  One hypothesis could be that it reached suitable habitat through seed transport via bird droppings.  But the great distances between disjunct populations precludes this possibility.  The seeds, if they even stayed viable within the bird’s digestive system, would be excreted long before they reached the other territories.  Wind distribution is a more viable hypothesis.  Winds carry insects, pollen, and light seeds great distances, and this light organic material eventually settles.  Still, this seems an unlikely explanation because sand myrtle should occasionally be found growing in areas between their current distribution, even if the habitat is unsuitable.  The most likely hypothesis requires a bit more complicated explanation.  Sand myrtle may have existed throughout the entire region during the dry climatic phase of the late Pliocene/early Pleistocene.  Today, sand myrtle favors open sunny conditions on poor rocky or sandy soils.  Arid grasslands expanded when dry climates prevailed in the south.  These dry prairie and scrub habitats were subjected to overgrazing by herds of megafauna, leading to bare soils, especially during droughts.  Windy conditions stripped the top soil.  Sand myrtle was able to grow on these poor soils with little competition from trees.  When climatic conditions changed to a wetter cycle, deciduous forests expanded and outcompeted sand myrtle by shading them.  Grassy savannahs were also unsuitable now because frequent lightning strikes led to more fires.  Sand myrtle is both fire and shade intolerant and can only survive in communities with poor shallow soils where fire is infrequent. This probably explains why sand myrtle is currently found in rocky mountains and sand hills and nowhere else.

A Note on my Cod Liver Experiment

In my last blog entry I reported my visit to the Buford Highway Farmer’s Market.  One of the products I purchased was cod liver in a can.  I had a chance to try it yesterday.  When I opened the can, I was surprised to find that most of the volume was filled with oil rendered down from cooking the liver in the can.  I removed over half of the liver and squirted lemon juice on it.  The first bites tasted like canned tuna, and maybe a little like oysters.  But the texture was very soft.  I started having a hard time accepting such a soft texture, so I ate the rest of this portion on buttered toast.  This soft texture was not unlike that of scrambled eggs.  I’m used to eating scrambled eggs, but I usually put lots of shredded cheddar cheese and smoked chipotle pepper in my eggs, and I also put them on buttered toast.  Even with these additions, I still prefer eating my scrambled eggs with either salsa or brown mushroom gravy.  Eggs are just so bland by themselves.  I debated with myself whether to eat the rest of the cod liver for lunch today, but last night I fed it to the cat.  Instead, I’m going to have a nice salami sandwich.

The Buford Highway Farmer’s Market

January 21, 2015

The woods look drab this time of year in Georgia, even for a naturalist like me.  I satisfied my hunger for the natural world by visiting the Buford Highway Farmer’s Market instead of taking a stroll through a winter-dulled park.  Most people don’t think about this when they go grocery shopping, but every vegetable, fruit, and animal product in the store descends from a species that lived during the Pleistocene.  The stories behind the origins of each could fill volumes of history, but I’m just going to focus on a couple I noticed on this visit.

HPIM1514

The Buford Highway Farmer’s Market in Doraville (a suburb swallowed by Atlanta’s suburban sprawl).  It was featured on Andrew Zimmern’s series Bizarre Foods.

The Buford Highway Farmer’s Market is located in Doraville, Georgia; a former suburb of Atlanta that’s been engulfed by that city’s sprawl.  The store is just off the I-285 bypass at Exit 32.  The produce section is enormous with high quality fruits and vegetables from around the world.

HPIM1511

The produce section is huge.  This is just half of it.

There were some items I’d never seen before including white immature coconuts, spiny chayotes, and fresh jackfruit. The size of the jackfruit (Artocarpus heterophyllus) surprised me.  They look like a fruit for a giant species of megafauna, and indeed elephants do feed on them.  The jackfruit belongs to the same family as mulberries and figs.  I didn’t purchase any because 1 jackfruit could feed a family of 20.  I have eaten canned and dried jackfruit.  They are very sweet and have a texture similar to pineapple but the taste is unique.  Jackfruit is native to the tropical forests of southwestern India, but man has spread them throughout tropical Asia, Africa, and Brazil.  Jackfruit trees grow wild as an invasive species in Brazil where coatimundi and monkey populations have benefited from the abundant new source of fruit.  The coatimundis and monkeys also eat birds’ eggs, so bird populations decline in Brazilian jackfruit forests.  Jackfruits have been cultivated for thousands of years–nobody knows exactly when they were first deliberately planted by man.

HPIM1512

Jackfruit is as large or larger than watermelon.  Looks like just the right size for an elephant.

Here’s video of an elephant eating jackfruit in India.

HPIM1513

This is the first time I’d ever seen white coconuts.

Beyond the amazing produce aisle, the store is divided into ethnic sections–Mexican, Eastern European, American, Indian, Chinese, Japanese, Korean, etc.  I found some delicious kimchi in the Korean wing of the store.  Kimchi is the national condiment of Korea made from fermented napa cabbage, daikon (a long radish), green onions, red hot peppers, ginger, fish sauce, and salt.  I love it.  Kimchi has been made for thousands of years but 1 important ingredient–red pepper–wasn’t used until its introduction to the region in 1598.  Napa cabbage (Brassica rapa Pekinese) is not actually a cabbage (Brassica oleracea) but rather a turnip bred for the luscious stem and leaves instead of the root.  The same holds true for bok choy (B. rapa. chinensis).  The brassica family also includes mustards.  Brassica pollen is often found in Pleistocene-aged pollen samples.  During the Ice Ages wild cabbage, turnip, and mustard grew in temperate region wet meadows.

HPIM1515

These are some of the goodies I purchased.  Honey which ironically is from an apiary in Waynesboro 30 minutes from my house, sweet potato chips, cod liver in a can from Norway, and kimchi imported from Korea.    The kimchi is so good it sent me into ecstasy not unlike the look on the face of Freddie King  (on the cd cover below the canned cod liver).  He is one of the greatest electric guitar players of all time.

The flavor of kimchi depends upon a fermenting bacteria known as Lactobacillus kimchii.  This is not unusual–cheese and sourdough bread require fermenting bacteria to give them flavor.  I like to mix kimchi with cream cheese and eat it on crackers.  The spicy acidity of the kimchi plays well with the rich fat of the cream cheese.  The flavor of kimchi varies with its region of origin.  I’ve had some so salty I considered it inedible but the brand in the above photo is excellent.  I’ve also made my own from vegetables I grew in my garden including napa cabbage, turnip, and hot red peppers.  I added ginger and salt. It was good and got even better when I let it sit in the refrigerator for a couple of weeks to develop the funky flavor.

The only unusual food I purchased was canned cod liver imported from Norway.  I’ve never eaten fish liver before.  I’m planning on breading and frying it.  I’m not afraid of fish organs.

 

 

The Giant Raccoon (Chapmalania altaefronis)

January 16, 2015

 

A procyonid (Cyonasaura) was among the first North American mammals that island-hopped to South America before a landbridge between the 2 continents full emerged. Like its living cousin, the raccoon, the cyonosaura was attracted to aquatic environments, thus explaining how, perchance, it found its way across islands to South America.  An ecological niche for a bear-sized omnivore was available on this continent, so cyonasaura evolved into chapmalania, a beast that was really just a giant raccoon.  There were few carnivores capable of stopping chapmalania from muscling in on a carcass here then.  Scientists have discovered evidence chapmalania scavenged a dead glyptodont–teeth marks on 1 individual fossil exactly match those of the giant raccoon.  However, chapmalania probably had a varied diet that included plant matter and aquatic organisms.  Chapmalania lived during the Pliocene from 5 million years BP-1.9 million years BP. Bears finally made it to South America at the end of the Pliocene, and they eventually occupied chapmalania’s ecological niche.  They probably outcompeted and replaced them.

Posted Image

Size comparison between the giant raccoon, a human, and a Volkswagon.

Although chapmalania became extinct, there are still at least 17 living species of procyonids.  The most familiar are the abundant North American raccoon (Procyon lotor), and the crab-eating raccoon (P. cancrivan) of South America.  The pygmy raccoon (P. pygmaeus) is restricted to the Cozumel Island off the Yucatan peninsula of Mexico.  This island has been isolated from the mainland for 100,000 years, and genetic studies suggest the Cozumel raccoon diverged from its ancestral population about 60,000 years ago.

The pygmy raccoon of Cozumel Island off the coast of Yucatan.  They differ from more familiar raccoons in their smaller size and golden ringed tails.

There are 4 species of coatimundis.  The white-nosed coatimundi (Nasua naria) ranges throughout Mexica and as far north as Arizona.  N. nasua lives in the tropical jungles of South America, while the other 2 species of coatimundis are restricted to cloud forests there.

Coati foraging.

White-nosed coatimundi, an inhabitant of Mexican deserts.

The ringtail (Bassariscus astutus) inhabits rocky arid habitats throughout Mexico and as far north as Oregon and as far east as Kansas.  They’re known as miner’s cats because they tamed easily and lived in miner’s cabins where they kept mice populations low.  A new species of ringtail (B sumichasti) was discovered in 2013.

Pair of ringtails

Ringtails.  Another procyonid that prefers arid habitat.

The kinkajou (Potus flavus) and olingos (Bassaricyon sps.) inhabit the canopies of tropical forests where they subsist on fruit and insects.

Photo: Kinkajou holding a balsa blossom

The kinkajou lives in tropical forest canopies.

The Giant Teratorn (Argentavis magnificens)

January 13, 2015

The largest flying bird known to science was the giant teratorn, an extinct condor that lived in South America during the Miocene over 5 million years ago.  It had a wingspan of 21 feet and weighed an astonishing 155 pounds.  It inhabited the Andean Mountains and dry flat pampas, but fossils from this era are rare, and we don’t really know the full extent of its range.  A bird of this size likely had a long lifespan of 50-100 years.  Scientists disagree about its dietary habits.  Some think it was an active predator, swallowing relatively small prey whole because its beak was not built for tearing open large carcasses with tough hides.  However, others believe it was mostly a scavenger because a bird of this size would require 20 pounds of meat per day, and it’s unlikely consuming small animals could satisfy this appetite.  I agree with the latter speculation, though the teratorn may have ingested small animals, if given the opportunity.  It was related to storks and New World vultures, both of which are opportunistic feeders.

Size comparison between the largest flying bird known to science and a school bus.

Specimens of the giant teratorn are only known from 4 localities in South America.  Scientists are interested in figuring out how such a large heavy bird could fly, but the amount of fossil material available from this species is meager, making it difficult to determine this from the few bones they have.  Happily for them, there is abundant fossil material of the closely related North American teratorn–Teratornis merriami. Over 100 specimens of this late Pleistocene species have been excavated from the Rancho la brea tar pits in California.  Additional fossil specimens of North American teratorns have been found in Arizona, Nevada, Florida, and New York.  It had a continent wide distribution but probably occurred in low numbers–a slow breeding yet long-lived species.  T. merriami had a wingspan of 11 feet, less than that of its South American cousin, but still impressive.  Nevertheless, the similarity in anatomy between the 2 species allowed scientists to use specimens of T. merriami to determine how the giant teratorn could fly.  Scientists think it had to run downhill against the wind to get airborne.  Then, it could ride rising warm air (thermals) to get high in the sky where it searched for carrion. It was more of a glider than a flyer.  Just a slight slope in the land would have been adequate for a teratorn to get airborne.  Thermals can occur in a very small space, and teratorns could circle inside these quite narrow thermals to attain height.

 

 

 

Fig. 4.

Diagram from paper referenced below (Chatterjee 2007) showing how the giant terratorn took off and landed.

No extant species of flying birds approach the wingspan and weight of the giant teratorn, but some are almost as big as the late Pleistocene Merriam’s teratorn.  The kari bustard (Ardeotis tardi), a kind of crane, reaches 40 pounds.  The largest turkey (Maleagris gallopavo) ever killed by a hunter weighed 37 pounds.  Dalmatian pelicans (Pelecanus crispus) are heavy flying birds.  The greater albatross (Diomedea exulans) has a wingspan of 11 feet.  This species gets airborne by running into the wind downslope from the top of waves, much like the extinct teratorns.  The Andean condor (Vultur gryphus) is the most similar living species to the teratorn.  They are closely related and likely occupy a similar ecological niche.

Andean condor in front of an Homo sapiens.

Video of the extant bird with the longest wingspan–a great albatross.  Note the difficulty they have with take off.

References:

Chatterjee, S.; and R. J. Templin, and K.E. Campbell

“The Aerodynamics of Argentavis; the World’s Largest Flying Bird from the Miocene of Argentina”

PNAS 104 (30) 2007

Palmqvist, Paul; and Sergio Vizcaino

“Ecological and Reproductive Constraints of Body Size in the Gigantic Argentavis magnificens (Aves: Teratornighidae) from the Miocene of Argentina”

Ameghiniana 40 2003

Choloepus Tree Sloths are Closely Related to the Largest Extinct Ground Sloths

January 8, 2015

If I could bring just 1 species of the extinct Pleistocene megafauna back to life, it would be Eremotherium laurillardi, an enormous ground sloth that ranged from tropical South America to the warm coastal regions of southeastern North America during warm climate phases.  Although artists always depict all ground sloths as heavily furred beasts, scientists aren’t so certain about Eremotherium.  Some ground sloths undoubtedly were heavily furred–the mummified remains of 1 species found in a cave did have fur.  But this particular species was found in a colder region of South America.  Tropical species of large ground sloths may have been lightly haired like modern warm climate megafauna such as elephants, rhinos, hippos, and humans.  The difference between Eremotherium and Jefferson’s ground sloth (which ranged as far north as Alaska) might have been comparable to the difference between an African elephant and a woolly mammoth. The megatheridae, the extinct family of really big ground sloths, were closely related to the megalonychidae family which has 1 surviving genera of sloths.  There are 2 species in this genus–Linnaeus’s tree sloth (Choloepus didactlylus) and Hoffman’s tree sloth (C. hoffmanni).  They are mistakenly referred to as 2-toed sloths, but they actually have 2 fingers and 3 toes.  Algae grows on their fur, so they are well camouflaged in the evergreen canopy of tropical forests.  They are also closely related to the dwarf ground sloths that colonized Caribbean Islands and lived there until about 4000 years ago. two-toed sloth pic

Hoffman’s tree sloth is closely related to  the Megatherium and Eremotherium ground sloths.

Oddly enough, anatomical and genetic studies suggest the only other surviving genus of tree sloths is not closely related to Chonoepus sloths or any known species of ground sloth.  The Bradypus genus of tree sloths is considered a “sister taxon” of all other sloths.  Despite the similarity in appearance and habitat adaptations, sloths in the Bradypus genus evolved from a different lineage than Chonoepus sloths.  Both genera evolved their arboreal adaptations independently–an incredible example of convergence.  Most intact jungle ecosystems in South America have 1 species of each genera living in the tree tops.

I believe this is a brown-throated tree sloth.  I found this on google images where it is mistakenly labeled as Hoffman’s ground sloth. It is not closely related to extinct ground sloths and evolved its arboreal habits independently of Choloepus tree sloths.
The Bradypus genus includes 4 species–the brown-throated (Bradypus variegatus), the maned (B. torquatus), the pale-throated (B. tridactylus), and the endangered  pygmy (B. pygmaeus).  Tree sloths mostly eat leaves but also consume fruit, flowers, bark, and rodents.  This is evidence giant ground sloths consumed meat when they could obtain it.  Tree sloths are also known for raiding human latrines where they get minerals from human waste.
i-314025abf3ae0c3de414862c7d1bc64c-toilet_sloth_mum-with-baby-M-Stojan-Dolar_April-2010.jpg
Mother tree sloth climbing from a septic tank with a clinging baby sloth.

Invasive Species are more Beneficial than Alarmists will Admit

January 4, 2015

Every organism that ever evolved became an invasive species.  It colonized new territory where it previously had not existed.  The concept of an invasive species that is harmful to the environment is a construct invented by man, the most environmentally damaging species to ever evolve.  The Homo sapien is such an hypocritical species.  The biogeographical history of the earth is a tale of species invading new territories.  The Bering Landbridge allowed a back and forth migration between Eurasia and North America, and the emergence of Central America offered a highway for another interchange of flora and fauna.  Man, the ultimate invader, has facilitated and accelerated the transfer of many species. Environmentalists focus on the harmful results invasive species wreak on ecology but ignore the obvious benefits that may in most cases outweigh the damage.  I mentioned 1 example on my blog last week–Burmese pythons reduce the population of predators that prey on endangered sea turtle eggs.  A recent study (referenced below) gives many more examples of beneficial invasive species that according to the authors of that study should be referred to as “recently arrived species.”

–The honeybee is not native to North America, yet without this “recently arrived species” industrial scale fruit and nut orchards would not be economically viable.

–Environmentalists mistakenly thought non native tamarisk trees were causing low water levels on the Colorado River floodplains.  Millions of dollars were spent eradicating this species.  But later studies showed tamarisk trees were not responsible for causing these low water levels.  Their misguided policy greatly reduced nesting habitat for the endangered willow flycatcher, a species that uses tamarisk in lieu of willow.

Endangered southwestern willow flycatcher’s nest in a non-native tamarisk tree.  The government and groups like the Nature Conservancy spent millions eradicating this species of tree based on the false premise that it lowers water levels.  Now this rare bird has far less nesting habitat.

–Native trees can’t be re-established on eroded Puerto Rican forestlands unless non-native trees are planted first.  With the help of non-native trees, 20 species of native trees were able to grow on badly eroded soils.

–The presence of non native honeysuckle vines increases the population of robins and catbirds that feed on the berries.  The increased bird populations acted as dispersers that helped increase native honeysuckle vine abundance.

–Non native guavas in Kenya helped increase the population of fruit-eating birds there.

–Non native grasses planted on reclaimed strip mines increased the population of endangered Henslow’s sparrows.

–Non native shad serve as forage to help feed  Pacific salmon.

–Non native mussels serve as food for raccoons.

–Butterflies utilize non native species as sources of food.

–Non native cattle maintain early successional habitat, thus helping native species dependent upon this habitat.  They’re a substitute for extinct Pleistocene megafauna.

–African honeybees traverse the areas between fragmented forests in Brazil, aiding the pollination of plant species that could become inbred and sterile.

Some regions provide refuge for species that are endangered in their land of origin.  The Aldabra tortoise is native to a Seychelles Island but is more common in Mauritia where it occupies the ecological role of a now extinct species of giant tortoise.

Aldabra Giant Tortoise Geochelone gigantea edit1.jpg

The Aldabra giant tortoise has been introduced to the island of Mauritia where another species of giant tortoise was overhunted into extinction centuries ago.  It serves as an important disperser of native plants.

Banteng, an endangered species of cattle native to southern Asia, breeds successfully in northern Australia.

Banteng bull caught on camera trap in Malua BioBank. Photo by: Sabah Wildlife Department (SWD).

Banteng cattle face extinction in their homeland but have successfully established a wild breeding population in northern Australia.

Hippos (imported by a rich cocaine baron) thrive in Colombia.  Game ranches in Texas are the best hope for breeding black rhinos, currently extinct in Africa.

Recently arrived species can cause the extinction of competing native species, but they can also instigate the evolution of new species.  Non native house sparrows appear to be speciating in North America, according to the geographic region they have colonized.  Desert populations of house sparrows have distinct physical characteristics from those found in eastern woodlands.  A new species of honeysuckle fly exists today, thanks to non native honeysuckle vines.  This species resulted from the hybridization of 2 closely related flies that hosted 2 different species of native honeysuckles.  The 2 different species of fly both hosted non native honeysuckles, explaining how they began breeding with each other.

The lonicera fly is the result of hybridization between 2 different species: Rhagoletes menax X R. zephyra.  This new species resulted from the introduction of non native honeysuckles.

The authors of the below referenced study suggest recently arrived species should be more carefully evaluated and managed and not blindly eradicated, simply because they are non native.

Reference:

Schlaepfer, Martin; Dow Sax and Julian Olde

“The Potential Conservation Value of Non-Native Species”

Conservation Biology 25 (3) June 2011

 

 

Debunking the Claim that Burmese Pythons are causing Severe Mammal Declines in the Everglades

December 29, 2014

The National Academy of Science often publishes some really bad studies.  Two years ago, the journal of this organization published a paper entitled “Severe Mammal Declines Coincide with the Proliferation of Burmese Pythons in Everglades National Park.”  This study was authored by Michael Dorcas, an herpetologist from Davidson College, along with a long list of other scientists.  I’m always leery of studies with a long list of contributing scientists.  I suspect the lead authors of these studies do most of the work, and misleadingly include many co-authors.  With minimal input, the many co-authors lend legitimacy to a study in exchange for getting the publishing credit that is so important for their academic careers.

Michael Dorcas.  This scientist authored a really bad study of Burmese pythons that led him to conclude they were wiping out mammal populations in the Everglades National Park.  His study was debunked by the Florida Fish and Wildlife Conservation Commission.  Nevertheless, the media took his ridiculous conclusions as gospel.  Not a single journalist questioned this terrible amateurish study.

I read Dr. Dorcas’s study and knew the results didn’t fit within ecological reality.  He went back to records of road-killed animals in Everglades National Park during the 1990’s before the population of Burmese pythons had become significant and compared them with the number of road side sightings of these same species 10 years later.  He concluded that the populations of raccoons, possums, bobcats, and marsh rabbits had been decimated and in some cases had been reduced by 100%.  This doesn’t make any sense ecologically.  If the population of prey declines in abundance, than the population of predators declines as well because there is nothing for the predators to eat.  Burmese pythons couldn’t decimate mammal populations without eventually succombing to starvation themselves.  So the results of Dr. Dorcas’s study were unbelievably ridiculous.  Nevertheless, every news media outlet picked up this alarmist nonsense and not a single journalist questioned the credibility of such an absurd conclusion.  This demonstrates the ignorance of basic ecology among the average layperson.  I mentioned my logical objections to this study’s findings on my blog about a year ago but thought I was a lone voice in the wilderness.  However, I discovered someone from The Florida Fish and Wildlife Conservation agrees with me.  They found the following flaws in Dr. Dorcas’s study.

1. The survey for road-killed animals (Dr. Dorcas’s data from the 1990’s) didn’t include critical information–how many observers, the number of miles driven, the number of days the survey was done, and the procedures used to avoid double counting.  In other words this data is anecdotal and useless.

2. The year of the pre-python survey was a high water year when more animals were forced to take refuge on the high ground where the road exists.  This explains why more animals were counted during the survey than during later drought years.  Road-side surveys yield dubious data.  Dr. Dorcas should have used live trapping to get an accurate count of mammal populations.

3. There is no actual data on python densities.

4. The timing of the python population increase and the supposed decline in mammal populations is not documented.  Scientists can’t explain how python populations could increase following prey population declines (my point exactly).

5. There is no mention in Dr. Dorcas’s study of coyotes.  Coyotes recently re-colonized south Florida and may play a role in the decline of mammal populations there.

6. The differences in prey density inside and outside Everglades National Park are likely due to differences in habitat, not the presence of pythons.  Everglades National Park is actually very poor wildlife habitat.  More wildlife lives outside the park than inside.  With very few exceptions most of the best wildlife habitat left in the world is occupied by humans.  We give animals the wastelands that are too expensive to commercially develop and call them national parks.

Burmese python killed by alligator.  Burmese pythons are beneficial additions to Florida’s ecology, despite what alarmist environmentalists claim.  South Florida’s ecology was in desperate need of a large predator.

Contrary to the claims of alarmist environmentalists, Burmese pythons are a beneficial addition to South Florida’s ecosystem.  During the Pleistocene in this region there were 5 species of big cats plus dire wolves, bears, and alligators.  Now, there are just alligators and pythons.  (Very few Florida panthers live in Everglades National Park.  Most occur on cattle ranches located well north of the park.) Without the presence of large predators, the populations of smaller predators such as raccoons and possums increased.  These predators eat reptile eggs and put a big dent in the population of 17 endangered and threatened species of reptiles, including rare sea turtles.  Pythons help control the numbers of raccoons and possums, helping increase the nesting success of endangered reptiles.  Pythons are beneficial for twice as many endangered species than ones they might prey upon.

Scientists’ estimates of Burmese pythons populations in Florida are not based on scientific data.  They are wild guesses bordering on fantasy.  The oft-cited number of 30,000-150,000 is a wild overstimate.  Over the past 12 years, 2000 pythons have been removed from Everglades National Park.  That’s less than 200 per year–nowhere near what one would expect, if there were 30,000 large snakes slithering inside the park.  Last year, there was a python round up.  For a month 1500 snake hunters looked for Burmese pythons to kill.  They netted just 50.  This is strong evidence Burmese pythons are not even close to being as abundant as researchers claim.

Reference:

Dorcas, Michael; et. al.

“Severe Mammal Declines Coincide with Proliferation of Invasive Burmese Pythons in Everglades National Park”

PNAS December 2011

Unnamed author

“Commentary on Mammal Declines in Everglades National Park”

Florida Fish and Wildlife Conservation Commission report 2012

 

The Great American Biotic Interchange

December 26, 2014

South America broke from Antartica and Australia about 60 million years ago and became an island continent where its fauna evolved in isolation.  The most common mammals were marsupials, edentates, and primitive hooved animals unfamiliar to most non-paleontologists.  Circa 30 million years ago, caviomorph rodents and monkeys arrived from Africa via clumps of floating vegetation originating from that continent.  During this time Africa and South America were closer together than they presently are.  Floods in African rivers must have carried these little islands of vegetation with their clinging inhabitants  far into the sea where favorable currents brought the lucky animals to South America.  These new colonizers diversified into many species.  South America remained an isolated continent until 9 million years ago when volcanic islands began emerging  below North America.  Although there was not yet a landbridge between the 2 continents, the fossil record shows there was an early exchange of species.  Ground sloths went north, while tapirs, peccaries, and primitive mastodons known as gompotheres went south.  All of these animals are excellent swimmers.  Apparently, they island-hopped, swimming to reach new islands and eventually coming to a continent where they became successful newcomers.

An external file that holds a picture, illustration, etc.<br /><br /><br /><br /><br /><br /><br /><br /><br />
Object name is 10914_2010_9144_Fig2_HTML.jpg

 

 

 

 

Map showing the islands that  collided with South America eventually forming the Isthmus of Panama. This joined North America with South America.  Some species of mammals island-hopped and colonized the other continent before the landbridge completely emerged above sea level.

Elephants can swim for miles without getting tired.  They can breath through their trunks while swimming.  This explains how gompotheres (an elephant-like beast) colonized South America 9 million years ago, long before a land connection existed between the 2 continents.

Tapir swimming.  They can breath through their snouts while swimming submerged.  All of the early colonizers in the Great American Biotic Interchange were excellent swimmers.  They island-hopped before the existence of a complete land connection.

A now extinct relative of the raccoon (Cyonasaura) was next to colonize South America 7.3 million years ago.  An extinct species of raccoon (Chapmalania) that was as large as a bear lived in South America during the Pliocene.  Sygmodontine rodents (rats, mice, gophers) from North America arrived in South America 6 million years ago.  Pampatheres (a giant armadillo) and the terror bird spread to North America 5 million years ago.  They were followed by glyptodonts and capybaras 4 million years ago.  The Central American landbridge emerged above sea level ~3 million years ago bringing a cavalcade of animals south–llamas, horses, canids, and weasels; while porcupines headed north.  A new climatic phase ~2 million years ago allowed even more mammals to head south–deer, rabbits, skunks, cats, and bears.

Other vertebrates took advantage of newly available habitat.  South American forms that moved north included cichlid fish, bufo toads, tree frogs, parrots, tanagers, hummingbirds, and flycatchers.  North American vertebrates that went south included lungless salamanders, ranid frogs, snapping turtles, wood turtles, trachemys turtles, rattlesnakes and other pit vipers, coral snakes, sparrows, and condors.

These faunal invasions occurred in pulses influenced by changes in climate.  During Ice Ages sea level fell and this greatly expanded the land area of Central America.  Average temperatures fell by as much as 14 degrees F here, though because the region is so close to the equator they were not subfreezing.  Nevertheless, pollen records indicate tropical forests were replaced with grassy savannahs and temperate species of trees such as oak, sweetgum, myrtle, elm, walnut, and even spruce and fir at higher elevations.  The change to a more open environment allowed horses and llamas to traverse Central America to colonize land further south.  Warm interglacial conditions favored the expanded ranges of tropical species such as very large ground sloths and glyptodonts.  These species eventually made it to southeastern North America.  Some lineages of mammals colonized 1 continent, evolved to a new species, then returned to the original continent of their ancestor.  Examples of these are the collared peccary and jaguarundi.

More species of South American-originating fauna survive in North America than vice-versa, but most are restricted to the Central American tropics.  There are many species of edentates, marsupials, monkeys, and caviomorph rodents here.  But, excepting Central America’s faunal composition, North America’s invasion to South America could be considered more successful.  There are just 4 successful South American species living today in North America (not counting Central America)–opossum, armadillo, porcupine, and nutria whereas South America is home to tapirs, peccaries, llamas, foxes, cats, sygmodontine rodents, squirrels, rabbits, and shrews.  However, a modern review of this disparity is misleading.  Ground sloths, glyptodonts, and pampatheres were quite successful during the Pleistocene in North America, but humans caused their extinction.  Toxodons and litopterns (primitive South American hooved animals that made it as far north as Mexico) were also vulnerable to human hunting and would likely still live today if not for man.  North America also has a more temperate climate. It is difficult for species that evolved in tropical climates to adapt to freezing temperatures.  The only real losers resulting from this faunal interchange were South America’s marsupial carnivores and the terror birds.  North America’s carnivores eventually outcompeted South America’s meat-eaters.

Reference:

Woodburne, M.O.

“The GABI: Dispersals, Tectonics, Climate, Sea Level, and Holding Pens”

Journal of Mammalian Evolution 17 2010


Follow

Get every new post delivered to your Inbox.

Join 110 other followers