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Nile Crocodile Found in Florida: Is World’s Largest Crocodile a Resident?

Nile Crocodile

Uploaded to Wikipedia commons by Tim Muttoo

Yet another Floridian reptile drama has made headlines.  Earlier this month (March, 2014) officials from the Florida Fish and Wildlife Commission (FFW) reported that a Nile Crocodile (Crocodylus niloticus) had been captured in the northwestern Everglades.  Although the origin of this particular animal may be known, it is not the first Nile Crocodile to have been captured in the state, which is now home to an astonishing 500+ species of non-native animals (and a great many plants)!  And while Nile Crocodiles are a rarity in Florida, the possibility of hybridization with the native American Crocodile (C. acutus) may be a concern.  In the course of my work in zoos and via contacts with commercial croc farming projects, I’ve seen many examples of hybrid crocodiles.  I cared for a Cuban Crocodile x American Crocodile cross, and Siamese Crocodiles are regularly interbred with others on farms.  Hybrid crocs were even openly offered for sale as “pets” back in the “Wild West” days of the pet trade (and perhaps still are?).

 

Nile Crocodile Origins

The recently-captured Nile Crocodile measured 5 ½ feet in length and weighed 37 pounds – too small to have reached sexual maturity (another, also an escaped exhibit animal, measured 9 feet in length when re-captured). It is believed to be the same individual that has been sighted several times over past 2 years.  FFW officials are looking into the possibility that this animal escaped from a Miami facility just before the sightings began.  If genetic evidence confirms

Ameriocan Crocodile

Uploaded to Wikipedia Commons by Mattstone911

this, the owners could be subject to a fine and/or imprisonment under Florida law.

 

Crocodiles and the Leather Trade

There has been speculation that live crocodiles imported to the USA for use in the skin trade may be another source of escapees.  However, all operations that utilize Nile Crocodiles are, according to the IUCN’s latest report, located in Africa (please see article linked below).

 

Nile Crocodiles are second only to American Alligators in terms of the number of skins sold each year.  The IUCN reports that between 2006 -2008, 1.5 million crocodile, alligator and caiman skins were legally traded.  Thirty countries and 13 crocodilian species were involved.  The global economic downturn has suppressed demand since that time.

 

Financial Concerns

Florida has the dubious honor of hosting more non-native invertebrates, fishes, reptiles, amphibians, birds and mammals than anywhere else on earth.  An astonishing 500+ exotic species have been observed, and many if not most have established breeding populations.  Last year, the federal and Florida state governments spent 80 million dollars in eradication attempts.  Threats to agriculture and habitats posed by introduced plants are also significant.

 

Other costs are involved as well – over the past decade, for example, 100 million dollars has been spent on re-establishing the endangered Wood Stork.  Nile Crocodiles and Burmese and African Rock Pythons are capable of preying upon Wood Storks, and other species could impact these endangered birds in ways that have not yet been identified.

 

Mexican Spinytail Iguana

Uploaded to Wikipedia Commons by John J. Mosesso, NBII

Notable Exotics: Reptiles and Mammals

Many of Florida’s introduced reptiles are very well-known, even to those without much interest in animals.  In some areas, Green Iguana populations are denser than in natural habitats…denser, in fact, than populations of any other lizard, anywhere on earth (please see article below for an interesting study on iguana-raccoon interactions)!  Brown Anoles seem to have replaced the native Green Anole in many areas, and 6-8 other anole species are established as well.  And, of course, one cannot escape news of introduced Burmese and African Rock Pythons and Boa Constrictors.

 

Less well-known is the fact that Spectacled Caimans (Caiman crocodylus) have been breeding in Florida since the 1960’s, which was their heyday in the pet trade.  Other surprising transplants include Javan File Snakes (Acrochordus javanicus), Texas Horned Lizards (Phrynosoma cornutum), Mexican and Black Spinytail Iguanas (Ctenosaura pectinata and similis) and Indochinese Tree Agamas (Calotes mystaceus).  There are many others…please post below if you wish a complete list.

 

I’m surprised that, with the exception of Armadillos and Nutrias, Florida’s introduced mammals do not seem to generate much interest.  The list really is quite amazing, and includes such large and unusual creatures as Asian Sambar Deer, American Elk, Jamaican Fruit Bats, Capybara, Mexican Red-Bellied Squirrels and Rhesus, Squirrel and Vervet Monkeys.  Please post below for more info, and see the linked article on Florida’s many feral parrots.

Sambar Deer

Uploaded to Wikipedia Commons by N. A. Naseer

 

Extermination efforts have rarely been successful, regardless of the species involved.  In fact, the FFW has given indications that the Burmese Python campaign may shift from “eliminate” to “control” mode.  I’ll post updates as they become available.

 

Hi, my name is Frank Indiviglio.  I’m a herpetologist, zoologist, and book author, recently retired from a career spent at several zoos, aquariums, and museums, including over 20 years with the Bronx Zoo.

 

Please check out my posts on Twitter and Facebook.   Each day, I highlight breaking research, conservation news and interesting stories concerning just about every type of animal imaginable.  I look forward to hearing about your interests and experiences as well, and will use them in articles when possible.

 

Please also post your questions and comments below…I’ll be sure to respond quickly.  Thanks, until next time, Frank.

 

Further Reading

Raccoons and Iguanas in Florida – an Interesting Dilemma

 

Florida’s Introduced Parrots

 

Commercial Crocodile Farming (IUCN report)

Guam Brown Tree Snake Eradication: Bad News for People & Wildlife

Threat display

Uploaded to Wikipedia Commons by Soulgany101

As a Bronx Zoo animal-keeper in the early 1980’s, I became involved in a breeding program for Guam Rails and Micronesian Kingfishers. Both birds were facing extinction due to a most unusual threat – the introduced Brown Tree Snake, Boiga irregularis.  Back then, major problems caused by trans-located snakes were unknown.  Although Burmese Pythons had been established in Florida since the early 70’s, these now-famous invaders had not yet grabbed the public’s attention.  A zoologist friend journeyed to Guam to investigate, and he was soon regaling me with fantastic stories.  In keeping with its species name, this snake was most “irregular” – biting at the moving eyelids of sleeping children, stealing burgers from grills, and often being found in bird cages – too engorged to slip back out after having swallowed the family pet!  Today, the rail and kingfisher are gone from Guam, and other birds, lizards and bats have become extinct.  Yet the Brown Tree Snake has not, as was predicted, eaten itself into oblivion.  Huge populations – to 13,000 snakes per square mile – are sustained by other prolific invaders, one of which is the Green Anole!

 

The Brown Tree Snake’s History on Guam

Flowerpot Snake

Uploaded to Wikipedia Commons by Hinrich Kaiser and Mark O’Shea

Although many accounts describe Guam as “snake-less” prior to the Brown Tree Snake’s arrival, the island does have one native species, the tiny Brahminy Blind or “Flower Pot” Snake, Rhamphotyphlops braminus (please see photo)Able to reproduce by parthenogenesis, it is a common stowaway in plant shipments.  Feral populations exist in many places, including (of course!) Florida.

 

The Brown Tree Snake most likely arrived on Guam during World War II, secreted in crates sent there from US military bases on the Admiralty Islands.  Huge populations of native lizards and birds that had evolved without snake predators allowed it to explode in numbers.  The snake began gaining attention in the 1950’s, and occupied the entire island by 1968.  The invasion gained widespread notice in the early 1980’s, due to massive declines in bird populations and increased human-snake encounters.

 

Description

The Brown Tree Snake is a rear-fanged species that averages 3-6 feet in length, but those living on Guam sometimes approach 11 feet.  Guam specimens range from olive-green to dark tan in color, and are marked with darker blotches.  Other populations are colored brown, greenish-tan or beige with rusty-red markings.

 

Their venom has not caused human fatalities but is a concern for certain individuals (please see below).  Prey may be partially immobilized by the snake’s body, but they are not constrictors in the true sense of the word.

 

The individuals that my friend brought back from Guam were among the most aggressive snakes I’ve seen.  Bold and high-strung, Brown Tree Snakes bite many people on Guam.

 

Range and Habitat

The Brown Tree Snake’s natural range stretches from the northern and eastern coastlines of Australia to New Guinea, the Solomons, Sulawesi and many neighboring islands.

 

Guam Rail

Uploaded to Wikipedia Commons by Greg Hume

Less well-known than Guam are the many other locales to which the Brown Tree Snake has been transported.  The most far-flung is Corpus Christi, Texas, where one was found after a 7 month journey in a crate shipped from Guam.

 

It is not known if this world traveler has established breeding populations elsewhere, but it has been collected on Hawaii, Saipan, Okinawa, Wake, Taiwan, the Cocos, Rota and many small Micronesian islands. Anecdotal reports suggest that it has appeared in airports in Japan, Spain and Singapore.

 

Common name notwithstanding, the Brown Tree Snake adapts well to brushy scrub and relatively treeless habitats.  It readily colonizes villages, farms and cut-over woodlots.

 

Brown Tree Snake’s Effect on Guam’s Wildlife

Lizards

Although best known for annihilating Guam’s birds, the Brown Tree Snake has had a significant impact on most native vertebrates. Six of the island’s 12 lizards have now disappeared.  Several, such as the Azure-Tailed Skink, Emoia cyanura and the Moth Skink, Lipinia noctura, are poorly studied and may be in trouble elsewhere as well.

 

Three fast-breeding introduced lizards, the Green Anole, Anolis carolinensis, the House Gecko, Hemidactylus frenata, and the Curious Brown Skink, Carlia fusca, seem responsible for the continued success of the Brown Tree Snake on Guam. They now make up most of the snake’s diet, but remain common.

 

The Mangrove Monitor, Varanus indicus, is also in decline, but this may be due to yet another introduced herp – the Marine Toad, Bufo marinus.  Monitors that eat toads are killed by its virulent toxins.   It is not known whether the Mangrove Monitor is native or was introduced to control rats (it seems better at controlling chickens and their eggs than rats!).

 

Mammals

Guam was home to only three native mammals, all bats.  Two have been extirpated by the snake, and the Marianas Fruit Bat is now limited to a single small colony.

 

Micronesian Kingfisher

Uploaded to Wikipedia Commons by Dylan Kesler

Birds

The birds with which I worked years ago, the Micronesian Kingfisher and the Guam Rail, are now well-established in zoos.  However, as Guam is their sole habitat, they are extinct in the wild.

 

The Brown Tree Snake has also eliminated all of Guam’s nesting seabird colonies (White-Tailed Tropicbird, White Tern, Brown Noody) and 10 of its 13 forest-dwelling birds. Micronesian Starlings survive by nesting in cities, and some Marianas Crow nests are protected by electric barriers – but fruit doves, honeyeaters and others have vanished.

 

Effects on People

The Brown Tree Snake has impacted Guam’s people and economy in a manner unprecedented for a reptile.  Examples include:

 

Bites, especially to sleeping children, are very common.  Small children may exhibit signs of envenomation, and in some cases must be treated for respiratory distress.  Allergic, elderly, and immune-compromised individuals are also at risk.  The fear and trauma factor is also quite high.

 

Power outages caused by electrocuted snakes cost up to 4 million dollars yearly.

 

Property values and tourism have declined, with people and businesses relocating.

 

Guam’s air cargo industry has suffered due to the lengthy examinations required.

 

Lizard and bird extinctions may have led to recent mosquito-borne dengue fever and Salmonellosis outbreaks and to a sharp decline in farming due to insect predation on crops.

 

The poultry industry has been decimated; most eggs now imported.

 

Brown Tree Snake Eradication Attempts

In addition to vanquishing many native species, the Brown Tree Snake is besting its human enemies as well.

 

The most controversial attack method is airplane-drops of mice laced with Paracetamol, a snake-toxic pain killer. The mice are attached to tiny cardboard parachutes (who makes these?!) designed to keep the bait in trees and away from children and domestic animals.  The “tiny assassins” program costs the US government an estimated $8,000,000 annually.

 

Trapping has proven to be the most effective control technique, but success hinges on using many traps.  As the modified minnow traps are baited with live geckos and mice, maintenance is very labor intensive.

 

Snake-detecting dogs, debris and scrub-growth removal, and snake barriers are also used with varying degrees of success.

 

Research

Research is being conducted by many organizations, including the US Geological Survey, Princeton University and the National Zoological Society.  Manipulation of breeding biology, snake diseases and parasites, poisons, and heat-fumigation treatments for cargo areas are being explored as control measures.

Hi, my name is Frank Indiviglio.  I’m a herpetologist, zoologist, and book author, recently retired from a career spent at several zoos, aquariums, and museums, including over 20 years with the Bronx Zoo.

Please check out my posts on Twitter and Facebook.   Each day, I highlight breaking research, conservation news and interesting stories concerning just about every type of animal imaginable.  I look forward to hearing about your interests and experiences as well, and will use them in articles when possible.

 

Please also post your questions and comments below…I’ll be sure to respond quickly.  Thanks, until next time, Frank.

 

Further Reading

Toxic Mice Dropped Over Guam

 

Red Eared Sliders Out-Compete Native European Turtles

 

Python Eats Crocodile – Tales of Big Snake Eating

Anaconad, me and MariaRecently, dramatic photos of an Olive Python, Liasis olivaceus, swallowing an Australian Freshwater Crocodile, Crocodylus johnstoni, have been much in the news.  A very interesting story, no doubt, but actually a 3-4 foot long croc is well within the size range of prey taken by large pythons.  In past articles I’ve mentioned some of the astonishing snake meals I’ve been witness to (please see articles linked below).  One, a 60 pound White-tailed Deer taken by a huge Green Anaconda in Venezuela, would be hard for me “to swallow” (sorry!) had I not been awakened by the snake disgorging it below my hammock in the wee hours!  A 5-foot-long Spectacled Caiman grabbed by another took 6+ hours to subdue.  I’ve also searched my notes for feeding accounts recorded by Messrs. Ditmars, Pope, Greene, Kauffeld and other notables, and thought I’d take this opportunity to share them with my fellow snake enthusiasts…Enjoy!

 

Following are some of the more memorable meals that I’ve witnessed or read about.  Please see the linked articles, or post below, for further information, and be sure to let me know of your own experiences.

 

Big Anaconda Meals I have Witnessed

The Green Anaconda I mentioned above was captured as part of a study on their natural history in the western llanos region of Venezuela.  The snake, which measured nearly 17 feet long, was transported to our research station for tagging.  During the early AM, it disgorged the deer, which had been recently consumed.  The Anaconda pictured in this article was the largest I came across, measuring just over 17 feet long and weighing in at 215 pounds; this seems to be about their maximum size in that habitat (seasonally-flooded grasslands), but larger ones are to be found in forested rivers.  The blood on my hand is courtesy of one of her teeth, which remains imbedded in my wrist as a souvenir…

 

Gator-Burmese Python battle

Uploaded to Wikipedia Commons by Lori Oberhofer, National Park Servic

Other notable Green Anaconda meals include a 5 foot-long Spectacled Caiman, Caiman crocodilus (witnessed by a co-worker at the same site; photo to right is of an American Alligator turning the tables on a Burmese Python in Florida) and a 10 pound Red-Footed Tortoise, Geochelone carbonaria (unfortunately, an exhibit-mate at the Bronx Zoo, long ago!).  I and fellow Anaconda-chasers also called to a site where one was said to be swallowing a large Savanna Side-Necked Turtle, Podocnemis unifilis.  The 14-15 foot long snake had given up or been outwitted by the time I arrived, but she bore long, narrow wounds along the neck – the result, perhaps, of trying to swallow the ill-advised meal.  This snake later died, apparently of an infection.

 

Size isn’t the only means by which Green Anacondas have managed to surprise me.  Pigeon-sized birds known as Jacanas and other small species were commonly taken by snakes measuring 12-15 feet in length.  We also recorded fish and other Anacondas as food items – not all that surprising, but not often documented.  Capybaras were often hunted as well; these rodent giants were also favored by Pumas – a co-worker saw one catch a capybara in broad daylight.

 

Despite their seemingly-unrefined palates, captive Anacondas can be very picky.  Ducks are the old zookeeper’s standby for reluctant feeders, but one Anaconda under my care would take only Muskrats, while another relished free-ranging Norway Rats but refused lab-raised rats of the same species.

 

People, Dogs, Cats, and Ibex on the Big Snake Menu

Reticulated Pythons, although lacking the Anaconda’s girth, are also well known for taking enormous meals.  And, perhaps because they often adapt to life among people, (please see Urban Pythons, below), human predation has been documented.  In fact, a recent study in the Philippines revealed that from 1939-1973, 26% of all Agta men had been attacked by Reticulated Pythons, resulting in at least 6 fatalities!  Please see People as Python Prey http://blogs.thatpetplace.com/thatreptileblog/2012/01/30/people-as-python-prey-giant-snakes-attack-150-kill-6-in-philippines/#.UxehEYVnupE for details.

 

Some years ago, animal keepers visiting from the Singapore Zoo informed me that a free-ranging Reticulated Python took a 40 pound Cape Hunting Dog from an outdoor exhibit.  Please see this article http://blogs.thatpetplace.com/thatreptileblog/2013/09/12/rock-python-kills-full-grown-husky-in-florida/#.Uxfl3oVnupE to read about a husky that was killed by a feral African Rock Python in Florida.

 

Legendary zoo-man Carl Hagenbeck reported that a 25 foot long Reticulated Python residing at the Hamburg Zoo consumed a 71 pound Ibex and two domestic goats of 28 and 39 pounds, for a total of 138 pounds of food within a few days!  In the “small but surprising” meal category is a Siamese cat that was eaten – bells, collar and all – inside the palace of a former king of Siam (modern-day Thailand)!

 

King Cobra

Uploaded to Wikipedia Commons by Greg Hume

King Cobra makes a Meal of its Mate

The world’s largest venomous snake, the King Cobra, favors other snakes above all other foods, and seems not to have as wide a jaw-gape as do similarly-sized individuals of other species (given their alertness and speed, I avoided working close enough to them to check, and am happy to speculate!).

 

But that does not limit their capabilities in all respects.  During a breeding attempt at the Bronx Zoo (well, we considered it a breeding attempt, the snakes obviously had other opinions!), a 12-13 foot male consumed a 10-11 foot female. We had caged them side-by-side for weeks prior, and the male was well-fed, but to no avail.  Even the deer-eating Anaconda did not appear quite as stuffed as that male King Cobra!

Rock Python consuming gazelle

Uploaded to Wikipedia Commons by Alex Griffiths

The Largest of all Snake Meals?

The title-holder among giant meal-eaters may well be an African Rock Python that downed a 130-pound Impala (South Africa, 1955).  You can read more about this and similar observations in one of my favorite books, Clifford Pope’s classic The Giant Snakes (1961, A. Knopf, NY).  Even by giant constrictor standards, African Rock Pythons seem unusually well-adapted to taking large meals.  Unfortunately, these snakes have consumed people within their native range, and captives have caused human fatalities here in the USA.

Other Snakes

Harry Greene’s wonderful book Snakes, the Evolution of Mystery in Nature, holds several accounts of large and unusual meals taken by snakes of other species.  As I recall, some prey items neared and even exceeded the mass of the snakes that consumed them!  Don’t miss this book…and please be sure to post your own observations below.

Hi, my name is Frank Indiviglio.  I’m a herpetologist, zoologist, and book author, recently retired from a career spent at several zoos, aquariums, and museums, including over 20 years with the Bronx Zoo.

Please check out my posts on Twitter and Facebook.   Each day, I highlight breaking research, conservation news and interesting stories concerning just about every type of animal imaginable.  I look forward to hearing about your interests and experiences as well, and will use them in articles when possible.

 

Please also post your questions and comments below…I’ll be sure to respond quickly.  Thanks, until next time, Frank.

 

Further Reading

New Reptile and Amphibian Species in 2013

Hi, Frank Indiviglio here.  I’m a herpetologist, zoologist and book author, recently retired from a career of over 20 years with the Bronx Zoo.  Not a week – much less a year – passes without an exciting new herp species being discovered.  Included among this year’s surprising finds are the world’s smallest vertebrate, geckos and frogs isolated on mountaintops for millions of years, a “political” snake, and legless lizards living in and near major US airports and cities.  Please also check out the linked articles to read about large, colorful monitor lizards and other awe-inspiring creatures that were brought to light in the past few years.  Following is just the tip of the iceberg…please be sure to post your own favorite finds below.

New Reptile and Amphibian Species in 2013

Paedophrene amauensis

Uploaded to Wikipedia Commons by Rittmeyer EN, Allison A, Gründler MC, Thompson DK, Austin CC

The World’s Smallest Vertebrate

The distinction of being the smallest creature with a backbone generally shuffles between frogs and fishes (the world’s smallest snake, which can coil up on a dime, is also very impressive).  This year, a tiny Southeast Asian fish that held the title since 2006 was nudged out by a Microhylid frog, Paedophryne amanuensis (shown here sitting on a dime, with room to spare!).  Endemic to Papua New Guinea, adults can be as small as 0.28 inches, while the largest individuals barely top 0.3 inches.  But packed into their minute bodies are lungs, a brain, liver and all other such organs (they do have a uniquely-reduced skeleton, however – compromises must be made!).  By contrast, the Blue Whale, world’s largest vertebrate, tops out at approximately 90 – 100 feet in length.
Read More »

Darwin’s Frog is Extinct – Males “Nursed” Tadpoles in their Vocal Sacs

Hi, Frank Indiviglio here.  I’m a herpetologist, zoologist and book author, recently retired from a career of over 20 years with the Bronx Zoo.  When it comes to inventive – some might say bizarre – breeding habits, amphibians are without equal.  Several, such as the skin-brooding Surinam Toad, are well-known, but recent studies have revealed others that could not have been predicted – i.e. tree-dwelling tadpoles that consume bark and others that gorge upon their father’s skin (which re-grows for their dining pleasure!) or on “egg omelets” whipped up by mom (please see articles linked below).  But even Charles Darwin would be shocked by the habits of a small frog he first described on his famous voyage, the Darwin’s Frog, Rhinoderma darwini.  Males guard their eggs and then gobble them up.  The tadpoles live in the vocal sac, feed upon nutritious parental secretions, and then emerge from their fathers’ mouths as fully-formed froglets!  Sadly, all evidence indicates that this astonishing creature is almost extinct – the latest victim of the infamous chytridiomycosis epidemic.  A related species, the Chilean Darwin’s Frog (Rhinoderma rufum), utilizes a modified version of this bizarre strategy…this species appears to be extinct (please see below).

Darwin's Frog

Uploaded to Wikipedia Commons by Mono Andes

Stomach-Brooding Frogs have also Vanished

A deadly amphibian disease that assumed epidemic proportions approximately 20 years ago has been blamed for the likely extinction of the Darwin’s Frog, the only amphibian known to rear its tadpoles entirely within the male’s vocal sacs.  Read More »

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