That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

The dangers posed by a specific snake species depends upon a great many factors (please see below).  It is clear, however, that venomous snakes are a serious health concern…according to a recent study, each year’s 4.5 million venomous snakebites result in 100,000 deaths and 250,000 permanent disabilities (figures are approximate, please see the article linked below for details).  Certain large constrictors have also caused fatalities. In the course of field research in Venezuela, I observed a Green Anaconda attack a co-worker in what clearly was a feeding attempt.  Please see “Further Reading”, below, to read about both this incident and a recent study of human predation by Reticulated Pythons.   Today I’ll focus on the 2 most dangerous species that I’ve found most challenging as captives – the world’s largest and Africa’s longest venomous snakes, the King Cobra (Ophiophagus  hannah) and the Black Mamba (Dendroaspis polylepis).

 

A Note on “The Most Dangerous”

Widespread species that adapt well to human presence, such as Puff Adders, bite far more people than do, for example, sea snakes and others that might have more potent venom, but which rarely encounter humans.  Wild Black Mambas readily colonize farms and villages, benefitting from the increased availability of shelter and food (rodents, nesting birds).  King Cobras, on the other hand, tend to live in more undisturbed habitats.  Venom evolution, a snake’s size, the availability of antivenin, individual sensitivities and a host of other considerations also complicate the issue.

 

Here I’m mainly considering captive care (in zoos…venomous snakes should never be kept in private collections!).

 

Large, Alert, Fast and Smart!

Cobras and mambas are classified in the family Elapidae, which contains 354 members.  Among them we find several species that are considered to be high-strung and aggressive when confronted.  While King Cobras and Black Mambas often retreat if able, encounters in homes, barns or, in my case, zoo exhibits, may lead to attacks.  And the large size attained by each increases both the potential strike range and the amount of venom that may be delivered by a bite.

 

Another difficulty presented to zookeepers is the fact that cobras and mambas are hard to move via a snake hook.  Incredibly-fast and quick to figure out what’s going on, they more often than not land on the floor when being “hooked”.

 

For safety’s sake, I try to rely upon hunger and other “hands-off” tricks when relocating these formidable creatures (please see below), but that is not always possible.  While rummaging through a storage area in the Bronx Zoo’s reptile house, I once found a homemade shield used decades ago by keepers entering the King Cobra exhibit.  One keeper in particular was said to become very concerned if the cobras seemed hungry, or their cage needed servicing; armed with his shield, he would enter quite often (the King Cobras under my care moved into their shift cage when I needed to enter…or else they remained hungry!).

 

“Curious Cobras”

Those who work with King Cobras often describe them as “curious”.  I can’t disagree, although when servicing their exhibits I found this trait to be un-nerving, to say the least!   Actually, all cobra species I’ve cared for exhibited an unusual degree of alertness, and responded immediately to what was going on around them.  For example, both Egyptian and King Cobras, perhaps sensing my footsteps in the service area behind their exhibits, would rear up and face the small sliding window I looked through before opening their exhibit doors.  As I slid back the window’s cover, a cobra was nearly always peering back at me…in a lifetime of working with snakes, I’ve not seen this done by any other species.

 

My most harrowing King Cobra incident involved an escaped individual at an airport.  Fortunately, I went the “brains over brawn” route and emerged unscathed – much to the disappointment of the several young onlookers who expected a battle!  Please see this article for the details.

 

How Do You Get a Black Mamba into a Pillow Case?

This disturbing question confronted me when I was called upon to ship the Staten Island Zoo’s resident specimen to another institution.  If anything, mambas are faster and harder to deal with than cobras…individuals cornered in homes have quickly caused multiple fatalities.  An adult can deliver 120 mg of venom in a single bite, and the lethal dose is only 10-15 mg, so this is not a creature to be taken lightly.  Again, I shamelessly used under-handed tricks to accomplish my task…please see this article for the details.

 

King Cobra and Black Mamba Natural History

While much is made of the dangers posed by these snakes, less attention is paid to the details of their lives in the wild.  Mamba and cobra diets, breeding behaviors, threat displays and colonization of human-dominated landscapes are especially fascinating, and quite unique.  I’ve written about their natural behaviors in the articles linked below.

 

 

Further Reading

Anaconda Attacks: Notes from the Field

Human Predation by Wild Reticulated Pythons

Venomous Snakebites Worldwide

King Cobra Natural History

Black Mamba Natural History

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

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.

 

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.

 

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.

 

 

Further Reading

Toxic Mice Dropped Over Guam

 

Red Eared Sliders Out-Compete Native European Turtles

 

Recently, 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…

 

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 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!

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.

 

 

Further Reading

I’ve spent decades working with venomous snakes, setting-up snakebite protocols in zoos, and responding to snakebite emergencies.  Today, I’m sometimes criticized for my strong stand against the keeping venomous snakes in private collections.  But I have learned that, even under the best of circumstances, treatment can be hampered by gaps in our knowledge.  For example, we know that the chemical characteristics of venom vary over the ranges of certain species.  This can affect treatment, and, as we’ll see below, may mean the difference between life and death for a victim.  In fact, the venom of some Southern Pacific Rattlesnakes is so unique that it is unaffected by the antivenin currently in use! Are they the most dangerous snake in the USA?

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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.  The magnificent Eastern Indigo Snake, Drymarchon couperi, is the longest of all snakes native to the USA, but occupies one of the smallest ranges.  These facts, along with stunning coloration and its reputation as a responsive pet, place the Indigo on the wish lists of serious snake keepers and zoos worldwide.  I had the good fortune to assist with an Eastern Indigo breeding/release program headquartered at the Bronx Zoo, which was both fascinating and frustrating.  Today I would like to pass along some thoughts on its natural history and captive care.

Description

The Eastern Indigo Snake is among the longest of all North American snakes; in the USA, only the Bullsnake, Pituophis catenifer sayi, regularly rivals it in size.  Robust and alert, the Eastern Indigo Snake averages 5-6 feet in length, with a record of 8 feet, 5 inches.  The glossy, blue-black coloration is unique to this species.  Some individuals, greatly favored in the pet trade, sport heads and chins highlighted by a reddish tint.

Natural History

The Eastern Indigo Snake is restricted to southeastern Georgia, southeastern Mississippi, and Florida.  Although coastal dunes, Palmetto scrub, agricultural areas and marsh fringes are colonized, healthy populations seem to require large expanses of longleaf pine forest and similar upland environments.  Human development within prime Indigo habitat has severely threatened this species’ future.  Today, only captive-born individuals may be legally sold, but over-collection was a severe problem in the past.

The Texas Indigo Snake (D. corais erebennus) ranges from southern Texas to central Mexico, while other relatives, known as Cribos, inhabit Central and South America.

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