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

Although I’ve cared for Latin American and Asian vine snakes in zoos, and have searched their natural habitats, I had somehow missed the fact that one occurs in my own country, the USA. In extreme south-central Arizona may be found a “tropical-looking” snake seems somewhat out-of-place (to me, at least!) – the Mexican or Brown Vine Snake (Oxybelis aeneus). Being rear-fanged, high strung and quite demanding as to its diet, the Mexican Vine Snake is not recommended for other than well-experienced keepers. However, in both behavior and appearance it is most fascinating, and well-worth more interest and study.

 

 

Range and Habitat

 As mentioned, the Mexican Vine Snake is unique among similar species in that its range extends into the USA…but just barely. The US population is limited to the Atascosa, Patagonia and Pajarito Mountains in the south-central tip of Arizona. The remainder of its range is huge, extending from Mexico to Brazil, Peru, and Bolivia, and including the islands of Margarita, Trinidad and Tobago.

The Mexican Vine Snake inhabits relatively arid environments, including dry forest edges, overgrown thickets, wooded grasslands, brushy hillsides and densely-vegetated canyons. In common with the other 3 species in the genus, it is entirely arboreal.

Size and Coloration

Mexican Vine Snakes are very thin and “vine-like” in profile (no surprises there!). Although somberly-colored, their various shades of gray, silver and copper blend together in an attractive manner. A dark line extends from the snout through the eye and down the neck. The chin and area below the eyes are usually bright yellow in color. Typical adults measure 4 1/2 – 5 feet in length.

The Mexican Vine Snake is a rear-fanged species that uses venom to kill its prey (please see below).

Also included in the genus Oxybelis are three other Latin American species, the Green Vine Snake (please see photo), Cope’s Vine Snake, and Roatan Vine Snake.

The Terrarium

Mexican Vine Snakes are best housed in large, vertically-oriented terrariums or custom-built cages. Zoo Med’s Repti-Breeze cage would be a good choice for a moderately-sized individual, but a large adult would require more room.

Climbing space is essential. The enclosure should be provided with numerous branches and tangles of real or artificial vines. Ideally, their living quarters should also be stocked with live plants, which will provide a sense of security and hiding spots. Hanging potted pothos has worked well for me. Most individuals prefer sheltering among plants and vines to hollow cork bark or other arboreal caves. If live plants are not used, hanging artificial plants and dry Spanish moss may be substituted. Mexican Vine Snakes will not thrive in small enclosures, or if denied above-ground cover.

Like many arboreal snakes, Mexican Vine Snakes will drink water sprayed onto the body; some will also accept water from a bowl. As they do not take well to disturbances, cypress mulch or similar materials that allow for spot-cleaning are preferable to newspapers as a substrate. The cage should be located in a quiet area of the home. An ambient temperature range of 75- 80 F is ideal, with a basking site set at 88 F.

Some keepers believe that low levels of UVB light and UVA exposure are beneficial to this and related species.

Diet

The natural diet is comprised of lizards, treefrogs and small birds; small arboreal rodents and insects may also be taken, but detailed field studies are lacking. Brown Anoles, Mediterranean Geckos and several other small lizards that have been introduced to Florida are the most reliably-available captive foods (in my experience, anoles were favored over others). Chicks and pink or fuzzy mice are taken by some individuals. The use of large food items has been linked to intestinal blockages, and I’m not certain that a rodent-only diet would be ideal long-term.

Youngsters feed primarily upon frogs and lizards, and usually refuse all else. Scenting a pink mouse leg with a frog or anole may induce feeding.

Care Notes

Waste must be removed in a manner that does not disturb the snake or expose one to a bite. The cage should be misted lightly each day, but dry conditions should prevail. As individuals offered for sale will likely be wild-caught, a veterinary exam is recommended for all new additions to your collection.

Breeding

Captive breeding has rarely been accomplished, and is not well-documented in the literature. Research into this area by private keepers would be most valuable to this snake and its relatives. Field observations indicate that 4-8 eggs are typically produced.

Temperament

Mexican Vine Snakes are notoriously high-strung, and should be viewed as creatures to observe rather than handle. When approached, they open the mouth to expose its black interior and strike repeatedly (please see photo of Asian Green Vine Snake threat display).

Although the venom produced is not considered dangerous to people, the possibility of an allergic reaction, and the consequences of a bite to a child, elderly person, or immune-compromised individual, must be considered. Your doctor should be consulted before a rear-fanged snake of any species is acquired.

Other Vine Snakes

Asian snakes of the genus Ahaetulla also go by the common name of “vine snake”. Although they closely resemble the New World species in form and habits, they do not appear to be closely related. Several are available in the trade from time to time. I’ve kept the strikingly-beautiful Green or Long-Nose Asian Vine Snake (Ahaetulla nasuta; please see photos) at the Bronx Zoo – the experience was well-worth the time and energy invested in its care! Please post below for further information.

The Cloudy Snail-Eating Snake, Blunt-Headed Treesnake (please see photo) and 1-2 others of the genus Imantodes sometimes appear in the pet trade under various “vine snake” names as well.

 

Further Reading

Rough and Smooth Green Snake Care

Keeping Snakes in Planted Terrariums

The term “rear fanged” is applied to a variety of unrelated snakes that possess a venom-producing gland and 1-3 enlarged, grooved maxillary teeth in the rear of the mouth. We do not yet know how many species possess these venom-conducting teeth (“rear fangs”), but evidence indicates that snake venom evolved some 60 million years ago – before non-venomous snakes came into being. Therefore, all present day species may have evolved from venomous ancestors, and may possess at least the traces of venom glands. The rear-fanged snakebites I’ve dealt with in the course of my career have elicited only mild reactions. Some rear-fanged species, however, have caused fatalities – two very “famous” fatalities, in fact (please see below).

 

Snakes Best Kept in Zoos

As individual sensitivities and other factors can greatly affect one’s reaction to a bite, even “mildly venomous” species must be considered as potentially dangerous. A lifetime of experience as a zookeeper and herpetologist has taught me that it is impossible for a private snake owner to adequately prepare for or treat a venomous snakebite at home, or, prior to a bite, to arrange for treatment in a hospital.

 

Until we learn more about them, rear fanged snakes are best considered as suitable for display in zoos rather than private collections. Tentacled Snakes (Erpeton tentaculatum) and certain others may be an exception, but I advise consulting a herpetologist and an experienced medical doctor if you feel compelled to acquire a rear-fanged snake of any species.

 

 

 

Overview

Rear fanged snakes are classified in the huge family Colubridae (the “Typical Snakes”), but are not necessarily closely-related to one another. The term is applied to a variety of species that possess the venom-producing Duvernoy’s Gland. One, two, or three of the maxillary teeth in the rear of the mouth are enlarged and bear grooves on their front surfaces. Venom released by the Duvernoy’s Gland flows down these grooves and into a prey animal or foe. A period of “chewing”, in the manner of cobras and other Elapids, may be necessary in order to fully discharge the venom.

 

This method of introducing toxins into a wound is rather ineffective when compared to that employed by rattlesnakes and other Viperids. Also, many rear fanged species produce venom that is most or only effective against the specific animals upon which they feed. Therefore, not all present a threat to people.

 

However, much remains to be learned. For example, Boomslangs (Dispholidus typus) and Twig Snakes (Thelotornis kirtlandi) were not widely believed to be dangerous until each killed a prominent herpetologist! (I use “widely” because both were feared by local people).

 

Size

At an adult size of 8 inches, North and South America’s Crowned Snakes, (Tantilla spp.), are the smallest rear fanged species known.

 

Widely-distributed through much of Southeast Asia, the 7-foot-long Mangrove Snake (Boiga dendrophila), is the largest. This spectacular snake’s size and striking coloration render it much desired in the trade, and many are held in private collections. Those I’ve kept in zoos have remained high-strung and difficult to work with. Fatalities have not, as far as I know, been attributed to their bites, but large individuals can store up a substantial quantity of venom – I’d leave these beauties alone!

 

Diet

Many rear fanged snakes have evolved toxins that specifically target reptiles and amphibians, and may specialize in hunting lizards (Mexican Vine Snake, Oxybelis aenus), frogs and toads (Malagasy Giant Hog-Nosed Snake, Lioheterodon madagascariensis) or fish (Tentacled Snake, Erpeton tentaculatum).

 

Others, such as the Mangrove Snake (Boiga dendrophila), are generalists that consume a variety of creatures, including birds and mammals. The tiny Crowned Snakes, Tantilla spp., limit their diet to earthworms, centipedes, beetle grubs, and other invertebrates.

 

“Harmless Snakes” with Venom

Recent research has shown that 2,000 or more snake species, many considered “harmless”, likely produce true venom. Most do not have efficient rear fangs, and produce toxins that pose no danger to people, but this does point out the need for caution and research.

 

 

Further Reading

Venomous Snakebites: My Experiences and a New Study

The USA’s Most Dangerous Snake?

 

Boa Constrictors have been pet trade staples for decades. Of the 10 described subspecies, the Colombian or Red-Tailed Boa (Boa constrictor constrictor) is the best known, and is in fact one of the most popular snake pets. Commercially bred in huge numbers, the Colombian Boa is an excellent choice for some, but not all, snake enthusiasts.

North America’s Rosy Boa (Lichanura trivirgata), on the other hand, has only come into its own recently as a pet, but interest in now skyrocketing. Those with limited space who are seeking a “big snake in a small package” need look no further than this inoffensive beauty.

In the following article I’ll compare the care needs of Colombian and Rosy Boas, so that you’ll be able to plan ahead and maximize your pet-keeping experience and your snake’s quality of life. Detailed care information is provided in the articles linked under “Further Reading”. As always, please also post any questions you may have, and let me know which species gets your vote.

 

Handle-ability

Although individual personalities vary, both adapt well to gentle handling. Rosy Boas tend to hide their heads when frightened, and their smooth, glossy scales may render handling a bit tricky. As with any snake, care and adult supervision must be exercised, and the animal’s head should never be allowed near one’s face.

 

Colombian Boas are not domesticated animals and must never be handled carelessly, as even long-term pets may react to scents or vibrations that people do not perceive. Bite wounds from Colombian Boas can be severe, and pets should never be carried about one’s neck (other similarly-sized constrictors have caused human fatalities by tightening quickly about a handler’s neck). Two experienced adults should always be on hand when specimens over 6 feet in length are fed, cleaned or handled.

 

Size

Colombian Boas average 5-8 feet in length, and are stoutly built. However, some individuals grow quite a bit larger – up to 13 feet, 6 inches and 14 feet for the record holders, both captured in Surinam.

 

Averaging only 24-30 inches in length but also heavily-built for their size, Rosy Boas are obviously much easier than Colombian Boas to house and maintain.

 

Activity Levels

Neither is overly active, but they regularly move between basking sites and shelters, and are likely to wander about the cage when hungry.

 

Life Span

The published longevity for a Colombian Boa is just over 40 years; pets regularly survive into their 20’s and 30’s.

 

The published longevity for a Rosy Boa is 29+ years (living at time of publication), and many captives approach and exceed age 20.

 

Breeding Potential

Both species breed reliably, and make an excellent introduction to this fascinating aspect of reptile-keeping. I especially like the fact that they bear live young, doing away with the time, expense and worry (for us!) of egg-incubation.

 

Cost

The purchase price for a normally-colored individual is similar for both snakes. Prices increase for rare or unusual color morphs – to $5,000 or more for “special” Colombian Boas!

 

However, the normal coloration of each species is spectacular, and natural variations, especially for the Rosy Boa, are seemingly endless. Several Rosy Boas that I encountered while studying insects in Baja California, which were blue-gray and marked with 3 pinkish-orange stripes, stand out as being among the most beautiful snakes I’ve seen.

 

The Colombian Boa’s great size makes it vastly-more expensive to keep when compared to its smaller cousin, the Rosy Boa.

 

Terrarium Size (single adult)

Colombian Boa: 250-300 gallon terrarium or a huge custom-built cage

 

Rosy Boa: 20-30 gallon terrarium

 

Temperature

Colombian Boa: 75-85 F, with a basking site of 90 -95 F; basking bulb and sub-tank pad recommended.

 

Rosy Boa: 75-85 F, with a basking site of 90-95 F

 

Diet

Food intake will vary among individuals and with temperature, season, life cycle stage, and other factors. Both accept pre-killed rodents.

 

Colombian Boa: 1 appropriately-sized mouse each 7-10 days for youngsters. Adults do fine when offered an appropriately-sized rat each 10-14 days. Some keepers use guinea pigs or small rabbits for especially-large adults.

 

Rosy Boa: Fuzzies and young mice are preferable to adult mice (Rosy Boas have rather small heads and their jaws are ill-suited to swallowing large meals). Youngsters should be fed each 7-10 days, adults each 10-14 days.

 

 

 

Further Reading

Breeding the Rosy Boa

Boa Constrictors and Their Relatives: Care and Natural History

 

 

 

Powerful and boldly-marked, the Russian Ratsnake (Elaphe schrencki)  is one of the largest of the robust constrictors commonly known as ratsnakes. Even those with a lifetime of snake experience (myself included), are awed by their first encounter with this impressive beast. To me, it’s always seemed somehow fitting that such spectacular creatures as the Siberian Tiger and Amur Leopard share the Russian Ratsnake’s range. Also known as the Amur Ratsnake, Siberian Ratsnake, and Manchurian Watersnake, it has long been hard to come by, but European and American snake enthusiasts are now producing captive bred animals regularly.

 

Rat Snake Description

An indigo to black background marked with bright yellow or white cross-bars renders the Russian Ratsnake a most striking creature. One of the longest snakes in northern Asia, it may reach or slightly exceed 6 feet in length.

 

A number of interesting color morphs, such as all-black, white-blotched, striped, and high-gold, as well as hybrids with Japanese Ratsnakes (E. climacophora; please see photo), have been developed by breeders.

Range and Habitat

The Russian Ratsnake’s range is centered in Siberia’s Amur River Basin, and radiates out to eastern Mongolia, northern and central China and Korea. An introduced population is established in Elder, the Netherlands (I almost instinctively typed “Florida”!). This group apparently originated from animals that escaped local greenhouses, where they are kept as a rodent-control measure. The government is studying their effects on local wildlife and eradication possibilities.

 

Russian Ratsnakes are usually found near a water source, and adapt to temperate forests, alpine woodlands, marshes, overgrown fields, brushy scrub, agricultural areas and a variety of other habitats. Like Texas Ratsnakes and other American species, Russian Ratsnakes often colonize farms, where they are alternately valued as rat-killers and reviled as chicken thieves. Excellent climbers, they seem equally at home on the ground or in trees.

The Terrarium

Those experienced with Corn Snakes and related species will find Russian Ratsnakes to be more active than their American counterparts. They should be provided with proportionally larger accommodations. While a 55-75 gallon aquarium will suit small adult, larger individuals are best housed in custom-built cages measuring at least 6 x 5 x 5 feet. Ample cage height and stout climbing branches will be appreciated.

 

Cypress mulch, eucalyptus bark and similar materials may be used as a substrate. In common with Indigo Snakes and other active, robust reptiles, Russian Ratsnakes tend to make a mess of the old snake substrate standby, newspapers. A dry shelter and another stocked with moist sphagnum moss should be provided.

 

Ambient temperatures should be maintained in the range of 70-76 F, with a basking site of 82 F.

 

Breeding

Captive breeding, although far from regular in the past, is becoming more common. A 3-4 month cooling off period at 50-52 F will stimulate reproduction.

 

Clutches range from 6-30 eggs in size, and are usually deposited in June-July. As an adaptation to the short summers in their native range, female Russian Ratsnakes retain their eggs for a time, and deposit them in a well-advanced state. At an incubation temperature of 82 F, they typically hatch within 40 days.

 

The hatchlings measure 11-15 inches in length and differ markedly from adults, being light gray in color and sporting black specks and reddish blotches.

 

Diet

The Russian Ratsnake’s appetite knows no bounds. Wild individuals take squirrels, rabbits, bats, gerbils, birds and their eggs, voles, chipmunks, and many other creatures with equal gusto. Pets do well on a diet comprised of mice and rats; large adults will accept guinea pigs and weanling rabbits as well.

 

Temperament: Most individuals are quite calm in demeanor once accustomed to their surroundings. However, as with all large snakes, one must exercise appropriate caution when they are handled.

 

 

Further Reading

Black Ratsnake Care

Keeping the Red-Tailed Ratsnake

Working with Spitting Cobras has been a fascinating, if sometimes un-nerving, experience. In addition to being able to deliver venom via biting or ejection through the air, Spitting Cobras also have the alertness and speed that is typical of nearly all the world’s 353 Elapid species. On two occasions, I’ve had to re-capture a total of 6 escaped Red Spitting Cobras (Naja pallida) – once because a man helped his little son to kick in the glass of an exhibit at the Bronx Zoo! (please see article linked below) But despite these incidents, and decades of working closely with related species, the only venom to wind up in my eyes came not from a Spitter, but rather courtesy of a species that “cannot spit” – the Western Diamondback Rattlesnake (Crotalus atrox).

 

 

Illegal Rattlesnakes: Live and Cooked

Most of the obvious risks associated with venomous snake care are easy to avoid (in a reputable zoo, that is…one cannot properly prepare for a bite delivered by a snake in a private collection). When working with Spitting Cobras, for example, safety glasses are always worn. Emergencies occur, of course, and then you must sometimes make do without. In the escape mentioned earlier, for example, I arrived on the scene not knowing that Red Spitting Cobras were involved, and I had to immediately evacuate visitors, many of whom were children, from the area.

 

But, as in most fields, the greatest dangers arise from unexpected situations – those that we don’t imagine or believe can happen. This was the case one day when I was in a Bronx Zoo holding area, checking on some newly-arrived Western Diamondback Rattlesnakes. The snakes had been confiscated the night before, in a store in NYC, of all places. Several police officers had entered following a report of a burglary, and found snakes instead of criminals. The snakes, mainly Western Diamondbacks, were being held in a variety of slip-shod containers; several dead individuals were in cooking pots, alcoholic drinks, and “medicines”. As usual, the Bronx Zoo was summoned.

 

“Hey…Rattlesnakes Can’t Spit”

Co-workers and I had installed the snakes in screen-topped aquariums in an isolation room at the zoo’s Reptile House. As is dictated by protocol (and common sense!), I was careful not to lean on any screen tops as I checked the animals. All were highly agitated. Unable to see one individual clearly through the tank’s glass side, I peered down into the screen top. The snake struck at the top, and I instantly felt a splash of liquid in both eyes.

 

The standard wisdom is that only Spitting Cobra venom can cause eye damage. In the rare event that another type of venom enters the eye, it needs merely to be washed out; a follow-up with a doctor, to assure that an infection does not take hold, should follow. But this incident was unique for two reasons. First, the force of the snake’s strike against the screening had propelled the venom into my eyes. Second, I had just returned to work following a cornea transplant. There were numerous stitches in my eye, and they were not all that stable.

 

I felt a stinging sensation (which is not typical for other than Spitting Cobra venom) and thought that perhaps the venom had seeped under my cornea through the stitches. I wondered if the transplant could be ruined, and if I might suffer a typical envenomation as well, once the venom moved further along in my body.

 

Just When You Thought You Had Seen Everything…

The Bronx Zoo’s snakebite protocol relies upon the NYC Police Department for transport to the hospital. Fortunately, several NYPD Officers are always on the grounds. I was on friendly terms with all – one, in fact, was a former BZ animal keeper, and all were top-notch. It’s hard to surprise an officer who’s spent some time in the Bronx, but I did a good job that day! In less time than I could imagine, I was at Jacobi Hospital being attended to by a young doctor who, after some time in a busy Bronx emergency room, thought he had seen it all!

 

All went smoothly, and I suffered no symptoms of envenomation. It would have been interesting to learn if the venom had entered my body via a cornea stitch, but in those years Bronx hospitals were unbelievably busy (often with unbelievable, at least to me, cases) and there was no time for speculation or experimentation – I was shuttled out as quickly as I’d arrived!

 

 

Further Reading

A Close Call with a King Cobra

Snake Escapes!