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

Southeast Asia’s bizarre tentacled snake (Erpeton tentaculatum) is a long-time favorite of mine and I’ve kept and bred a great many in zoo collections over the years.  Despite watching them intently for so long, I’ve never quite been able to figure out how they manage to so effectively catch fast-moving fishes while striking out in a direction that seems designed to insure that they miss the intended target.

A Unique Escape Strategy

Recently published (Vanderbilt University, Tennessee: June, 2009) research has provided the answer.  Many fishes, it seems, utilize an escape maneuver known as the C-Start.  Upon sensing danger, the body contorts into a “C” shape, the tail is flicked and the fish, in a millisecond, darts away.

Exploiting the Defensive Maneuver

Tentacled snakes, anchored to submerged objects by their tails and resembling water-logged roots, lie in wait for passing fishes.  The snake always holds itself in a very distinctive “J” shaped position.  As a fish approaches, the snake “feints” with its body by sending a ripple of water towards the fish.  This incites the C-Start reaction and propels the fish directly toward the snake’s jaws.

Once initiated, the C-Start maneuver cannot be altered, so the hapless fish is doomed.  The snake’s “J” position allows it to strike not at the fish but rather where the fish will be once it flees.  What’s more, the strike nearly always catches the fish in the head region, assisting the snake in swallowing its slippery prey.

Further Reading

To learn more about the natural history and captive care of tentacled snakes, please see my article The Tentacled Snake, an Unusual Pet Serpent .

 

Watersnakes are largely ignored by herptoculturists, and I’ve never quite understood why. Hardy, prolific, and often colorful, their utilization of two habitats makes for very interesting observations. Today I’d like to focus on the northern watersnake (Nerodia sipedon sipedon), and to mention a few others.

Description
Background color varies through shades of pale gray to dark brown, with reddish to black cross-bands. Juveniles are brightly marked, while the colors of older animals usually darken. Stoutly built, the northern watersnake may reach 4 ½ feet in length, but averages 3 feet.This species interbreeds with its subspecies, the midland water snake, which may confuse identification at range overlaps.

Range
The range extends from southeastern Quebec, Canada to North Carolina, Alabama and Mississippi. Related subspecies occur as far west as Colorado.

The endangered Lake Erie water snake (N. s. insularis), a subspecies of the northern, is found only along Put-In-Bay, Lake Erie.

Habitat
The northern water snake frequents swamps, ponds, lakes, rivers and streams. It rarely strays far from the water’s edge, but frequently basks on logs and overhanging branches. Although preferring quiet waters, I sometimes encounter them along swiftly flowing rivers.

Status in the Wild
This snake can build up large populations in suitable habitat but, in my experience, does not adjust well to human presence (it is sometimes killed in the mistaken belief that it is venomous and reduces game fish numbers).

Several years ago I visited formerly well-populated ponds on Long Island, NY, as part of a government-sponsored survey. Despite adequate habitat and a healthy prey base, I found nearly all to be barren of snakes, and local fishermen confirmed their absence.

Diet
Watersnakes seem almost “crazed” when food is scented. Legendary reptile man Raymond Ditmars reported catching them on fishes tied to a string, a feat I repeated a half-century later with admirable results. I have also taken them in minnow traps.

Watersnakes feed upon a wide variety of frogs, tadpoles, salamanders and fishes and crayfishes.

Reproduction
Mating occurs in early spring. The young, 9-100 in number, are born alive after a gestation period of 2-3 months (March-July).

Miscellaneous
This snake was once common within NYC but has declined dramatically. I re-introduced it to the grounds of the Bronx Zoo in 1986, and a small breeding population is now to be found there.

Northern water snakes are harmless but aggressive when disturbed, and are often mistaken for the venomous water moccasin. The confusion is greatest in the Southeastern USA, a watersnake-lovers paradise, home to 12-15 subspecies. The massive Florida green water snake (N. floridana) reaches 6 feet in length and even holds its mouth open when threatened, in a manner reminiscent of the moccasin’s display.

Various watersnake species regularly hybridize, producing a bewildering array of forms in the species-rich southeast. Despite the passage of over 20 years, I still clearly recall a gorgeously-patterned individual that I narrowly missed capturing in south Florida. It was almost certainly a mangrove watersnake (N. clarkii compressicauda), perhaps hybridized with a Gulf salt marsh or Florida watersnake. I realize that my awe seems odd in these times of captive-bred “designer snakes”, but to encounter such a creature in the wild was quite a thrill.

 

Further Reading
You can learn more about the natural history of the 10 Nerodia species at http://www.jcvi.org/reptiles/search.php?submit=Search&exact%5B%5D=genus&genus=Nerodia.

Nerodia sipedon image referenced from Wikipedia and originally posted by Brian Gratwicke

Nerodia rhombifer image referenced from Wikipedia and originally posted by LA Dawson.

Please see Part I of this article for further information.

Handling and Enrichment

Red-tailed ratsnakes are best suited as exhibit animals.  Most do not hesitate to bite when approached, and fight vigorously when restrained.  Some may become moderately tame, but such individuals must be watched closely and not allowed in the vicinity if one’s face or near children (or, obviously, your parakeet!).

Naturalistic terrariums suit red-tailed ratsnakes well, but it can be difficult to remove them from among vines and branches.  A tall cage that allows you to clean while the snakes remain safely overhead will go a long way in reducing stress on both the snakes and yourself (not to mention wear and tear on your skin!).

They are very alert – “scenting” the cage with novel odors – i.e. a snake or lizard shed, or an egg – will keep the snakes occupied and provide a peek into their foraging behaviors (in zoo circles, this long-known practice is now termed “enrichment” and is currently very much in vogue).

Breeding

Red-tailed ratsnakes under my care and housed together in pairs have bred throughout the year without being subjected to a variation in temperature or humidity levels.  Others have bred after being subjected to a 3 month period at 70 F, during which time they had access to a basking site of 76 F.  Given their wide distribution in the wild, I suspect that these snakes are quite adaptable in this regard, or that populations vary in their breeding biology.

Most females that I have kept produced 2-3 clutches per year, with one female laying 3-4 times each year for a period of 8 years or so.  Gravid females seek secluded, moist sites in which to lay their eggs; damp sphagnum moss within a cave,  flower pot, or cork bark retreat is ideal.  Some individuals seem to prefer elevated nest sites; perhaps in the wild eggs are sometimes deposited in tree hollows and similar situations.

Please see “Reproduction” in Part I of this article for further details.

Jansen’s or Sulawesi Black-Tailed Ratsnake

The red-tailed ratsnake’s closest relative, and, per recent taxonomic changes, the only other member of the genus Oxycephala, is the Jansen’s ratsnake, also known as the Sulawesi black-tailed ratsnake, G. jansenii. 

Limited in distribution to Sulawesi, Indonesia and some small nearby islands, this gorgeous snake is variably colored in black-flecked olive or tan, and sports a black tail.  Those on Sulawesi are heavier-bodied than typical red-tailed ratsnakes, and are said to spend a good deal of time on the ground. Specimens from Salayar, an island south of Sulawesi in the Flores Sea, are pure black and quite striking in appearance.  Thinner in build than their relatives on Sulawesi, they are, like red-tailed ratsnakes, highly arboreal.

Although not widely available at this point, Jansen’s ratsnakes are prized by collectors and will likely become established in the trade in time.

Further Reading

An interesting review of the 55 snake species that inhabit Sulawesi is posted at http://www.seh-herpetology.org/files/bonnensis/035_DeLang.pdf.

The range of the Taiwan beauty snake overlaps with that of this species, and their husbandry needs are similar.  Please see my article The Natural History and Captive Care of the Taiwan Beauty Snake  for further information.

 

Image referenced from Wikipedia.

 

My first contact with the strikingly marked red-tailed ratsnake came many years ago, when they were rarely seen in the pet trade.  It was a wild caught adult and showed up, unexpected, in an order sent to an animal importer for whom I worked at the time.  She would eat only birds, which, fortunately for her, were in good supply (bird imports in those years were not well managed, and shipping-related deaths were all too common).

After a few months, she was so set on an avian diet that even bird-scented rodents would not pique her interest.  Eventually, the snake was purchased by one of the few people who could supply her preferred diet – a hobbyist with access to inexpensive chicks from the chicken farm near his home on Long Island!

NATURAL HISTORY

Classification

Red-tailed ratsnakes are placed within the family Colubridae.  They were formerly classified, along with corn, black rat and similar North American species, in the genus Elaphe.

In the pet trade, red-tailed, mandarin and bamboo rat snakes, along with Taiwan beauty snakes and similar species, are often collectively referred to as Asian or Old World ratsnakes.

Physical Description

These slenderly built snakes vary widely in color throughout their huge range, but are generally pale to emerald green, with a red or reddish tail.  A yellow band of varying width separates the green and red-colored areas.

Gray and silver individuals are common in Java, and yellow specimens are known from Thailand and the Philippines.  Orange and yellow/black speckled strains are being selectively-bred in the pet trade.

Red-tailed ratsnakes average 5 feet in length, with rare individuals reaching 7.5 feet.  Females are generally longer and stouter than males.

Range

Red-tailed ratsnakes range widely throughout south and Southeast Asia, and occur in Myanmar, Cambodia, Indonesia, Laos, Malaysia, Thailand, Vietnam, the Philippines and on the Andaman and Nicobar Islands off India.

Habitat

Mangrove swamps, primary rainforest, bamboo forests, overgrown fields, agricultural areas, brushy areas on village outskirts and large parks.

This snake is highly arboreal, often dwelling 40 feet or more above the ground, but occasionally descends to earth in search of prey.  In some areas, it is said to frequent timber and thatched-roofed dwellings.

Status in the Wild

This species’ status in the wild is largely unstudied, but they are likely threatened due to habitat loss in many areas.  However, if unmolested, red-tailed ratsnakes will take up residence on farms and near houses, where they prey upon the rodents and birds that frequent these areas.

Diet

Bats, mice, rats, squirrels and other mammals, birds and their eggs, treefrogs and lizards.

Prey is killed by constriction; the tail is highly prehensile, allowing for long strikes at fast-moving, arboreal prey.

There is some evidence that, especially in young animals, the red-tipped tail is waved as a lure to attract frogs, lizards and birds to within striking range.

Reproduction

Mating occurs during the rainy season, which over much of this snake’s range falls between November and March.  The eggs, 5-8 in number, are laid approximately 60 days after mating.  The clutch is deposited in a sheltered, moist location, sometimes within moss and epiphytic plants among tree branches.  The young hatch in 100-140 days, and are 12-18 inches in length.

Well-fed females can lay up to 4 clutches each year, an unusually large number for a snake.

Miscellaneous

The ratsnake’s color offers exceptionally good camouflage among vines and tree branches, and this is its first line of defense.  However, even when there is an opportunity to flee, disturbed individuals often stand their ground.

When threatened, red-tailed ratsnakes compress and inflate the first third of the body while rearing up in an “S” shaped coil.  If this display fails to intimidate the foe, they strike repeatedly.

Check back soon for an article on the captive care of the Red-tailed Ratsnake.

Image referenced from Wikipedia.

Iridescent coloration is exhibited many snakes, but in none is it as spectacular as that featured by the rainbow boa (Epicrates cenchria cenchria).  The “glow”, of its brilliant coloration, caused by microscopic scale ridges that refract sunlight, have long made this species a pet trade favorite.

A rather plain colored (and less expensive!) subspecies often disappoints novices who expect it to bloom into a sparkling beauty.  This snake has now been reclassified as a distinct species, the brown or Columbian rainbow boa, Epicrates maurus.

Classification

There are 8 rainbow boa subspecies, and 11 species within the genus Epicrates.  One subspecies, E. c. barbouri, is limited in distribution to Brazil’s Marajo Island.

Interestingly, molecular research carried out in 2006 indicates that the rainbow boa is more closely related to the anaconda than to other members of its genus.

 

Physical Description

Rainbows average 5 feet in length, with exceptional individuals nearing 7 feet.  They vary in color from red to orange/mahogany-brown, and are patterned with dark lateral rings and spots.  In sunlight, the colors are brilliantly iridescent.

Range  

The most commonly available subspecies, E. c. cenchria, is found from southern Venezuela, Guyana and Surinam south through Brazil’s Amazon Basin.

The various subspecies occupy much of Central and South America, from Costa Rica to Argentina.

Habitat

Rainbow boas may be found in wet and dry forest, scrubland, savannahs, farms and village outskirts.  They are largely nocturnal, but may be about by day during the cooler seasons.

Status in the Wild

If unmolested, rainbow boas will colonize farms and other developed areas that support large rodent populations.  In some regions, however, they are threatened by deforestation and other forms of habitat loss. Listed on CITES Appendix II.

Diet

Opossums, rats, mice, squirrels, bats, rabbits and other mammals are favored, but chickens, jacanas, iguanas, tegus and a wide variety of other animals are taken.

Like all boas, the rainbow has facial pits along the upper and lower jaws that detect heat, allowing it to locate warm-blooded prey at night.

Reproduction

Females give birth to live young after a gestation period of 8-12 weeks.  The number produced ranges from 2-35, and, at 15-20 inches long, they are relatively large for a snake of this size.

CAPTIVE HUSBANDRY

Light and Heat

Captive care for rainbow boas presents few difficulties, and captive longevity approaches 25 years.  Ambient temperature should be maintained at 80-85 F, with a basking site of 90 F.  Temperatures can be reduced to 75-80 F at night.

Boas do not require UVB light, but may benefit from the provision of UVA.  The Zoo Med Halogen Bulb  provides UVA and heat…a Ceramic Heat Emitter is useful for night-time heating.  A Night Viewing Bulb  will emit heat at night without disturbing your pet’s natural cycle, and will enable you to view its nocturnal activities.

Diet

Wild-caught individuals that I worked with in zoos years back were notoriously picky eaters, often holding out for chicks, spiny mice, gerbils or other such fare.  Captive bred rainbows readily take rats and mice, although they sometimes switch preferences from one to the other.

Please write in with specific husbandry questions, and see my other snake articles, such as The Captive Care of the Ball Python, for general care guidelines.

Further Reading

You can read about rainbow boa subspecies and related snakes such as the Cuban boa at http://www.jcvi.org/reptiles/search.php?submit=Search&genus=Epicrates.

 

Image referenced from Wikipedia and originally posted by KaroH.