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

Females of many animal species are polyandrous, meaning that they mate with several males. Often, we are learning, the sperm survives for some time inside the female, and competes with the sperm of other males. In this way, only the “fittest” sperm will prevail and fertilize the eggs, assuring vigorous offspring. Females choose mates based on a wide variety of factors, and the criterion used by Australia’s painted dragon lizards turn out to be quite unique.

In contrast to most lizards, male painted dragons have either red or yellow heads, and are chosen by females based on their head color. Research published this week (Wollongong University) has revealed that female dragons do not choose 1 color over another, but rather seek to mate with 1 male having a red head and 1 with a yellow head.It is theorized that by choosing males of both colors, the female is assuring that she is mating with more than 1 male, and not with the same male twice.

Polyandry among reptiles can result in amazing spectacles – I shall never forget the sight of a huge “breeding ball” – 9 males and 1 female- of green anacondas, Eunectes murinus, on the Venezuelan llanos. In many different animals, sperm can remain alive and able to fertilize eggs for years to come. Queen termites mate once and somehow produce fertilized eggs for up to 20 years after!

Further information concerning research with this species at Wollongong University is available at:

http://www.ncbi.nlm.nih.gov/pubmed/16254915

The prevention and treatment of disease in captive reptiles and amphibians has advanced greatly in recent years. Unfortunately, however, there is still a great deal that baffles us — our knowledge of amphibian medicine in particular is quite poor. On the positive side, we do know a quite a bit about the diagnosis and treatment of disease in tropical fishes, and much of the basic research behind this is applicable to amphibians.

General Notes Concerning Amphibian Health Care
Among the most important steps you can take to insure the health of your pet amphibians is to establish a relationship with a qualified veterinarian. Veterinary practices specializing in amphibian medicine, although by no means common, are on the increase. Your local herpetological society should be able to provide some leads.

Many medications designed for use with aquarium fish work well on related conditions in amphibians. Bare in mind, however, that amphibians absorb medication over a much greater area surface area that do fish — in many cases, the entire skin of the amphibian will allow transfer of the medicine. Although I have had success using certain medications in the same dosages as are recommended for fish, I always begin treatment with a 50% dilution and watch carefully for signs of stress (gasping, swimming about wildly, scratching, skin sloughing).

Good hygiene is the basic starting point for avoiding sickness, and, in some cases, even for treatment. Again, the porous nature of amphibian skin is a consideration – ammonia from waste products and other toxins in the terrarium will be absorbed through the skin if not removed.

Bottled spring water (not distilled water) should always be on hand. Salamanders and frogs suffering from ammonia or other chemical toxicity can sometimes be revived by placing them in such water and allowing it to flush harmful chemicals from the body.

Considering how little we know concerning the treatment of disease, prevention is vital. Always be sure to keep your pets in a secure, stress-free environment and provide each species with the appropriate temperature, humidity, light cycle and diet.

Amphibian skin is extremely delicate, and its mucous covering repels attacks by harmful microorganisms. Extreme care must be taken in administering injections and in handling frogs and salamanders. Amphibians should be held with wet hands only, or confined within a water-filled plastic bag when being examined. Catching a frog or salamander with a stiff nylon net may also remove some of the skin’s mucous coating and expose the animal to bacterial infection. When in doubt, use a preparation designed to replace the mucus coating of aquarium fish.

Due to the nature of reptile and amphibian circulatory systems, injections of most medications are given in the front legs. If multiple injections are needed, a different leg, and a different site on each leg, should be used. This will go a long way in avoiding damage to the delicate skin.

The details of all the medical treatments administered to your pets should be recorded. Not only will this prevent mistakes, especially when you’re experimenting with different dosage levels, but a record of what you have done will also be very useful to yourself and others in the future, and may even lead to a new discovery. Trust me on this – write it down, you will not remember in years to come!

Overview
The black rat snake and the related corn snake, E. guttata, were among the first to become firmly established in North American herptoculture, and remain pet trade staples. At least 11 species of the genus Elaphe are found throughout North and Central America.

The taxonomy of this genus is confusing due to a wide variation in the appearance of individuals of the same species, and to the fact that different species inter-breed where their ranges overlap. The black ratsnake was formerly known as E. obsoleta, but that name is now assigned to the Western ratsnake. Recently, genetic evidence has shown that many North American ratsnakes should actually be classified within the genus Pituophis, along with the bull, gopher and pine snakes.

Physical Description
Although usually a uniform black in color, with an off-white underside, some individuals show traces of dark gray blotches and stripes. Juveniles differ markedly from adults, being pale gray and strongly patterned in dark gray or brown. Hobbyists have developed a number of unique color morphs, including albino individuals, and frequently hybridize this snake with related species. Black ratsnakes average 3 – 5 ½ feet in length, with the record holder being a giant of 8 ½ feet recorded from Westchester County, NY by noted herpetologist Raymond Ditmars.

Black ratsnakes living from North Carolina through the Florida Keys vary greatly in appearance from northern specimens, being various shades of yellow and orange in color. Formerly classified as distinct subspecies, known as the Everglades’s ratsnake and yellow ratsnake (both popular in the pet trade), they are now considered to be local color variations of the black ratsnake.

Range and Habitat
Black ratsnakes occupy much of Eastern North America – from SW New England and S Ontario to the Florida Keys and from SW Wisconsin to Oklahoma and N Louisiana. Happily for NYC-based “herpers” such as I, they are still to be found within NYC limits (parks in the Bronx and Staten Island), and in suburban Long Island and Westchester. Quite adaptable as regards habitat, they utilize forests, fields, rocky hillsides, swamps and overgrown suburban lots. It is one of many snake species drawn to farms, stone walls, trash dumps and abandoned buildings in search of mice and rats. In some habitats, black ratsnakes are highly arboreal and shelter in tree hollows.

Status in the Wild
Population levels appear stable in most areas, although the species is listed as of “Special Concern” in Minnesota and elsewhere. It adjusts well to some human presence and, if left alone, may become common on farms and near refuse disposal areas. Large scale captive breeding has removed collection pressures from wild populations.

Diet
Black ratsnakes are powerful constrictors. They tend, as adults, to focus on mammalian prey such as squirrels, chipmunks, rabbits, bats, voles, deer mice, rice rats, small opossums and similar creatures, but also take birds and their eggs. Young snakes include lizards, frogs and large insects (i.e. cicadas) in their diet.

A colleague of mine observed 6 foot-long (yellow-phase) black ratsnake attempting to constrict a white-tailed deer fawn on St. Catherine’s Island, Georgia. The fawn, which might have set a new “snake swallowing record” had it been overcome, eventually escaped.

Reproduction
Mating occurs from March to May, with 6-30 eggs being laid 27-28 days thereafter. Second clutches, laid in August, have been reported in captive situations but not in the wild. The eggs are secreted in cavities below fallen trees and rocks, or within rotting logs and stumps. The young, 11 – 13 ½ inches in length, hatch in 47-85 days.

Miscellaneous
The black ratsnake frequently shares hibernation dens with rattlesnakes, copperheads and other species. In some parts of the country it is known as the “pilot blacksnake” or “rattlesnake pilot”, in the mistaken belief that it guides rattlesnakes to their winter retreats.

Black Ratsnakes as Pets

General
With their moderate size and even temperaments, black ratsnakes make excellent pets. They are hardy enough for beginning hobbyists, and yet are so interesting that even well- experienced keepers often reserve a place for 1 or 2 in their collections.

Space and Other Physical requirements
Black ratsnakes do well in glass terrariums or aquariums which, ideally, should be a bit longer than the snake itself and as wide as possible. Be sure to secure the tank’s screen top with cage clips, as snakes are notorious escape artists. Cypress mulch or other substrates designed for use with snakes should cover the cage bottom. A reptile-safe disinfectant should be used to swab the cage floor after the snake defecates.

Rat snakes appreciate a shelter in which to hide and a bowl large enough for soaking. The water bowl should be filled to a level such that it will not overflow when the snake enters, as damp terrarium conditions may lead to respiratory and skin infections. If space permits, a stout branch for climbing and basking should be included.

American hobbyists favor a fairly “sterile” set up for rat snakes, but in Europe they are commonly kept in large, planted exhibits. Black ratsnakes take well to these, and, while management is a bit more complicated, the range of behaviors exhibited by snakes in such settings makes the undertaking well-worthwhile. I shall write more about keeping snakes in naturalistic exhibits in a future article.

Light, Heat, Humidity, etc.
Cage temperatures should range from 75 – 82 F, with a basking spot of 88 – 90 F. This species has no need for UVB light, but full spectrum lamps emitting UVA may be of some value. The cage should be kept dry at all times (see above).

Feeding
Black ratsnakes thrive on a diet of mice and rats. They take readily to dead prey and should not be offered live rodents due to the likelihood of injury to the snake. Adults should be fed every 7-10 days.

Captive Longevity
The captive longevity record for this species is just over 34 years.

Handling
Although black ratsnakes will, like most animals, bite in self-defense, they are, as a whole, mild-tempered. Most respond well to gentle handling, but individual animals vary greatly in this regard. Never startle a snake by picking it up suddenly, and do not handle snakes after you have touched food animals. Future articles will deal with the specifics of handling in detail.

Breeding
Breeding will be covered in depth in a future article. Except for snakes originating in the southern-most portions of the range, black ratsnakes breed most reliably when subjected to a winter cooling period. This species has been bred in captivity through multiple generations.

Miscellaneous
A number of European and Asian relatives, such as the Russian ratsnake, E. schrencki, may be kept as described for the black ratsnake. Other species referred to as “ratsnakes”, such as the arboreal red-tailed ratsnake, Gonyosoma oxycephala, have slightly different husbandry requirements. Please be sure to research potential pets carefully, as trade names can be misleading.

Additional Resourceshttp://people.wcsu.edu/pinout/herpetology/eobsoleta/index.html (detailed information on natural history)

Although species and individuals varied markedly in their capacities, one constant seemed to be that all recognized and responded to changes in their normal routine. This makes sense, of course, from the viewpoint of survival, but I was none-the-less always impressed by the rapidity at which most learned.

Rhinoceros iguanas, Cyclura cornuta, and water monitors, Varanus salvator, were particularly striking in this regard. Animals in the collection for over 15 years, long in the habit of approaching or ignoring a single keeper in their exhibit for routine maintenance, would flee if 2 people entered. It took but 1-2 incidents for them to learn that 2 people meant trouble – i.e. a veterinary exam, but that 1 person meant no harm. The animals unfailingly retained this knowledge over a period of years, even without reinforcement by new events.

An interesting article on intelligence in monitor lizards is posted at:
http://findarticles.com/p/articles/mi_m1134/is_9_112/ai_110737007