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Introduction
 
Captive-bred colubrids are some of the most popular pet snakes in the world today. Dedicated hobbyists are breeding these wonderful animals every year, making it easier to acquire many varieties of kingsnakes, milksnakes and ratsnakes, especially here in the United States. Captive bred specimens are generally heartier and more colourful than wild-caught specimens, and their accessibility through breeders helps alleviate stress on wild populations and destruction of natural habitats from over-collecting. In the wild, daylight is constantly changing and a wide range of temperatures is provided for these animals. Their biological rhythms are cycled as the light and heat change throughout the seasons. Through this natural process, they know to hibernate in winter, emerge and feed in spring and seek mates with which to breed.
 
Seven years ago I got hooked on these colourful colubrids through my experience as a veterinary technician. Gaining knowledgeable advice from my veterinarian and many experienced breeders from across the US, I began the process of selecting and acquiring suitable enclosures and healthy animals. I wanted to provide an environment that would simulate nature as closely as possible for my snakes. When they are more comfortable in their surroundings they are less stressed, resulting in contented, healthier animals that are more likely to breed than they would in a less desirable environment.

There are many acceptable ways to house these animals that are much less pricey and/or complex than the method I chose I selected a cage style that provides them with several niches to use and one that incorporates the necessities to properly cycle them to produce healthy offspring. I attribute their health and success at breeding to this captive environment combined with proper husbandry techniques.

The habitats are made of polyurethane stained plywood, have sliding glass doors across the front, fine-mesh screening on the upper half of the rear panel for proper ventilation, and a false floor. There are two drawers under this floor. Access from each drawer to this upper level is via a tube crafted from two-inch ABS pipe. This system provides enough living space for one large and up to three smaller colubrids. In one drawer, as on the upper level, course pine shavings are used for a substrate, while in the other drawer I use moistened vermiculite in a plastic shoe-box that conveniently fits the drawer dimensions. The snakes may choose to stay in either wet or dry dark areas or on the large lighted upper level where their water bowl is located. Several of my snakes spend most of their time in the vermiculite drawer which provides them the necessary humidity they need, especially when its time for them to shed.

A fifteen-watt incandescent bulb is provided in each cage. A glass jar serves as a lamp globe to prevent the snakes from being burned. To control the unwanted heat from these bulbs, a light dimmer is used during the hot summer months. The lights are also connected to a timer to automatically turn them on one hour before sunrise and off one hour after sunset. Under the false floor of each cage, along the back edge only, is a heat tape that hangs on hooks suspended from the floor. This resistive tape is normally used to wrap around water pipes to prevent them from freezing in cold climates. They are found in most hardware stores. It provides a heat gradient across the floor from the back to the front and is connected to a light dimmer to regulate the heat needed in each season. The temperature is never more than 85 degrees Fahrenheit across the back of each cage and generally runs four to five degrees cooler in the front. During the hot summer months here in Arizona, the heat tape is turned off.

The two drawers are slightly shorter than the depth of the cage to provide the area in which the heat tape hangs. Conveniently, the rear of each drawer is also heated by the tape, reflecting the same heat gradient in these as is found on the floor above. This lighting and heating arrangement helps to simulate the four seasons the colubrids experience in the wild and has proven to cycle them similarly, resulting in successful breeding seasons.

During November my snakes are prepared for hibernation. The duration of light in the cages has been slowly reduced over the summer and fall so that by now only eight hours are provided for them daily. The females have been heavily fed since they laid their last clutches and are full- bodied without being obese. The snakes are fed their final meal during the last week in October. The heat tape is left on for two weeks longer to provide the heat necessary for proper digestion. During the second week of November, the heat tape is turned off a little each day..On November 15th the lights are turned off and each snake is placed individually in a clean drawer containing pine shavings and a four ounce water bowl. The two-inch ABS tubes are capped off for the duration of hibernation. I now thoroughly disinfect the water bowls and the upper level of each cage. The cleaning process disturbs them less now than it would later when they are dormant.

As winter approaches, the room temperature slowly reduces to 60 degrees Fahrenheit or below, if possible, and remains this way for three months. If colubrid species normally found in colder climates such as black rat snakes or mountain king snakes are kept, they must be cooled at even lower temperatures to assure proper egg fertilisation. My animals are checked at least twice a week during hibernation and the water bowls are disinfected and refilled. They drink water throughout this cooling period and defecate regularly, although less frequently than normal. I’ve never observed any weight loss in my animals and am always pleasantly surprised at the amount of growth that many of my younger breeding snakes acquire during hibernation.
 
During the second week of February I turn the cage lights on to begin the warm-up period. This gradually increasing photo period follows the times previously mentioned, eventually amounting to fourteen hours of light every day by late summer. Two days before the snakes are freed from their drawers the heat tape is turned on. A thermometer is placed in the cages and the heat tape regulated so as to match the above-mentioned temperatures. During an unusually warm winter the snakes may become aroused a bit earlier and begin to stir in their drawers. It is advised to allow them up at this time if they choose because they will rub their noses raw on the wood. After the ABS tubes are uncapped they slowly emerge and warm up to ambient temperature over a two-day period. The hibernating drawers are cleaned, disinfected and re-bedded.

The snakes are now ready for a very small first feeding, making sure they pass faeces before a second slightly larger meal is given. After three more days have passed they are fed their normal amount. Now that the snakes are warmer and more active, I insure that the females eat enough so they will not become emaciated after laying their first clutch. I feed my snakes with mice I raise for two reasons: it’s cost effective and yields nutritious snake food. My mice are fed a high quality, commercially produced laboratory mouse chow containing 17% protein and 11% fat. This well-balanced diet produces healthy, plump individuals and large litters. Remember, what goes into your mice, goes into your snakes. I usually feed my colubrids every four to five days during breeding season, feeding the females larger meals. I have had a few males stop eating once mating begins, but have noticed no ill effects from this behaviour. The females are aggressive feeders during the breeding season until their pre-egg laying shed, although an occasional individual may continue to eat until she lays.

Two to three weeks after hibernation my snakes begin to go into shed. For my early spring breeding colubrids: corn snakes, Florida, California and speckled king snakes, black and Everglades rat snakes and Pueblan or Mexican milk snakes, this shed is sometimes called a pre-ovulatory shed. This means that the female’s ovaries will release eggs into the oviducts approximately eight days after she sheds and she will be ready to accept the male for breeding. If the male and female are not already together, I place them together right after the female sheds. The males usually do not molest the females until they become ready to breed after ovulation.
 
The colubrid species that breed later in the season, such as my Sinaloan and Honduran milk snakes, remain together directly after hibernation and breed successfully as nature calls. If it becomes necessary to stimulate a complacent male to breed, I have occasionally removed pine shavings from another male’s cage and placed them into the breeding pair’s cage. Once the complacent male thinks another male is present, his competitive instinct takes over and copulation soon begins. My males and females remain together for the entire breeding season except when the females are laying their eggs. The laying usually takes place over a period of one-day. I let my females rest a few days and allow them to eat and drink undisturbed before readmitting the male.
 
There is a five to eight week period between mating and the pre-egg laying shed, depending on the species. Once this occurs, they lay their eggs in four to fourteen days. The last one-third of the females body swells significantly as the eggs mature in the oviducts. If you allow the female to slowly pass between your thumb and the tips of your fingers it’s possible to feel the eggs in her abdomen. If you are sure she is gravid and fourteen days have elapsed since her shed and she hasn’t laid, then it would be advised to consult a veterinarian. Most of my females exhibit a dramatic behavioural change two to three days before they lay. They become very active, but eventually go into the nest box and burrow themselves into the moist vermiculite to begin laying within the next thirty-six hours. I replace the large water bowl with a small one to deter the female from laying her eggs in the water. I try to be present to remove the eggs so that they may be arranged individually in another shoe-box containing slightly moistened, fresh vermiculite.
To prepare the egg incubation box, I place two inches of dry vermiculite into the shoe-box and soak it with tap water. I then pour off as much water as possible and rarely add more to the medium during the incubation period. One half to two thirds of each egg is left exposed to the air for respiration. The shoe box has several small holes drilled about one inch from the top edge along both long sides. These holes permit carbon dioxide and oxygen to exchange during egg respiration while they are being incubated. A cover is placed onto the box, secured with elastic bands, and the box is labelled with the date and female identification before being placed into the incubator. If a female does not emerge from her nest box in thirty-six hours after laying, I gently place her on the upper lighted level to awaken and drink. Sometimes they soak in the water bowl for several days. Once she has recovered from this egg-laying ordeal and has eaten, I’ll readmit the male to her cage if I think her condition will safely permit her to double-clutch. I usually feed one appropriately sized fat mouse to these females every three days to replace the body fat lost due to egg production.
 
My females generally take between six and eight weeks to lay their second clutch depending on the species. The eggs are incubated between 82 and 84 degrees Fahrenheit and hatch in 50 to 60 days. The care and feeding of these neonates is an interesting subject worthy of discussion in a separate article. My males are returned to their own cages after breeding ends, depending on the breeding times for each individual species. The colubrids have a three to four month period to recover and gain weight before the cycle repeats itself with hibernation the following November.
 
I follow this procedure every year and my females produce hearty offspring because they were cycled as naturally as possible in a captive environment. My colubrids display contented behaviour with this arrangement and have provided me with years of satisfaction and hundreds of beautiful hatchlings. I truly hope my experiences in this fascinating field help you to enjoy your colubrids to their greatest potential.

We would like to thank the Reptillian Magazine for permission to print this article.
This site has information on the following genera of Ratsnakes ... Spilotes, Spalerosophis, Ptyas, Zamenis, Elaphe, Rhinechis, Senticolis, Pseudelaphe, Pantherophis, Bogertophis, Orthriophis, Gonyosoma, Oreocryptophis, Oocatochus, Euprepiophis, Coelognathus, Archelaphe