Monday, 10 August 2009

The black rat snake

he black rat snake (a.k.a. mountain black snake or pilot black snake), Elaphe obsoleta obsoleta, is a large rat snake from North America. Black rat snakes average around five feet long, but some specimens may reach lengths of over six feet. The record for a black rat is almost eight and a half feet (101 inches) long! The ground color of these snakes is deep black, with white, yellow, orange, or red patches of skin often showing between the scales. Some remnants of the juvenile pattern may persist into adulthood, especially in areas where the black rat integrades with other subspecies. The belly is white or yellowish diffused with gray. A checkerboard pattern of dark pigment may exist; especially near the head. The chin and throat area is plain white or cream colored. Neonates start out gray with distinct dark gray blotches. As the snake grows, it will slowly attain the adult coloration. A three foot snake will usually have only traces of pattern left.
The black rat snake has a wide range from Central New York and Western Vermont west through Wisconsin and south into Extreme Northeast Texas and Georgia. There is a disjunct population in the St. Lawrence River Valley in both New York and Ontario, Canada. They can be found in rocky timbered hillsides, in the open grasslands, in trees or shrubs, and in farmland where they are attracted to the numerous rodents. In the wild, they will eat rodents and birds, often raiding nests for chicks or eggs.

Mutations and Varieties:

Red Albino: An amelanistic strain of the black rat that has red blotches on a white to buff background. This mutation is a simple recessive trait.

White Albino: An amelanistic strain that has yellow to buff blotches on a white background. This mutation is a simple recessive trait.

Brindle: An interesting mutation where the entire body is covered in black speckles instead of the normal total black coloration. The blotches can still be made out, but the speckling gives them an indistinct quality.

Cage Setup:

Minimum cage size for an adult black rat snake should be at least a 30 gallon long tank (36" long X 12" wide X 18" high), but preferably larger. The lid should fit on snugly and be made specifically for reptiles as rat snakes are notorious escape artists. The cage requires a temperature gradient in order to allow the snake to regulate its body temperature by moving to either the warm or cool end of the enclosure. There are different ways to achieve a good temperature gradient. One way is to use an under tank heat pad available from pet stores, or you can use a drug store heating pad. Place the heat pad under one side of the tank, and measure the temperature. This area should be approximately 82F to 85F. Now, measure the temperature at the cool end of the enclosure. This area should be in the high 70's. Other heating methods include heat tapes or cables that are likewise placed under one side of the tank to heat it. Regardless of how you heat the cage, I would recommend a rheostat or dimmer switch to regulate the amount of heat given off by these devices. A cheap dimmer switch purchased from a hardware store or home improvement center will work fine. A dimmer switch will allow you to fine-tune the temperature in the cage. The expense of a dimmer switch is well worth it if it can prevent the death of your snake. Proportional thermostats, such as those made by Helix Controls, are probably the best way to control heating devises. They measure the temperature inside the cage and automatically adjust the heat output of the heating devise to maintain the correct temperature. Although expensive, I use Helix controls due to their accuracy. No specific light requirements are needed, but a fluorescent light will allow you to better see your new pet.
Cage furnishings can be kept simple. For substrate one can use newspaper, aspen wood shavings, or cypress mulch. Pine or cedar wood shavings should NEVER be used as they contain TOXIC chemicals that could kill your snake. The cage will also need a sturdy water bowl large enough for your snake to completely submerse itself in. Snakes will often soak prior to shedding their skin or after eating. A rock large enough to be difficult for the snake to move should also be provided to allow the snake to rub against in starting a shed. Lastly, two hide boxes need to be placed in the cage: One on the warm side and one on the cool side to allow the snake to feel comfortable when inactive. A good hide box or container has just enough room for the snake to squeeze into after a meal. The tighter it is the more secure the snake will feel. A hide with a top entrance hole seems to be better than a side entrance. A third hide box is sometimes used which contains moist sphagnum moss. This humidity box will help in sheds and prevent over-soaking in the water dish. An optional item in the cage would be a climbing branch. For black rats I would strongly recommend a climbing surface of some kind. Any sturdy branch will do. Remove the bark of a live hardwood branch (no conifers) and bake it in the oven at around 350F for an hour. This should kill all microbes and other parasites like mites that may be on or in the branch. Black rat snakes are fairly arboreal, and will use a climbing branch regularly if provided. Using a branch and/or elevated platform will increase the useable amount of space in the cage, and will stimulate increased activity.
Baby or neonate snakes should be kept in smaller enclosures as it will let you monitor the snake better and will make the snake feel less vulnerable. A ten gallon tank or a Rubbermaid container make good enclosures for the first year. These cages are set up the same as the adult's cage above except the Rubbermaid container has no light and will need many small holes drilled into all four sides (1/8" is a good size). Remember, the heat pad or cable should be under only one end of these small enclosures and not the entire cage. Use a thermometer to check the temperatures! Guessing is not good enough.


Black rat snakes will do very well on a diet consisting solely of domestic rodents. Baby rat snakes will usually start out eating a new born mouse pink without any trouble. As the snake grows, you can feed increasingly larger mice. Baby rat snakes should be fed every 4 to 6 days while adults will do well on adult mice or rat fuzzies fed every 7 to 10 days. The size of the prey item should be no larger than the maximum diameter of the snake. I like to feed my snakes until satiated.
Small prey items like mouse pinks, fuzzies, and hoppers as well as rat pinks and fuzzies can be fed alive or dead depending on what the snake will accept and what is most convenient for the owner. Larger prey items should be fed dead to eliminate any chance of the rodent injuring the snake. Some owners prefer to buy rodents frozen in bulk to save money, and this can be a very convenient supply of food items. Other keepers prefer to buy live rodents at the pet store. Rodents can be bred at home, but unless you have a number of snakes to feed this is probably more trouble than it is worth.
Several things can be tried to induce a troublesome neonate to eat its first meal. First, place a newborn mouse pink inside the snakes enclosure overnight. If the snake does not eat it, then take the snake and the pink and place them both in a much smaller container like a deli cup overnight. If this still does not work, give the snake a couple days of rest then try a split brain pink. This involves taking a DEAD pink and cutting into the head to expose the brain. Place the split brain pink and the snake into a deli cup overnight. This will often work. If not, then try again with a lizard scented pink. Anoles and house geckos work well. Cut open the abdominal cavity of a frozen lizard and rub a thawed pink into this cut and place this scented pink and the snake into a deli cup overnight. This can also be tried using a small piece of lizard skin dried onto the head of the pinky. If a humidity box is used, then try placing a live pink on the outside lid of the humidity box. If this doesn't work, try a dead pink. These techniques and a lot of patience should get a troublesome hatchling to eat. However, it is the breeder's responsibility to make sure that any snake that they sell is eating unscented mice before selling it.
Another thing that will sometimes work to get a troublesome baby to eat is to try a different food item. If available, a pink deer mouse will often elicit a very strong feeding response in most North American snakes of the genera Lampropeltis, Elaphe, and Pituophis. Although the information above is a bit frightening and at times gruesome, do not be discouraged as most pet owners will never have to deal with these problems, especially with a rat snake. However, if you intend to breed your snakes then you will need to be familiar with these techniques.


Prebreeding Conditioning: Before beginning to breed or brumate your snakes, inspect them closely. They should be in optimal health and have good weight. They should have a minimum size of 36 inches and weigh at least 150 grams. If your snakes are smaller than this or are thin or otherwise not in optimal health, then wait until the following year to breed them. Otherwise, you may end up with a dead snake or experience problems like egg binding. The generally accepted method of breeding corn snakes involves a period of cooling called brumation which is similar to hibernation but the snakes still remain active to some extent. This involves first stopping feeding two weeks before the cooling period is to begin. This is to eliminate any remaining food still inside the snake, which could rot inside the snake during cooling and potentially kill it. After the two weeks are over, slowly decrease the temperature over several days until a temperature of about 55F to 60F is reached. Keep the snakes at this temperature for two to three months usually from December through February. Check on the snake's health frequently, and change their water weekly. If any signs of respiratory infections are seen then warm the snake up and treat the infection. Do not feed the snakes during this time. At the end of the cooling period, slowly warm the snakes up to the normal maintenance temperatures and begin feeding. Feed the females as much as they will eat in order to fatten them up before breeding.

Breeding: After her first or sometimes second shed, the female will be ready to breed. Start to introduce the female into the male's cage. Watch the pair closely, if the female is ready for breeding she will produce pheromones from her skin which will attract the male. The male will start to chase the female and rub his "chin" along her back. Actual breeding usually lasts about 20 minutes or so, but could last an hour or more. If they do not breed after an hour or two, separate them and try again in a day or two. If they do breed, then separate them afterward and reintroduce them every couple of days until she has been bred at least three times. This should ensure the fertility of the eggs. After the female has been bred, again start an accelerated feeding schedule. Feed the female smaller, easily digested food items every few days. She will need these nutrient reserves to produce the eggs. About six weeks after breeding, the female will undergo a shed cycle. At this time you will need to give her a nest box to lay her eggs in. This box should contain moist but not wet sphagnum moss in a closed dark container. I use a plastic storage box (shoebox) with a hole cut in the lid. Remember to cut the hole larger than normal, as she will be swollen with eggs. About 10 days after shedding, the female will become very active as she searches for the best place to lay her eggs. She will usually settle down inside the nest box and lay her eggs, from 5 to 30 depending on the size of the female, sometime over the next couple of days. If she settles into the water dish, you may want to replace it with one that is too small for her to enter and without a lid. This will encourage her to look for another place to lay her eggs. After she lays her eggs, feed her a smaller than normal prey item for the next couple of feedings. She will be weak from her pregnancy and small prey items will be easier for her to eat and digest. If a second mating and egg clutch are to be attempted, than again feed her on the accelerated feeding schedule. After her next shed, start to reintroduce the male as before. Remember though that a second clutch of fertile eggs is possible without a second breeding due to stored sperm. After the second clutch is laid, it will be even more important for the female to regain her lost weight. Feed her as much as she will eat until she has regained good weight.

Care for the eggs and babies: The eggs should be placed inside a container (plastic food containers without the lid work well) of coarse, damp vermiculite. The vermiculite should be mixed with water 1:1 by weight. This should make the vermiculite damp enough to just clump when squeezed together. The container should then be placed inside an incubator of some kind that will maintain a temperature of around 82F. Watch the eggs closely, if they begin to dimple or cave in, then add a little more water. The eggs should hatch in 6 to 8 weeks. Various incubators exist, but a good, small incubator is the Hova-bator incubator sold through pet supply dealers or at feed stores where they sell them for incubating chicken eggs. These incubators cost around $30 to $40, and are well worth the money.
When the eggs start to hatch, the baby (neonate) snake will slit open the leathery egg by means of a temporary egg tooth located on the tip of their snouts. They will often remain inside the slit egg for a day or two with just their heads sticking out of the slit. Do NOT try to force the baby out of its egg before it is ready, as it will be attached to an umbilicus and yolk sac. Forcing it out of its protective egg may result in killing the snake due to dehydration as water will be quickly lost through the yolk sac and umbilicus. Also, do not cut the umbilicus as it will cause the snake to bleed to death. The umbilicus will fall off on its own in a day or two so wait until the snake leaves its egg on its own. Set up each neonate into its own separate enclosure. I use plastic shoeboxes with many very small holes drilled into all the sides. Use paper towels as substrate and keep careful records of sheds and feedings. The baby snakes will usually start eating sometime after their first shed. Start them off on a live newborn pink mouse. If you plan to sell or give these animals to other people than provide them with these records.


Conant, R. 1975. A Field Guide to Reptiles and Amphibians of Eastern/Central North America. The Peterson Field Guide Series. Houghton Mifflin Company, Boston, Mass. 429pp.

Griswold, B. V. 1996. Care and Captive Breeding of North American Ratsnakes. [Online] Available Here

McEachern, M.J. 1991. Keeping and Breeding Corn Snakes. Advanced Vivarium Systems, Lakeside C.A. 60pp.

Riggs, D. 1997. Black Rat Snake. [Online] Available Here


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