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Two years ago, when I started keeping snakes, I bought several red-tailed ratsnakes, Gonyosoma oxycephalum. I thought they were very beautiful snakes, but many of the snake keepers I knew at the time told me that I was crazy. I was told that red-tailed ratsnakes were large and extremely aggressive snakes and that the species was difficult to keep. Now, after two years of working with the species, my opinion is that they are not at all difficult to keep and are not aggressive.

In this article I will document my experiences with this beautiful species, including their captive reproduction. During the past year I have witnessed breeding activity among my animals that has resulted in several clutches of fertile eggs.
1. One can see the characteristic dark face stripe of red-tailed ratsnakes on this adult. Also the pale green belly is visible. This is a beautiful species of ratsnake. My animals are alert, but they allow me to handle them without making any attempt to bite.

2. Red-tailed ratsnakes are extremely arboreal. They possess many of the morphological adaptations made by other arboreal snakes, including laterally-compressed bodies, long slender bodies, and prehensile tails.
The red-tailed ratsnake, Gonyosoma oxycephalum, is a large arboreal colubrid snake that occurs throughout much of Southeast Asia. This species occurs in Peninsular Malaysia and Burma, east to Vietnam. It occurs throughout western Indonesia. The type locality for the species is Java in the Sundas the species is distributed from Sumatra to Lomboc, it is recorded on many of the smaller islands in the Straits of Malacca, and it is found throughout Borneo. The species also occurs throughout the Philippines, excepting Mindanao.

Red-tailed ratsnakes have long heads, large eyes with round pupils, laterally-compressed bodies and long prehensile tails. The tongue is dark in many specimens the tongue is blue, dark blue, or dark with blue tips. Most red-tailed ratsnakes are forest green snakes with paler green or yellowish bellies and lower sides. Most specimens have a black line from the nostril, passing through the eye, to the temporal area just above the angle of the jaw. The posterior body and tail of most Gonyosoma oxycephalum is reddish-brown. Some Indonesian specimens of red-tailed ratsnakes have been exported that were apparently axanthic and were gray in color. Some specimens may have yellowish or gray tails. This is a large species that is known to exceed 2.3 meters (7½ feet) in total length most adults are about 1.7-1.8 meters long (5½-6 feet).

My own three adult animals are a bright grass green with a red-brown tail that is separated from the green by a clear yellow ring. All of them have well-defined black lines on the sides of their faces. Their eyes are green with a black iris. The anterior and posterior portions of the iris are black as the black line on the side of the face actually passes through the eye. My ratsnakes have remarkable blue tongues they very slowly flick out their tongues, deliberately waving the tips up and down several times before drawing them back into their mouths. At two years of age, they measure approximately 1.7 meters (5½ feet) in total length. The male is the smallest of the three, and is noticeably more slender than the two females.

My three animals are kept together in a one-meter-high white melanin vivarium with a floor measuring 1.2 meters x .6 meters (47" x 23" x 39"(h).) One side of the enclosure is glass which opens to allow access inside the cage.

I use beech chips as a substrate in the cage. I believe that this product is most similar to the aspen bedding in wide use in the U.S. There is grape vine and a tree branch that are fitted into the in the cage on which the snakes spend most of their time. The branch has been stripped of its bark. When the animals were smaller I kept live plants in their cage. Now as mature snakes, they are too heavy for the plants. I have added some plastic plants make it a little more attractive. There are no hiding places in the enclosure. In the beginning I placed some flowerpots on the floor of the cage, intending for them to serve as hide boxes or retreats however, the snakes did not use them and I later removed them. A water bowl completes the housing but the animals do not often drink from the bowl.
In contradiction to what I was told when I first got them, the feeding of my red-tailed rats has not been a problem. While the species has a reputation for not readily accepting mice, mine have always fed on mice, rats and hamsters. Normally each week I feed each adult either two mice or one big hamster. They will accept rodents either live or dead. Occasionally the male will refuse food for a time but never for more than three weeks. I have found that it is necessary to separate my group when I feed them, as they are really crazy when the food arrives. The few times I have fed them together, it has resulted in two or three snakes all attempting to eat the same mouse. I then have to separate them and this is really the only time that my snakes might bite me.

Two mice a week may seem like a lot of food, but the females need this food as once they mature, they will lay multiple clutches of eggs in a year. My females lay a clutch ever 3-4 months throughout the year.

My trio of snakes are housed together. Throughout most of the year the daytime temperature is kept between 25°C and 30°C with a night drop to 22°C. During winter, the ambient temperatures are kept 3°C lower. I spray my snakes every evening with lukewarm water, which I believe is very important for a positive breeding result.
At the end of October 1999, I noticed that one of my females was gravid. The scales on the posterior half of her body were slightly separated from the fullness of her body in this species, the separation of the scales makes visible the white interstitial skin, and the condition is consequently made more obvious.

After her next shed, I placed this female in another cage. In addition to branches suitable for climbing, in this cage I placed a box filled with vermiculite, with a hole cut in the top of this box. Ten days later the eggs were laid in this nesting box.

In this clutch were six large white eggs. The eggs were adhered and fairly uniform in size and shape. I was a little nervous to handle them, but I did measure that the eggs were approximately 6 cm long by 2.5 cm (2.4" x 1").

The eggs were placed in a plastic box filled with moist vermiculite. I drilled one hole in each corner of the cover of the box. This box was placed in my incubator, and I incubated the eggs at 29°C during the day and 28°C at night.

Now the countdown began. From the literature and from Gerard Heijnen, a keeper in the Netherlands with experience breeding this species, I learned that the eggs of red-tailed ratsnakes had been observed to hatch after 95 to 120 days of incubation. For a novice, that seemed like an incredibly long time. At 104 days of incubation one egg slit. Thirteen days later a second egg hatched. It turned out that the other four eggs were infertile. I feel that it's possible that the young age of the female parent (15 months) may have in some way contributed to the infertility of the eggs.

The two young were housed separately in small cages with a small flowerpot as hiding place and a small water bowl. I used kitchen paper as substrate. The baby that had hatched second was significantly smaller than the first, and it died one week after birth.

The next clutch was laid by the second female and consisted also of 6 eggs. Several weeks before the time when I expected these eggs to hatch, I cut open one egg because it had collapsed in fact it contained a developing embryo. I now realize that it is advisable to not open eggs before the hatching date if there is any chance that the embryo in the egg might still be alive.

Two eggs hatched after 112 days. The three other eggs were slit after 120 days to reveal one incompletely-developed embryo and two babies that were well formed but dead.

The long jaws of the red-tailed ratsnake give them considerable gape and they are able to swallow relatively large prey. Typically they swallow rodents head-first, but eating a mouse tail-first presents no problem.

My first female then laid a second clutch of 6 eggs. After 105 days two babies slit their eggs. They successfully hatched. I opened the other four eggs to find that one egg was undeveloped and apparently infertile the other three eggs each contained a fully formed dead baby.

On 15 May 2000, my second female then laid her second clutch of 8 eggs. The first baby slit his egg after 96 days of incubation. Following the general guidelines for slitting eggs outlined by Tracy Barker in the July 2000 entry of her VPI Diary, I slit the other eggs to find 6 more live and healthy babies and one fully formed dead baby.

On 28 May 2000, my first female laid a third clutch of seven eggs. Again I slit all the eggs as soon as I saw the first egg slit. This time there were a total of five live and healthy babies in the clutch and two infertile eggs.

Noting the number of well-developed young that did not make it out of the eggs in the first three clutches, it became clear to me that something negative was taking place as it came time for the eggs to hatch. I first thought that maybe there was not enough oxygen in my incubation boxes. A Belgian breeder of green tree pythons, Morelia viridis, reported to me that he had the same problem with python eggs he was incubating. Once he began to open his incubation boxes every day in the last 14 days of incubation, he did not have the problem.
I now believe that the solution is to slit the eggs as soon as the first baby starts hatching. I make a 3-4 cm (1.2"-1.5") cut in the top of the shell, taking care not to snip the babies inside. I do not try to hatch the babies or get them to breathe. After making the slit, I just sit the eggs back down in the vermiculite and let the babies hatch when they want.

Care of Hatchlings
I house the babies individually in small containers, giving them good branches on which they spend much of their time. The young must be teased to start eating. Using long forceps to hold a dead pink mouse, I keep bumping a little ratsnake gently on the face with the pink until he strikes and bites it I then gently let go. Starting out, the little ratsnake usually will drop the meal. I keep at it until the ratsnake holds onto the meal. Then, if I am careful not to spook the baby, it will eat the pink. If a baby becomes extremely agitated and begins to wildly strike at the food as if in fear, I then stop the feeding attempt. Some of my animals took as long as two months before they accepted their first meal. After only three tease-feedings, the first baby to hatch voluntarily ate a live pinkie that was placed on the floor of its cage. Most of my babies require 6-10 tease-feedings before they begin to voluntarily eat. I have been able to get all of the babies I have hatched to voluntarily feed.

In conclusion I would like to say that I believe that the red-tailed ratsnake, Gonyosoma oxycephalum, is surely one of the most beautiful ratsnakes. It is my experience that captive-bred specimens do well in captivity and are easy to keep. The aggressive behavior for which wild-caught animals are well known is completely absent in my captive-bred snakes. If after reading this article someone should still have some questions, please feel free to contact me.
1. This picture is taken at the time of laying. To date, this is the largest clutch of eggs that my snakes have laid. All of these eggs are fertile eggs. After 96 days of incubation, the first baby to hatch slit his egg. I then slit the remaining eggs. Seven of these eggs produced healthy babies; one egg contained a fully-developed dead baby.

2. The long jaws of the red-tailed ratsnake give them considerable gape and they are able to swallow relatively large prey. Typically they swallow rodents head-first, but eating a mouse tail-first presents no problem.

3. My three adult red-tailed ratsnakes typically sit together in the branches of their cage. These animals spend little time on the floor of the cage.
I wish to thank Gerard Heijnen from The Netherlands for the trust he had in me to sell me these fantastic snakes.
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