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Corallus batesii (Gray, 1860)

Amazon Basin Emerald Tree Boa

Class: Reptilia
Order: Squamata
Suborder: Ophidia
Superfamily: Henophidia (Booidea)
Family: Boidae
Subfamily: Boinae
Genus: Corallus
Specie: batesii

Introduction

In 2005 it was made a phylogenetic comparison (Vidal et al.) between different specimens of Corallus caninus from 5 different locations all around the distribution area of the species.
The difference of the sequences ranged from 1.7% of the specimens of Guyana and Venezuela, to 16.5% between Peru and the remaining specimens.
To complete the work of Vidal et al., and to continue a review on the geographical variation of the genus Corallus already started by Henderson in 1997 and again in 2001. Robert W. Henderson, Paulo Passos, and Darlan Feitosa have completed in 2009 a study based on observation and counting the number of scales of specimens from different locations and improving data with observation and description of the pattern (detailed below), and analyzed the results in a statistical analysis in order to assess the status of the taxonomic species until now recognized as Corallus caninus. Study carried out by analyzing the variance of the data collected and observed, dividing the distribution area into three large groups, delimited by three large rivers that hypothetically could be used as natural barriers designed to separate gene pools:
Group-1, north of the Amazon River and east of the Rio Negro (the well-known Guyana Shield);
Group-2, the Amazon basin, south of the Amazon River and east of the Rio Tapajos (known until now as Amazon Basin);
Group-3, the Amazon basin, west of the Rio Negro and west of the Rio Tapajos (known until now as Amazon Basin).

Considering the results of the phylogenetic study of Vidal et al. (2005), and the latest geographical and morphological study of Henderson et al. (2009), we can confirm the distinction between specimens from the Guyana Shield (group 1) and those of the Amazon Basin (groups 2 and 3); distinguishing those of the Amazon basin in a separate species recalling the invalid name Chrysensis batesii (Gray, 1860) in a new combination, Corallus batesii.
Therefore remain classified as Corallus caninus the specimens known as “northern” until today.

The epithet batesii is the "Latinized" name in honor of Henry Walter Bates (1825-1892), English naturalist who spent 11 years in the Brazilian Amazon, collecting and studying samples of local flora and fauna.

Geographical distribution and biology

Corallus batesii lives in the rainforest of the Amazon based in the south of the Amazon River and west of the Rio Negro, through Colombia, Ecuador, Peru, Brazil and Bolivia, to the south in the Amazon basin.

It is found at altitudes ranging between sea level and 1000 meters of altitude, and it lives in areas with an annual rainfall average of at least 1500ml/mq, which make this a very damp environment.
It has strictly arboreal habits and practically never falls to the ground; it lives surrounded by thick vegetation, where it finds its favorite prey: small lizards (for the very young specimens), mammals and birds. On the branches it holds the typical “saddle” position: coiled on a branch forming spirals with the body, at whose center is placed the head (occasionally held to the side).
It conducts activities mainly nocturnal.

It is interesting to observe the convergent evolution with Morelia viridis, determined by the specialization in relation to an environment very similar, which brought these two animals, taxonomically and geographically so far away (a boa in South America and a python in Indonesia), to achieve a similar appearance (chromatic youth, youth ontogenetic change, background color of the body of adults) and a way of life with many points in common: position on the branches, arboreal habits, types of primary prey (although Corallus caninus eat more frequently birds than Morelia viridis).

Description

These boids reach an average size of 170-200cm, and a weight that generally approaches or exceeds 1.5 Kg.
Females reach larger sizes than males (specimen measuring 223.5 cm; longest belonged to JM Polanco), which usually stop at around 150-170cm. Other signs of sexual dimorphism are the greater development of the male's cloacal spurs. The development of temporal lobes is greater in males than in females, but as method is too empirical and unreliable.

The head is imposing and clearly separated from the body by a slender neck. It has thermo-sensory dimples, above and below the labial, that able to sense the heat from surrounding bodies, giving the snake an infrared image helpful to predation. The eyes, not too prominent, have vertical pupils and have a color can vary from yellowish to dark gray, passing through the various shades of green and brown. They have curved tusks and highly developed that, in the larger specimens, may exceed 1.5 cm in length.

The body is fusiform, with a section that tends to an ovoid (almost triangular) shape, which usually does not exceed 5-7cm. The muscle bands are well distributed throughout the entire length of the body. They give this snake to the ability to make quick and very pronounced bursts. In these moments, the animal remains at the same time held securely to the branch (or any other hold) due to the prehensile tail, and is therefore able to kill their prey by constriction, keeping them suspended. 

The back color ranges from shades of green up to very dark tones also tend to black (the rare black basin). Frequently, the coloring of the upper part of the back presents a band more or less darker throughout the entire length of the body.
The belly can range from creamy white (sporadic) to different varieties of cream and yellow (usually cream in specimens from the western part of the Amazon forest, and bright yellow in the specimens of the eastern part), usually has an uniform color and homogeneous, but sometimes could be "dirty" in the final third of the body. Color belly also extends to the base of the flanks for different rows of scales, for a larger overall height in the front part of the body (till 10-13 rows of scales) which decreases gradually going towards the final part (2-6 files scales). Gradient that goes fragmenting and interspersed the green at the top, where the yellow goes to approach the green.
The sub caudal area has the same color of the belly.
The color of the head is usually homogeneous and reflects the body, but  sometimes it can be spotted or tinged with a darker green or almost black (black head). The labial is yellowish or cream-colored, sometimes has spread shades of green, and the lower part of the skull is also cream or yellow, and presents an area of hollowed ​​tissue in the center, it is typically black or gray, rarely whitish.
Dorsally there are white spots triangular or more similar to a plug, present in a variable number typically between 23 to 36 (average 29-30), but they may be many less up to a few units, or many more up to nearly fifty. They are irregularly placed along the median axis of the back which support their "base". The bases of these designs may touch or even coincide with each other, but always at random, they are absent or thin (shaped plug) in the first third of the body and wider in the middle part; last third (triangular shape), often bordered with deep green or dark, rarely black.
A white dorsal stripe may be present or not, and it may be continuous throughout the length of the body or even just mentioned. When present, it can have a thickness of 1-2 rows of scales up to 3-4. This stripe, as mentioned, may be present or absent completely, even in specimens from the same Localities. The dorsal pattern continues on the tail as it appears in the rest of the body (as described up to now).
Along the sides there may be white spots, usually from 10 to 26 (average 18-19), but they can also be absent (as some specimens related to the town of Mato Grosso and Rondonia) or get close to forty.
Some specimens have yellow scales along the body, or as a side dish of  dorsal and/or lateral white spots. 

Is generally possible to find both clear or dark specimens, with particularly extensive pattern or with very small patterns; but except in special cases, there are no distinctions between different locality if not in a very general way by observing the color belly and hips. An interesting exception, however, could be that of the Marajò Island. They are specimens from the homonymous island rainforest, located in the state of Para, Brazil. These specimens are characterized by a very dark green color, intense and bright yellow belly, reduced pattern, with singular presence of yellow scales within and around the dorsal and lateral white designs.
These examples, however, are rarely found on the market, due to export restrictions imposed by the Brazilian laws... and we are proud to have a female (confirmed by J.M. Polanco, T. Nicoli, Zoobotanicals).
Always generalizing, and so a bit 'risky, it can be said that the size of Corallus batesii increase going down to the south of the Amazon forest, until thoroughly overcome the 200cm in the specimens that inhabit the Amazon basin.

The main character that distinguishes this new species, until recently considered to be only one locality, from Corallus caninus is in shape, size and number of scales covering its snout: caninus has wide plates and then to a lesser number, usually 2 -4 (rarely 5-6), measured between the joints of the 3rd and 4th scale sores, while batesii presents scales smaller and more numerous, medium 5-8, but plenty ranging from 3 to 12.
In addition to this basic characteristic, we remember the above possible presence of the dorsal stripe (never present in caninus), the presence of white spots side (typically absent in caninus, or present in very small quantities), and now we list the count of the scales of the body:
- Rows of dorsal scales in the front part of the body: 46-61, on average 50-56;
- Rows of dorsal scales at the median, 61-88, 66-75 on average;
- Rows of dorsal scales at the rear: 29-54 on average 37-43;
- Ventral scales: 186-218, on average 196-208.

Terrarium nd housing

Due to the strictly arboreal habits of Corallus batesii, the cage should have a vertical development of not less than 50-60cm for an adult, and it should be equipped with several vertical branches and / or other support, such as PVC pipes, bamboo, or branches, placed at different heights, also useful for facilitate thermoregulation.
Although this snake is very static, the cage should have a fair amplitude to stimulate the movement, in order to induce this sedentary snake, with its slow metabolism, to make some movement in order to avoid to have an obese and  lethargic animal; this can also facilitate the shed.
We breed our specimens individually in terrariums 100cm wide, with a height ranging from 50 to 70cm..

The optimal average temperature of the cage should be between 26 and 28°C, with a limited and restricted point of basking that can also reach 30-31°C.
Due to slow metabolism of these animals, in fact, too high temperatures may lead to fermentation of the intestinal bolus, resulting in digestive problems and probable regurgitation (unfortunately frequently for not well-housed animals).
Very important is the change of the air inside the theca due to the need to maintain a high rate of RH (relative humidity), which on average during the day should not fall below 70-75%, with one or two day saturations, also obtained by nebulising the cage.
The harm for insufficient ventilation is the proliferation of mold and bacteria, which can be harmful to the health of the snake.
A rate of R. H. too low, however, can cause dehydration, dysecdysis (incomplete shedding), and long-term (but not really long), respiratory diseases.

The lighting should not be too strong, due to the shy character shown by specimens of this species; if the light environment of the room where the theca is placed is good, another internal lighting is not necessary. However, a small spot, preferably at the top, to one side of the terrarium, will help to create a thermal gradient.
Some gray area that can provide shelter is very appreciated, easily recreated with the help of plants, even fake.
One of our females in the past, went down to the ground every time the artificial light was on, then climb on the branches in the early evening hours. As soon as the lamp was removed from the theca she resumed her normal arboreal life, without getting more down from the highest branches of the terrarium.

Usually they do not have a particularly aggressive nature, and when we talk about CB animals or well acclimatized, aggressiveness becomes a truly rare event. Having said that, bearing in mind the attack speed of these snakes and the size fangs, it remains an animal to pay attention, because a bite may appear potentially dangerous.
It seems that the specimens belonging to this species are, on average, more peaceful and less mordant than Corallus caninus, and in our experience we can assure you that, after well acclimatized in our cages, no specimen has never shown signs of aggressiveness or nervousness.

Breeding

Corallus batesii is an ovoviviparous species, which therefore gives birth to fully formed and autonomous babies. In the wild pairs occur throughout the year, but in captivity it seems is not so obvious and simple, so you need to "cycle" the animals to stimulate the reproductive instincts and consequently increase the chances of ovulation by the female and sperm motility of the male.

In the early days of November we start to lower the temperature at night in a slow and gradual way until reaching 21° C. Once this value is reached, after a few days, we begin to inserting and removing at intervals of 3-4 or even 5 days the male into the  female’s cage.
The explanation for these rapid and frequent movement is to increase the number of meetings between male and female, and then increase reproductive stimuli from the male, so that this beginning courtships, then get to the copulation.
Meetings between male and female will continue until the end of March, while the night temperature will be restored to normal towards the end of February or beginning of March, of course gradually.

If everything goes as it should, the male, after a few meetings, will start courting the female, and after a few more will succeed in meeting copulation.
Clearly, the time intervals in which the animals are joined, and then remain separate, from these moments can be modified according to the interests of the male towards the female, and based on the reactions of the female: it could also happen that the female, not feeling "ready" to mate, the male also rejects with some force, with violent and decisive shots tail. In this case it is better to separate the specimens and try again after several days.

The female usually ovulate around the middle / end of March, with a showy (really showy in our case) ovulation, of course preceded by follicular production (in our case very noticeable even this one), and after a few weeks will make a shed, precisely post-ovulatory shed.

From the date of this shed it can be calculated the period of the birth by counting from POS 150 days (5 months). It is obvious that with a gestation period so long, the timing may vary considerably: for example, the prolongation of only 5% of the estimated time is transformed into an elongation of about 7-8 days of pregnancy.

The female will give birth to babies without descending from the branch, but only unrolling the terminal part of the body, leaving the tail dangling.
If the cage is particularly high, we recommend placing soft material on the substrate, which may possibly cushion the fall of the litter.

Hatchings, on average, ten, are very active since birth, trying to clamber to find shelter wherever they can, even clumsily trying to climb the mother's tail!
Our first birth was made up of 15 specimens 13 live births and 2 deaths, and a slug ... a very large number, a sign that the female was in a physical state more than good!

Wening babies

The babies are red or orange-red (rarely greenish) with some white on the back and on sides (pattern which is usually just a hint of what will become with growth, and that will develop in the first few months of life, or even for over the first year, according to their genetics). They are active since immediately after birth, and forthwith try to find a grip, a branch or a plant, where to go and perch and rest: being born is really a difficult job for these small and delicate creatures.

At birth, they often still attached yolk sac, which usually lose after a few minutes or hours. Spent much still have the umbilical cord, which they sometimes drag on for a whole day.
If you notice difficulty on the part of the small "lose" the yolk sac, or the cord that keeps him connected, you may need to manually intervene, but being a delicate operation, especially if you are not familiar with this kind of manual , it is best to contact urgently a good and experienced breeder, or better a veterinary surgeon. Them in any case will have to come at your home, because it is unthinkable move for miles and hours these little ones.
The necessary action could be to cut the cord to approximately 1 cm from the body of the snake and hold it for a few moments to make it heal, or even make a small knot if necessary (you will almost never need to practice a stitch).
Residual of the cord will then be lost naturally after a few days.

We have the habit of housing the babies together in the same terrarium in the first days of life, to be able to offer a certain thermal gradient and a more controlled environment, but they can be separated right from the start in single boxes.
The average temperature will be maintained about 27-28° C, without a significant decrease at night (we usually lower than 1 up to 2° C in the first months of life), and the humidity should be rather high by nebulising morning and afternoon.
After about two weeks after birth the babies will make their first shed, and after a few days you can start with first attempts to feed.
(Throughout this period you can see the faeces of babies, as a sign of disposing of previously absorbed yolk sac).

Feed the babies is not easy, because the stimuli that we offer through the prey that we propose, are often not sufficient to "let him know what to do", because in nature, a natural food in the first months of life consists of little geckos and other micro lizards.
The sensation is exactly that, attempt after attempt, they learn to use the tools at their disposal, to come gradually to understand how and what to do!
The best preys are small fuzzy mouse thawed, which however have to serve very warmed, so as to activate the thermo-receptors of the babies (this new toy without instructions) and moved repeatedly in front of the snakes.
Indeed smaller prey, such as mice pinkies, too soon disperse the heat, and after a few moments not offer any stimulus to the snake.
A speech equivalent applies to the live prey: the pinky mice are less active, and in a few moments they reach the room temperature, while fuzzies are more active and, thanks to the greater size and the presence of the fur, are able to.maintain longer the body temperature.
Better prey would be or large fuzzies or specimens recently weaned of the smaller varieties of mice, which are thus of a size comparable to a classic fuzzy, but much more active and able to maintain longer their body temperature (JM Polanco, pers. com.).

Eventual not-eating babies usually need simply more time and patience than the other, therefore they DO NOT need to be force fed until they appear particularly debilitated or emaciated.
Not eating eventual babies usually need only more time and patience than the other, therefore DO NOT have to be fed until they appear particularly debilitated or emaciated.
One of our children, although not eating, was as big as the others, continued to defecate regularly, and shed as the brothers... after almost three months from birth it has eaten alone.

For our babies babies use thawed mouse fuzzies, warmed in hot water, to almost 40° C (do not cook!), Show them to the babies and moved in front of the snakes, sometimes touching them gently and steadily on the neck and sides, (but be careful not to scare them) and those who first, who later, all bebies ate independently.
In the first attempts, the young do not seem to know what to do, most do not consider the prey, do not bite even if tantalized for a long time. often they try to climb the forceps perhaps seen as a branch, and they perching near the hands, on the handgrip or on the hands themselves, undermining the work done up to that point.
Attempt after attempt the babies learn what to do. They become increasingly resourceful, observing the movements of the prey offered, following the direction of his head, using the tongue to taste the air, and finally attempting to bite, at first with difficulty and almost awkwardly, unable to restrain her, and day after day with more decision, finally able to hold it between the coils and eat it.
We suggest to wait at least 2-3 days in an attempt to avoid unnecessarily stressing the babies.
Once having shed and started to the meal, the babies are really more rustic and robust than you might imagine, and if requirements are satisfied housing, they will not give any further problems.

Notes e comments

The delicacy, the tendency to suffer from stress and the lack of tolerance for variations and anomalies of housing, as well as the lack of "autonomy" in the event of illness or other problems, combined with the potential hazard in the event of a bite (given the size fangs) make Corallus batesii a kind taboo for those who did not have experience with other snakes (preferably arboreal and mostly from warm and moist areas).
Before purchasing our first  specimen, we have bred other species for years (finally Morelia viridis), and today we are proud of that. There have been a lot of difficulties, more than we could have imagined, and without the accumulated experience with the other species, breed batesii would have been really difficult.

Angelo Cabodi
Silvia Tangredi

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