All of my Emeralds with the exception of one young male feed on defrosted rats. For some reason this solitary male will reject any rat put his way but will snatch up any adult mice that are on offer.
The size of the meal is obviously dependent on the size of the individual but most of my females are in the region of 6 feet and have a girth of around 12 inches at their thickest point. They are normally fed on a medium sized rat every 3-4 weeks, throughout most of the year. The males, that are somewhat smaller than the females will take a smaller rat once every 4-5 weeks and sometimes longer.
On occasions I have fed my large females fully grown rats without any problems, but allowing for full digestion before attempting to feed again. I have done this prior to breeding to provide extra body fat for the long months of fasting that may lie ahead.
Emeralds have the notorious reputation of being bad feeders. This is not generally the case as people also have a tendency to attempt to overfeed them, thinking that they are slightly on the thin side. This refusal to feed regularly, then contributing to this reputation.
It is not unusual for males to refuse food altogether for several months, and as long as they are healthy, this is generally of little concern. I do not believe in overfeeding Emeralds, especially males.
On the whole Emeralds tend to be quite inactive snakes, with a slow metabolism, and do not require a great amount of nutrition. For this same reason they are prone to intestinal compactions and they should be monitored to ensure they defecate reasonably regularly. Generally I will not feed the snake its fourth meal until such time that it has defecated. (Note that good hydration also improves defecation rate). It would not be unusual to prolong its next meal by several weeks until such time that it has defecated. If this is still not successful, I will remove the all the perches in vivarium and place the perch that the snake is resting on onto the ground. That evening as the snake becomes active and not able to climb up onto a suitable perch, the extra activity will hopefully result in the snake defecating.
Should this fail, the final resort is dangle the snakes posterior region into a pool of warm water (approx 80 degrees Fahrenheit). Once the intestinal contractions begin, the snake normally remains calm and motionless, until it has defecated into the water. This technique rarely fails to induce a snake to defecate. The snake is not just completely dropped into a bath of water, though it will bring about the same effect, they tend to thrash about wildly attempting to leave the water. Maybe Linneaus should have compared the Emerald to cats rather than dogs.
When gravid, they can go for long periods without defecation, due to almost total inactivity. Though it is obvious that they need to defecate, they can hold it in without any obvious problems.
The Emerald natural prey item is not well documented or known for that matter.
It has been generally assumed that a large percentage of their prey were birds or flying mammals such as bats. The prey was then plucked from out of the air, as they flew nearby (Photographic evidence is available to add strength to this). The long teeth helping in penetrating the thick feathers and establishing a firm grip on the prey. Thus preventing the prey from escaping or falling down to the forest floor, to be taken by another predator or carrion eater.
More recent findings have revealed that the Emerald is more likely to feed on arboreal rodents. Similarly juveniles are believed to take small lizards and amphibians, but are more likely to feed on small rodents.
Over the years I have tried feeding adults and juveniles all sorts of food items, ranging from frogs, lizards (anoles) and birds (finches) with no success. In the end a rodent is what has always tempted an Emerald to feed irrespective of size and age.
Emerald are crepuscular (of twilight) and nocturnal. They begin to stir at dusk, sometimes much later.
Naturally feeding will take place at night (although I have fed both babies and adults in the day). Avoid any external lighting distracting the snake. I only have a small sheltered desk lamp on the floor of the room, that I also use to warm up the prey to the desired temperature.
I generally only attempt to feed them once they are awake and actively seeking prey. This usually means that they are dangling below the branch, held on by their prehensile tails and the head and neck coiled into an S shape, ready to strike. Offering a warm rodent at this moment will rarely fail to elicit a strike.
It should be noted that Emeralds rely heavily on their heat receptors in their labials to detect the presence of prey. In the 'heat' of the moment, it is not unusual for the snake to strike out for any source of heat. This can be the heat source within the vivarium or possibly your hand. This brings me to the conclusion that Emeralds like their prey very warm and will generally ignore cooler prey offerings and go for the warmest target.
So it is best to ensure that the prey is well warmed up before offering, to elicit a strike and also prevent the snake from injuring itself on the mesh around a heat source. There has been several occasions when my snakes have caught their teeth in this mesh and have broken them in the ensuing struggle to free themselves.
As the snake is generally seen dangling below its perch anticipating prey, it makes sense to offer the prey from below.
The prey item is held by long forceps and slowly extended towards the snake, avoiding any quick, aggressive or unpredictable movement. The manner in which the snake takes the prey seems to differ according to the character of the snake.
Some will strike aggressively and coil immediately. If the prey is not warm enough, they may ignore it and waggle their heads about as though expecting something that doesn't seem to be there. Quite commonly though they will just open their mouths and gently take the food, let it dangle for a while in their mouths before constricting.
This may be a side effect of prolonged captivity, unless they are prone to foraging and feeding on carrion in the wild (but this detracts from their preference for warm food).
I have found that with my males that take their prey in this manner, may hold onto it dangling from their mouths for up to an hour or more before finally constricting and ingesting the food. The females generally don't waste that much time consuming their meal.
If the snake shows little or no interest in the food, it is then left alone and feeding is attempted again in a week or so. It is unnecessary to agitate the snake further. No attempt is made to further entice an Emerald, that is usually a good feeder.
A gravid female, that is offered a meal, may strike and butt the prey with their snouts, take it into their mouths and then drop it to show that she is not interested in the meal. This butting of the prey is also evident with males that are not interested in the food.
There is a certain amount of notoriety attached to the Emerald tree boa, not least of all its feeding problems.
Newly acquired, wild caught animals can prove to be difficult feeders and can take a lot of patience to encourage the animal to develop a regular feeding habit. A newly acquired individual should be left to settle in before attempting to feed it. Check out acclimatization.
Several methods can be employed to entice a stubborn snake to feed.
Placing live prey in the vivarium is a method that is sometimes employed but in my experience has never been successful, but does seem to be quite successful with my Chondros. Leaving dead prey also has never produced any results and I have tried all means of simulating life out of dead prey items.
Care must be taken when leaving live animals in a vivarium to ensure that no harm will come to the snake and that the prey cannot climb up onto any of the perches. It has been known where the prey has turned on the predator with dire consequences.
Freshly killed rodents are sometimes preferred by newly acquired specimens and can be used to get them into a feeding regime. Once feeding regularly, defrosted and well warmed rodents can be offered as they work just as well as freshly killed ones and less messy.
Day old chicks may be tried and have worked for me one one occasion, but I do not recommend that this diet of chicks is maintained but just used as a means to entice the snake into forming a feeding habit. Chicks consist largely of feathers and hot air with very little nutrient value.
Smaller prey items such as hairless rat pups, mice and gerbils are also items that can be used to entice a stubborn feeder to eat. Often holding the food item above the resting snake, whilst gently pinching the underside of its belly, can stimulate the snake to look for the source of the annoyance and result in a reflex strike towards the warm prey object. This may result in a successful feed.
If all else fails, force feeding may be the final option. This is not a practice that I am too keen on and one must persevere with the other options thoroughly first. It is highly stressful for the snake and there is no guarantee the snake will ever feed in any other fashion. A certain amount of technique is required to accomplish this procedure successfully.
The prey item should be small and well lubricated (I have used water mixed with a little olive oil). It is then gently pushed into the mouth with forceps, carefully working it to the esophagus. Care needs to be taken to ensure that the forceps do not puncture the throat. The food is pushed down the throat as far as possible with the forceps and then has to be massaged down the length of the esophagi into the stomach from the underside of the snake. Once in the stomach there should be less chance of any regurgitation. Good hydration of the snake previously is also known to prevent regurgitation.
Perhaps an easier technique and less stressful to both parties is to introduce nutrients by way of a catheter. A puree of rat pup provides the liquid food , diluted with water to provide a consistency that is easily ejected through the catheter. The length of the catheter will be approximately one third the length of the snake and the liquid will be pumped straight into the snakes stomach. One must take care not to place the catheter into the extendable trachea of the snake, resulting in possible drowning should the liquid be pumped into the lungs.
All sorts of criteria have been associated with regurgitation syndrome in Emeralds ranging from incorrect heating, humidity to parasitic and bacterial infections. It is difficult to pinpoint any one cause or remedy for this matter.
I have found that thorough acclimatization of an individual previous to any feeding attempts can go a long way to avoid this problem.
I have only ever experienced this once with a newly acquired male, but after careful acclimatization over a couple of months, and he seemed to grow out of this and has not done it since. Once some specimens start this behaviour, it can be very difficult to eradicate.
Good husbandry practices should prevent this problem from recurring.
Preventative measures are usually to feed smaller food items, less often, with furless rodents being primary candidates. Good hydration of the animal is essential, so keeping the humidity levels relatively high is important. Allowing the temperature to drop too low (less than 74 degrees Fahrenheit) and higher than 90 degrees Fahrenheit, has also been documented to induce regurgitation in Emeralds, and hence should be avoided if this problem persists.
It is not unusual for Emeralds to have prolonged periods of fasting. This is common with females once they are gravid but soon resume feeding after parturition.
More commonly, males tend to do this from time to time for no apparent reason. This is of little concern with a healthy individual, which may not eat for several months. But there comes a time when you wish him to begin feeding again. I have found that a slight change to his normal diet does the job. I have always used a black gerbil, which they have snatched for enthusiastically, to entice a male into feeding again after a lengthy fasting period.