Feeding Your Emerald Tree Boa: Diet, Frozen vs Live & Style

Feeding time really is a highlight in the keeping of Corallus. There are of course finicky eaters on occasion that can add frustration during feeding. However, when corallus are feeding well, feeding time is fun time. I am going to outline the feeding techniques that I use and present the reasoning behind some aspects. First, a few words about the incredible Corallus physiology as it relates to hunting.

Hunting Style

The nightly hunting and ambush behaviors of emeralds and amazons in captivity clearly demonstrate they are nocturnal hunters by nature. Emeralds are still-hunters that remain motionless, hanging down ready to strike at passing prey. Amazons will do this as well but frequently tend to roam in search of food. These differences in hunting styles (active versus still) may explain some of the variation in temperament between emeralds and amazons. On a nightly basis, amazons surely encounter threatening situations more frequently than emeralds. Amazons, being on the move, can have their presence revealed as the they encounter a variety of other animals including potential predators. Such encounters may require immediate striking and threatening displays to escape potential harm. Emeralds on the other hand rely on remaining still while hunting and can allow approaching threats to simply pass. The difference being the active hunting style of amazons requires immediate aggression for dealing with frequent, intimate, and possibly dangerous encounters with other fauna while emeralds can more easily avoid detection from danger by remaining motionless. The different hunting methods also help explain the contrasting metabolisms of emeralds and amazons. Amazons likely capture more prey with their hunting style but require more energy to actively search for prey whereas emeralds capture less prey by hunting from one location and therefore need less energy.

Heat Sensing

Few other snakes have the surface area of heat sensing pits lining their upper and lower labials that Corallus do, Corallus caninus mainly. In nature, as night time temperatures drop, the body temperatures of cold-blooded vertebrates (retaining some daytime warmth) as well as the warm bodies of mammals become accentuated in the cooler night air. The temperature variance between animal and air is the life blood of emeralds and amazons. Being arboreal adds to the need for advanced thermal sensitivity as prey animals either scurry by on branches or fly by. Opportunity to strike may last only an instant as a bat or an arboreal rat goes zipping by. Almost instantaneously emeralds need to calculate the size and speed of passing animals to decide whether to launch a strike. Additionally, the broad head of an emerald allows a broadened arrangement of the labial heat-sensing pits. The wider the arrangement of the pits the wider the peripheral sensitivity. This wider peripheral sensitivity allows prey to be detected and sized sooner so a quick strike can be rapidly calculated. I have heard some say the strike of an emerald is slow in comparison to other snakes. That is a fair statement to make during the day; however, I dare anyone to wave their warm hand under a hunting emerald at night. With that disturbing image in mind let’s talk about teeth.

Behavior

While hunting, emeralds mainly strike with the direction of gravity which can only help the speed of their strike. Being arboreal still-hunters has also led to a formidable set of teeth. Their teeth are very long, especially the first few in the front of their mouth. In an arboreal world where gravity must be overcome when catching and eating prey, the emerald found a solution in long curved needle-sharp teeth. The front teeth act like gaffs and increase the percentage of successful strikes. Emeralds can essentially capture a fast prey animal with a quick strike landing only a couple of the front large hook-like teeth. Once prey is captured, the long gaff-like teeth help emeralds avoid dropping their catch as they swallow it. Dropped prey from the forest canopy is costly as finding it again is unlikely. Emeralds are truely specialized for nocturnal arboreal feeding with their long teeth and spectacular advanced thermal sensitivity. That is why feeding them is fun.

Feeding Doors

A good sign that your emerald is settled in and comfortable with its captive environment is the display of hunting behavior. After the lights go out, hunting emeralds will hang down from their perches with the first third of their bodies tightly coiled in preparation to strike. Newly acquired animals will normally take a while to settle in and display hunting behavior; it is therefore a good practice to wait a couple of weeks before offering food to new animals. The feeding techniques I use are designed to naturally present frozen/thawed prey to hunting snakes with as little artificial disturbance to them as possible. In order to achieve this, the Corallus enclosures have specially designed “feeding doors”. The feeding door openings are just large enough to allow passage of appropriately sized prey. When not in use, the doors are kept shut with clear plastic sliders. The feeding doors are located on the lower portion of the enclosures; this is done so prey can be offered from below the hunting emeralds, just as they prefer it. A warmed frozen/thawed prey item presented in this fashion is readily and aggressively hammered. Feeding doors are safer and easier than what most enclosures allow for during feeding as there is: no danger of exposed hands, snakes coming out of their enclosures in pursuit of prey, awkward maneuvers to get prey to the snakes, opening lids to carefully offer prey from above, or the need for the keeper to hide to avoid distracting hungry animals. Feeding doors have been especially helpful in getting finicky youngsters to eat as they are often easily spooked. As a matter of fact, the thought of a feeding door was spawned due to a shy feeder.

Adult enclosure with feeding door and aluminum tracking for the clear plastic slider.
Juvenile enclosure with feeding door and clear plastic slider. Three screw heads serve as tracking for the slider.

A feeding door is best utilized in conjunction with a “feeding probe”. A feeding probe is comprised of a handle with a metal rod that is bluntly rounded on the end. I make my own feeding probes with stainless steel rods and wood for handles. Rodents are put on the probe by inserting the probe into the rodents rectum. Probes are made in various diameters to accomodate different prey sizes. Only frozen/thawed rodents are used, so there is no misconception regarding the method. Once a rodent is on the probe it can then be easily inserted through the feeding door to be grabbed by a hunting snake. The feeding door with probe method allows prey to be offered in a realistic manner to just below a waiting emerald or amazon. Rodents slide right off the probe after being grabbed. Tongs in this case would be cumbersome to manipulate through the small feeding doors. Tongs also result in dropped prey before the animal has struck. Using a feeding probe alleviates the possibility of clashing teeth and metal, common with tongs as snakes strike the rodent. The simplicity of a feeding probe’s design allows it to be easily and quickly cleaned after each snake eats. Yet another plus for using probes is the snakes’ mouths never actually come in contact with the probe, making the feeding probe a fairly sanitary method overall; convenient when feeding several animals.

Frozen/thawed rat on a feeding probe ready to be inserted through a feeding door.

Live vs Frozen Rodents

Feeding probes made of stainless steel and wooden handles. These three sizes accomodate all sizes of rodents.

As far as what to feed your corallus, I recommend feeding a diet strictly of rodents. With regard to feeding live or frozen rodents, I prefer to feed the collection previously frozen rodents over live for a few reasons. Frozen rodents of course cannot inflict injuries to the snakes; live rodents can conceivably take out a snakes eye with a properly placed bite. Though a “rare” occurance, the possibility is best avoided. Freezing rodents kills most of any bacteria and parasites the rodents may be harboring. In order for freezing to be effective in reducing the pathogen load of your rodents, the rodents should remain frozen for a minimum of thirty days. The freezing process also causes lysis of the rodents’ cells which allows easier digestion by the snakes. Basic handling of frozen rodents is easier than dealing with live. Frozen rodents can also be conveniently stored in bulk, making food availabilty less problematic. As previously mentioned, I believe in a natural presentation of food for the collection; frozen in this regard has one disadvantage. After emeralds and amazons grab their lifeless rodent, the intense instinct to constrict and kill is for the most part unnecessary. Over time, the constricting and killing behaviors of captive animals can become relaxed and in some cases nonexistant. I have had emeralds that have eaten frozen for a long period of time simply start eating thawed rodents without bothering to strike or constrict. This type of stangnant lazy behavior is probably not healthy. To avoid compromising the aggressive feeding response of your emeralds and amazons it is important to duplicate what a live rodent acts like when grabbed by a snake. I do this by prodding the rodent, with the feeding probe, after the snake has wrapped around the rodent. I actually prod rather aggressively several times. Upon doing this, the snakes will continue to tighten their coils and put some effort into securing their kill as they would with a live prey item. This may seem like a minor point, but I believe it is just one more piece of the puzzle that makes for a healthier captive animal overall. Anytime you can do something to maintain natural behavior; there are associated benefits. Additionally, prey items should be fairly warm upon being offered so the emeralds can “see” the prey with their heat imaging pits. I defrost rodents in hot water and they are appropriately warm from the process. Occassionally a rodent needs to be warmed more and for this purpose I use an independently wired ceramic heating element like those used to heat enclosures. I simply plug the element in for about thirty seconds or so until the element is hot but not hot enough to cook or burn the rodent. These elements heat up rapidly so you need to be careful. The rodent is then rolled on the heating element until it is very warm and then offered to the snake. A nice warm rodent will be aggressively snatched without delay.

Feeding Frequency

150 watt ceramic heat element for heating thawed rodents.

The frequency of feeding that I use to maintain the collection is fairly standard. Young emeralds and amazons up to the age of three years old are fed approximately every ten to fourteen days. Sub-adult and adult animals three years old and older are fed approximately every two to three weeks. Nature does not provide food by exact scheduling and nor do I. I like to keep the snakes on their “toes”. The thing not to do is over-feed; it is a good idea to withhold feeding an animal that has fed three times without a bowel movement. This is applicable mainly to emerald tree boas as amazons tend to be more active and defecate regularly. Record keeping is helpful. If an emerald has not defecated after a few meals you may want to consider taking them out of their enclosure for an exercise session. Many times simply crawling around will cause emeralds to defecate on the spot or later that night.

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