Caretaker Habituation, CTs
Contrary to assertions that one should minimize contact (e.g., Evans, 1983; Buglass Hiss, 1988; Reese,1994), I have found that 'taming' wild infant rabbits during the first two days following admittance with frequent handling is a critical component of their survival during rehabilitation. Piver (1991) similarly advocates a 'touch' approach to rehabilitating infant cottontails.
However, upon introduction
of solid food and within a few days,
the rabbits typically develop diarrhea and
die in a matter of hours
When not handled in this way, wild baby rabbits become stressed every time a human comes near. Thus, they have a low likelihood of survival in captivity. Based on my experience, I do not recommend that bunnies be kept rehab centers, but rather be fostered out to a home where they will have only one caregiver, and where stress factors can be dramatically reduced.Diet-associated diarrhea has proven more difficult to manage,especially when rehabilitation begins with baby rabbits whose eyes have not yet opened.Diarrhea commonly caused by "overfeeding of nutritional inadequate diets" (Evans, 1983) can be circumvented through carefully monitoring the animal's stomach during feeding and by using a milk-replacer formula combination that closely reflects the mother rabbit's milk in gross nutritional composition, as described in this article. However, upon introduction of solid food and within a few days, the wild baby rabbits typically develop diarrhea and die in a matter of hours, most likely from enterotoxemia caused by pathogenic bacteria in their gut (Cheeke, 1987). Efforts to manage this problem have been used with limited success by using antibiotics and/or by providing 'harmless' bacteria (e.g., Lactobacillus; Bene-bac®, etc.) to prevent colonization of the gut with pathogenic microbes and inoculate needed gut flora (e.g., Buglass-Hiss,1988; Reese, 1992, 1994).In fact, Evans (1983) recommends against the "blanket use" of antibiotics with cottontails. In my experience, none of these techniques has worked with rabbit babies who were separated from their mother prior to their eyes opening. Weaning-onset mortality was 100 percent.This article presents a novel approach to preventing weaning-onset diarrhea in cottontail rabbits, based on knowledge of the biology of these animals. (Please see part two - covering weaning to release in the Winter 2000 issue of Wildlife Rehabilitation Today).It is well-known that adult rabbits engage in coprophagy, in which they produce and consume a special type of "soft" or "night" feces, separate from the excretion of their "regular" hard pellets (Cheeke, 1987). (The soft feces are more technically called cecotropes or caecotrophs, and for brevity I will hereafter refer to these as 'CTs.')In the rabbit gut, specific microbes act on food in the cecum, a sac-like structure at the juncture of the small and large intestines. This fermented, bacteria-laden material is coated with mucous. It is voided to produce the CTs. When consumed, CTs provide additional nutrients, including protein, minerals and certain vitamins (Cheeke, 1987).Ingestion of CTs also provides a continual supply of the appropriate microbes that are necessary for proper functioning of the rabbit's gut (Cheeke, 1987). My observations suggested that baby rabbits obtain their gut flora needed to process solid food via eating some of their mother's CTs. Thus, the protocol described below provides CTs to baby rabbits prior to weaning onto solid foods. I have used this technique since 1987 to avoid weaning-onset diarrhea during successful rehabilitation of dozens of baby cottontails (Sylvilagus floridanus) and marsh rabbits (S. palustris).
I have used this technique
since 1987 to avoid weaning-onset
diarrhea during sucessful rehabilitation
of dozens of baby cottontails
My protocol for successful rehabilitation of these animals involves handling/ taming of the babies, which results in wild baby rabbits that are calm in my presence. I am the only person caring for the babies. The only other person that they ever see is my spouse; thus they remain frightened of others, as they should be. Upon release, they "wild out" without any problem and yet remain unafraid of me. This allows me to closely monitor their post-release progress, as they remain near our home on wooded acreage, where we provide specially-constructed brush piles and other hiding places.As evidence of the success of this rehabilitation protocol, I have witnessed several of my released rabbits reproduce. They also have much better than average survival - two to six years - in this 'wild' setting despite the presence of various predators, including hawks, owls, foxes and raccoons.I will address weaning, including the use of CTs to prevent diarrhea, as well as caging and release, in the Winter 2000 issue of Wildlife Rehabilitation Today.
Wild Baby Rabbit Initial Care
During intake assessment of a wild baby rabbit, the primary concern is for its safety.It is a very rare bunny that ever tries to bite. Rabbits' main method of defense is kicking with their hind legs. Though they are capable of inflicting significant scratches, the main danger is to themselves, in that improper holding can result in a fractured spine from the kicking, and also from a fall.Therefore, hold the bunny securely by placing a forefinger of one hand over its ears and forehead with the other fingers and thumb over its shoulders and forelegs. Use your other hand to support and secure its hind legs and rump. Always be alert; bunnies have an uncanny way of relaxing, tending to cause the handler to relax, and then they try to leap out of your grip. Quickly assess the bunny for life threatening conditions that would require emergency care: severe bleeding, shock, difficulty or cessation of breathing, hypothermia or hyperthermia, brain or spinal injury, poisoning, seizures, vomiting, severe burns, severe dehydration, etc. If you are not familiar with protocols for dealing with these problems, see the International Wildlife Rehabilitation Council Basic 1AB course book or the National Wildlife Rehabilitators Association Principles of Wildlife Rehabilitation (1997) manual for details. Or you can consult an experienced wildlife rehabilitator orveterinarian.Make a determination of hydration status by pinching the skin together into a tent on the animal's back at shoulder blade level, and time how long it takes for it to become flat again. Less than one second indicates five percent dehydration; greater than five seconds is severe. No return requires veterinary emergency care.All animals are considered to be mildly dehydrated upon admission, therefore begin administering a rehydration solution (Pedialyte®, Normosol® or lactated Ringer's) every 30 minutes until a normal hydration level is achieved. If the baby appears to be stressed, do not proceed with the physical exam at this time. Instead, stabilize the animal by treating its emergency conditions and place it in a warm incubator in a darkened, quiet area free from human activity and potential predators so that it can calm down, settle in and warm to its normal body temperature (101-103 degrees F).The first step in the physical examination is to observe the baby in the holding container for any additional signs of problems. Examine it from head to tail - does it appear normal, maintain a normal body posture, move correctly, use all limbs, behave naturally, etc.? Use your senses of sight, smell, and hearing when conducting a physical exam. Record the information on a standard physical exam form. Any abnormalities should by appropriately addressed; discussion of these details is beyond the scope of this article.Note that babies that do not have their eyes open can be held and comforted soon after intake. Older babies with their eyes open may require several hours or days to become accustomed to you and to its new surroundings before taming down. As you regularly feed the baby, clean its cage and talk softly to it, you will notice that it will soon become used to you and your hands.Also, it is important to raise more than one baby together; these are social animals when they're babies and need to have playmates and the comfort of cuddling with others.
Homemade Incubator
Wild Babies under two-and-one-half weeks of age should be housed in an incubator. To build an inexpensive, efficient and safe incubator, use a plastic see-through sweater box; drill 1/4" holes 3" apart in rows spaced every 3" across the top. The heat source is a seven-watt night light fixture with the shade removed, plugged into an extension cord and placed into the bottom of a wide- mouth pint canning jar or a glass peanut butter jar. Place the jar in a fuzzy athletic sock, turned inside out; close the sock at the top of the jar with a "twist em" and again at the top of the sock onto the cord. Pin a tent made with sweatshirt material on the side of the jar. Line the incubator with a baby receiving blanket or tee shirt. Place the heater jar in one end of the incubator, making certain there is room all around it for the baby to move without getting stuck.This provides a nice 'warm fuzzy' for the baby to cuddle up to and a cozy cover, almost like Mom! If the room is too cool, you might need to place a towel over some of the holes in the incubator top to hold in more heat, but DO NOT cover the holes over the heating jar or it will get too hot.Another heat source, but much more expensive both to purchase and to use (150 vs. seven watts), is a heating pad placed under one end of the incubator, set on low.
Formula Feeding
After the wild baby rabbit is fully hydrated, palpate and visually check the stomach for remaining mother's milk.Once the stomach is mostly empty, begin the transition to full strength formula, using the following schedule.(Note that there should be a total of at least nine feedings with pre-mixed formula diluted with Pedialyte® before introducing full strength formula).
| Pre-mixed rabbit formula 1 | Pedialyte® | Give enough to lightly fill stomach every: |
| 1 part | 3 parts | 1/2 hr (for 3 feedings) |
| 1 part feedings | 1 part | 1 hr (for 3 feedings) |
| 3 part feedings | 1 part | 2 hr feedings (for 3-4 feedings) |
1 The pre-mixed rabbit formula used here is given below. Note that the powdered formula is mixed with water first, and then diluted with Pedialyte®. Do not make up the powdered formula with Pedialyte®. An established formula that comes close to matching the milk of mother cottontails in gross nutritional composition (Marcum, 1997) is:
| Zoologic 42/25® or KMR® | 1 part |
| Zoologic 30/55® or Multi Milk® | 1 1/2 parts |
| Water (distilled or boiled) | 2 parts |
Other published combination formulas are too protein deficient; even this formula is somewhat lacking in protein. Evans (1983) recommends the addition of commercial protein supplements, although I am not aware of any specific work that has been done to establish this method.Neither Esbilac® nor KMR® should be used alone; Esbilac is very protein deficient and too high in carbohydrates. KMR is deficient in fat and excessively high in carbohydrates, which contributes to diarrhea.Mix only enough powder and water to provide formula for a day's worth of feeding, and keep the unused portion refrigerated to minimize bacterial growth. The recommended feeding utensil is a 1cc syringe with a Catac® nipple, or a nipple made from cutting a 1 1/2 inch piece of #10 or #12 size gastric tube.Babies that have not yet opened their eyes have an essentially sterile gut system, which is maintained by an interaction with the high fatty acid content of the mother's milk (Cheeke, 1987). We cannot duplicate this using existing formulas, and thus it is very important that we do not introduce any bacteria when feeding. Therefore, it is necessary to wash your hands thoroughly and to sterilize all feeding equipment by placing in boiling water before each feeding.When refrigerated, the formula becomes very thick and will need to be spooned out of the storage container. Heating it achieves a more liquid consistency. Warm only the amount of formula that you will feed at one feeding and discard any leftovers. Place the formula in a sterilized medicine dose cup or 35mm film canister and heat it briefly in a microwave or in hot water until it is close to the baby's body temperature. It should feel very warm to your wrist. You should keep the formula warm by immersing its container in a baby food jar of heated water.Hold the baby rabbit in an upright position for feeding. Babies whose eyes have not yet opened should be picked up and laid back in your hand at a 45 degree angle. If the animal resists feeding, it can be encouraged by lightly coating the nipple tip with Nutri Cal® or baby food (e.g., banana or sweet potato flavors). Feed slowly and pay close attention to the crease between the baby's lip and nose - wipe away any milk that goes up toward the nose. Most babies ( before their eyes open) will suck readily on the nipple; older ones may just lick formula off the nipple.
Rather than following
published feeding charts,
observe and palpate the
stomach as you feed.
Unlike squirrels, bunnies are not prone to overeating. However, it is important not to overfeed, as that will cause diarrhea. Rather than following published feeding charts, observe and palpate the stomach as you feed. It should be slightly rounded out and slightly firm, but never hard or taut. Babies that do not have their eyes open are fed every three hours and with much smaller amounts than what you will see in published feeding charts.Many articles on rabbit care state that babies are only fed once or twice a day by their mothers andthus that we should feed on a similar schedule. However, I recommend more frequent feedings, for two reasons. First, rabbit mothers in the wild may actually feed more often - once or twice during the night, as well as at dawn and dusk (Harrison & Harrison, 1985). Second, substitute milk formulas are digested much more rapidly than rabbit milk, which due to its acidity, forms a thick curd in the baby's stomach and digest slowly over several hours.Adjust the feeding schedule so that the baby's stomach is mostly empty before feeding again. Some bunnies digest faster than others.Babies with eyes closed must be stimulated to urinate and defecate. Some may defecate on their own but you should stimulate them after each feeding.Bunnies that are accustomed to being held will allow stimulation for elimmination long after their eye have opened. This allows you to closely monitor the character of both urine and feces, and keeps the cage cleaner.
Always be on the alert for the first sign of mushy feces, and make corrections, such as by reducing the amount or frequency of formula feeding, changing or reducing the amount of weaning foods given, reducing the stress level, etc. Mushy feces may also indicate a need for administration of another couple doses of CTs (this is be covered more fully in part two in the Winter 2000 issue of Wildlife Rehabilitation Today).Babies whose eyes have yet to open should be weighed every other day, as a consistent loss in weight is a sign of a problem.In a previous article (Kenyon, 1999), I introduced a protocol for the successful rehabilitation of orphaned wild infant cottontail and marsh rabbits that avoids the often-fatal diarrhea commonly seen during wild rabbit rehabilitation (Evans, 1983; Reese, 1992).This approach includestwo features:(1)habituating('taming') the rabbits to captivity through early frequent handling, and (2) providing the infants with 'soft feces' (also termed cecotropes) from an older wild rabbit to help establish their gut flora prior to weaning them to solid food.My previous article addressed initial care for the rabbits, making an incubator and formula feeding.Here I describe the remaining components of this protocol, including weaning to solid food, caging and release procedures.
WEANING
Weaning-onset diarrhea is a very common occurence in wild baby rabbits that have been separated from their mother prior to their eyes opening.Once such diarrhea begins, I know of no way to stop it, and it usually is fatal.To avoid this, within a day or two of the eyes opening and BEFORE ANY solid foods are offered, begin the following probiotic (microbe supplying) regimen. Obtain fresh cecotrope material (hereafterreferred to as CTs) from an older healthy wild rabbit.There are two forms that can be used. The most common is the CT "packet", the clump of closely clustered grape-like 'soft feces' that are expelled by the rabbit during the night or dawn hours. CTs are dark brown to black, soft and moist, with a strong odor, in contrast to the individual, lighter colored round pellets that are excreted (these are also harder, drier and less odorous than CTs).Rabbits usually eat CTs directly from their anus, and thus they are not readily found in a rabbit's excrement.The best way to obtain CTs is to put an Elizabethan collar on a domestic rabbit overnight. The rabbit should be in an elevated cage with clean newspaper underneath to catch the CT material.Analternate method for obtaining CTs is to get the cecal sac from a butchered healthy rabbit. It does not matter what age or sex the rabbit donor is.What does matter is that it is healthy, without parasites, and that it is not on any type of medication.Remove 2-3 of the soft pellets and offer them to the rabbit.Some bunnies will readily lick these off one's finger.Otherwise, mix them into 1cc of formula and syringe feed.In either case, make certain that all of the material is eaten. Feed this once each day for 3 or 4 days.If fluid from the cecum is used, withdraw this directly into a 1cc syringe and feed 1/3 cc per day on the same schedule.Experimental studies (i.e., controlled double-blind, etc.) need to be done to determine the precise CT dosage and schedule. For example, smaller doses over a shortened time may be adequate.However, since 1987 I have used the protocol described here with complete success on dozens of rabbits, and thus I strongly recommend that it be followed until additional data are available.Because of the difficulty in obtaining CTs, it would be helpful if these could be frozen for future use.Thus, studies also need to be done to determine whether and how long the CTs remain viable under freezing or other methods of preservation.I have frozen the cecal sac liquid and based on microscopic examination after thawing, it has appeared to remain 'alive' for at least a few weeks.Once this schedule of CT feeding has been completed, weaning onto solid foods can begin.The weaning diet should consist ofhigh quality, name brand rabbit pellets and high quality, well washed natural vegetation (e.g., grass, clover, dandelions and plantains) that you are certain has not been sprayed with, or was not in a drift area of, pesticides or fertilizers.Also include high quality alfalfa hay.It is imperative that the hay be completely dry and stored in an air tight container to avoid the risk of molds.A good transitional food is raw rolled Quaker{R} oats.Bunnies are always eager to eat this and will continue to favor it; thus you must wean them off the oats inorder to get them to eat the pellets.
Although rather young wild rabbits may be seen outside their nest during weaning, this does not necessarily mean that they are weaned from their mother's milk (Reese, 1992). For example, I have observed a wild mother rabbit (one that had previously been rehabbed and released), near her nest nursing babies that were a few weeks beyond eye-opening.In fact, cottontails are not fully weaned until 4-5 weeks of age (Chapman et al., 1982).Thus, you should continue to feed formula during the weaning process.To avoid spoilage, do not add liquid formula to the oats or the pellets.Also, do not put formula in a dish, as the bunnies will step in and run through it, getting it all over themselves and contaminating it.Trying to clean formula from bunny fur is very stressful both for the bunny and you!As the bunny gets older, you can offer a dish of liquid formula and see if they can drink it without making a mess.However, do not leave a dish of liquid formula in the cage formore than about 30 minutes because of potential bacterial growth.
Keep fresh water available at all times, preferably in a water bottle (vs. a dish) for cleanliness (note that bunnies reared with a water bottle readily convert later to a dish or natural water source).Make certain that all babies are eating the weaning diet.Weigh them every 3rd or 4th day, and continue to monitor fecal quality.Offer supplemental foods (well washed fruits and vegetables) only after the bunnies are routinely eating the rabbit pellets.Keep in mind that supplemental foods should comprise no more that 10% of the total diet-- they are treats.Some suggestions for these are broccoli (stems only), carrots, endive, kale, romaine lettuce, water cress, cauliflowerand occassionally blueberries, strawberries or raspberries.Add one small piece of supplemental food at a time, and then wait a couple of days so that if a problem develops, you know which food may have caused it.Keep a heavy dish (for stability) of rabbit pellets available at all times, and feed the greens at dusk and early mornings, the normal foraging times for rabbits (Harrison & Harrison, 1985).
CAGING
Once the wild rabbit babies leave the incubator, they can be housed in a standard2' x4' x 1 1/2' commercial rabbit cage as long as the cage is inside a protective enclosure.Outfit these cages with hiding places, including boxes, tunnels, tubes made of pvc drainage pipe and piles of hay.Also provide dishpan-sized sand trays for digging and play.Do not use these cages outside as predators(e.g., raccoons and cats) can reach through them and grab a bunny, and snakes can crawl inside.Do not use screening for rabbit enclosures, as raccoons and dogs can break through screening.It is important to house bunnies in an enclosure with only bunnies, or with only bunnies and squirrels.Make certain that they cannot see, hear, or smell ANY potential predator.Keep in mind that their senses are much more acute than our own.Reese (1992) suggests keeping cages near the ground because rabbits are ground-dwellers.This is good logic, but in my experience I have found that a person rising high above caged rabbits tends to scare them.Therefore, I recommend that cages be elevated; also, an elevated cage will bring the rabbits above the eye line of an outdoor predator.
Bunnies at this stage are relaxed, curious, and playful, both with each other and with their foster mom. I have observed wild-born litters that have left the nest playing vigorously with each other, as well as playing by themselves, and even trying to engage their real mother in play.Play is a critical part of developing the predator-avoidance skills of speed and jumps that result in a 180 degree turn.It is a tragedy to allow a baby rabbit to remain so frightened throughout its early development that it never is at ease enough to play, and that it has to be confined in a very small cage so that it doesn't injure itself, as some rehabbers have suggested. When the bunnies begin to pace, dig and chew the wire, or fight, it may not mean that they are ready for release but rather that they need to be moved into a larger enclosure.It is important at this stage to try to keep the group of bunnies no larger than what is dictated by the size of the cage.Continue to observe them, especially at night, for signs of fighting (e.g., clumps of fur on the floor or scratches on the bunnies) and be ever alert for signs of stress.If these problems occur, and you do not have a larger enclosure, you can intervene by separating out an aggressive bunny, or by releasing it.
Enclosures for outside should be made of galvanized 1" x 1/2" welded wire (preferred), or galvanized 1/2" x 1/2" welded wire, elevated 2 feet off the ground with the bottom area under the cage closed off to prevent predator access, and two sides should be visually blocked to a height of18 inches.The enclosure that I have for my outside bunnies is8' x 12' x 8' tall, and has a plywood floor, with a small area with a wire floor for airing their undersides (which they like to do), and for excretory purposes.They are very easy to 'potty train' to a specific area by using urine-soiled newspaper.In this enclosure bunnies are content, unstressed and playful, and they come to greet me when I enter!
RELEASE
Rehabilitators seem to be aware that typically, most orphaned wild baby rabbits get diarrhea and die soon after their eyes open. Many assume that the diarrhea is due to stress, which can be one cause, but more commonly the likely cause is enterotoxemia from pathogenic bacteria in their gut (Cheeke, 1987).The high frequency of diarrhea has led to the establishment of protocols, based on erroneous beliefs, to cease giving formula and to release the animal shortly after the rabbit's eyes open, or when it begins eating solid foods.Described by Reese (1992) as a common mistake, and as I have heard others mention,the goal of many rabbit rehabilitators is to release the animals before they die in captivity,using the reasoning that'It doesn't matter, anyway, because they are just going to be eaten by a predator.'It is certainly true, at this very young age that, without a nest in which to hide, and without much savvy of the dangers in the wild, they will soon be eaten, and if not they will most certainly die from diarrhea!Given such a self-fulfilling prophecy, one has to ask "Why bother 'rehabbing' them?"
Wild rabbit babies in my care are usually 1/2 to 3/4 grown before I release them, and therefore they are not going to immediately become a meal for a predator; their speed and avoidance techniques by this time are well honed!Although they are comfortable around me, they are frightened at the approach of other persons.To release them, their enclosure is opened and they are free to leave whenever they are ready.If they have not left by nightfall, the door is closed to prevent predators from entering, and opened again the next day.They do not disappear in a panic retreat, but rather leisurely explore their new freedom, sometimes returning to their enclosure, and generally staying in the area for months and sometimes several years, and are periodically watched by us at feeding and/or watering stations, with their own babies, etc. On at least three occasions a mother rabbit had her babies under the 'Critter Hut', the enclosure from which she was released.
In general, for on-site releases, slow release methods are preferred as they allow, the bunny to leave when IT is ready, rather than when the rehabilitator is ready, and this allows the rehabilitator to keep track of the animal and provide assistance if needed.Following is a list of questions to consider before releasing rabbits that have been rehabbed:
1.)What is the weather like and what is the forecast? Is the rabbit in good enough physical condition to withstand these conditions?
2.) Is the rabbit at normal body weight for its age (i.e., not too thin, with good muscle tone, etc.?
3.) From what injuries did it recover? Can it run properly? Does it have good strength and stamina? Does it have normal vision?Can it hear?Are the stools normal? Is it good general health?
4.) Does it have a dense coat of fur?
5.) Is the release site in the proper habitat: woodland with thick undergrowth, brush piles and a meadow area, with ample food and fresh water (creek, stream, pond or lake)?Iffood is seasonally sparse, will you be able to continue to offer handouts?
6.) Is there evidence that some rabbits are living in the release habitat? If not, figure out the reason-- it may be ominous!Are there too many predators in the area, human hunting or trapping, etc.?
7.) Does it recognize its predators, from the air as well as the ground?Is it afraid of persons other than yourself?
8.) Is it acclimated to the outside ambient temperatures? This is critically important.
9.) What are the hunting and trapping seasons of the area? Try to wait until hunting season is over!What about plans for construction? Don't release in an area that is soon to be bulldozed!Always obtain permission from the owner before releasing animals on property other than your own.
CONCLUSIONS
In this and my previous article (Kenyon, 1999), I have described a protocol for successful rehabilitation and release of infant rabbits.I have developed and applied this protocol over the past 12 years with dozens of cottontail and marsh rabbits.Prior to this, rabbits that were brought in for rehabilitation beforetheir eyes opened (some were newborns), and had developed entirely normally to this point, would invariably get diarrhea and die soon after I began weaning them to solid food. Now, by habituating them to captivity and handling, AND by feeding them CTs prior to weaning, my bunnies do not get diarrhea, they thrive during rehabilitation and they are successfully released.Subsequent observations on these rabbitsin the wild confirm their long-term survival and reproduction, essential components of successful rehabilitation.
