I NEED YOUR HELP-I only feel qualified (just barely) to write about species which I keep. In order to have the most information available I need you to help. If you keep a species which is not covered here, and want to help, please send your care guides to email@example.com. If a care guide is not written by me, then I do not necessarily agree with it. I will not place care guides which I think are grossly inaccurate (this is up for me to decide). However I do believe the more information the better. I believe most, if not all, monitors can be cared for in similar ways, and thus the information on this site can be applied to the majority of monitors available in captivity. Regardless people always say yeah but what about__________(insert your monitor here). For them I dedicate this page.
Savannah monitors are often labeled beginner monitors. THEY ARE NOT. They have been assigned this label for a variety of reasons. First, they are readily available and very inexpensive. They only cost importers less than $5.00 each and are imported by the thousands. Savannah monitors also have a reputation for becoming tame. However, of the hundreds of thousands of imported Savannah monitors how many survive never mind becoming tame? The answer is very few. Not because they are fragile animals nor is it because they do not make good captives. It is because they fall into the hands of beginners, who are not ready for taking care of a (Captive Savannah monitor foraging in a field.)
monitor lizard. Often times these monitors are fresh imports who are mal-nourished, carry parasites, and need to be nursed back to health. Virtually all Savannah monitors are imported, so if somebody is offering a CB Savannah monitor ask them for proof. If you are a beginner get a captive bred monitor, such as an ackie, it will save you a ton of headaches.
Savannah monitors reach a moderate size for a monitor. Males can reach over 4' in length while females are typically smaller. They are a heavily bodied monitor and care must be taken that they are not overfed and become obese. Young Savannah monitors can be fed mostly an insect diet. They will readily take crickets, worms, snails, and roaches. Be sure to dust insects with a good calcium supplement such as repto-cal or miner-all. As they increase in size they may become less interested in the smaller insects and it may become more practical to feed mice.
Hatchlings can be housed in a 55-gallon aquarium. However these monitors will grow extremely fast and you will soon need to be thinking about larger accommodations. When my Savannah monitor was 14" I moved him into a 6'x2'x2' cage. An adult should be housed in a 8'x4' but larger is better. Savannah monitor love to burrow so a deep substrate is needed and dirt is preferred. There should be a basking spot of 130+ degrees and the ambient on the cool side should be around 75.
Ridge-tailed monitors or ackies are in my opinion one of the best beginner monitors available. The high cost of the monitor itself often turns beginners off, but I encourage you to consider them. In the long run the Ackies will be cheaper for many reasons. They are all captive born so they should not have to be treated for parasites which means no expensive vet visits. They eat less amounts of food than larger monitors and can be fed crickets their entire life. They only attain a relative small size and do not require large (Ackie basking)
Ackies are generally easy going monitors who do not mind interactions, although there are plenty of exceptions. The best advantage of ackies and other "dwarf monitors" is being able to house a trio or pair of them in a relatively small enclosure. You will be able to learn a great deal about monitor behavior and monitor needs, which will provide essential information if you decide to keep other species.
Ackies reach a small size in the monitor world. They tend to get around 2' although many are smaller and some larger. Ackies can live on a diet of insects their entire life. I feed almost exclusively crickets with the rare pinky mouse as a treat. They will readily take worms, roaches, and other insects as well. Be sure to dust insects with a good calcium supplement such as repto-cal or miner-all.
I prefer to try and keep my monitors in the same cage throughout their lives. That said, I have keep my trio in a 5'x2'x2' trough. A 6'x2'x2' would be best but slightly smaller will suffice. You can put them in a smaller cage if you must, but they grow rapidly and will need a larger enclosure in about 6 months. Ackies like most monitors love to burrow so a deep substrate is needed and dirt is preferred. A minimum of 12" is recommended but if you can provide more then by all means do so. The substrate should be moist but not wet. This is important because if kept in a too dry of cage you will experience many problems due to retained sheds. This includes toes falling off. There should be a basking spot of 130+ degrees and the ambient on the cool side should be around 75. A water bowl should be provided and a few branches for them to climb on will no hurt either.
(Two ackies sharing a burrow)
Written by Chad Jacobs
Here is my take on the care for argus monitors. This care sheet is for a single animal or a breeding pair.
CAGE SIZE- 8 feet long, 4 feet wide , 4 feet tall. Make sure you build it to open from the top. Side opening cages don't work well.
SUBSTRATE-Dirt works best. It should be no less than 2 feet deep. A tip to make (Two argus monitors, one tripoding photo by Chad Jacobs)
burrowing easier, which is very important, is to lay plywood on top of the substrate.
HEAT-The cool side of the cage should stay around 80 degrees. The basking temps I use are 125-130 degrees.
FOOD- I feed adult mice as the main diet. I'll also give them roaches and turkey with Miner-all, but only when I'm out of mice. As far as how much to feed them, let's just say a lot. I was able to fill up one of my argus monitors in six days costing $36 on the seventh day it was full. Note on feeding, if your basking spot is too cool your argus will not have the energy and appetite it should, and if you feed without the proper heat you will end up with a fat animal. FAT ANIMALS DIE YOUNG.
HUMIDITY- With the high temps needed, you will need to maintain high humidity. One of the most common ways to do this is to control the air flow leaving your cage.
WATER-I use a large water dish just to be on the safe side. It is not too often that I see them drink but it's there if they want it.
ATTITUDE- If you ask most argus monitor keepers if Argus are tame, they will laugh in your face. The "tame" argus is rare. If you are looking at an argus and it seems inactive, you should take it to the Vet or check your husbandry. If you are looking for an animal that will keep you watching its cage to see what it will do next. Then maybe an argus is for you.
Written by Chris Dieter of Salvator Farms TX
The first time I viewed an Asian water monitor the animal was being passed off as a Komodo dragon in the movie " The Freshman". This is understandable as the lizards large size, bulk, and generally easy going personality make it a more than adequate stand-in for it's more famous relative. I have always had an interest in the larger reptiles and with my interest piqued by the film decided to acquire a water monitor for my personal collection. The first animal to come available was a two year old specimen that had been kept in less than optimum conditions and was only 18-20 inches in length. This animal was shy and more inclined to remain hidden than act anything like the tame water monitors I had been told stories about, let alone the animal in the movie. In fact this animal had a terrible attitude, biting, tail slapping, vomiting, and defecating at the slightest provocation. Strangely through all this I was growing fond of this animals spirit, it's beauty, and its intelligence. I also was becoming acutely aware of the growth potential of the world's second largest lizard. When given proper conditions this animal grew from two feet to just over five feet in less than eighteen months. Given the animals positive attributes, size potential, and scarcity of quality captive-bred specimens I decided to make the Asian water monitor my next breeding project.
The specimen I had in my possession was a male which meant that I needed at least one female and preferably two to have a chance at a successful reproductive event. Male water monitors can be differentiated from females on the basis of large hemipenal bulging at the base of the tail . The males will also generally have broader heads. Finding mates for my male specimen proved to be no easy task. Female monitors as a whole are much more scarce than males, and in my opinion worth there weight in gold. Through much searching and a little haggling I acquired my first female, a young, approximately three foot. This female had laid eggs previously and was just entering her reproductive years. With monitors the onset of reproductive viability is generally considered a byproduct of size instead of age. In Asian water monitors that size is generally around three feet of total length. As luck would have it I was able to acquire another pair from a friend in the East Texas Herptelogical Society. These two animals where in relatively good condition and where approximately four feet in length at the time of acquisition. I paired my male( now known affectionately as the albatross) with the California female and left the two four foot animals together.
To breed Asian water monitors, or any reptile for that matter, the animals must be properly established in an environment where there needs are being completely provided. An animal will not properly reproduce or reproduce at all if there most basic living requirements are not being satisfied or exceeded. I attempted to provide the largest housing possible for my water monitors while retaining some means of control for separation and routine maintenance. The basic cage design was subdivided to break up sightlines and to provide for easy separation of the animals should it become necessary. I feel that the breaking up of sightlines helps to reduce the monitors overall stress level. The reduction or elimination of excess stress enables the animals to feel secure and more relaxed.
The cage itself was 12ft x 7ft x 4ft which was then subdivided into three 4ft x 7ft x 4ft sections. Each section was divided with a solid sheet of wood with a hinged and lockable access door in each partition. The construction materials must be strong and reinforced as the strength of these lizards, as well as their propensity to dig, is incredible and should not be underestimated. I use an all-purpose gravel/mulch/soil mix as the substrate and it has proven visually appealing as well as easy to clean. Hiding areas in the form of cinder blocks and multilevel wooden structures are provided on both the warm and cooler regions of the cage. A large plastic basin is used for the water supply. It should be noted that changing a large volume of water can be an arduous task but since these lizards generally defecate in their water complete cage cleaning becomes infrequently needed.
Two hundred and fifty watt infrared heat bulbs are the primary heat source in the enclosures. Secondary heat may be provided with fiberglass heat blankets such as those available from Bush Herptelogical. The basking site under the heat lamps is extremely warm. In the midst of our Texas summer ,which was one of the warmest on record and when the most intense breeding activity occurred, the basking site would routinely exceed 120 degrees and on one occasion made my electronic thermometer read an error. The overall ambient temperature in the cage varied between 85-95 degrees. Despite the high overall ambient temperature the water monitors in my collection would bask frequently in the mornings, after feeding, and periodically in the afternoon. This has suprised some as V.salvator is supposedly a species who prefers temperatures at or near 85 degrees. The behavior of my captive specimens indicates that perhaps there is more information needed about this species thermoregulatory behavior.
A healthy Asian water monitor is very cosmopolitan in it's dietary preferences. This varanid will accept fish(whole and filleted), rodents, chicken, turkey, eggs, beef, and insects. During my breeding project with V.salvator my animals where almost exclusively fed on a diet of ground turkey, scrambled eggs, and whole chicken parts. The lizards where fed virtually daily in small to medium sized quantities. The offerings where always eagerly consumed often with both animals feeding at the bowl not unlike cattle at a trough. Remember that small to medium sized quantities when dealing with Asian water monitors is relative. Often times there would be several pounds of food eaten at a feeding.
I consider daily feeding a vital component of the successful varanid breeding plan. The female will need extra calories and nutrition in order to successfully produce the large eggs Varanus salvator produces. It has been speculated that the ready availability of food is one of the primary precursors to cycling in the female varanid.
In my collection the water monitors are kept either in pairs or as a trio. For the reproductive events to be discussed here the animals where kept in pairs. For use a reference they will be referred to as pair A and pair B. Pair A consisted of a 5.5ft male and a young three foot female. These animals where housed and kept in the manner stated above. After about a month of being housed together the male began pursuing the female wherever she traveled frequently using quick, rapid headshakes in combination with mounting of the female. He would go up and down the females body headshaking for the duration. The animals also began using the same areas to sleep in at night where previously they had slept in separate areas. On May 28th, 1998 I witnessed the first successful copulation. The female was underneath the male with the tail raised and the animals exhibited a slight pulsing motion. The animals mated for approximately an hour before separating. A few days following copulation the animals exhibited normal behaviors, generally remained separated and did not sleep in the same area.
Within two weeks the female began to swell noticeably. She also began digging in various areas of the cage. The nest site I provided was a large sterilite container with an opening cut and filled with sphagnum moss and potting soil. The first egg was laid in this nest box July 1st, 1998 followed by three eggs on July 9th,1998 and one egg on July 10th, 1998. All proved to be infertile. Pair A mated again August 21, 1998 with no eggs being produced before I sold the pair.
Pair B consisted of two essentially equal sized animals of approximately 4.5ft. These animals where sexually mature when acquired and where maintained in the manner mentioned above. This was a much more active pair than pair A. Matings where visually observed on the following dates: August 2nd, 9th, 13th, 19th, 20th, 23rd, and 26th as well as September 1st, 2nd, and 4th. Undoubtedly I missed several copulation's as these are only the observed events. The behaviors exhibited by this pair where nearly the same as the first pair in that the male used head shakes and scratches to entice and subdue his potential mate. Pair B also shared the same sleeping area, generally always side by side. Pair B however, preferred to copulate in the large water container present within the cage in contrast to the more terrestrial mating of Pair A.
On the evening of September 10th the female was observed digging deeply in the nest box. Upon closer examination it was clear she was depositing eggs. The eggs where collected and positioned in a sterilite container in which 1.5 inches of perilite dampened to a 1:1 ratio of substrate to water had been placed. The five three inch eggs had an average mass of 44.5grams. These eggs where quite large given the relatively small size of the female.
The five eggs where placed in a Neodesha incubator purchased from Bush Herptelogical. The temperature was maintained at a steady 86.2 degreesF and humidity was monitored so that water droplets where clearly visible on the clear sides.
Two eggs failed within two months while the other three continued to increase to truly incredible proportions. These three eggs where obviously fertile and after 90-100 days had nearly doubled their girth. As the incubation progressed towards day 150 I began to open the lid and air the container out virtually daily to decrease humidity within the container and facilitate gas exchange. On May 15th, 1999, 181days into incubation, I proceeded to open the container only to find one of the 3 eggs had collapsed. Upon opening the egg I found a fully developed monitor lizard with a substantial yolk sac unused. The animal was preserved for display in my classroom. The following day March 16th, 182days into incubation, I opened the container to find a head sticking out from one of the two remaining eggs. The lizard seemed fatigued but otherwise healthy. I left the monitor in the container overnight. On March 17th, 183days into incubation, the container was opened to find the second hatchling sitting on top of it's egg. The first animal remained in its egg. Both animals where left in the incubator for another night. On March 18th the second hatchling was removed to separate housing with the first hatchling joining his sibling after being carefully removed from the safety of it's egg.
The newborn monitors where approx. 11 inches in length and had slight "dents" in their tails which quickly filled out. Within two days of being placed in their new environment the monitors began consuming crickets. Within a week the newborn varanids where accepting live pink mice. Once accustomed to the larger prey the animals began taking prekilled pink mice, ground turkey, scrambled eggs, and fish on a daily basis. Young water monitors grow at an incredible rate when proper conditions are available. In the wild it is thought that they reach sexual maturity between two and three years of age. I am of the belief that in captivity it is possible for the lizard to attain sexual maturity in half the time required for a wild specimen. This fast growth and a virtually year round reproductive potential make the Asian water monitor a candidate for farming. Unlike smaller varanids however the space and food requirements are much greater for a group of V.salvator and given the numbers imported today may present economic dilemmas for potential breeders. Given the much higher quality of captive bred monitors in comparison to the sickly thousands of imported water monitors most hobbyists would be wise to purchase any certifiably captive bred specimens.
Monitor lizards are a very hot commodity in todays reptile marketplace. There are many species for a varanid enthusiast to choose from. Unfortunately most of the available species are wild caught animals. This is slowly changing however as in the last few years understanding of the reproductive biology of varanids has been moving at a quickening pace. This has been a long time coming. Likely the future of varanid herpteculture for most individuals lies in the keeping of the smaller species. There will, however ,always be a place for the large, potentially tame monitor in herpteculture and every effort should be made to establish and distribute effective breeding protocols. This will ensure a steady supply of high quality animals as well as provide a much needed alternative to imported animals.
We are currently awaiting our first F2 hatchlings from the hatchlings above.
KOMODO DRAGON Varanus komodoensis Compiled by: Trooper Walsh, National Zoological Park, U.S.A. Gerard Visser, Royal Rotterdam Zoo, The Netherlands Compilation date: 21 April 1999 INTRODUCTION AND NATURAL HISTORY Description: Adult male Komodo dragons, Varanus komodoensis, generally grow larger than females and may be 3 m total length and 90 kg. Females are usually under 2 m and weigh less than 50 kg. The body mass of large V. komodoensis is proportionately more bulky than that of smaller specimens. Ontogenetic morphology includes color change and transition in body structure. Juveniles to about age four years are multi-hued(yellow, green, brown, gray), speckled, and banded and have proportionally longer tails than mature specimens (1:2 vs. 1:1 SVL to tail length). Ground color in mature animals is rather uniform (Captive Komodo Dragon photo by Trooper Walsh) but varies in different populations. Body color of adult animals from Flores is typically an earthen red with yellow heads whereas specimens from other islands range from slate gray to black. Age at sexual maturity is estimated to be about six years in captive specimens (7). Longevity is known from captive lizards to be over 20 years (4, 8, 20). Distribution and Habitat: The distribution of V. komodoensis is restricted to a few Indonesian islands of the Lesser Sunda chain including Komodo, Rinca, and the western half of Flores. Reports of animals on smaller nearby islets, including Padar and Gili Motang, are probably based on records of transient animals. These latter populations are somewhat ephemeral with the species occasionally being totally absent. This has been attributed to periodic fires and the lack of suitable prey. The depopulation and repopulation of Padar and Gili Motang is proof that these lizards can swim and survive for relatively long periods in seawater. The total land area occupied by this saurian is less than 1000 sq km, making it the smallest range of an alpha predator anywhere in the world (4). The volcanic islands on which V. komodoensis lives are arid up lifts with steep angular slopes and alluvial fans. The stream beds and valley floors are rocky with shallow soils. The vegetation communities are simple; the low rainfall and its seasonal occurrence produce open, semiarid types such as monsoon forest, savanna, and steppe, dominated by the savanna. The species is most abundant in the lowland monsoon forests and savanna communities up to 700 m. The range of V. komodoensis includes the driest areas of Indonesi a and receives less than 75 cm of rain a year, falling almost entirely during the months of December to March. Average annual air temperature at sea level on Komodo is 26.7°C (43°C annual maximum and 17°C annual minimum). November is the warmest month and February the coolest (4). Ecology and Life History: Adult V. komodoensis have large activity ranges, moving an average of 2 km a day. This range includes a core area, where most of the animals' activities take place, and a larger foraging area. Although the animals avoid each other's core areas, their foraging areas overlap. The core areas contain the animal's burrow and favorite thermoregulatory sites. Core areas are defended by the resident alpha individual. Adult animals dig their own burrows or utilize natural shelters between rocks or cavities in river banks. Juvenile specimens live an arboreal lifestyle which enables them to avoid the larger, cannibalistic adults (4). Varanus komodoensis is an opportunistic carnivore at the top of it food chain in lands absent of large mammalian predators such as tigers and wolves. It has been suggested that this alpha predator can survive and thrive on the islands because the lizard is an ectotherm requiring less food than its mammalian counterparts (4, 34). They feed on both live prey and carrion and are capable of taking down deer, wild boar, and water buffalo (all introduced species). Approximately 10% of adult V. komodoensis diet consists of smaller, weaker conspecifics. Their keen sense of smell enables them to locate food from as far away as 10 km if the wind conditions are right and the scent strong. Their teeth are curved and serrated for tearing off large chunks of flesh and their claws are strong and sharp for ripping open carcasses. The saliva of wild specimens is known to harbor over 50 forms of virulent bacteria, probably the result of feeding on carrion (4, 13f). Even an incidental bite from this varanid may lead to blood poisoning and death in a short period of time if not treated. As an adaptation to survival during long periods of low prey density this large saurian can eat up to 80% of its own body weight in one meal. When necessary it may not feed for months at a time. Young specimens, living in a different niche, feed on insects, small birds and mammals, and other reptiles which may be more readily available throughout the year. Carrion of any type is acceptable to this monitor in all age groups (4). Courtship and breeding usually occur May through June often in for aging areas near carrion and frequently in the presence of other lizards. Females dig nesting burrows in their core areas which they backfill after egg laying. The nest mounds of the brush turkey, Megapodius reinwardt reinwardt, are sometimes used by V. komodoensis for egg laying. Egg laying usually takes place July through August. Laying females may defend nest sites for a period of time after oviposition. After approximately nine months the eggs hatch and the young are on their own (4, 13k). CONSERVATION STATUS Wild Population: Although not officially described to modern science until 1912 (24), this unique saurian enjoyed protection by local Indonesian rulers in conjunction with the Dutch government as early as the mid 1800s (19). Today this saurian is listed as CITES Appendix I and as endangered by the International Union for the Conservation (Komodo Dragons In Idonesia photo Trooper Walsh) of Nature and Natural Resources (IUCN) and the United States Department of the Interior. Indonesia accords this animal its highest level of protection and considers it a national treasure. The range of V. komodoensis, with the exception of Flores, was declared Komodo National Park (KNP) in 1980. In 1991 the park was classified as a World Heritage Site. In December 1995 the IUCN sponsored a V. komodoensis Population and Habitat Viability Assessment (PHVA) workshop in Bogor, Indonesia (25. Participants and decision makers at the PHVA consisted of 40 international zoo and field biologists, zoo directors, wildlife managers and authorities, university administrators, and Indonesian government officials. The PHVA resulted in recommendations for management of both captive and wild populations. Priority actions for in situ management included: · updated census within the KNP · study, census, and protection on Flores · habitat assessment and census of prey species · development of simple and reliable sexing techniques · determination of genetic characteristics throughout its range and on individual islands · study of the effects and impact of ecotourism The wild population of several thousand animals was projected to be relatively stable except possibly on the island of Flores where V. komodoensis competes with local farmers for resources. The PHVA suggested that major threats to wild monitors may include habitat alteration, poaching of prey species, and perhaps tourism (25). In November 1998 the Thoiry Zoological Park sponsored an internat ional V. komodoensis conference in Thoiry, France. Participants and decision makers included 60 zoo, field, and laboratory biologists, zoo, museum and university administrators, veterinarians, and French government officials. Information presented included updated data and new accounts of in situ and ex situ conservation efforts for this species (13). Field research presented included: · a DNA profile of the wild populations showing the greatest genetic divergence in the east to west extremes of the natural range (13b) · establishment of normal physiological values for wild dragons (13f) · study of the blood and saliva for pathogens and possible development of a natural antibiotic for use in human medicine (13e, 13f) · prey assessment and dragon carrying capacity on Padar Island to determine the feasibility of reintroduction (13b) · female nest guarding behavior and egg hatching sequences in the wild (13k) · an updated distribution profile of the species on the island of Flores with suggestions on how to involve indigenous peoples in conservation efforts (13b) A working subgroup of the Thoiry conference helped identify future research goals, management plans, and fund raising methods for continued field work (13p). Priority in situ actions listed included: · the need for a complete census of the Flores population and measures taken for its protection · development and implementation of DNA sexing and fingerprinting of the wild population · microchip pit tagging of wild specimens during all future field work · development of a core group of European zoos to fund raise within their community and to help guide future field endeavors with the international community CAPTIVE MANAGEMENT Captive Population: In January 1998 the first edition of the international studbook was published by Johnny Arnett of the Cincinnati Zoo and Nell Bekiares of Southern Illinois University, Department of Zoology (3). As of November 1998 there was a total global captive population of 272 (65.50.157) reported in the International Species Inventory System (ISIS) in 49 institutions (5). Thirty-eight of these animals (17.20.1) are wild caught (potential founders) of which only 10 (5.5) are represented in the founder population. Their locations are as follows: · Indonesia: 160 (39.23.98); in 10 institutions, of which 19 (7.11.1) are wild caught with 5 (2.3.) founders represented · North America: 82 (16.13.53) in 30 institutions, of which 10 (6.4) are wild caught with 5 (3.2) founders represented · Europe: 14 (6.8.) in 5 institutions, of which 4 (2.2) are wild caught (no breeding yet) · Asia: 8 (2.4.2) in 2 institutions, of which 1 (0.1.) are wild caught (no breeding yet) · Australia: 8 (2.2.4) in 2 institutions, of which 4 (2.2.) are wild caught (no breeding yet) About a dozen successful breedings have been recorded worldwide. The first documented captive breeding took place at the Gembira Loka Zoo in 1968 (9). The most recent hatching occurred at the Miami Metrozoo in October 1998 (13c, 13i). The following institutions have had breeding successes with this species: 1. Ragunan Zoo, Jakarta, Indonesia 2. Surabaya Zoo, Surabaya, Indonesia 3. Gembira Loka Zoo, Yogyakarta, Indonesia 4. National Zoological Park, Washington, D.C., United States 5. Cincinnati Zoo, Cincinnati, United States 6. Miami Metrozoo, Miami, United States The captive working group of participants at the 1995 PHVA suggested that efforts be made to selectively breed unrepresented potential founder animals to increase the genetic diversity of the captive population. There was also a consensus that founder stock should be increased and dispersed into capable institutions worldwide. The zoo carrying capacity for dragons has yet to be established, although Indonesian zoos estimated that 130 adult animals could be maintained in their institutions (25). The 1998 Thoiry working subgroup made a number of decisions and recommendations concerning the international captive population and future management plans, changes in zoo protocol, and areas to direct research (13p). One outcome of the Thoiry meetings was the mobilization of European zoo workers to form a core management group which will develop a regional studbook and protocol. Zoos currently involved include Thoiry (France), Colchester and Chester (Great Britain), Lisbon (Portugal), Rotterdam (The Netherlands), and the Canary Islands (Spain). Attempts will be made to include other European zoos holding dragons into this management group such as Berlin (Germany) and Pilzen Zoo (Czech Republic). Gerard Visser of the Royal Rotterdam Zoo, The Netherlands, will develop and hold the European regional studbook. Kmt. A. Tirtodiprojo of the Gembira Loka Zoo, Indonesia, agreed to develop an Indonesian regional studbook and possibly take over responsibility for the international studbook from Arnett and Bekiares at a later date. Arnett and Bekiares would then manage the North American studbook. With new information presented at Thoiry concerns were expressed that we may be producing captive specimens very unlike their wild counterparts, and if so these animals may not be suitable for reintroduction programs or long term survivability in captivity. Research is needed to fully assess the competence of these animals and may result in further redesigning of facilities and protocol to meet potential management challenges (13p). Examples of physical and behavioral attributes cited as concerns include: · recent evidence showing captive lizards are maintaining lower core body temperature than active wild specimens (34°C vs. 37°C). It was hypothesized that captive specimens need not require the higher temperatures as they do not need to expend energy patrolling large territories and foraging for food (32, 35) · fifteen year old adults at the National Zoo and the Surabaya Zoo have what appears to be an arthritic condition in the knees which causes abnormal gaits and reduced activity (13l, 13o, 33). Clinical exams of two National Zoo animals revealed degeneration of the knee joints, possibly due to weakened muscles and ligaments resulting from a lack of exercise (13l, 13o) · captives at the Gembira Loka Zoo have been fed ad lib in order to avoid cannibalism in communal enclosures. Compared to lizards raised in North American zoos these animals appear to be growing at an accelerated growth rate with a possible linear social hierarchy resulting in alpha animals eating the bulk of the food. This is different from the wild where juveniles are solitary and must actively forage for food. Concern was expressed that ad lib feeding may lead to health problems later in life (9, 13p, 31). Some of the Gembira Loka animals have developed unusually fat tail bases which drag behind the individuals and may be diet related (13f, 13l ,13o). Other captive management recommendations made at Thoiry (13p) included suggestions to focus on: · breeding unrepresented founder animals · not breeding F-1 animals with founders · not breeding F-1 animals as long as founders are alive and reproductively viable · determining the global carrying capacity in zoos · studying social behaviors of communally vs. individually reared animals · applying DNA sexing and fingerprinting of the entire captive population · developing more holding facilities globally for adult animals incorporating larger enclosures with access ability to sunlight · developing research priorities and resources, developing management protocols and determining means for disseminating information more efficiently (WEB pages, e-mail exchange, scientific and popular articles, other scientific meetings and conferences) · encouraging international cooperation of common goals and objectives among zoos and government agencies The majority of lizards in the U. S. population are permanently pit tagged for identification with implanted TROVANä microchip transponders (InfoPET/TROVAN Electronic Animal Identification System, manufactured by AEG/Daimler-Benz, Germany). The standardized implantation site is on the left side of the animal in the hip region. Some animals now leaving Indonesia have been tagged with the AVID™ microchip system (AVID Identification Systems, Inc., Norco, California 91760, USA). Typically the microchip scanner from one company will not reliably show the ID number of the other's microchip product. Another company, HOME AGAIN™ (Schering Corporation, Union, New Jersey 07083, USA), has developed a universal pocket scanner that identifies and reads TROVAN, AVID, and HOME AGAIN microchip transponders with good accuracy (33). Ultimately the entire captive population should be microchipped with an internationally accepted product available to all zoos with some form of standardization (13p). HUSBANDRY PARAMETERS Housing: As a large alpha predator this taxon will benefit from some of the same caging parameters which big cats have come to enjoy in zoos, such as quality and quantity of space. Indonesian zoos have had success maintaining groups of V. komodo ensis and have bred them in large outdoor facilities (200 to 400 sq m) under natural conditions (9, 13m, 13o, 21, 23, 25, 28). Environmental factors important to long term maintenance and the display of natural behaviors in this varanid include: adequate space and visual barriers, earthen substrate for denning and nesting, natural sunlight, the opportunity to bask at high temperatures, and seasonal climatic change. Through the mid 1980s these lizards rarely thrived and did not breed in zoos outside of Indonesia. There are at least two possible reasons for this: larger, older animals which were easily stressed by capture and export to zoos did not acclimate well. Also, European and American zoos typically kept V. komodoensis in small, sterile, concrete cages with limited heat sources which did not adequately meet the needs of this large saurian. In the late 1980s North American zoos began to incorporate some of the environmental ingredients that worked well in Indonesian exhibits. In 1988 the National Zoo developed a 68 sq m L-shaped duplex facility for a pair of adults which ultimately proved adequate for the first breeding outside of Indonesia. This exhibit is a dirt floored greenhouse incorporating multiple retreat and basking areas, a nesting area, pools, and a variety of plants which serve as visual barriers. The exhibit is divided into two fully complemented enclosures so that animals can be maintained separately as needed (21, 25, 30). Currently about a dozen North American institutions have neoteric facilities for holding adults: Audubon, Cincinnati, Ft. Worth, Memphis, Metro Toronto, Miami Metrozoo, Minnesota, National Zoo, San Antonio, San Diego, and White Oak Conservation. Of these, three zoos have proven facilities (Cincinnati, Miami Metrozoo, and National Zoo) where dragons have successfully reproduced. As other zoos world wide are developing new holding and breeding facilities we encourage them to design bigger exhibits with access ability to direct sunlight (13a, 13f, 13m, 13n, 13o, 13p). Environmental Concerns: This varanid should be kept in a xeric environment with a thermal gradient of 25-45°C. Animals should not be allowed to come into direct contact with heating elements. Fresh drinking water should be available at all times. Recent research shows that V. komodoensis need ultraviolet light (UV-B in the 295-315 nm range) for processing vitamin D-3 and for proper bone mineralization, and these lizards do seek out natural sunlight. Current in situ and ex situ studies suggest that young and reproducing females may benefit the most from UV light (1, 13f, 13o). Where climate allows, we advocate outdoor enclosures be incorporated into exhibits. In temperate climates greenhouse facilities with UV-transmitting panels are desirable. We currently suggest Solacryl SUVT™ panels (Polycast Technology Corp., Stamford, CT 06902, USA), as the best choice with 85% UV-B transmission. Varanus komodoensis kept indoors should have access to UV-B producing fluorescent lights situated 20 - 50 cm above basking areas. Preliminary indications in North American Zoos show that the new 300 W mercury vapor lamp, the Westron Dragonlite™ (Westron Corporation, Oceanside, NY 11572, USA), produces useful UV-B light when mounted 200 cm above an animal, resulting in D-3 blood levels comparable to conspecifics in nature (13f, 17). Juvenile and young adults are excellent climbers so this should be taken into consideration when choosing cage furnishings and restraints. We suggest avoiding abrasive materials like rough concrete block with exposed corners or wire mesh which allow escapes and foot injuries. We advocate smooth surfaced, solid walls and viewing areas be used in enclosures and that they should be at least 180 cm high in outdoor exhibits. Footers need to be buried at least 50 cm to discourage animals from digging out. Secondary hot wire restraints have been used with success at a number of institutions including the Cincinnati Zoo, Singapore Zoo, and White Oak Conservation. Natural and artificial burrows are readily used by this monitor lizard as sleeping dens at night and as retreats from the heat of the day. Soil, sand, hardwood mulch, or a combination thereof are acceptable exhibit substrates as they allow natural digging behaviors and are non-abrasive to feet and tails. Substrate integrity should be considered when animals are digging to avoid collapsed burrows and suffocation. Varanus komodoensis will dig under partially buried logs which gives structural integrity to the burrow entrances. If large rocks or detached cement pools are used in the exhibit the lizards may burrow underneath making it difficult to access the animals. This species rarely digs vertically beyond 50 cm but may tunnel horizontally for several meters (2, 13a, 13o, 29, 33). We recommend that exhibits should be as spacious as possible with optimal parameters of at least 100 sq m per adult specimen to provide suitable activity and core areas (13a, 13l, 13m, 13n, 13o, 13p, 33. To effect these goals in limited space we suggest exhibits incorporate visual barriers between multiple basking, denning, and nest sites and should explore enrichment opportunities. At the tropical Indonesian zoo of Gembira Loka a special soil mixture is used in nesting areas for successful natural outdoor egg incubation. The soil mixture encourages heat retention, good drainage, and structural integrity and consists of volcanic sand, beach sand, river sand, ground red stone, lime, and dried leaves and twigs (13m, 29). Nest areas should be sectioned off to allow isolation of gravid females and should have 60 - 100 cm of soil. Regarding temperate zone zoos we recommend breeding facilities with ambient air temperatures of 28°C have an overhead heat source warming the surface of the soil to 40°C to attract females for nesting. In addition to isolated nest sites, we advocate individual holding areas be available in group enclosures to sequester injured or subordinate specimens. Several zoos have developed specialized shift boxes for animals to facilitate manipulations, examinations, x-rays, and medical procedures. Specimens will utilize pools both as retreats and to thermoregulate. We suggest pools, shift doors, and keeper entrance ways should be elevated from the floor to avoid interference from substrate when it is shifted by inhabitants. Nutritional Requirements: Indonesian and American zoo workers feed their lizards differently. At the Gembira Loka Zoo on Java, hatchlings are fed daily for the first eight months and then every three days through the next year. This frequency of feeding is necessary to avoid cannibalism among young specimens being raised communally (29, 31). These lizards are provided a diet of 20% whole mice and 80% chopped beef or lamb with vitamin/mineral supplements. It is not yet known what possible long term effects may result from such frequent feedings in juveniles which may be growing at an accelerated rate; however, the majority of animals hatched at Gembira Loka in the 1960s died from overfeeding (9). Recently concern has been expressed about the "fat tail" condition seen among some of the Gembira Loka F-1s, possibly an artifact of too much food or too rich a diet (13f, 13l). Subadult and adult animals at Gembira Loka are fed less frequently on lamb and beef with organ meats included. All of these animals, including hatchlings, are given daily access to hot spots and direct sunlight to aid digestion and bone mineralization. Most North American and European zoo workers have been raising their neonates based upon a protocol established by the National Zoo. Hatchlings at the National Zoo are started on whole 15 g mice offered every five days until approximately 10 months of age when they are fed proportionately larger meals once a week. Reluctant feeders are stimulated to eat by offering freshly killed eviscerated mice with blood, organs, or brain cavity exposed. At one year of age they are introduced to small rats. Adults eat 1.5 - 3 kg of rats each per week depending upon the size of the lizard and the time of year. The National Zoo philosophy is to feed small meals to specimens on a regular basis rather than allowing them to gorge and fast for extended periods; they are not given any vitamin/mineral supplements. It is felt that a diet of whole animals combined with access to hot spots of 40°C and natural or artificial UV-B light are enough to promote healthy growth and development. Since 1992 the National Zoo has been tracking the growth of 55 neonates produced from the National Zoo female in an effort to document growth patterns in this species. These animals, now residing in about 30 zoos world wide, are growing into adulthood at different rates based upon different feeding regimens, but all are still alive and appear nutritionally healthy six years later (7). Varanus komodoensis is easily conditioned to audio or visual cu es by food which can be used to advantage in management for shifting the animals. Health: Varanus komodoensis is generally disease tolerant but is known to be susceptible to amebic and bacterial infections as well as internal and external parasites (16, 17). Recent work supported by Antibody Systems, Inc.(Hurst, TX 76054, USA), shows wild lizards have one of the strongest immune systems of any megavertebrate (13e, 13f). Most health problems in captive animals seem to be the result of environmental factors. Animals kept too cool may regurgitate or refuse food (14). The lack of suitable heat may also lower resistance to infections. These varanids commonly suffer tail and foot injuries in zoos due to suboptimal caging situations. Cagemate aggression is also a serious consideration (8, 33). In 1992 several neonates at the National Zoo were discovered to have femoral fractures soon after hatching. Radiographs revealed that all of the young had poorly mineralized bones. Treatment consisted of providing UV-B light with florescent fixtures and reduced handling of the animals. X-rays at four months of age showed greater bone densities and healing of old fractures. Subsequent groups of young have also shown poorly mineralized skeletons upon hatching but have not experienced fractures when raised under these revised husbandry procedures (33). Research at the National Zoo using Varanus exanthematicus showed that these lizards also have poorly mineralized bones as hatchlings (1). It is the opinion of the authors this may be a naturally occurring phenomenon in hatchling varanids which is of little consequence if proper husbandry is applied. The authors believe chemical restraint to be an important tool used for the responsible and safe management of this species, particularly as animals grow into adulthood. Anesthesia protocols for physical examination and treatment were pioneered at the National Zoo for all age groups (27). Subadult animals up to three years of age and 7 kg in mass are successfully anesthetized using manual restraint and masking down with 1 - 3% isoflurane gas (Aerrane, Ohmeda PPD Inc., Liberty Corner, NJ 07938, USA). Larger animals up to 55 kg are initially immobilized by injection with dart or pole and then isoflurane is administered. The current cocktail of choice for injection is a mix of ketamine (Ketaset, Aveco Co., Fort Dodge, IA 50501, USA) at 10-12 mg/kg and midazolam (5 mg/ml, Versed, Hoffman-LaRoche, Nutley, NJ 07110, USA) at 0.2-0.4 mg/kg. Social Management: In nature these top line predators live solitary lives (4), but in captivity they may be kept in groups with careful management and suitable caging although further study is warranted in this area (13p). In Indonesian zoos adults of mixed sex but similar size are often collected simultaneously from the wild and caged together. It is unclear if these groups are always able to establish hierarchies without casualties. It has been suggested that newly introduced specimens may experience aggression from established captives (8, 15). Juveniles are raised together in Indonesian zoos from the time of hatching with their siblings. Aggression was reported when neonates from unrelated clutches were introduced and when siblings were separated and later reintroduced (29, 31). The Indonesian method of raising them together has many advantages and is reminiscent of crocodile farming. Advantages include maximum use of available space and socialization which may prove useful in establishing communal exhibits for older animals. Disadvantages inherent to communal rearing include a lack of control and monitoring of individuals, the need to feed these normally solitary lizards frequent meals to prevent cannibalism, and difficulty in tracking breedings. Alternatively most North American zoos keep adults singularly or in pairs, and neonates are caged individually due to limited space and concern about aggression. Concerns were expressed at the Thoiry conference that these zoos may be raising animals that are less likely to integrate socially as they mature (13j, 13o, 13p, 29). In the Berlin and Singapore Zoos F-1 lizards hatched at the National Zoo are currently being kept together successfully. Some zoo workers promote hands-on protocol while others do not. It is the opinion of the authors that careful familiarization of lizards to keepers in some capacity is important to successful captive management (13p). Considerations on the subject include limitations in exhibit design affecting management needs, individual temperaments of captives, and keepers abilities to read and communicate with their charges. Caution should always be taken in working with this species; it should be remembered that V. komodoensis is a potentially dangerous megacarnivore on par with large mammalian predators. Some captives show individual recognition of people and may bond to regular keepers (14, 30). The sense of smell appears to be very important to these animals and olfactory familiarization with keepers and potential cagemates may help with management. Staff at the National Zoo routinely leave worn articles of clothing in exhibits with this intention. The presentation of scat from prospective mates was employed prior to the introduction of animals at the National and Cincinnati Zoos. REPRODUCTION Sexing Techniques: Varanus komodoensis is difficult to sex visually with the exception of very large animals (3 m and 90 kg) which are likely to be old males. Auffenberg (4) reported that males possess two sets of rosettes formed by scales anterior to the cloaca but this character does not appear to be consistent in all individuals based upon more recent sexing techniques (33). Likewise the use of manual sexing probes and hemipenal eversion are methods which are unreliable (13b, 13o, 33). There are a variety of promising techniques being developed for sexing these varanids including hormone assay, x-ray, laparoscopy, ultrasound, and DNA analysis (10, 12, 13h, 13l, 13o, 18, 22, 26). Of these methods, transintestinal sonography and transcutaneous sonography confirmed by blood hormone assay currently seem to be the quickest and most reliable ways to sex dragons of all sizes (18, 22), at least until DNA sexing becomes a reality (13g). Reproductive Groupings: To trace parentage we suggest single compatible pairs be kept together with access to separate quarters for nesting and other management concerns. DNA fingerprinting, which is being worked on by Ciofi and Halverson (11, 13b, 13g), will prove a useful tool in conservation management of both captive and wild lizards. Unless spacious enclosures with individual core areas are available gravid females should be separated from other dragons several days prior to oviposition. Laying females may defend egg sites from all intruders throughout incubation (13k, 13o, 29). In communal situations males may engage in combat for territories or females, and females may fight over nesting areas. Combat and courtship behaviors may appear similar and can be stimulated by feeding sessions. These behaviors can include rapid tongue flicking to the neck and cloacal areas, jerky chin rubbing, neck arching, raking with claws, biting, pinning, and mounting. Male to male copulation has been observed and is thought to be a display of dominance but this deserves further study (2). Seasonal Reproductive Patterns: Varanus komodoensis in the wild and in Indonesian zoos is reported breed June through August (4, 13m, 15). This is the dry season and the time of shortest day lengths in the Southern Hemisphere. Seasonality of females producing mature follicles is evidenced by a bloated belly condition which, when confirmed with ultrasound, is a good indicator for pairing sexes (13l, 13o). Oviposition occurs after a six to eight week gestation period. In the wild most are thought to hatch in April-May, just after the short wet season when the density of potential prey (insects, fledgling birds) is the highest (4, 13b, 13k). Thus far the Cincinnati Zoo, Miami Metrozoo, and National Zoo have been the only institutions outside of Indonesia that have reproduced this taxon. In North America this saurian typically breeds in December and January which coincides with the shortest photoperiod and coolest temperatures in the Northern Hemisphere. Oviposition has normally taken place in January and February. At the National Zoo a wild caught female has laid two clutches in one year on several occasions, but this activity was not considered normal for the species in nature (4) and was probably an artifact of captivity by bringing the female back to prepartum weight more quickly than in the wild. We do not recommend biannual breeding as protocol. Oviposition occurs 40-50 days from conception. Egg clutches have varied from 20 to 30 eggs. Clutch mass can be as much as 20% of the female's prepartum weight. Incubation periods have ranged from 205 to 256 days with an average of about 220 days. Staggered hatchings ranging from eight to 40 days in a clutch have been observed both in captivity and in the wild (13k, 13o, 25, 30). (Hatchling Komodo Dragon photoprovided by Trooper Walsh) Incubation Techniques: Indonesian zoo workers typically incubate egg clutches naturally in outdoor exhibits under conditions described earlier. In some instances protective wire caging was placed over nest sites to protect them from predators and to confine hatchlings (15). In other cases the laying females have successfully guarded the nests throughout incubation and keepers were positioned in the exhibit to collect hatchlings as they emerged (29). Of five egg clutches successfully hatched in North American zoos all but one were incubated in Model #I-35-L Percival environmental chambers (Percival Manufacturing Co., Boone, IA 50036, USA) as dry box incubators (6, 25). Sealed plastic sweater boxes were utilized to hold the eggs and medium. The egg medium was vermiculite (Terr-Lite, grade 3, W.R. Grace, Cambridge, MA, USA) which was initially baked dry and then mixed with water by weight. Eggs have hatched out at water to soil ratios kept at 1:1 (very wet) to 1:4 (very dry). Predetermined moisture potentials were maintained in the soil by adding water weekly. Incubation temperatures ranging from 28-29.5°C have been used (6). The best hatching results at the National Zoo were from eggs initially set up at a 1:3 water potential and 29°C. After one week the temperature was increased to 29.5°C. These conditions were sustained for the next 180 days after which the temperature was dropped to 28.5°C and no more water was added to the soil. By day 230 all of the eggs hatched yielding vigorous, healthy young (25). This latter regimen was also used by the Miami Metrozoo to hatch 27 of 29 viable eggs in October 1998 (13c). Neonate Husbandry: At hatching, neonates are approximately 40 cm total length and weigh about 100 g. Current protocol at the National Zoo has involved setting up hatchlings inside the incubator for up to two weeks in an effort to reduce stress and to allow their bones to further (Komdo Dragon Hatching photo provided by Trooper Walsh) mineralize. The hatchlings were placed individually in plastic shoe boxes (32 x 17 x 8 cm) on dry paper towels and hydrated everythree days by soaking them for several hours. First meals were offered to the neonates while they were still in the incubator. After two weeks the young were housed individually in plastic tubs (38 x 58 x 36 cm) containing a hide area, a basking platform, and a water bowl. Astroturf was used as substrate for ease of cleaning. Heat was provided by 75 W spot bulbs which produced temperatures up to 40°C at the basking area. Ultraviolet-B emitting fluorescent tubes were used in conjunction with the spot bulbs and were situated six inches over the basking area for maximum benefit. Both light systems were put on a 12 hour photo/heat cycle (30). Introductions of individually raised, captive hatched young in North American zoos have met mostly with aggression to date. This behavior is in contrast to the seemingly compatible nature of young specimens raised communally in Indonesia and warrants further study. COMMENTS AND DISCUSSION Varanus komodoensis is a high profile endangered species which has recently enjoyed some reproductive success in zoos both inside and outside of Indonesia and has proven to be a hardy captive animal given modern protocols. The PHVA in Indonesia and the more recent Thoiry international conference in France have highlighted some of the pressing issues about this species in situ and ex situ. Further, ongoing zoo, laboratory, and field studies will help b etter determine the population dynamics, reproductive biology, and long term needs of wild and captive populations. Priority actions should include pit tagging and DNA fingerprinting of both wild and captive populations and a complete census of the Flores population with considerations towards better protecting this population, possibly by inclusion into the Komodo National Park system. It is important to increase awareness and appreciation of V. komodoensis among the Indonesian people because this animal is a unique national treasure with resource potential. Indonesian government agencies, zoos, and researchers are currently meeting these challenges in conjunction with international counterparts. Captive bred specimens finding their way into the worlds' zoos help highlight the specialty and fragility of this and other endangered species and serve as an important zoo conservation-education model (13p, 31). Unrepresented founder stock needs to be incorporated into the global captive gene pool. As more V. komodoensis become available to the world's zoos there is need for commitment to develop additional facilities for adult animals, particularly holding complexes which incorporate newly determined optimum parameters. Current zoo research interests include metabolic and calcium absorption studies in eggs and progeny, food and growth studies, investigations of thermal preferences and social behaviors in young and adult animals, and determining the competence of captive animals. Work also continues on developing practical sexing methods for this taxon. DNA fingerprinting and sex determination using a quantitative sample of captive animals is in progress and should result in readily available tests in 1999. ACKNOWLEDGMENTS We would like to thank the people of Indonesia for the opportunity to work with this unique national treasure, the Komodo dragon. In particular we would like to thank Djoko Tirtodiprojo, Director of the Gembira Loka Zoo, and Vincent Gepak, General Curator of the Surabaya Zoo, for so freely sharing their wealth of experience in breeding and rearing dragons. Thanks to Johnny Arnett and Nell Bekiares for assistance with up to date studbook information. And finally we would like to thank Allison Alberts, Colomba de La Panouse, George Horn, Patricia Ann Jaffray, and Jim Murphy for reviewing this manuscript. REFERENCES 1) Allen, M.E., M.F. Hoilck, M. Bush, O.T. Oftedal, R. Rosscoe, and T. Walsh. An update on vitamin D and ultraviolet light in basking lizards. Unpublished data. 4 pp. 2) Arnett, J. Personal Communication. 3) Arnett, J. and N. Bekiares. 1998. International Studbook for the Komodo dragon, Varanus komodoensis. Cincinnati Zoo, Cincinnati, Ohio. 47 pp. 4) Auffenberg, W. 1981. The Behavioral Ecology of the Komodo Monitor. Univ. Florida Press, Gainesville. 406 pp. 5) Bekiares, N. 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