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Species Conservation Assignment

Taxonomy

The Komodo dragon (Varanus komodoensis) is the largest lizard in the Varanidae family, growing up to 3 metres in length and weighing up to 75 kilograms (Pough, Janis and Heiser, 2012). Until recently the species was believed to have killed its prey with toxic bacteria, when in fact, the true source of predation (found during an MRI scan), was discovered to be venom glands located in its jaw (Fry et al, 2009). Others in the clade Toxicofera, such as the V. varius and V. salvadorii, (which are phylogenetically closest to V. komodoensis), the suborder Serpentes and the suborder Iguania; similar discoveries were made, leading to a belief of a common ancestral venomous species that existed over 200 million years ago (Fry et al, 2003).

Natural History

Discovered in 1912 by Major P. Ouwens (Rees, 2011), living solitarily amongst the islands of Southern Indonesia, this species uses the Vomero-nasal organ (VNO) to detect prey (such as water buffalo, deer and carrion) up to 10km away (Warren, 2003). Exerting only 15% of the force of that of a crocodile with the same sized skull (Pough, Janis and Heiser, 2012), with serrated teeth and venom glands, it waits for its prey to die from a bite before consuming a large meal, making it an effective scavenging predator.

During breeding season (May and June), potential males compete for access to females through rearing on their hind legs and wrestling another (Warren, 2003). With an average clutch size of 18.7, the eggs incubate for around 220 days (Murphy et al, 2002), but it has been widely documented that this species can go through parthenogenesis, meaning that a male is not always necessary, but the genetic diversity may decrease if this occurs (Rees, 2011). Once hatched, the young survives up a nearby tree, feeding upon any small invertebrate that it can sustain itself on, for example invertebrates, mammals and small birds (KMP, 2007), until large enough to dwell on land, feeding upon much larger prey.

Conservations status & distribution

In the wild, there are many different estimates for population numbers for the V.komodoensis, with the most accurate being around 5000 individuals, being spread across Komodo, Flores, Gilli Montang and Rinca (CBSG, Hudson et al, 2012) and 53 institutions that keep some captive worldwide (ISIS). Until 1975, the species was also present on the island of Padar, but became extinct. On the IUCN Red List, this species is classed as Vulnerable, with habitat loss, poaching of ungulates and geographic isolation as a main threats (Murphy et al, 2002). As shown in Figure 1, the distribution of this species is very limited to these volcanic islands, but as explained in the next section, since 1915 it has been protected, with several in-situ trusts being established.

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Figure 1 - Varanus komodoensis Distribution Map

Threats to future survival in the wild

As previously mentioned, habitat loss, poaching and geographic isolation are some of the major threats facing the Komodo dragon, with human encroachment as a main factor. With the population ever expanding amongst the islands in Indonesia comes the pressure from governments to provide for residents, hence more of the limited resources available to the species (i.e. harvesting timber) being used. This results in a loss of habitat and possible corridors for genetic diversity between habitats (as seen in Flores) being a great influence on the availability of the species to breed and survive with “estimated low levels of gene exchange” (Murphy et al, 2002).

Among the areas where the ungulates are present, poachers use fire to draw out deer, so that the hunt for them is much easier. With this, soil quality is affected as the soil is exposed due to the damage of fire, hence harder for a new terrestrial area to regenerate, resulting in soil erosion. Along with deer, buffalo are also hunted illegally, meaning that the available food source for the species is greatly affected, hence less likely to survive.

As well as human-related threats, natural disasters are also taken into account, with the islands containing several active volcanoes (especially Gilli Montang) and being located near an at risk area for tsunamis. With these occurring, the available habitat for the Komodo dragon is affected, as natural disasters would make areas inhospitable for any life for a certain amount of time.

Conservation measures

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In-situ conservation consists of the Komodo National Park (KNP), Ecotourism and the Wae Wull Nature Reserve (situated in Southwest Flores). Started in 1995, through the Department of Forest Protection & Nature Conservation (PHKA), law enforcement and regular patrolling has become much stricter with regards to illegal poaching in and around the KNP. Since this, illegal activities have significantly reduced whilst providing “alternatives for locals” and helping the regulation of ecotourism and tourist activities on the island. For the species itself, “population ecology and demographic” of dragons has been researched, to aid with population viability whilst providing management in the long-term. KNP is also classed as a World Heritage Site, providing an extra level of protection (Murphy et al, 2002).

Through sustainable agriculture (for example, near Pota) ecotourism activities have been built, with a proposition to create another reserve here and providing a sustainable method of “using land available, whilst supporting development” (Murphy et al, 2002).

Wae Wuul Reserve, situated on West Flores contains a mixture of cultivated areas for residents (to draw them away from mainland Flores), with patches of “dry deciduous monsoon forest and secondary vegetation” (Murphy et al, 2002). This will aid with the conservation of the species, as they will be able to survive easier within the mainland of Flores, if less human influences affect the survival of the 500 Komodo’s left.

Ex-situ conservation is mainly a European Endangered species Programme (EEP), ran by Gerardo Garcia of Chester Zoo, England, since 2001 (EAZA, 2011). This programme is designed by a co-ordinator to manage the future of a particular species, including management of studbooks, “carrying out demographic and genetical analyses” (EAZA, 2011). There are 30 reported Komodo dragons in the studbook from Rotterdam Zoo in 14 institutions, one captured around 1996 from Indonesia and the rest of Zoo bred, mostly from Galdar (Visser, 2006). Overall, this will increase the gene availability of the species, whilst providing a healthy amount to be a viable for a flagship species. In Colchester Zoo (England) special enclosures have been created to mimic the natural habitat as much as possible, whilst still being environmentally friendly. In addition to this, they support the Wae Wuul Nature’s reserves rehabilitation project, with €1000 being donated annually (Colchester Zoo, 2005).

Husbandry requirements

The requirements of the V.komodoensis can be broken down into: enclosure, light, temperature, feeding and breeding carrying capacity.

The enclosure humidity, temperatures and photoperiods need to change, in accordance with the natural cycle of the species, in order to promote natural behaviour and reproductive conditions (i.e. ovulation) and overall health. The enclosure for the Komodo dragon needs to be 100m2 per individual, or if it contains a breeding pair, barriers and vegetation needs to be in place to reduce aggression for the 2 years (or 2 reproductive cycles) that they are housed together as stated by AZA Komodo Dragon Working Group (Murphy et al., 2002). With regards to substrate of the enclosure, it needs to mimic the natural habitat as much as possible, with earthen substances highly recommended in order to promote burrowing. During the day, these burrows are often used as thermoregulatory sites as refuge, and sleeping sites at night, ideally from a “mixture of soil, sand and hardwood mulch” that will not cause any abrasion to the feet and tail of the dragon. However, when designing the burrows in the enclosure, there is a risk of collapse, so the design of such is crucial, with partially buried rocks mostly used, “supported by rebar elements and footers” (Murphy et al., 2002). When also designing the enclosure,

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the age of the Komodo dragon needs to be taken into consideration, as young dragons are primarily climbers, so secure fittings need to be in place to prevent damage. In addition, with climbing presents a risk of injury caused by falling, so having smooth or expoxied surfaces to clearly define climbing areas will aid in reducing the risk.

With light being a crucial element in the process of Vitamin D3 for dragons, it is recommended in captivity to have a UV-B range of between 295-315mm (Murphy et al., 2002). The UV-B is especially important in young dragons, to reduce risk of Metabolic Bone Disease and in reproductive females to avoid complications with egg production. It is recommended by Murphy et al., (2002) that the transmitting panels need to be ideally 20-50cm above the area of basking. If possible, without affecting the temperature inside the enclosure, natural light should also be provided as dragons “seek out natural light in the wild” (Murphy et al., 2002).

As well as light being very important, temperature of the enclosure is crucial, as Komodo dragons are ectothermic, the temperature needs to be between 25-45°C across the enclosure, with designated areas for thermoregulation, to bask or cool down, so that the body temperature can remain stable. In addition, a small pool can help with thermoregulation, and is also useful for a water source for drinking in the species.

From hatching, it is recommended by Murphy et al., (2002) that a 15g mouse is offered every 5 days, with 10 month old dragons offered a large mouse once a week. If a dragon becomes reluctant, enticement with blood, organs and brains exposed in the “freshly eviscerated mice” will help promote regular feeding. Once large enough (i.e. around 1 years of age), mice are substituted for rats and fed between 1.5-3Kg a week, depending upon age and time of year (Murphy et al., 2002). Once fully grown, large meals consisting of chickens or other permitted animals may be offered to the dragon.

As the Komodo dragon is a solitary animal, requiring a large space and specific husbandry requirements, zoos must take this into account before accepting to breed a pair for genetic purposes, as the enclosure for a breeding pair must be large enough for both, whilst still giving ample room to reduce aggression amongst the pair whilst they are housed together.

Veterinary challenges

Medical management within zoos is a constant challenge for those working with Komodo dragons, requiring highly trained staff present at all times with the main risk of danger from the sheer size and strength of the species. Below covers the main issues faced whilst dealing with dragons.

General examination can result in harm caused whilst restraining young dragons with handling. Dragons over 25 years old, lethargy, gradual weight loss and little feeding response is common, and associated with unilateral vision loss. Hearing problems are often an issue, as only one inner ear bone (stapes) is present, with a limited hearing range. As the species is venomous, great care is needed when handling or examining the oral area, which itself can be tricky to do (as covered later). Nails require regular maintenance, through use of cautery or dermal tools to reduce overgrowth, with foot or toenail lesions common also. In addition, in young dragons, limb trauma is a frequent occurrence, as enclosure-related falls may occur.

Vitamin D3 is incredibly important for all lizards, especially at the hatchling stage, as lack of correct exposure to ultraviolet light or sunlight may lead to metabolic bone disease. With this in mind, for

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circulating 25-hydroxy vitamin D levels (as used in captivity), 100-250ng/ml is recommended for an adequate level to avoid this disease (Murphy et al, 2002).

Administering anaesthesia one of two methods may be used; manual restraining the dragon (limiting oral access as snout is taped) or use of a restraint box (providing access to end doors, side and top of specimen). The restraint box is used mostly, as stress levels are greatly reduced and limits unpredictable behaviours. It is used for minor procedures; for example venipuncture (identification), wound treatment, ultrasound, weighing and injections. In young, Isoflurane is typically used, but with a “quick recovery, the restrain box” use is highly recommended (Murphy et al, 2002). However, the amount needed in adults would be too great, so a darting method with ketamine and/or midazolam is often used, reducing the amount somewhat, but still at a high level (resulting in a high cost for anaesthesia). As serosal detail is poor in lizards during radiography, it is often difficult to clearly see the membrane of chorion in embryos. However, in gravid females, large egg masses can be identified easily.

Arthritis & obesity is often linked in older dragons, providing a problem for keepers to engage in a weight loss program for them.

In captivity, the main parasites found are often bloodworms, several species of Staphylococcus and Streptococcus, with Ascarids, Strongyle, Capillaria and Hemogregarines often found in the wild (Murphy et al, 2002).

Salmonella is the main bacterial zoonotic disease present in Komodo dragons, with E.Coli being the most commonly isolated disease (in-situ dragons) and in captive dragons, Staphylococcus being the most frequent found (Murphy et al, 2002).

In terms of reproductive issues, Oophoritis and Coelomitis are most commonly found, with several causes, such as post-ovulation abnormalities. In combination with egg yolk rupture, this can often be associated with death in captive hatchlings in zoos (as seen in American Zoos). Follicular stasis can occur also, although this is not well documented, which may lead to weight loss and anorexia in female dragons.

References

A. Warren. Komodo dragon [Arkive web site]. Date authenticated: 07/07/2003 by K. Buley. Date accessed: 27/12/2012. Available at http://www.arkive.org/komodo-dragon/varanus-komodoensis/#text=Biology

CBSG, 1995. Hudson, et al, 1994. (2012). Population and Conservation Status. Available: http://library.sandiegozoo.org/factsheets/komodo_dragon/komodo.htm. Last accessed 01/02/2013.

Colchester Zoo. (2005). Wae Wuul Nature Reserve Rehabilitation Project. Available: http://actionforthewild.org/index.cfm?fa=campaign.detail&id=5. Last accessed 03/02/2013.

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European Association of Zoos and Aquaria. (2011). EEPs and ESBs. Available: http://www.eaza.net/activities/cp/Pages/EEPs.aspx. Last accessed 03/02/2013.

Fry, B. et al., (2006). Early evolution of the venom system in lizards and snakes. Nature 439 (7076): 584-588.

Fry, B. et al., (2009). A central role for venom in predation by Varanus komodoensis (Komodo dragon) and the extinct giant Varanus (Megalania) priscus. Proceedings of the National Academy of Sciences, 106: 8969 - 8974.

"ISIS Abstracts". ISIS. Last accessed 03/02/2013

KMP Interactive Marketing and Technology (2007) Komodo dragon http://www.chesterzoo.org/animals/Reptiles/snakes-and-lizards/komodo-dragon Date accessed: 14/12/2012.

Murphy, B. et al., (2002). Komodo dragons: Biology and Conservation. Washington and London: Smithsonian Institution Press. Pages 28-29, 121, 178-209, 212-230

Pough, F.H., Janis, C.M. and Heiser, J.B., (2012). Vertebrate Life, 9th ed. IL, United States of America: Pearson. Pages 312-313.

Rees, P (2011). An Introduction to Zoo Biology and Management, West Sussex: Wiley-Blackwell. Pages 28 and 183.

Visser, G. (2006). Komodo dragon EEP Studbook. Available: http://www.rotterdamzoo.nl/import/assetmanager/9/2659/Komodo%20Dragon%20EEP%20Studbook.pdf. Last accessed 03/02/2013.

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