KOMODO DRAGON
(Varanus komodoensis)
Location: Komodo dragons are native to four southeastern islands of Indonesia: Flores, Gili Motang, Komodo and Rinca. As of the 1970s, they have also been found on the island of Padar.
Habitat: These lizards inhabit seasonally arid grasslands, savannas and monsoon forests, usually in the lowlands. Their habitat is very harsh with steep slopes and little available water most of the year. The average annual temperature on Komodo Island is 80°F.
Komodo dragons are the largest lizards in the world. They can reach up to 10 feet in length and can weigh 150-300 pounds. Adult komodos are mostly black, green or gray with patches of yellow-brown or white. They have a large, powerful tail which they will use for defense. The yellow color of their long, forked tongue and their deadly bacteria reminds people of mythical dragons that spit fire. Males and females look similar, other than a noticeable size difference with males being larger.
Komodo dragons are generally solitary animals, except during the breeding season. Males will maintain and defend a territory of approximately 1.2 miles, depending on the size of the dragon. Feeding ranges will extend further and may be shared with other males. The dragons maintain burrows within their core ranges which they use for body temperature regulation. They are also very good swimmers. They will swim about ¼ of a mile from island to island for new food and new territory.
In the wild, the primary prey for adult dragons is the Sunda deer. They also feed on birds, snakes, fish, crabs, snails, small mammals, pigs, water buffalo, eggs, wild horses and younger komodos. They can eat prey that is up to 5 times their own size such as a water buffalo that weighs about 2,000 pounds. They are also scavengers and will eat carrion. For the first few years of their lives they spend much of their time up in the trees, to avoid being eaten by adult komodos. Young komodos will roll in buffalo dung as a biochemical defense. Adult dragons do not like the smell of the dung and will not eat anything that smells like it. During this time they eat mostly insects, mainly grasshoppers and beetles, and smaller reptiles such as geckos. At about 4 years old and 4 feet long, a young komodo is large enough to escape its predatory elders, and has become too large to be safely supported by the trees in the monsoon forest.
Despite their size, komodos are fast moving, good climbers and like all monitors they are good swimmers. They can run about 11 miles per hour, which is about as fast as a human. However, they do not chase their prey. They use their sense of smell, hearing and sight to detect an animal nearby. Like most reptiles, komodos have an excellent sense of smell. They can use their long tongues and the Jacobson’s organ on the roof of their mouths to detect rotting carrion from almost seven miles away. Their tongue is 12 inches long and they can taste the scent of an animal hours after it has left the area. Due to the location of their eyes, komodos have monocular and binocular vision, and they have a visual range of 240°. Dragons can go about 9 months without water but then need about 120 gallons of it per year. Since there is little water in their habitat, many of the animals frequent the watering holes and it is a good place to find their prey. Once they know an animal is nearby, they wait in tall vegetation until the right moment, and then they lunge at the intended prey. Sometimes the prey is killed by the dragon, but usually it escapes with just a bite. An animal that has been bitten by a komodo will not survive long. It could take hours or as long as a week or two for the animal to die. The saliva of komodos contains about 50 species of bacteria, at least seven of which cause severe blood poisoning. Providencia rettgeri, Staphylococcus aureus, Proteus mirabilis and Proteus morgani are 4 of these bacteria that are fatal to humans. The bacteria build up because food gets stuck in the serrations of their teeth. The smell of the decomposing body will attract any komodos within a 7 mile radius.
During feeding time, larger, older adults have priority and younger komodos grab what they can. About 88% of the prey animal is consumed, with the dragons using their very sharp teeth to tear off large hunks of meat. The komodo’s teeth are rare for a lizard but commonly seen in flesh-eating sharks. They have about 60 teeth with serrated edges and 5 replacements behind each tooth. They have a highly flexible skull, which allows it to swallow large pieces of its food. Due to the feeding style, large animals are consumed in a very short time. A komodo dragon can consume up to 80% of its body weight in one meal, and not need to eat again for several days.
It is unusual for lizards, or any reptile, to be a top predator in a habitat. However, on the eastern Indonesian islands prey animals are relatively scarce within the dragons’ range. Most mammals need a lot of food every day to survive. For example, a tiger needs about 12 pounds of meat per day. In comparison, a komodo dragon needs about one pound a day. Therefore most top predatory mammals would not survive, whereas the komodos survive very well.
After mating, the females utilize a nest mound of brush in which they will lay a clutch of up to 30 eggs. Some females will return to a previously used nesting site year after year. After about 8 months, the young hatch from their eggs. The hatchlings are typically 12-15 inches long and weigh less than 4 ounces. Juveniles are yellow, green, brown and gray with speckled and banded skin. Recent studies show that some females may reproduce year after year, but many do not. This suggests that it may take some females over a year to save up enough energy to enter into a reproductive phase.
The life span of a komodo in the wild is estimated at 50 years. In captivity, they have lived to be more than 25 years old. Usually, captive animals live longer than animals in the wild because they do not have to deal with the hardships of hunting, predation and natural disasters. Recent studies have shown that dragons kept in captivity maintain a lower core body temperature of almost 4ºC, compared to wild dragons. This may make them more susceptible to disease. In the past, there has been a lack of knowledge about the care of komodo dragons, and it has been difficult to mimic their natural habitat.
Komodo dragons are classified as endangered by the U.S. Fish & Wildlife Service and by the Convention on the International Trade in Endangered Species (CITES). Population estimates vary, but there is an estimated 1,000 – 5,000 of these animals in the wild. The major threat to the komodos is habitat loss. This is due to the expansion of human populations and the hunting of the komodos’ prey, as well as major natural disasters such as fires and volcanic eruptions. The government of Indonesia created Komodo National Park in 1980 which protects much, but not all, of the komodo’s range. Many western organizations have also provided assistance for komodo research and conservation. The American Zoo and Aquarium Association (AZA) has created a Species Survival Plan (SSP), which is a cooperative breeding program, for the Komodo Dragons. Eco-tourism is another thing that seems to be helping the populations of dragons. Due to the remoteness of the islands, visitors must stay in local hotels and hire local guides. This is very beneficial to the local people by making them less likely to turn to poaching for their income.
AT THE AKRON ZOO
The Akron Zoo currently houses one male Komodo Dragon, TNT. TNT was hatched at the Miami Metrozoo in 2001.
REFERENCES
American Museum of Natural History. “Ora (Komodo Island Monitor or Komodo Dragon)”. March 3, 2005. http://www.amnh.org/nationalcenter/Endangered/ora/ora.html
American Zoo and Aquarium Association. “Species Survival Plan Programs.” October 13, 2005. http://www.aza.org/ConScience/ConScienceSSPList/#D
The Big Zoo.com. “Komodo Dragon Varanus komodoensis”. March 3, 2005. http://www.thebigzoo.com/Animals/Komodo_Dragon.asp
CRES. “Population Biology and Reproduction of the Komodo Dragon in Indonesia.” October 13, 2005. http://cres.sandiegozoo.org/projects/sp_population_biology_komodo.html
The Kratt Brothers’ “Be The Creature: Komodo Dragons”. National Geographic Channel. July 2, 2005.
Honolulu Zoo. “Komodo Dragon”. March 3, 2005. http://www.honoluluzoo.org/komodo_dragon.htm
Walsh, T., Visser, G. and Lewis, R. Komodo Dragon Husbandry Manual of the AZA/SSP & EAZA/EEP. Third Edition. Accessed online on October 13, 2005 at http://www.varanusweb.com/species_content/Kd-HDL-2004.pdf
