Life History

The life cycle of Komodo dragons comprise four distinct phases, and similar to many lizards begin with females laying her eggs. Let look at each of these life stages in order of occurance:

The egg stage- Female Komodo dragons are capable of producing somewhere between 12 and 38 eggs (on average about 24) each time they lay.  Most female Komodo dragons lay eggs once per year, never more, sometimes less. However, like birds, Komodo dragon must also make a nest in which they lay their eggs. Here, females will dig out several large chambers into the ground, one of which they deposit their eggs. In many cases, females often use the abandoned mound nests of megapode birds to lay their eggs. Presumably females do this because it saves them time and energy from making their own nest from the beginning.  Also eggs are laid quite deep (e.g. 2 m) into the ground to make sure that the environment in which eggs will develop maintains a stable temperature and moisture. Despite living in a tropical habitat, Komodo dragons are very seasonal in their egg laying habits- as it only in “winter” between August or September- a period about half way between the wet and dry season-when eggs are laid.  Eggs will then take up to 9 months (“like humans”) to develop before baby dragons are ready to hatch. Unusual for lizards, female dragons will spend considerable time guarding their nest from potential predators. This is no easy task, as females will have much less time to hunt for food and often loose considerable weight during this activity.  Females will stop nest guarding at the start of the wet season (December), generally around the time when the monsoonal rains arrive. Why females leave their nest then is not entirely clear but perhaps they need to start eating more regularly, or because the risk to predators finding their eggs has decreased. Nevertheless, after this, the eggs are on their own for the next few months until they become fully developed.

 

Hatchling stage- At the end of the wet season (March/April), hatchling Komodo dragons will break open their leathery egg shells and tunnel upwards deep from within their nest to the surface. The timing of this emergence is no accident as it coincides when the environment is richest from summer rains allowing plants to develop new foliage, which in turns provides food for insects whose number increase dramatically. These conditions are ideal for hatchling as it provides them with an abundance of food and cover. Importantly, hatchling Komodo dragon (40 cm long) are extremely brightly colored with yellow and orange stripes and dots, that likely serve as camouflage, helping hatchlings hide from predators or to hunt prey. A key difference in the ecology of hatchling Komodo dragons is that they spend almost all their time for the next year or so living in the canopy of trees. This is a sensible strategy as it means that they do not need to be on the ground where they would make easy prey for larger dragons. Also living in tree means hatchlings have a wealth of the right sized food including insects, geckos and other small lizards. During this stage, baby Komodo dragons only rarely come onto the ground, and if they do so then they typically move to a nearby tree. So for the first few months of life, Komodo dragons maybe found reasonably close to the nest they hatched from.

 

Immature stage-Life in the trees does not last for too long, as after about a year and certainly by the age of about 2 years, young Komodo dragons have become much more focused on living on the ground. This transition from trees to the land reflects that Komodo dragons are rapidly growing and their dietary requirements are changing and increasing. The diet of Komodo dragons is very related to their body size as they get larger they will eat larger prey items. For immature Komodo dragons, as they increase in body size and begin to hunt on the ground they will add to their diet bird’s eggs, rats, other reptiles including snakes. In fact, immature Komodo dragons spend much of their actively searching for food and will often walks several kilometers to find food. Like many reptiles, immature Komodo dragons are not particularly social and rarely interact with one another even though they may overlap considerably in their use of space. It is during this immature stage that Komodo dragons will do much of their growing and over the space of 5-6 years they will increase their body mass up to about 15 kg, with males putting more energy into growth than females.

 

Adult stage: For wild Komodo dragons, we think that female reach adulthood (i.e. reach sexual maturity) at about 8-10 years of age and at a weight of about 18 kg. As it is at this size at which we have first observed female Komodo dragons attempting to nest. For males, it is more difficult to tell when they reach adulthood as there really are no external signs to indicate this. However, like many other large reptiles (e.g. crocodiles), it maybe that male Komodo dragons are physiologically ready to breed at a similar age to females but are unable to do so because they are not large enough to compete with much bigger and older males. The large body size of male Komodo dragons is likely to be very important for determining their access to females for breeding.  So unlike the growth of adult females that slows dramatically, indicating they invest much of their energy into reproduction, males continue to grow for several more decades. A large healthy male Komodo dragon can weight in excess of 70kg and reach over 3 meters in length. So adult males are considerably larger than females.  The large body size of adult Komodo dragons means that the active searching for prey that they used when they were smaller is no longer very efficient as they would need to move large distances to find enough small prey to meet their energy requirements. Instead, with the added advantage of much heavier body mass and strength, adult Komodo dragons target very large prey including deer, pigs and at a few localities kill water buffalo.

The large difference in body size between males and females is important because it signals not only different strategies, aimed at maximizing reproductive opportunities for each sex but also indicate that the males and females have differences in their life expectancies. Our estimates of longevity suggest that females live considerably less than males, perhaps as much as half the life span of males, which are thought to persist until they reach an age of 60. One of the most unknown aspects of the Komodo dragon life cycle is really about mating and reproduction. We presume from infrequent observations of male and females mating that reproduction takes place in June or July. It is possible that males must actively search for reproductively active females which if they find they will mate with. One of the unusual things that we have observed suggest that males may guard females for some period of time to perhaps ensure that they are the only male to sire her eggs. Adult males are expected to have the potential to breed every year, but this may not be the case for females who may need in excess of 1 year to store enough energy to make eggs. One fertilized a female will begin a month long process of locating and preparing her nest before she lays and the whole cycle starts over again.