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Why Komodo Dragons Are Like The Entire Cat Family

As a fully grown adult, a Komodo dragon is a formidable 10-foot (3-metre), 200-pound (90-kilogram) predator, whose steak-knife teeth and sizeable claws can bring down large prey, and whose bulk and chain-mail skin make it impervious to everything except humans. But when it first hatches, a Komodo is just a hand-sized lizard that weighs a tenth of a kilogram, hides in trees, and relies on mottled scales for camouflage. It takes around a decade reach its final form.

What happens during those years?

To find out, Deni Purwandana and Achmad Ariefiandy from the Komodo Survival Program, a Indonesian non-profit, have been monitoring the lizards in the wild since 2002. They’ve watched at least 25 individually identified dragons taking down their prey. They’ve analysed vomited remains. They’ve wrangled the lizards with noose-poles, photographed them with camera traps, and mapped their movements with radio trackers. Their efforts have painted a comprehensive portrait of a Komodo dragon’s life.

Video: Living Among Ancient Dragons. See how these predators bring down prey.

The team found, unsurprisingly, that the dragons take on larger prey as they get bigger. But this transition isn’t smooth. At first, they stick to small, lightweight prey like rodents. But when they hit the 20 kilogram mark, they switch to taking down prey much larger than themselves, including 50-kilogram rusa deer and water buffalo. The change is sudden and total. One year, they’re going after scurrying, lightweight meals. The next, they’re feeding entirely on hoofed quarry.

This abrupt switch is mirrored in other aspects of their lives. As youngsters, they forage actively for small prey, moving a lot but sticking to a small range. Once they hit the 20-kilogram threshold, their average daily movement rates go down, but they start wandering over larger areas. They become ambush predators, which mostly sit in wait for passing prey, but stride over large distances to find new lurking spots.

A baby Komodo dragon.
A baby Komodo dragon.
Photograph By Chester Zoo

You can find similar transitions in other groups of predators. The cats, for example, range from the diminutive rusty-spotted cat to the mighty Siberian tiger, 300 times heavier. It’s been said that “all cats over 25 kilograms kill large prey, and all cats under 15 kilograms kill small prey.” Again, there’s a 20 kilogram threshold where species go from killing things smaller than themselves to tackling bigger prey.

But here, we’re talking about species of different sizes, not individuals of different ages.

Among mammal carnivores, youngsters and adults tend to feast on prey of similar sizes, because parents provide the juveniles with food. But reptiles typically aren’t that social, and their hatchlings must fend for themselves. That’s why their tastes in prey change so radically as they get bigger. You see this in everything from snakes to scorpions, but it’s especially obvious in Komodo dragons because they span such a wide range of sizes.

The youngsters behave like small rodent-hunters, like ocelots or wildcats, while the grown-ups are the equivalents of leopards or lions. As Purwandana and Ariefiandy write, Komodo dragons “function as an entire vertebrate predator guild.” In other words, these lizards play the role of the entire cat family.

11 thoughts on “Why Komodo Dragons Are Like The Entire Cat Family

  1. Someone correct me if you know me to be incorrect, but isn’t this also true for the larger species of crocodiles (and maybe alligators)? They are only a few inches long at birth – when they feed on prey as small as insects – and grow to be many feet long – when they feed on large prey like wildebeest. Similar to the dragons, crocs provide minimal parental care (they protect the nest site and the hatchlings but I don’t believe that they provide the young with food). Any idea how fast the prey-size transition is for crocs as they grow?

  2. Makes sense. The young occupy a different ecological niche vs. full sized adults. Sometimes they fill the niche as prey for the adults, which explains the camouflage, tree climbing etc. as well.

  3. David Attenborough’s Life Stories has a segment about Komodo Dragons. He says that the prey that dragons eat nowadays (pigs, buffalo) were brought by people and not too long ago there were no large prey items on those islands. It is a puzzle as to how the dragons get so big, and it is hypothesized that they exist on the trophic chain stacked on several tiers dependent on size. The young animals, agile and quick, were able to eat the small prey items that existed on the island. At some point they become the largest animal there, and so they become prey to each other. The larger dragons ate the smaller dragons. If this is the case, it would make sense that there would be a shift in the juvenile dragons to consider their brethren as food rather than what they had eaten before.
    Here is the recording of the David Attenborough segment I am referring to

  4. This has been suspected anecdotally for years, but this study nicely confirms it. Indeed, earlier thoughts on this subject are what led to my tyrannosaur niche-shift hypothesis that’s been around for a decade and a half.

    1. @Dr. Holtz,

      I immediately thought of that hypothesis while reading this. Have tyrannosaur hatchlings been found in recent years to confirm that they were self-suficient hunters rather than fed by adults? I don’t ever recall seeing skeletons of newborn tyrannosaurs, replicae or otherwise

    2. Hi Thomas – not sure if you’re THE professor Thomas Holtz a renown paleontologist? If you are, I would love to read upon your hypothesis regarding T-Rex (obviously related to other large carnivores), please where could i find it, is there a URL? I am a enthusiast of paleontology, and NOT a paleontologist.
      Do you think it is conceivable to believe that young therapods (for example) T-Rex led to the diversification of small therapods that we tree climbers with feathers, much like today’s hoatzin?

      Kind regards,
      Nick Groves


  6. An evolutionary advantage? They perhaps eventually learned that as adults they should leave small prey alone or their own offspring will starve. In that vein … it would be interesting to see if and how well the times at which they switch to eating larger prey correlate to when they begin to breed.

  7. I also heard a theory that Komodo dragons are so small because they evolved to hunt *dwarf* elephants. Small relative to Megalania, that is.

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