L169 Komodo dragons

Komodo dragons live on a handful of islands in Indonesia, but their reputation has spread far and wide. Reaching lengths of up to 10 feet, the razor-toothed monitor lizards hunt deer in packs and have even attacked humans on occasion. But actually, they are real homebodies, according to a study published Wednesday in Proceedings of the Royal Society B.

根据周三发表在英国皇家学会B学报上的一项研究表明， 科摩多龙生活在印度尼西亚的几个岛屿上，但它们的名声却广为流传。这种牙齿有的像剃刀一样的蜥蜴长达10英尺，它们大量地捕猎鹿，有时甚至还会攻击人类。但实际上，他们是真正恋家的动物。

A decade of observations at 10 sites on four islands has revealed that the dragons essentially never leave the valley where they were born. It’s not that they can’t. They are capable of traveling many miles and through rough terrain, if necessary. They just don’t seem to feel like it.

Many island species, as it happens, show a marked tendency to stay close to home. It feels like a bit of a paradox: Their forebears may have arrived on that island through some great feat of survival or exploration, but the present generation prefers familiar comforts.

“Once they colonize an island, despite these incredible feats of long-distance dispersal, they decide, ‘Enough is enough!’” said Tim Jessop, the professor of ecology at Deakins University in Australia who led the study.
The causes of this behavior are likely to differ depending on the species and the situation. But it is puzzling: If animals stay in one place for many generations, they run the risk of inbreeding, facing resource scarcity and other dangers that moving elsewhere could allow them to avoid.

Is the problem that komodos are not confident navigators? Over the course of the study, researchers moved seven adult dragons away from their home territory. Some were transported as much as 13.7 miles away on the same islands, while others were ferried across a slip of water just over a mile wide to another island.

Within four months, the Komodo dragons transplanted overland all turned up again at home, clearly capable of making a journey. The dragons on the new island — much closer to where they started, and capable of swimming back — stayed put. Swimming home just didn’t seem to be worth the effort, apparently

One explanation for this sedentary behavior, Dr. Jessop proposed, is that once you’re isolated on an island, any mistakes could be extremely costly. Having a whole continent to move across, with a landscape that changes relatively slowly, would make exploration less risky.

But a Komodo dragon that moves to a new island or a new island valley might find that it’s out of luck if, for instance, it’s unable to mate with any of the locals it encounters in its new home. There may also be survival benefits to being intimately familiar with one’s surroundings, like knowing exactly where to find prey.

“They are quirky animals,” Dr. Jessop continued, noting that the juveniles have a habit of climbing trees to escape cannibalism from their elders. They may look like ruthless top-level predators, but their goals as island creatures are considerably more modest that you may realize.