National Geographic

Giant, fruit-eating monitor lizard discovered in the Philippines

Varanus_bitawawaHumans have travelled all over the planet but many uncharted regions of the globe still hide unknown animal species waiting to be discovered. With some exceptions, these new finds are largely small creatures that are hard to spot amid the bustle of a tropical forest. So imagine Luke Welton’s surprise when he came across an entirely new species of giant monitor lizard in the forests of northern Philippines.

At two metres in length, it’s not quite as large as its close relative the Komodo dragon, but it’s hardly inconspicuous either. It’s also brightly and beautifully coloured with intricate golden spots running down its otherwise black back. As is often the case, the lizard may be new to science but the local tribespeople – the Agta and Ilongot – have known about it for centuries. It’s actually one of their main sources of protein. Their name for the monitor, bitatawa, is now part of its official species name – Varanus bitatawa

Rafe Brown, who leads Welton’s group, says, “Clues to its existence had filtered in over the last ten years.” Photos of the mysterious animal had been circulating since 2001, but the clincher came when Welton and another student, Cameron Siler, salvaged a specimen that had been brought to them by a hunter. “They knew it was something special, either a rare colour pattern or a new species,” says Brown.

The dead lizard went on a round-the world trip from the Philippines to Kansas. There, Brown’s team counted its scales, examined its internal organs and sequenced its DNA. Their meticulous examination revealed that the animal was closely related to the Gray’s monitor (Varanus olivaceus), which also lives on the same island. But it was distinct enough to count as a species in its own right. “The team in the field were very celebratory,” says Brown.

Varanus_bitawawa2V.bitatawa has an unusual habit that separates it from all but two other monitor species – it mostly eats fruit. Even before the animal had been discovered, the field team had suspected that a fruit-eating monitor lizard was prowling the forests, based on scratch marks all over the local fruiting Pandanus trees. The final bit of evidence came when Welton opened up the stomach of the specimen he recovered. Inside, he found Pandanus fruits, figs and pili nut fruit, with no trace of a single insect, rodent or bird. Snail shells were the only sign that the lizard occasionally eats other animals.

Luzon_IslandSo far, the team have recovered three specimens of the new lizard and it seems that V.bitawawa only lives in a small band of mountainous forests in the Philippine island of Luzon. It shares the island with the Gray’s monitor, but the two animals are separated by over 150km that includes three river valleys. They’re unlikely to mingle.

How could such a large and conspicuous animal have gone unnoticed by the many biologists who have studied the northern Philippines? Welton admits that it’s an “astonishing set of circumstances”. He suggests that few scientists have tried to survey the reptile life of the area. And if the new species is anything like the Gray’s monitor, it is a secretive animal that almost never leaves the forests to cross open areas.

The discovery of such an eye-catching new animal cements the Philippines’ reputation as one of the planet’s most important hotspots of biodiversity. In the past decade, scientists searching the islands have found new species of lobsters, meat-eating pitcher plants, rails, flying foxes, parrots, mice, shrews, snakes, frogs and orchids.

You get the feeling that we’ve only just started scratching the surface of the islands’ wildlife secrets. Indeed, if the northern and southern parts of Luzon could harbour two distinct species of monitors, separated by physical barriers, there will probably be other pairs of sister species waiting to be found.

Sadly, as with many new discoveries, the animal’s future is being called into question just as it is unveiled to the world at large. Luzon Island has a thriving human population who have cut down much of its forests. The Gray’s monitor is classified as vulnerable due to the loss of its habitat, and V.bitawawa may be similarly endangered. Welton hopes that the new animal will be beautiful and charismatic enough to act as a “flagship species” for the local area, promoting the need to conserve this most bountiful of habitats.

Reference: Biology Letters http://dx.doi.org/10.1098/rsbl.2010.0119

Images: by Joseph Brown and Luke Welton

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There are 12 Comments. Add Yours.

  1. Colin Bartlett
    April 6, 2010

    Depending on how social this monitor is (most monitors are pretty gregarious, and given that it’s largely a frugivore they probably have a higher density tolerance than most), you could take advantagMovement. Like iguana ranches in south and central america, this would conserve the forest habitat the reptile depends on, give the local people a solid food source, and because it’s a local species that depends on intact habitat, still allow all of the normal forest products they’d depend on to grow and be extracted. Also like iguana ranching and unlike crocodile ranching, you don’t have to grow food for your food. You just need to cultivate fruit-tree (and snail) -rich forest. So it’s almost carbon-neutral meat!

  2. Ian
    April 6, 2010

    Really cool! Regarding the snails, is it possible the lizard just consumed them by accident? After all, snails are on occasion unintentionally eaten by herbivores.

  3. Albertonykus
    April 6, 2010

    “New” modern critters are always good to see.

  4. Sam W
    April 7, 2010

    Discoveries like this are what inspires me to do Zoology! The knowledge that there’s still so much out there that we don’t know about!
    I hope the lizards continue to be studied more, I’d love to see more work on how closely they are actually related and if they can form hybrids. Exciting stuff.

  5. marie
    April 7, 2010

    it is located in cebu city(in philippines) also, some guy found it in a tree where he caught it and actually pet the small lizard, he let me touched it and amazingly it was very friendly.

  6. TL
    April 7, 2010

    dear ed,
    ever since your blog moved to discover, some of the “more on …” links have been problematic. for example, the first one on “Venemous Komodo dragons” contains “/2010/04/06/2009/05/18/” in the URL, but the new date shouldn’t be there. :-)

    [Yeah, I know. Just keep pointing them out - I'll keep fixing them. - Ed]

  7. bulabog
    April 7, 2010

    I can’t believe this lizard, in my country, Philippines, is never yet discovered before. I say, we humans are very futile and puny in God’s creation.

  8. Truthinscience
    April 14, 2010

    Brown and Welton’s version may not be entirely accurate. According to http://www.mampam.com there had been a specimen in the National Museum of the Philippines since 2004, and it was the collection of a specimen of the already described species Varanus olivaceus that allowed them to make the “new discovery”. Reading between the lines there seems to be more to this than meets the eye.

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  11. JC
    February 10, 2012

    I encountered his lizard at Palanan, Isabela in 2009 while studying hornbills. They are pretty rare and very shy. I managed to see only five in a span of 4 months.

  12. JP
    June 15, 2012

    its definitely a race to save these creatures as their habitat is under heavy pressure from illegal logging, slash-and-burn practices and charcoal producers. I’m a phasmid (stick insect) enthusiast and there’s not much data on biological searches there on insects :(

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