Since 1999 the Butaan Project has been studying the rare, endangered, and unique fruit-eating monitor lizards of the Philippines. Butaan is just one of several races of frugivorous monitor lizards in the Philippines ("Putras Biawak"), all of which are of at least as great a conservation concern as the Komodo dragon, but receive virtually none of the attention. Putras Biawak occur only in lowland dipterocarp forest. The first species (Butaan) was discovered in 1845 and not seen alive by a scientist until the late 1970s. The next species (Mabitang) was discovered in 2001. Other species remain undescribed, and some may have gone extinct without ever having been recognised.
The butaan was first described to science in 1845 from a juvenile specimen collected by Hugh Cuming. It was labelled only "Philippines". It was named Varanus grayi. No other specimens came to light for over 120 years.
In the 1970s Walter Auffenberg found another specimen with a location
in Luzon, established that its correct scientific name was Varanus
olivaceus, and undertook a 22 month study of the species based in
Bicol. His study revealed that butaan occupy a unique ecological niche
and have a lifestyle quite unlike any other monitor lizard. Auffenberg used local hunters with dogs to catch the animals. Of 126
butaan caught
during his study, 116 animals were killed.
Butaan are so shy they frequently remain in a tree for more
than a week after being frightened. A large male we
rescued from a trap hid in a tree for 22 days before coming down!* . Most lizards do not appear traumatised by being caught and
released by scientists, and resume normal activity very quickly. But we think
that butaan, especially older individuals, may permanently alter their activity
areas after such an encounter. Because the animals are so shy, and highly
vulnerable to human disturbance, we have had to develop a range of techniques
that allow us to learn about them with the absolute minimum of interference.
We use feces to investigate diet and activity areas of butaan. In total we have examined more than 1500 samples, possibly the largest ever collected for a single population of reptiles.
Butaan and their relatives are huge specialised frugivores, much bigger
than any other specialised frugivorous animal in the Philippines. They
need a constant supply of fruit but lack the wings that allow other
frugivores to forage in different forest fragments. Large and immobile,
the butaan depends on a very narrow range of foods.
The dark green patch at center left in this unmanipulated Google Earth image is the last remaining fragment of unlogged lowland dipterocarp forest on Polillo Island, and our main study site for the last 11 years. Less than one square mile in size (220ha) and less than 100m above sea level, the Sibulan Watershed Reserve has lost much of its secondary boundary forest over the last six years through illegal and uncontrolled agricultural activities.
The only obligate fruit-eaters among reptiles are two species of monitor lizard that live in the Philippines. Frugivorous vertebrates tend to be able to fly (almost all are bats and birds) and so these lizards have a unique ecological role as highly specialized and relatively immobile fruit eaters. Before this project started, the only studies of this unique giant and endangered lizard had involved killing the animals. We have developed a set of techniques that allow us to learn about these animals in a completely non-destructive way.
A small collection of videos made by the Butaan Project. It took us three years to get the first moving images of wild butaan. Some recordings are made using camcorders tied to trees and triggered by passive infrared monitors, others are made by volunteers from camouflaged hides.
We desperately need your help. Although the other endangered monitor lizard (the famous Komodo dragon) has received vast amounts of funding to aid its conservation, the butaan has been almost entirely neglected. Just $10 will make a difference! Please consider helping us. We will acknowledge your support here and in subsequent publications and keep you informed of all developments.
Practical Conservation for Neglected Species
We work with endangered and neglected people, wildlife and habitats, finding practical solutions to serious problems.
Butaan jump from incredible heights, land on the ground
with a huge crash and walk away uninjured. Jumps to the ground from 30m were
recorded by Auffenberg and our spool and line tracking suggests lizards
regularly jump from heights of 4-15m when they are unmolested. The amazing
jumping power of the butaan is undocumented in any other monitors lizard and
may be one more unique aspects of the Putras Biawak group.
The lace goanna is the second largest lizard in Australia. It is widespread in eastern Queensland, eastern New South Wales and most of Victoria but is restricted to the extreme south-east of South Australia (Houston 1978). They also inhabit some islands off the eastern coast (e.g. Mackay 1959).
Butaan Project 
Since 1999 the Butaan Project has been studying the rare, endangered, and unique fruit-eating monitor lizards of the Philippines. Butaan is just one of several races of frugivorous monitor lizards in the Philippines ("Putras Biawak"), all of which are of at least as great a conservation concern as the Komodo dragon, but receive virtually none of the attention. Putras Biawak occur only in lowland dipterocarp forest. The first species (Butaan) was discovered in 1845 and not seen alive by a scientist until the late 1970s. The next species (Mabitang) was discovered in 2001. Other species remain undescribed, and some may have gone extinct without ever having been recognised.
The butaan was first described to science in 1845 from a juvenile specimen collected by Hugh Cuming. It was labelled only "Philippines". It was named Varanus grayi. No other specimens came to light for over 120 years.
In the 1970s Walter Auffenberg found another specimen with a location
in Luzon, established that its correct scientific name was Varanus
olivaceus, and undertook a 22 month study of the species based in
Bicol. His study revealed that butaan occupy a unique ecological niche
and have a lifestyle quite unlike any other monitor lizard. Auffenberg used local hunters with dogs to catch the animals. Of 126
butaan caught
during his study, 116 animals were killed.
Butaan are so shy they frequently remain in a tree for more
than a week after being frightened. A large male we
rescued from a trap hid in a tree for 22 days before coming down!* . Most lizards do not appear traumatised by being caught and
released by scientists, and resume normal activity very quickly. But we think
that butaan, especially older individuals, may permanently alter their activity
areas after such an encounter. Because the animals are so shy, and highly
vulnerable to human disturbance, we have had to develop a range of techniques
that allow us to learn about them with the absolute minimum of interference.
We use feces to investigate diet and activity areas of butaan. In total we have examined more than 1500 samples, possibly the largest ever collected for a single population of reptiles.
Butaan and their relatives are huge specialised frugivores, much bigger
than any other specialised frugivorous animal in the Philippines. They
need a constant supply of fruit but lack the wings that allow other
frugivores to forage in different forest fragments. Large and immobile,
the butaan depends on a very narrow range of foods.
The dark green patch at center left in this unmanipulated Google Earth image is the last remaining fragment of unlogged lowland dipterocarp forest on Polillo Island, and our main study site for the last 11 years. Less than one square mile in size (220ha) and less than 100m above sea level, the Sibulan Watershed Reserve has lost much of its secondary boundary forest over the last six years through illegal and uncontrolled agricultural activities.
The only obligate fruit-eaters among reptiles are two species of monitor lizard that live in the Philippines. Frugivorous vertebrates tend to be able to fly (almost all are bats and birds) and so these lizards have a unique ecological role as highly specialized and relatively immobile fruit eaters. Before this project started, the only studies of this unique giant and endangered lizard had involved killing the animals. We have developed a set of techniques that allow us to learn about these animals in a completely non-destructive way.
A small collection of videos made by the Butaan Project. It took us three years to get the first moving images of wild butaan. Some recordings are made using camcorders tied to trees and triggered by passive infrared monitors, others are made by volunteers from camouflaged hides.
We desperately need your help. Although the other endangered monitor lizard (the famous Komodo dragon) has received vast amounts of funding to aid its conservation, the butaan has been almost entirely neglected. Just $10 will make a difference! Please consider helping us. We will acknowledge your support here and in subsequent publications and keep you informed of all developments.
Practical Conservation for Neglected Species
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