Varanus bitatawa is the third species of monitor lizard to be
recognised by science that belongs to the "Pandan Biawak" group, all of
which are of at least as great a conservation concern as the Komodo
dragon, but receive virtually none of the attention. Pandan Biawak occur
only in lowland dipterocarp forest. The first species (Varanus
olivaceus or Butaan) was discovered in 1845 and not seen alive by a
scientist until the late 1970s. The next species (Varanus mabitang or
Mabitang) was discovered in 2001 and in 2010 Varanus bitatawa (Butikaw
or Bitatawa) was described. Other species of frugivorous monitor lizards
may remain undescribed, but many may have gone extinct without ever
having been recognised.
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 ("Pandan Biawak"), all of which are of at least as great a conservation concern as the Komodo dragon, but receive virtually none of the attention. Pandan 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 three 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 tape spool and line devices to butaan that have been caught and release them at the exact point of capture as soon as possible. Spool and line data gives us a detailed account of the animals' movementes for a few hours, days or weeks after release. We have also used spool and line very effectively on other animals, including the endemic Polillo forest snail Helicostyla portei.
An obligate frugivore is an animal whose diet throughout its range consist largely of fruit. Other obligate frugivores in the Philippines include flying foxes, hornbills and other birds. The butaan is much larger than any other obligate frugivore in the Philippines and had a much more restricted diet; on Polillo the diet of adult butaan consists almost entirely of eight species of fruits and two species of snails.
The best way to monitor individual butaan would be to extract DNA from fresh feces found on the forest floor. We can find the feces but we cannot afford the analysis!
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 mampam website has been running for 16 years and aims to provide full details of projects at no charge. All out of print books and multimedia guides are provided here and full image archives are being developed for each project. This will complete the website's mission.
An obligate frugivore is an animal whose diet throughout its range consist largely of fruit. Other obligate frugivores in the Philippines include flying foxes, hornbills and other birds. The butaan is much larger than any other obligate frugivore in the Philippines and had a much more restricted diet; on Polillo the diet of adult butaan consists almost entirely of eight species of fruits and two species of snails.
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 three 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 tape spool and line devices to butaan that have been caught and release them at the exact point of capture as soon as possible. Spool and line data gives us a detailed account of the animals' movementes for a few hours, days or weeks after release. We have also used spool and line very effectively on other animals, including the endemic Polillo forest snail Helicostyla portei.
An obligate frugivore is an animal whose diet throughout its range consist largely of fruit. Other obligate frugivores in the Philippines include flying foxes, hornbills and other birds. The butaan is much larger than any other obligate frugivore in the Philippines and had a much more restricted diet; on Polillo the diet of adult butaan consists almost entirely of eight species of fruits and two species of snails.
The best way to monitor individual butaan would be to extract DNA from fresh feces found on the forest floor. We can find the feces but we cannot afford the analysis!
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.
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