Northern Sierra Madre forest monitor (Varanus bitatawa)

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Varanus bitatawa

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  • The northern Sierra Madre forest monitor is longer than a tall man.
  • It is believed that, despite its size, the northern Sierra Madre forest monitor evaded discovery for so long due to its secretive nature, disinclination to cross open spaces, and preference for spending time high up in trees.
  • The northern Sierra Madre forest monitor’s diet consists mainly of fruit and snails.
  • Although only recently discovered by scientists, the northern Sierra Madre forest monitor has long been known to the Agta and Ilongot tribespeople that live on Luzon Island in the Philippines.
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Northern Sierra Madre forest monitor fact file

Northern Sierra Madre forest monitor description

KingdomAnimalia
PhylumChordata
ClassReptilia
OrderSquamata
FamilyVaranidae
GenusVaranus (1)

Closely related to the Komodo dragon (Varanus komodoensis), the strikingly distinctive northern Sierra Madre forest monitor (Varanus bitatawa) was formally described as a new species in 2010. Its large, robust body is black on the dorsal surface which contrasts against golden-yellow spotted patterning. Its black head and neck are also speckled with yellow, whereas the tail has regular yellow and black barring. This species’ forelimbs are predominantly yellow, compared to the hind limbs which are black with large yellow blotches (1).

The juvenile northern Sierra Madre forest monitor differs in often having more yellow patterning on its body compared to the adult, and having three ‘V’ shaped grey bands on its throat (1).

The colour of the northern Sierra Madre forest monitor does not appear to fade with age, unlike in its closest relative, Gray’s monitor (Varanus olivaceus) (1).

As in many monitor lizards, the northern Sierra Madre forest monitor has a double-ended hemipenis which is indicative of its species (1) (2).

Size
Length: c. 2 m (1)
Weight
c. 10 kg (2)
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Northern Sierra Madre forest monitor biology

There is currently little information available on the habitat requirements and behaviour of the northern Sierra Madre forest monitor, although its diet has been found to consist primarily of fruit and snails.

It is believed the northern Sierra Madre forest monitor previously evaded discovery by scientists for several reasons. It is thought to be a secretive lizard (1) (4), similar to the closely related Gray’s monitor (Varanus olivaceus), and it is possible that the species actively avoids open ground (1). In addition, the northern Sierra Madre forest monitor is also believed to spend a significant amount of time in trees, more than 20 metres above ground (2) (4). Very few surveys have been conducted within the Sierra Madre forest, and this may also have contributed to this species’ late discovery (1).

The bite of the northern Sierra Madre forest monitor is not reported to be venomous (5).

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Northern Sierra Madre forest monitor range

The northern Sierra Madre forest monitor is known only from forests in the central and northern Sierra Madre mountain range on Luzon Island in the Philippines (1) (3)

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Northern Sierra Madre forest monitor habitat

The northern Sierra Madre forest monitor occurs in pristine to moderately disturbed lowland and mid-elevation forests. This species is suspected to rely upon unfragmented forests with adequate numbers of fruiting fig, Pandanus and Canarium trees (1).

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Northern Sierra Madre forest monitor status

The northern Sierra Madre forest monitor is not yet classified on the IUCN Red List. 

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Northern Sierra Madre forest monitor threats

The island of Luzon is heavily populated (1) and the northern Sierra Madre forest monitor is threatened by deforestation (5). People of the Agta and Ilongot tribes hunt this species for its meat which is a major source of protein in their diet (1)

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Northern Sierra Madre forest monitor conservation

There are no known conservation measures currently in place for the northern Sierra Madre forest monitor. However, the Philippines are recognised as a conservation hotspot due to the region’s high number of species (1). There are several conservation organisations working to protect and restore the unique Sierra Madre forest, conducting scientific surveys to promote the region’s high biodiversity, as well as trying to secure legal protection for the area (6)

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Find out more

Find out more about the northern Sierra Madre forest monitor:

More on the Sierra Madre WWF ecoregion:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Dorsal
Relating to the back or top side of an animal.
Hemipenis (hemipenes)
A hemipenis (plural hemipenes) is one of a pair of reproductive organs, present in snakes and lizards. Usually held inverted, within the body, it is everted for reproduction.
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References

  1. Welton, L. et al. (2010) A spectacular new Philippine monitor lizard reveals a hidden biogeographic boundary and a novel flagship species for conservation. Biology Letters, published online 7 April 2010.
  2. Owen, J. (2010) New giant lizard discovery “an unprecedented surprise”. National Geographic News, 7 April. Available at:
    http://news.nationalgeographic.co.uk/news/2010/04/100407-new-giant-lizard-varabus-bitatawa-biology-letters/
  3. Walker, M. (2010) Giant lizard species discovered in the Philippines. BBC News, 7 April. Available at:
    http://news.bbc.co.uk/earth/hi/earth_news/newsid_8605000/8605699.stm
  4. Burnie, D. (2011)Animal: The Definitive Visual Guide to the World’s Wildlife. Dorling Kindersley Ltd, London.
  5. Guillermo, A. (2011) Historical Dictionary of the Philippines: Third Edition. The Scarecrow Press, Lanham, Maryland.
  6. Conservation International - Sierra Madre Mountains, Luzon Island (March, 2013)
    http://www.conservation.org/where/asia-pacific/philippines/Pages/sierra_madre_mountains.aspx
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Image credit

Varanus bitatawa  
Varanus bitatawa

© Brian Santos, Ph.D.

Brian Santos
'brian_santos@rocketmail.com'

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