Distribution and diversity patterns of herpetofauna in the Pantabangan-Carranglan Watershed, Nueva Ecija, Caraballo Mountain Range, Philippines

The recent extensive survey conducted in the Pantabangan-Carranglan Watershed, located in the Caraballo Mountain Range during the rainy season (October to November) resulted in the recording of fifty-nine (59) species of amphibians and reptiles (17 frogs, 14 skinks, 3 agamids, 6 gekkonid lizards, 2 varanids and 17 snakes). Out of 59 species, 42 species were Philippine endemics and 25 species are recorded only from the Luzon faunal region. Habitat analysis and mapping showed seven habitat types including lowland dipterocarp forest, grassland, lower montane forest, upper montane forest, pine forest, agricultural areas and riparian habitats.

GIS-based distribution mapping showed that the number of individuals and species are high in forest and associated riparian habitats at mid-elevation (1,000–1,250 m a.s.l.). The distribution pattern in the area is influenced by similarity in microclimatic conditions, availability of resources and niches which species can utilise. Species diversity is centred in mid- to high elevation forest and riparian habitats and in less disturbed areas. Snake diversity is adversely affected by increased disturbance, making them good indicators of the health of an area. The abundance-based Jaccard's Similarity Index showed that connected habitats and elevation gradients have higher species similarity.