Habitat Requirements of The Endemic Sri Lankan Green Pit Viper (Peltopelor trigonocephalus) in Sri Lanka

Abstract

Habitat use of Peltopelor trigonocephalus was studied in the main three climatic zones of Sri Lanka from April 2021 to October 2024. P. trigonocephalus is an endemic viper, locally known as “Palapolaga”. This species shows wide distribution in the island, except in the higher hills and arid zones. Three macro-habitat types were considered during sampling; forest, riparian, and open habitat. Visual encounter surveys were conducted to observe P. trigonocephalus along a 200 m transect searching up to 2 m on either side and up to a height of 6m. The first sighting of P. trigonocephalus was recorded, and the perches used by this species were categorized based on their structural characteristics. The height of the perch was measured. The position of P. trigonocephalus on the branch was categorized into three distinct sections: apical, proximal, and middle. Data on 68 individuals of P. trigonocephalus were recorded. Majority of these individuals (71.42%) were observed in riparian habitats. Most preferred perch height for P. trigonocephalus during the diurnal was within the mid-story range of 3-6 m, making up 42.85% of total encounters. The majority of P. trigonocephalus individuals (60.78%) were found in the apical region of the branches, with 36.4% occupying the middle region. A very strong positive linear relationship was observed between snout-to-vent length (SVL) and branch circumference, with a Pearson correlation coefficient of 0.969. The correlation is statistically significant (p=0.00), suggesting that P. trigonocephalus select branches based on their size. For ambush behavior, trees were the most frequently utilized substrate, with 80% of individuals observed using them for this purpose. This study provides important insights into the conservation and management of P. trigonocephalus by critically evaluating its differing habitat requirements. Preservation of its natural habitats and enrichment of ex situ habitats can be achieved through these findings.

Keywords: Climatic zones, Macro-habitat, Perch selection, Peltopelor trigonocephalus