Habitat quality and availability of the Sri Lanka Red Slender Loris <i>Loris tardigradus tardigradus</i> (Mammalia: Primates: Lorisidae) in the Kottawa Arboretum

Abstract

The Red Slender Loris (Loris tardigradus) is one of the three primate species endemic to Sri Lanka. Currently there are two recognized subspecies of the Red Slender Loris, the Sri Lanka Red Slender Loris (L. t. tardigradus) and the Sri Lanka Montane Slender Loris (L. t. nycticeboides). Of these, L. t. tardigradus inhabits rainforests in the southwestern region of the island while L. t. nycticeboides is restricted to the montane zone. Kottawa Arboretum harbors one of the few remaining L. t. tardigradus populations in the country. This study was conducted to determine the population density, habitat selection criteria and to asses the habitat availability of L. t. tardigradus in the Kottawa Arboretum. Using the line transect method, 34 sightings were made over a period of 21 months. Based on these observations the density of L. t. tardigradus in the Kottawa Arboretum and habitat selection criteria was ascertained. The calculated density of L. t. tardigradus in the Kottawa Arboretum is 41 animals/ km2. The average height of trees preferred by L. t. tardigradus is 13.97 m plus or minus 6.02. Most of the time lorises were observed at a height range of 3.5-15 m above the ground level. Average height from the ground level where L. t. tardigradus were observed to occupy the tree was 8.64 m plus or minus 5.00. Of the 50 tree species recorded in the Kottawa Arboretum, L. t. tardigradus was found to utilize only 16 species.