Delineation of core terrestrial habitat for conservation of a tropical salamander: The Hong Kong newt (Paramesotriton hongkongensis)

Abstract

Core terrestrial habitat, sometimes called fixed-width riparian buffer or life zone, is defined as the spatial delineation of 95% of an amphibian population that encompasses all breeding, overwintering, and terrestrial foraging habitats. It has been proposed as a measure of the extent of terrestrial habitat use by amphibians, from which species-specific guidelines on buffer zone width can be derived. The Hong Kong newt (Paramesotriton hongkongensis), one of few tropical salamandrids, is endemic to southern China and categorized by the IUCN as Near Threatened. Populations of P. hongkongensis have declined due to habitat degradation and overexploitation for the pet trade. Previous studies of aquatic habitat use by P. hongkongensis revealed distinctive patterns, with juveniles using terrestrial habitats exclusively and most adults remaining on land for about 10months each year. However, other information on the terrestrial stage is incomplete. We combined radio telemetry and terrestrial transect surveys to study habitat use and quantify movement and distribution patterns of P. hongkongensis during its terrestrial stage with the goal of delineating core terrestrial habitat for the species. Fifty-two P. hongkongensis radio-tracked during the wet season primarily used forest, maintained small home ranges (mean=0.04ha), and made frequent short distance movements (<7m/day) between cover objects. From transect surveys that detected 117 P. hongkongensis, we estimated that the core terrestrial habitat extends 113m from the nearest stream margin. Currently, there are no guidelines in place for establishment of fixed-width buffer zones to protect semi-aquatic animals in Hong Kong. We recommend that buffer zones of at least 113m be designed to protect the terrestrial stages of P. hongkongensis.