Radio-telemetry study of home range size and activities of the impressed tortoise, Manouria impressa (Gunther, 1882)

Abstract

Field work was conducted at Phu Luang Wildlife Sanctuary, Loei Province, Thailand from January 2010 - October 2012. A total of fourteen M. impressa, consisting of ten adults, five males and five females, and four juveniles were radio-tracked. The median annual home ranges (minimum convex polygon) were 9.84 ±2.91, 9.44±6.32 and 7.26 ± 6.45 ha for adult males, adult females and juveniles, respectively. The median home range sizes within each season and year-round were not significantly different among adult male, female and juvenile tortoises. The median home range sizes in the wet season were larger than in the dry season for most individuals, and dry season ranges did not entirely lie within wet season ranges and vise versa. The majority of individuals observed were inactive either in wet (May–October) or dry (November–April) season. Hiding is the main activity of tortoises for all seasons. However, in the wet season, the frequency of active behavior; walking, resting, basking, eating and mating was higher than in dry season. Adults tended to be more active than juveniles either both year-round and in the wet season. There were no significant differences between males and females in the wet season but males tended to be more active than females in the dry season. The elevation usages ranged from 1,013-1,425 m amsl and significant differences among seasons, sexes and age classes were not found. In year round result, montane forest was the most utilized habitat in both adults (male = 79.26%, female = 60.86% ) and juveniles (80.85%), montane forest mixed with bamboo was the second most utilized habitat (male = 14.05%, female = 30.75%, juvenile = 9.04%) whereas montane scrub forest was the least utilized (male = 2.16%, female = 2.36%, juvenile = 4.26). The year-round averages for air temperature and relative humidity where the males, females and juveniles were found were not significantly different. The result suggested that M. impressa was a specialist feeder, consuming only mushrooms. They showed no interest in other herbs surrounding the mushrooms. In wet season, Russula spp. (41.95%) was the main diet followed by Boletus spp. (23.34%). In dry season, both adults and juveniles fed on only 2 genus, Auricularia spp. and Russula spp. Auricularia spp. (60%) were eaten most frequently followed by Russula spp. (40%). From questionnaires distributed, a total of 8 new locations had positive response. Four locations; Doi Suthep-Pui National Park, Thungyai Naresuan (West) Wildlife Sanctuary, Phukaew Wildlife Sanctuary and Phu Kradueng National Park were confirmed to have M. impressa.