Radio-telemetry study of home range size and activities of the black Asian giant tortoise Manouria emys phayrei (Blyth, 1853)

Abstract

Home range sizes and activities of Manouria emys phayrei were studied at Kaeng Krachan National Park, Phetchaburi Province, Thailand from November 2005 - June 2007. A total of fourteen M. emys phayrei, consisting of eleven adults (seven males and four females) and three juveniles was radio-tracked. The median annual home ranges (95% minimum convex polygon) were 0.60 ± 0.33, 0.56 ± 0.07 and 0.08 ± 0.06 km² for adult males, adult females and juveniles, respectively. The median home range sizes of males and females were not significantly different but were significantly larger than the home range sizes of juveniles (Mann-Whitney U-test). The median home range sizes in the wet season (May – October) were larger than in the dry season (November – April) for most individuals. M.e.phayrei utilized 5 types of habitats; bamboo forest, dry evergreen forest, dry evergreen forest mixed with bamboo, stream and mud-swamp. In the rainy season (May - October), most adult tortoises were found foraging in the bamboo forest whereas juvenile tortoises were generally located in the mud-swamp. In the cold dry season (November-February), few tortoises were active and they were often found beneath fallen branches or leaf litter whereas in the hot-dry season (March - April) they were frequently found soaking in the shallow stream. The year-round averages for air temperature and relative humidity where the males, females and juveniles were found were not significantly different (ANOVA, p<0.05). Furthermore, the results showed that these tortoises are generalist herbivores, consuming at least 10 species of plants such as Lasia spinosa, Zingiber sp., Amorphophallus paeoniifolius, Musa sp., Marantha sp. and Bambusa sp.. Bambusa sp. and Lasia spinosa were main diets of adults and juveniles, respectively.