The ecological distribution of Thai endemic rodents with a new distributional range of Niviventer hinpoon

Abstract

Two species of Thai endemic rats, the limestone rat (Niviventer hinpoon), and the Neill’s rat (Leopoldamys neilli), have not been reported in existence in their own type localities for at least 31 years since their first discoveries. The type localities are now continuously disturbed by human activities which remarkably result in driving them to the blink of extinction. Intensive surveys were conducted to uncover the present existence of these endemic mammals in 3 locations in Saraburi and Lop Buri provinces, Thailand, using live trapping techniques. The results revealed that the limestone rats were encountered in 2 areas, Wat Khudkham (Dondung) in Lop Buri province (15˚ 08’ 35” N 100˚ 36’ 44” E), the first record of its occurrence outside the known distributional ranges; and Wat Tham Prathat in Lop Buri province (14˚ 48’ 15” N 100˚ 49’ 30” E). The Neill’s rats were found living in its type locality at Wat Tham Prapothisat in Saraburi province (14˚ 34’ 31” N 101˚ 08’ 43” E), same type locality as that of the limestone rats. The additional data of two specimens from the Centre for Thai National Reference Collections (CTNRC) revealed another locality in Nakhon Ratchasima province (14˚ 31’ 27” N 101˚ 23’ 33” E). Moreover, at least 17 samples collected from 8 provinces were likely misidentified e.g. L. sabanus as L. neilli. These provinces were considered as the expected distribution of L. neilli. The results indicated that the population numbers of Thai endemic rodents were extremely low and in very restricted distributional ranges. These implied that Thai endemic rodents were under the presumably high risk of extinction.