Diversity and seasonal abundance of small mammals in Bumdeling Ramsar Site, Trashiyangtse, Eastern Bhutan

Small mammals have multiple ecological roles and are important components of the terrestrial ecosystems. They are important ecological indicators of changes in the natural surroundings. However, little is known about the small mammals in Bhutan. We conducted this study in the Bumdeling Ramsar Site in eastern region of Bhutan, aimed at enhancing our understanding of the species composition, abundance, and seasonal diversity of small mammals. We laid linear transects, each measuring 500 m in six different habitat types: agriculture land (AG), fallow land (FL), Alnus sp. forest (AF), open grassland (OG), riparian forest (RR), and oak forest (OF). We placed 17 collapsible Sherman live traps (23x9x8cm) in each transect to capture both ground dwelling and arboreal small mammals. We conducted the trapping exercise twice in the year 2016 (28 March to 28 April during the wet season and 1 to 30 October during the dry season), amounting to a total of 1,224 trap nights. We trapped a total of 135 individuals of small mammals, yielding seven species of rodents (90 individuals; 66.7%) and four of insectivores (45 individuals; 33.3%). We found significant difference in the number of individuals trapped among the six different habitats (X²=66.43, df= 5, P<0.05) with the highest in AG (59 individuals, 43.7%) and the lowest in OG (1 individual; 0.7%) during the dry and wet season, respectively. In order to promote diversity of small mammals in the Ramsar site, we recommend reducing free-range cattle grazing and restraining domestic dogs in the vicinity of the Ramsar site.