Study area The field work was carried out in Lawachara National Park (LNP) and its adjacent areas. LNP, situated in Maulavibazar District in the north-east of Bangladesh, is a 1250-ha mixed-evergreen forest. Most of park’s original forest cover has been altered or substantially removed by rotation, with only some small remnant patches of primary forest still left (NACOM, 2003). The overall tree density in this site is 528.5/ha (Muzzafar et al., 2007). In-between the forest habitat, there are landscapes modified by human disturbances, including patches of agricultural lands, human settlements, modified vegetation for betel leaf (Piper betle), tea plantation, native bamboo plantation (Bambusa tulda, Bambusa polymorpha, Bambusa longispiculata, etc.), and monoculture plantation forest (e.g. Tectona grandis, Aquilaria crassna, Eucalyptus sp., Acacia sp., etc.). Numerous streams passed through the forest and the tea plantations, and there are several man-made perennial and seasonally inundated ponds in the tea plantation and the surrounding village settlements. This area falls within the monsoon climatic zone, with average annual rainfall of ∼3000 mm (most of which falls during June-September), and annual diurnal temperature ranging from 27°C (June-September) to 16°C (January). The area is undulating with slopes and hillocks and the average altitude range of roughly 10-80 m a.s.l. (NACOM, 2003). We attributed each snake record to a given category of habitat, based on the characteristics of the site where it was collected. We catalogued five different habitat types: (1) Mature Forest: this is the core natural area of LNP a plantation forest from 1920s-1950s with deciduous trees mixed with smaller evergreen trees and bamboos, and several sandy seasonal streams. The canopy cover includes Artocarpus chapalasha, Tectona grandis, Dipterocarpus turbinatus, Elaeocarpus floribundaas, Dillenia pentagyna, Castanopsis tribuloides, etc.; (2) Degraded Secondary Forest: this is the plantation forest from 1950s-2008. The tree species of this forest are similar to those of the mature forest, but the forest is highly degraded as its forest cover has been cleared or anthropogenically modified for betel vine (Piper betle) plantation, with extensive growth of woody climbers and patches of bamboo clumps with sandy seasonal streams; (3) Tea Plantation: this is dense tea plantation (Camelia sp.) with sparsely planted mature trees (Albizia saman, Eucalyptus sp., Acacia sp.) providing shade for the tea plants; (4) Paddy Fields: open seasonally flooded rice field adjacent to the village, tea plantation and degraded forest and (5) Village Habitat: these are the human settlements embedded in the matrix of tea plantation, degraded forest and the paddy fields with small patches of home garden and shrubs. There are several permanent and seasonal ponds in it. Field protocol Field work was conducted from 14 May 2011 to 18 November 2011, i.e. during wet (June-September) and dry seasons (October-November) and for a total of 138 field days. Conducting field surveys during both wet and dry seasons is important because tropical snake communities can show remarkable inter seasonal variation in probability of encounter due to variable phenology (e.g., Luiselli, 2006d; Akani et al., 2013; Eniang et al., 2013). For instance, some species are more nocturnal and/or less above-ground active in dry season, thus lowering their probability of encountering (Akani et al., 1999). We used three standard field methods for tropical snake studies (Akani et al., 1999), i.e. (1) road-killed individuals (death-on-road, DOR) encountered during standardized road surveys, (2) specimens opportunistically collected (OC), and (3) individuals encountered during visualen counter surveys (VES). In VES, snakes were actively searched for using time constrained searches in standardized routes throughout available habitats. We used two different routes in the natural habitat and three different routes in the human modified habitat to minimize any sampling biased. In the natural habitat, one route was on a sandy seasonal stream bed and the other route was on the existing forest trail constructed by the forest department. In the human modified habitat, one of the routes was along a sandy stream bed while the other two was on existing trails. A total of 1543 man-hours were spent for VES survey in five different habitat types, with all habitats surveyed for an almost identical time. Suitable spots like, logs, mammal burrow, leaf litter etc. were also checked. Field survey was conducted in standardized routes from approximately 9.00 h to 17.00 h, during both wet and sunny days. One to four surveyors walked the area in standard pace visually examining the area. However, fieldwork was suspended during heavy showers. Night surveys were conducted in the open forest habitat only occasionally because of security reasons. More specifically, less than 15% of total time was employed for nocturnal VES, from 18.00 h to 21.00 h. Many tropical snake species are nocturnal and therefore very limited night survey effort might under-represent the nocturnal species. However, we examined specimens killed by people at nights and also collected road killed specimens, thus reducing under-representation of nocturnal species. When seen, snakes were captured by hand or tongs, measured for snout-vent length (SVL) and tail length (TL) to the nearest 1 cm, and then individually marked by ventral scale-clipping. Snake specimens that were just sighted but that escaped before being identified were not included in the analyses. DOR specimens were collected along a 7-km segment of Sreemongol-Komgolgonj road that cut through the LNP. 3.5 km of this road segment passes along the moderately dense forest habitat and the rest dissects the human-modified habitat, with tea plantation on one side and the highly degraded, plantation forest in the other. DOR survey was conducted by walking at least once a day from July 11, 2011 to November 11, 2011, totalling 728 km. Survey time was typically from 16.00 h to 19.00 h. Since the survey was conducted almost daily, the majority of the DOR specimens were identifiable to species level. However, due to their small size and similar morphology, we were not able to discriminate to species all DOR specimens which were potentially belonging either to Ramphotyphlops braminus or to Typhlops spp. Therefore, for analysis, we classified them as Typhlopidae. DOR snakes were measured (total length, TL) using a measuring tape. After identification of the species, all DORs were taken out of the road to avoid double counts in following days. For OC, both live and dead (killed by people) snakes were collected opportunistically from plantation workers and local villagers from May 14 to November 18, 2011. Detailed data were collected from each captured individuals following the same protocol for the VES captured individuals.