© Zoo Outreach Organisation; www.zoosprint.org Manuscript 1374; Received 06 June 2005; Finally accepted 19 November 2005; Date of publication 21 December 2005 2115 January 2006 | ISSN 0973-2535 (Print edition); 0973-2551 (Online edition) Communities are dynamic entities. Within them, populations of species undergo fluctuations in abundance over time, often displaying regular population cycles (Halama & Dueser, 1994). The structure and dynamics of small mammal populations in general reflects variations in the demographic attributes of the individuals in that population as they interact with the biotic and abiotic factors of the environment (Happold & Happold, 1991; Skupski, 1995). Consequently, one would expect habitat characteristics to have an effect on population dynamics of small mammals and this has been demonstrated in many studies (August, 1983; Zollner & Lima, 1997). In the tropics, with continuing deforestation, many natural habitats are drastically altered giving rise to patches of natural forest that are often surrounded by agricultural land or human settlements. This paper investigates the variability of population densities of five rodent taxa across habitats subject to varying levels of human disturbance, in the Sinharaja rainforest in Sri Lanka. The Sinharaja forest is located in the wet zone of Sri Lanka, between 6021'-6026'N & 80021'-80034'E. The vegetation of the northwestern section of the rainforest, where this study was conducted, is classified as lowland wet evergreen forest. The forest was designated a Biosphere Reserve under UNESCO’s Global Network of Biosphere Reserves. Subsequently, UNESCO declared it as a Natural World Heritage. The five rodent taxa investigated are the endemic species Srilankamys ohiensis and Mus mayori, a non-endemic species Mus booduga and two subspecies of the non-endemic species Ratus rattus, namely, R. r. kandianus and R. r. kelaarti. METHODOLOGY Data from a 13-month trapping regime was used to compare the population densities of the five selected murids in different habitat types in Sinharaja. Four major habitat types were selected, namely, unlogged forest, consisting of pristine closed forest with a relatively dense canopy and trees of large height and girth; forest that had been selectively logged in the 1970s (called logged forest); border areas of the forest that had earlier been cleared, cultivated with cash crops and subsequently abandoned for several years and now in secondary scrub jungle (called abandoned habitats) and border areas that were cleared and is used for raising permanent plantations of pine, rubber, tea or cinnamon, and now having monocrops of these species (called plantation).