Diversity and distribution of smaU terrestrial rodents along a disturbance gradient in montane Costa Rica

Abstract: A total of 389 rodent captures in five unequally disturbed habitats in a Costa Rican montane cloud forest corresponded to 185 individuals (seven species, two faroilies). Species richness was similar for al l habitats, averaging 4-5 species/habitat. Population density and capture frequency were higher in moderately disturbed habitats; Peromyscus mexicanus and Scotinomys xerampelinus were four to five times more cornmon than other murids. These species represented 79.4 % of all captures and 73.5 % of all captured individuals. Heteromyid species were rarely trapped. The importance of disturbance-mediated within-habitat microenvironmental heterogeneity fOI terrestrial small-sized rodent populations is stressed. Key words: Costa Rica, disturban ce, montane cloud forest, rodents. Terrestrial rodents are known to be important seed dispersers and predators in tropical forest ecosystems (e.g. Adler 1995). Often they form the staple food of many avian and mammal predators and therefore play a prominent role in maintaining the structure and composition of species-rich tropical habitats