Influence of habitat structure on a streamside small mammal community in in Brazilian rural area

A capture-mark-recapture population study of small mammals was carried out in the Pamparrao valley, rural area of Sumidouro County, Rio de Janeiro, Br azil. Trapping was carried out every other month from June 1991 to July 199 6, for five trapping nights on seven transects along the valley, totaling 1 2250 trap nights. The roles of habitat complexity (vegetation density in ve rtical strata) and heterogeneity (horizontal physiognomy) on structuring th e small mammal community were investigated correlating heterogeneity and co mplexity with mammal abundance and richness. Heterogeneity variables were r elated to small mammal species and habitats, simultaneously, by a Canonical Correspondence Analysis. Marsupials were more related to the forest transe cts and to the presence of trees. Rodents were most related to the herbaceo us stratum near the ground. Abundance of mammals was influenced mostly by c omplexity. The study area presented low habitat complexity, and it suffered frequent anthropogenic disturbances. These factors provided low species ri chness by neotropical standards. A few generalist species presented the mos t stable populations and were numerically dominant, compared to the special ists.