1. Introduction Most information about the effects of habitat fragmentation on animals is focused on population and community parameters, but the effects on individual parameters remain largely unknown. We evaluated how landscape structure affect the body condition of two didelphid marsupials, Didelphis aurita and Philander frenatus, inhabiting forest fragments in the Atlantic Forest, Brazil. Discussion Body condition was higher in large fragments with more edge despite differences between genders and species in the effects of property ownership, and in the economic activity in the matrix. However, in male P. frenatus it was possible to detect the effect of land use in the matrix on the body condition of animals, possibly because large properties have lower human impact in the interior of fragments. Didelphis aurita may use the matrix more frequently than P. frenatus, which would explain females being affected more directly by economic activities in the matrix. The body condition index was able to detect effects of habitat fragmentation on individuals in the Atlantic Forest, especially regarding matrix use. Jayme Augusto Prevedello 1,2, Ana Cláudia Delciellos 1,3 and Marcus Vinícius Vieira 1 1. Laboratório de Vertebrados, Departamento de Ecologia, Universidade Federal do Rio de Janeiro, Brazil. 2. Programa de Pós-Graduação em Ecologia, UFRJ, Brazil; ja_prevedello@yahoo.com.br 3. Programa de Pós-Graduação em Zoologia, Museu Nacional – UFRJ, Brazil. HABITAT FRAGMENTATION AND LAND USE EFFECTS ON BODY CONDITION OF TWO DIDELPHID MARSUPIALS IN THE ATLANTIC FOREST, BRAZIL Methods Study sites were located in the Macacu river watershed, Rio de Janeiro State, Brazil. Small mammals were surveyed in 24 fragments from 1999 to 2008. Body condition was evaluated as the residuals between ln body mass and ln body size, calculated separately for males and females. Predictor variables: 1.fragment size 2.economic activity in the matrix (cattle ranching, agriculture, mixed use, and peri-urban areas), 3.property ownership (1–2 large rural properties, more than three small rural properties, and properties in peri-urban areas), 4.amount of edge, 5.abundance of the palm Astrocaryum aculeatissimum (an indicator of habitat structure). Models with these variables as predictors were compared using the Akaike Information Criteria and derived statistics. Results  For P. frenatus, 109 males and 108 females were captured, and for D. aurita, 52 males and 71 females.  For males of P. frenatus, property ownership was the main variable affecting body condition, followed by edge amount, fragment size, and palm abundance. Body condition was high in large rural properties, large fragments, and amounts of edge, reducing with palm abundance.  For females of P. frenatus, the best model also included property ownership, but the null model was equally plausible. Body condition of females also was high in large rural properties.  For males of D. aurita, no model was more plausible than the null model.  For females, economic activity was present in the four most plausible models, but fragment size and edge amount also were present. Body condition was low in agriculture, and increased with fragment size and amount of edge. UFRJ Fig. 1. Studied marsupials (Didelphimorphia, Didelphidae): a) Black- eared opossum, Didelphis aurita; b) grey four-eyed opossum, Philander frenatus. Fig. 2. Image of vegetative cover in the Macacu River watershed, Rio de Janeiro State, Brazil. Table 1. Performance of models predicting body condition of males and females of Philander frenatus in Atlantic Forest remnants. K = number of parameters of the model, AICc = Akaike Information Criteria corrected for small ratio sample size/number of parameters, Δi = AICci – minimum AICc, wi = Akaike weight. The model without variables represents the null model. Table 2. Performance of models predicting body condition of males and females of Didelphis aurita in Atlantic Forest remnants. Symbols as in Table 1. FNMA/MMA