Diet of the gracile mouse opossum (Gracilinanus microtarsus) (Didelphimorphia: Didelphidae) in a Brazilian cerrado: patterns of food consumption and intrapopulation variation

Authors

  • E. G. Martins,

    1. Programa de Pós-graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
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  • V. Bonato,

    1. Instituto de Ciências Biológicas, Centro Regional Universitário Espírito Santo do Pinhal, São Paulo, Brazil
    2. Faculdade de Ciências Matemáticas, da Natureza e Tecnologia de Informação, Universidade Metodista de Piracicaba, Rodovia do Açúcar, Piracicaba, São Paulo, Brazil
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  • H. P. Pinheiro,

    1. Departamento de Estatística, Instituto de Matemática, Estatística e Computação Científica, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
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  • S. F. Dos Reis

    1. Departamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
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Correspondence
Sérgio F. dos Reis, Departamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, 13083-970 Campinas, São Paulo, Brazil.
Email: sfreis@unicamp.br

Abstract

The diet of the gracile mouse opossum Gracilinanus microtarsus was studied in a cerrado remnant in south-eastern Brazil through the analysis of faeces sampled from adult individuals. Patterns of food resource consumption were assessed using the statistics of per cent occurrence. Intrapopulation variation in the number of food items detected in faeces as a function of relevant factors was inferred using generalized linear models. The latter statistical formalism also allowed variation in the number of food items detected in faeces to be interpreted in terms of rate ratios among levels of significant factors. Insects, spiders, snails and fruits were detected in the faeces of G. microtarsus, with insects, particularly termites, beetles and ants, being the most frequently detected food resource. These food resources were consumed in proportion to their relative abundance in the cerrado, suggesting that G. microtarsus is an opportunistic forager feeding primarily on insects. The generalized linear model identified sex, season and food resource as significant factors affecting the number of food items detected in faeces, as well as interactions between sex and season and season and food resource. Rate ratios calculated between sexes within seasons showed that the number of food items detected in the faeces of males was larger than that detected in the faeces of females in the warm-wet and cool-dry seasons. Rate ratios calculated between seasons within sexes showed different trends in the number of food items detected in faeces for each significant food resource. It is suggested that differences in the number of food items detected in faeces between sexes within season and between seasons within sexes are related to energetic requirements associated with reproduction.

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