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Response to Delibes-Mateos et al. : Pellet size matters

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... Delibes-Mateos et al. (2009) refuted the accuracy of this method by experimentally showing that adult rabbits produced similar proportions of pellets in each size class. However, Rueda et al. (2009) questioned these results, suggesting that the experimental design of Delibes-Mateos et al. (2009) was not suitable for testing the usefulness of their method. In the present study, we further assess the validity of using a 6 mm fecal pellet diameter as a threshold for differentiating adult and juvenile rabbits, following the recommendations of Rueda et al. (2009). ...
... However, Rueda et al. (2009) questioned these results, suggesting that the experimental design of Delibes-Mateos et al. (2009) was not suitable for testing the usefulness of their method. In the present study, we further assess the validity of using a 6 mm fecal pellet diameter as a threshold for differentiating adult and juvenile rabbits, following the recommendations of Rueda et al. (2009). Specifically, the proportion of adults in four wild rabbit populations living in seminatural conditions was compared with the proportion of pellets greater than 6 mm that were produced by the animals. ...
... Using this threshold, the proportion of adults was generally overestimated and explains the association between the proportion of pellets >4 mm and proportion of adults in population 1 (Table 1; Fig. 1). Rueda et al. (2009) recommended that animals be kept under semi-natural conditions with respect to both the type of food supply and environmental stressors/conditions. In this study we surveyed four wild rabbit populations living in semi-natural conditions. ...
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