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Revista chilena de historia natural

Print version ISSN 0716-078X


SILVA, SERGIO I.; JAKSIC, FABIÁN M.  and  BOZINOVIC, FRANCISCO. Nutritional ecology and digestive response to dietary shift in the large South American fox, Pseudalopex culpaeus. Rev. chil. hist. nat. [online]. 2005, vol.78, n.2, pp.239-246. ISSN 0716-078X.

We tested the role of dietary shifts (from rodents to fruits and to mixed diets) on the nutritional ecology of the culpeo fox Pseudalopex culpaeus, a native canid of South America. We studied the effects of food quality on digestive processes, nutrition, and mass balance, and the implications of diet quality for fox survival. We observed at the end of the nutritional trials that body mass differed significantly between the three diet groups (fruits, rats and mixed diets), while percentage of body mass change differed significantly only in the fruit diet treatment. Foxes fed with fruits consumed more food to meet their dietary and metabolic needs. Across diets, dry-matter as well as energy digestibility increased significantly with diet quality. Also, mean retention time was negatively and significantly correlated with dry-matter intake. We put forth that mixed diet may yield higher assimilation efficiencies and hence higher nutrient intakes than those predicted from the ingestion and assimilation of pure diets (i.e,. only rats, only fruits). We hypothesize that during periods of low availability of mammalian prey, a mixed diet should yield a positive energy/mass balance for the fox. We conclude that temporal and spatial variation in nutrient, energy, and water contents of prey available in a given habitat could have an important effect on fox nutrition, energy use, and mass balance. Finally, we postulate that P. culpaeus could not survive on fruits only past seven days

Keywords : nutritional bottleneck; fox; dietary shift; fruit consumption.

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