Revista Chilena de Historia Natural 78 (2): 239-246, 2005
RESEARCH ARTICLE
Nutritional ecology and digestive response to dietary shift in the large South American fox,
Pseudalopex culpaeus
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.
Key words:
nutritional bottleneck,
fox, dietary shift, fruit consumption
