Fat deposition and seasonal variation in body composition of red foxes (Vulpes vulpes) in Australia

We evaluated body composition of 165 adult red foxes (Vulpes vulpes) collec ted monthly from August 1995 to July 1996 in New South Wales, Australia. To tal body fat content and estimated protein content were determined as a per centage of skinned body mass (SBM) using chemical analysis of homogenized s amples. Mean percent body fat varied significantly over the year (P < 0.001 ) and differed significantly between the sexes in each month (P = 0.039). M ale body fat reserves peaked at 13% of SBM in June, prior to breeding, and female body fat peaked at 16% of SBM in July during gestation. Body fat res erves declined rapidly in both sexes from September through November, reach ing average values of 3-4% SBM by the time of weaning (November). Estimates of total body protein content varied significantly over the year (P < 0.00 1) but did not differ significantly between the sexes (P = 0.745). Protein content was lowest but stable at 21-22% of SBM from August to November and increased rapidly by December. Protein content then remained stable at 23-2 5% of SBM from January through July. The low body protein content in August through November corresponds to the decline in body fat reserves of foxes. These foxes appear to accumulate fat and protein reserves throughout the n on-reproductive phase of their annual cycle and then deplete these stores d uring their reproductive period.