REPRODUCTION OF THE RED FOX VULPES-VULPES IN CENTRAL ITALY

The reproductive output (ovulation rate, fertility, barrenness, produc tivity, pre-natal mortality) of the red fox Vulpes vulpes (n = 317) ha s been studied in a Mediterranean region (Pisa province, Central Italy ) in 1992 by post-mortem analysis. On average, female foxes shed 5.03 +/- 1.27 ova, had 3.95 +/- 1.25 placental scars and 3.88 +/- 1.55 live embryos. Twenty percent of foxes were barren, and intra-uterine morta lity was common: 47% of females lost at least one ovum before implanta tion; 43.5% of yearlings (less than or equal to 1 year old) lost at le ast one foetus, whereas only 16.7% of adults did so. Male yearlings ha d lower testis mass than adults. The reproductive output was higher fo r heavier females, but marginally so for those with greater head and b ody length. Barrenness and intra-uterine mortality were not related to body size. Amount of body fat and age were unrelated to reproductive output, with the exception of post-implantation mortality (higher for yearlings). All these results suggest that the reproduction of the red fox was not limited directly by food availability, but rather by soci al modulation. The reproductive output in this population was low in c omparison with other populations, in spite of faster physical developm ent. A review of the literature suggests compensatory reproduction in the red fox, litter size being larger in areas of higher mortality.