TIMING OF REPRODUCTION IN THE RED FOX, VULPES-VULPES

Ovulation date was estimated for 93 female red foxes (Vulpes vulpes) c ollected in central Italy. Three methods were used: ageing embryos, ex amination of ovarian bodies, and of placental scars. Most females ovul ated around 26 February (SD +/- 9.5 days). Estimates from different me thods gave consistent results Ovulation date was independent of physic al condition and size, but was 5 days earlier in the north of the stud y area than in the south. The testes of 154 males were also weighed. M ale testicular mass decreased after the end of February. Results from this and other studies are consistent with the hypothesis that timing of reproduction in the red fox is constrained by a winter trophic bott leneck in the north, but can be more variable in the south. Small-scal e variation in our study area was probably unrelated to food availabil ity.