Female red foxes gestate for 49-56 days before giving birth to 1-13 pups, averaging 5, while the male provides food outside of the maternity den.
Red fox sexual maturity is reached by 10 months.
Male red foxes will fight during the breeding season. Males have a cycle of fecundity, with full spermatogenesis only occurring from November to March.
The annual estrous period of female red foxes last from one to six days. Ovulation is spontaneous and does not require copulation to occur. The exact time of estrous and breeding varies across the broad geographic range of the species: December-January in the south, January-February in the central regions, and February-April in the north. Females may mate with a number of males but will establish a partnership with only one male.
Copulation usually lasts 15 or 20 minutes and is often accompanied by a vocal clamor. Implantation of the fertilized egg occurs between 10 and 14 days after a successful mating. Just before and for a time after giving birth the female remains in or around the den. The male partner will provision his mate with food but does not go into the maternity den. Gestation is typically between 51 and 53 days but can be as short as 49 days or as long as 56 days. Litters vary in size from 1 to 13 pups with an average of 5.