The Reproductive Processes of certain Mammals.—VIII. Reproduction in Foxes (Vulpes spp.)
1935
Parkes, I. W. Rowlands and A. S.
1 An account is given of the histo‐physiology of reproduction in the British Red Fox (Vulpes vulpes) and in the Silver Fox, a mutant of the American Red Fox (Vulpes fulva), now kept extensively in captivity. There appears to be no obvious difference in the reproductive processes of the two species. 2 Both species have one breeding season only per year and one period of œstrus. In the silver fox the mating season lasts from the middle of January to the end of March, litters being born, with a gestation period of fifty‐one days, from early in March to late in May. The British fox probably has a similar breeding season. 3 Records of 1370 silver fox litters born in Great Britain during 1925–32 fail to give any indication that the breeding season is lengthening or shifting in time of year under the influence of domestication. The time of the breeding season in Scotland seems to be identical with that in England. 4 Foxes of both species breed in the year following that of their birth, thus reaching puberty at about ten months old. 5 There are no external physical signs of œstrus, which can only be judged from the willingness to mate. Ovulation is spontaneous, and in the absence of mating is followed by a well‐developed pseudo‐pregnancy. 6 The male fox, which is strictly monogamous, has an anœstrus apparently nearly as long as that of the female, during which the reproductive organs are in a state of atrophic quiescence. 7 The morphological changes occurring in the female reproductive organs during the various phases of the cycle appear to be of the usual kind, except for the very remarkable changes in the uterus and vagina during pseudo‐pregnancy (p. 834), and also presumably during the early part of true pregnancy. 8 Possible methods of increasing the fertility of silver fox colonies are discussed.
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