Reproduction
Reproduction
Mating: Arctic foxes are monogamous and mating occurs in March-April. Gestation lasts 52 days, and they give birth in May-June (Smith et al. 1985). Actic foxes are monestrous and estrous lasts 3-5 days. Timing of estrous depends on latitude, weather and physical condition (i.e. energy supply) (Smith et al. 1985). The reproduction of animals depends strongly on food availability, and is an important factor for arctic foxes, as they live in a region where food abundance varies within an between years (Bronson 1989). In such environments, the energetic cost of reproduction and offspring value can fluctuate over time (Morris 1987). There are currently two hypotheses as to how weaning success and litter size is determined (Meijer et al. 2013).
Litter size: as previously discussed in Background, there are two ecotypes of arctic fox, depending on habitat: coastal (marine) and inland foxes. Considering these habitats have differing food availability, the reproductive strategies of these two groups varies. Arctic foxes with a stable food supply (coastal foxes) produce relatively few cubs every year, while foxes depending on fluctuating prey populations (continental foxes) have larger mean and maximum litter sizes. Coastal foxes have an average litter size of 4-5 cubs, despite being able to produce 11 cubs per litter, whereas inland foxes show much larger variation in litter size (1-18 cubs per litter), and the number of litters produced throughout a lifetime. (Tannerfeldt and Angerbjorn 1998) |
Reproduction
Mating: first occurs between 9 months to 1 year old. Wild fennecs will mater in Janurary-February and give birth in March-April; gestation length is 50-52 days. It is likely that specific timing of reproduction relates to latitude and local conditions. (Gauthier-Pilters 1967) The female fennec has a monoestrous cycle that has a proestrous phase of 6 days, and a 1-2 day estrous, with no sanguineous discharge associated with either of these phases, as seen in other members of the genus (Valdespino et al. 2002). Proestrous is characterized by vulvar swelling, while estrous is characterized by an increased number of cornified epithelial cells upon inspection of vaginal smears (Valdespino et al. 2002). Females signal readiness to mate by deflecting their tails horizontally and standing for mounting, followed by an exceptionally long copulatory tie that lasts up to 2 hours and 45 minutes (Valdespino 2000). After mating, the male becomes aggressive and protects the female, and provides her with food throughout pregnancy and lactation (Sowards 1981). In cycles where fertilization does not occur, ovulation is followed by a 50 day diestrous period, also termed pseudopregnancy, because it is equivelent in hormonal pattern and duration to gestation (Valdespino 2000). Litter sizes: range from 1-4 pups. Fennec foxes will most commonly give birth to one litter per year, but more than one litter is possible in some conditions, such as when a litter is lost (Gauthier-Pilters 1967). |