Three to five males may pursue one female concurrently during mating season, leading to aggresive charging among them. The courting behaviour of white-tailed jackrabbits consists of a series of aggresive charges and jumps. Circling between male and female lasts from 5-20 minutes and is followed by copulation.
Mating System: polygynandrous (promiscuous)
The breeding season of white-tailed jackrabbits lasts from February to July with a peak from March to June. Ovulation is induced, requiring copulation or suitable stimulation. (Chapman et al., 1982). One to four litters with from 1 to 11 (averaging 4 to 5) young are born each year. A maximum of one litter is produced in more nothern climates. The gestation period is commonly reported as 42 days but this length varies, possibly due to altitude and habitat (Kim, 1987). This species exhibits breeding synchrony with male spermatogenesis and a postpartum estrus that facilitates conception soon after birth of young (Kim, 1987).
At birth the young weigh approximately 90-100 grams, have open eyes, full fur, and limited mobility within half an hour. The young begin to forage at approximately 2 weeks of age and are fulled weaned at one month. Sexually maturity is reached by 7 or 8 months though there is little evidence of reproduction until the spring following their birth.
Breeding interval: From 1 to 4 litters are born each year, depending on environmental conditions.
Breeding season: The breeding season of white-tailed jackrabbits lasts from February to July with a peak from March to June.
Range number of offspring: 1 to 11.
Average number of offspring: 5.
Range gestation period: 36 to 43 days.
Average gestation period: 42 days.
Range weaning age: 15 (low) days.
Average weaning age: 30 days.
Average time to independence: 1 months.
Average age at sexual or reproductive maturity (female): 8 months.
Average age at sexual or reproductive maturity (male): 8 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); induced ovulation ; viviparous ; post-partum estrous
Average birth mass: 94.32 g.
Average number of offspring: 4.3.
Average age at sexual or reproductive maturity (female)
Sex: female: 333 days.
Female L. townsendii nurse and care for their young for about 1 month. Females often create nests for the protection of their young from dried grass, leaves, and hair. Young are born fully furred and are capable of some level of mobility shortly after birth.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)