Townsend’s moles are polygynandrous. Their fossorial habits have made it difficult to observe mating behavior, so not much is known about their reproductive behavior. It is thought that during the breeding season, males leave their permanent tunnels and construct temporary tunnels throughout the surrounding areas to look for females. Little is known about how males compete with each other for mates. Captured females have been observed to have vaginal plugs, deposited by males, likely to prevent other males from mating with them. This observation indicates that females mate with multiple males.
Mating System: polygynandrous (promiscuous)
Scapanus townsendii breeds once per year between November and February. Males in Oregon have been captured in breeding condition with enlarged testes as early as November. The breeding period peaks in January and February.
Females give birth to an average of 3 offspring per litter. Young moles are born in late March or Early April, 4 to 6 weeks after mating. Young are atricial but develop rapidly. Moles weigh about 5 grams and are born pink and without fur. At birth, they lack recognizable eyes, and the claws are not yet hardened. An interesting characteristic of the neonates is the already oversized front limbs. They begin to grow fur after 22 days, and have a complete coat by 30 days. By the time they are fully furred, young moles weigh between 60-80 grams. The young moles stay in the nest for 30 to 36 days and then they begin to disperse. Moles disperse throughout the surrounding areas depending on population density and habitat availability. Moles are reproductively mature at about 10 months of age.
Breeding interval: Townsend's moles breed once yearly.
Breeding season: Breeding occurs from late December through early March.
Range number of offspring: 1 to 4.
Average number of offspring: 3.
Range gestation period: 4 to 6 weeks.
Range time to independence: 30 to 36 days.
Average age at sexual or reproductive maturity (female): 10 months.
Average age at sexual or reproductive maturity (male): 10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous
S. townsendii males show no signs of parental care. Females build one of the most extensive nesting chambers of any North American Talpid. The large nesting chamber is generally constructed about 20 cm below the surface of the ground. Nesting chambers are often constructed in undisturbed areas, such as under fencerows. The chambers are often elevated from other portions of the burrow system, which prevents flooding and helps to take advantage of solar radiation. The female lines the nesting chamber with grasses, leaves, and moss, which she replaces periodically. The nesting chamber has several exit tunnels. Some have been found to have up to 11 exits. The presence of the nesting chamber is often given away from above by a huge mound up to 76 cm in diameter and 46 cm high, or by a ring of several smaller mounds. The female defends the chamber and young from intruders. The young disperse from the nest 4 to 6 weeks after birth and after this future contact with the parents is rare.
Parental Investment: no parental involvement; altricial ; female parental care ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)