Historically, mole skins were extensively marketed. Throughout the 17th, 18th, and 19th centuries mole skins were used for capes, trimmings, purses, and tobacco pouches. As late as the 1920’s they were still being trapped for their fur. After World War I, the mole skin business was extremely lucrative and a skin of S. townsendii was fetching between $0.50-0.60. By the mid-1930’s there was no longer a demand or a market for mole skins.
The primary method of perception for S. townsendii is its sense of touch. It has sensitive vibrissae on its snout with which it accurately perceives its nearby surroundings. Because of its subterranean lifestyle, its sense of sight is not necessary. Its highly reduced eyes can apparently only detect light intensity and not individual shapes. The senses of smell and hearing are also secondary in this species. Chemical cues are used to mark territories, and indicate mating availability. Abandoned territories are often overtaken when scent-marking chemicals lose their potency.
Communication Channels: tactile ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Throughout its range S. townsendii is fairly common as is evident by the conspicuous and numerous mounds seen where the moles are found. Human land management activities over the past 200 years have likely increased its favored habitat. The clearing of dense forest, the creation of hayfields and pastures, the spreading of manure, and the introduction of the large earthworms from Europe have expanded suitable habitat for the mole and probably increased its numbers from what they were before European settlement.
Because of its relatively limited distribution, there is some interest in monitoring Townsend's mole populations. In Canada, where its distribution only extends a few miles across the international border into southeast British Columbia, S. townsendii was listed as endangered in May 2003. There is a single population in Canada with perhaps only about 450 individuals. This population is under threat because of urbanization, habitat fragmentation, and pest removal activities.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Scapanus townsendii is held responsible for large amounts of economic damage to commercial bulb growers, cattle ranchers, golf course managers, and suburban lawn owners. Their burrowing activity can push up roots leaving them exposed and desiccated, their mounds can cover plants, and they are one of the only moles that is known to eat some plant material – including bulbs and tubers. Additionally, hundreds of homeowners go to various extremes to get rid of the moles from their lawns when the mounds first begin appearing. For all these vested interests, a great amount of finance and personal energy is expended each year in repelling, trapping, capturing, and poisoning Townsend’s moles. All of these are generally only a temporary fix, as moles will reestablish an area if the habitat is suitable. Eradication is not possible, either finacially or naturally.
One early example that calculated the economic damage of S. townsendii was documented in 1961. This study attributed more than $100,000 in annual economic damage to one dairy farm in Tillamook Co., Oregon. This damage was calculated by estimating: forage loss to cattle, equipment damage, the decreased the value of silage, and drying of plant roots. They were also found to be indirectly responsible for damage done by other rodents that use the mole’s tunnels as runways for access to plant material.
Even though their activities are often in conflict to human economic interests, the damage of S. townsendii is somewhat counteracted by it beneficial activities of preying on insect pests and increasing soil health.
Negative Impacts: crop pest
Scapanus townsendii has a considerable positive economic impact on humans. Members of this species prey on a significant amount of invertebrate pests. They keep in check many insect pests that are damaging to agricultural crops and lawns by eating them or their larvae. They also substantially aerate, fertilize, and mix soil layers, increasing productivity and soil health.
Finally, because they are considered a pest species the control of moles provides economic benefit in the form of jobs and research. This becomes readily apparent when observing the abundance of literature available from extension agents and pest control companies on the best methods and techniques for controlling mole populations.
Positive Impacts: research and education; produces fertilizer; controls pest population
Scapanus townsendii is a secondary consumer. It is both a predator and a prey species. It is a major predator in its subterranean environment, eating a substantial biomass of soil-dwelling invertebrates and ecosystem components. Scapanus townsendii, while not a significant prey species, is a minority food source for some predators.
The impact of S. townsendii on the soil ecosystem is significant. This species is an influential physical engineer of the soil ecosystem. The amount of soil moved around and paddled through by S. townsendii is extensive. Because of their movements and activities, they mix and aerate soil. They influence many aspects of the local environment: decomposition, fertilization, physical structure, and hydrology.
Their predator pressure on insect larvae and earthworms helps to keep these populations in check. Also, this pressure undoubtedly acts as an evolutionary driving force for these prey species.
The extensive tunnel systems of S. townsendii also act as communal runways for many other mammals. Voles Microtus townsendii, Microtus oregoni, mice Mus musculus, Peromyscus maniculatus, and shrews Sorex spp frequently use mole tunnels as runways. Other mammals that have been observed using mole tunnel system are ground squirrels, gophers, and rats.
Townsend’s moles have been found to host many ectoparasite species, including several species of chiggers, fleas, and ticks.
Ecosystem Impact: creates habitat; soil aeration
Commensal/Parasitic Species:
Scapanus townsendii primarily eats soil-dwelling invertebrates. Earthworms comprise the majority of its diet. Several studies have found earthworms encompassing more than 70% of its diet. The rest of its diet consists of differing percentages of other invertebrates, including insect larvae, centipedes, snails, and slugs, ad well as a small percentage of plant tubers, and bulbs. Interestingly, the large earthworms that it primarily eats were likely introduced from Europe more than 200 years ago. These are from the family Lumbricidae, such as Lumbricus terrestris. Historically, the moles likely ate more insect larvae than they do now. Studies have found small amounts of shrew and mouse matter in examined stomachs.
The teeth of S. townsendii are specialized for breaking up the tough exoskeletons of insects. The tunnel system operates as an efficient trap for worms, larvae, and other invertebrates that drop into it and are then captured by the patrolling mole. S. townsendii is a voracious feeder. Individual moles often consume more than 50% of their body weight and up to 1.5 times their body weight in a single day.
Scapanus townsendii is the only western mole documented to eat underground plant material. Because of this, tulip, iris, potato, and carrot farmers expend great amounts of energy getting rid of S. townsendii if they are found in their fields.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms
Plant Foods: roots and tubers
Primary Diet: carnivore (Vermivore)
Scapanus townsendii occurs only in the Pacific Northwest region of North America. Its distribution is west of the Cascade Mountains, occurring from the northwest corner of California and continuing north through western Oregon, Washington and a few miles into southeast British Columbia. In Washington a population extends west into the Olympic Mountains and in California it is restricted to the Redwood forests on the far Northwest coast.
Biogeographic Regions: nearctic (Native )
Scapanus townsendii occupies the moist lowland areas west of the Cascade Mountains. S. townsendii, like other moles, is almost exclusively fossorial. It prefers deep loamy soils and is rarely found in sandy soils. Scapanus townsendii occupies the subsurface domain of river floodplains, meadows, hayfields, pastures, residential lawns, prairies, and some fir forests. The Olympic Mountain population, S. townsendii olympicus, resides in an alpine habitat of grasses, sedges, alpine wildflowers, and subalpine fir forests.
Sympatric with S. townsendii, coast moles (Scapanus orarius) prefer drier soils that are better drained, sandier, and less likely to flood.
Range elevation: 0 to 1900 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: suburban ; agricultural ; riparian
Actual lifespan has not been documented. It is thought that S. townsendii has a ifespan similar to that of the closely related species, Scapanus orarius. If this is so, these moles live an average of 3 breeding seasons.
Scapanus townsendii is the largest mole in North America. Its pelage is purplish-gray to black and has a metallic appearance. Members of this species range in weight from 100 to 170 g, and are between 179 and 237 mm in total length. Males tend to be larger than females.
Its obvious characteristics are those that make it supremely adapted to a fossorial lifestyle. Its body is cylindrical and streamlined. The fur is short and able to bend easily in any direction. Its nostrils open upwards, its eyes are reduced, and its ears are reduced to the point that they are not externally visible. Perhaps the greatest digging adaptation of this species is its broad shovel-like front forepaws. They are as wide as they are long, and the digits have large claws. The pectoral girdle that supports the front limbs allows the limbs to rotate ventrally for more efficient digging. The humerus is broad and square-shaped and it articulates with the clavicle. Its hindfeet are much smaller and have shorter claws. Its tail is short and mostly naked, sparsely covered with course hairs.
Scapanus townsendii can be distinguished from other sympatric moles mainly by its large size. It is all-around larger and has a more prominent sublachrymal ridge than Scapanus orarius. Unlike Scapanus latimanus, its pelage has a metallic luster. It has wider forefeet and more teeth (44 instead of 36)than Neurotrichus gibbsii.
Range mass: 100 to 170 g.
Average mass: 130 g.
Range length: 179 to 237 mm.
Average length: 205 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Because they are almost exclusively fossorial, Townsend’s moles are relatively safe from predators. Adults are rarely captured by raptors or carnivores. Those moles that do end up as prey items are usually dispersing juveniles. This is when they are more likely to be moving above-ground. Raptors such as red-tail hawks, great horned owls, and barn owls have been known to eat S. townsendii. Carnivores such as coyotes (Canis latrans) and weasels (Mustelidae) will also prey on these moles. Domestic animals often kill S. townsendii. Dogs and cats often kill moles but do not eat them. Cows often inadvertently trample moles or their nesting chambers.
Scapanus townsendii has a fairly potent odor. This odor is thought by some to be an anti-predator adaptation that makes them unpalatable.
Humans are more likely than are other animals to kill S. townsendii. Townsend’s moles are often considered pests because of the mounds they excavate, and the small amounts of vegetable material they consume. Golf course owners, farmers, and urban residents who desire well-manicured lawns are perhaps the greatest mole predators.
Known Predators:
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); sexual ; 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)
