E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Scapanus townsendii (Bachman)
Townsend's Mole
Family: Talpidae
Species account author: David Nagorsen
Extracted from the Opossums, Shrews and Moles of British Columbia

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Distribution of Scapanus townsendii in British Columbia.
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Source: Opossums, Shrews and Moles of British Columbia by David Nagorsen © Royal BC Museum

Species Information


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Illustration Source: Opossums, Shrews and Moles of British Columbia by David Nagorsen © Royal BC Museum

Townsend's Mole is the largest mole in North America. It is essentially a large version of the Coast Mole (Scapanus orarius). Its fur is short, soft and velvety, ranging in colour from blackish-brown to grey, and paler in summer. In some populations a few individuals have aberrant pelages with irregular white or yellow markings on the undersides. However, these markings are not evident on the few specimens from British Columbia. The front feet are broad and shovel-like with long flat claws; the hind feet are not enlarged and have short weak claws. The snout is long and almost naked. The eyes are minute; external ears are absent. The tail is short and nearly naked. Males are usually larger than females. The skull resembles that of the Coast Mole, with 44 teeth.

Identification

The only mammal that Townsend's Mole could be confused with is the Coast Mole; see that species account for diagnostic traits.

Dental Formula

incisors: 3/3
canines: 1/1
premolars: 4/4
molars: 3/3

Measurements

total length: 205 (179-237) n = 30
tail vertebrae: 38 (31-45) n = 30
hind foot: 25 (23-29) n = 31
weight: 137.9 (121.0-164.0) n = 7 (males)
113.5 (96.0-122.0) n = 5 (females)

Biology

Reproduction

In Oregon the breeding season begins in early winter; males with enlarged testes have been found in November. By February the testes have begun to decrease in size and by mid March males are no longer in breeding condition. Pregnant females have been observed as early as mid March and no later than mid April. Female Townsend's Moles appear to have only one litter per year. Reproductive data for the British Columbian population consists of anecdotal information for a few museum specimens: a male with enlarged testes was taken on 24 March, and a female with a foetus about 20 per cent developed was captured on 27 April. These data suggest that the breeding season in British Columbia may be later than in Oregon. The gestation period has not been determined for this species, but it is assumed to be four to six weeks.

Females bear one to four young, with three most common. Newborn moles are naked, and lack teeth and distinguishable eyes; they weigh about 5 grams. By 10 days, their skin colour has changed to grey; the fur begins to grow within three weeks of birth. They are completely furred by 30 days, and weigh 60 to 80 grams. Within a month of weaning, young begin to leave their mother's nest and disperse. In Oregon, they disperse in May and June. Townsend's Moles are capable of breeding in their first winter after birth.
Diet

The diet of Townsend's Mole is predominately earthworms. In Oregon several studies based on stomach contents revealed that 70 to 90 per cent of the prey is earthworms. Small amounts of other invertebrates (centipedes, millipedes, snails, slugs, insects) and a few small mammals (shrews or mice) have also been identified in stomach remains. Vegetation (bulbs, roots, grass, carrots, parsnips, oats, beans) is also a major food. Probably because of its more restricted habitat, the diet of Townsend's Mole appears to be less diverse than that of the Coast Mole.
Natural History

A proficient digger, Townsend's Mole constructs several types of tunnels. It makes shallow surface tunnels (5 to 15 centimetres below ground) for foraging and possibly for locating mates in the breeding season. Usually these surface tunnels are used only once. Molehills are deposited on the surface along these runways. Townsend's Mole also makes permanent deep tunnels, usually 10 to 20 centimetres below the surface, although it may construct deeper tunnels (1 to 3 metres deep) under roads, buildings and fencerows. Soil from excavation is deposited as conical mounds above these runway systems. The average molehill is about 43 centimetres in diameter and 17 centimetres high.

In the breeding season, females construct nursery nests in underground cavities where they give birth to and raise their young. The nest chambers are situated 15 to 20 centimetres below ground; they are about 23 centimetres long and 15 centimetres high. Dirt from excavating these chambers is usually deposited on the surface in a large mound 70 to 130 centimetres in diameter and 30 to 45 centimetres high. Each nest chamber has three to eleven lateral tunnels and an escape tunnel that runs from the bottom of the nest to another tunnel or burrow. The nest has an outer layer constructed from coarse grass, moss or leaves, and an inner layer made from fine dry grass. Green plant material is often used for the outer layer and its drying may heat the inner nest. Some nursery nests are used only one year, others may be reused for several breeding seasons. Until a female gives birth, she will readily abandon her nest if disturbed and build a new nest within four or five days.

Captures of marked Townsend's Moles suggest that subterranean movements of adults with established burrow systems are limited: distances between capture sites ranged from 3 to 116 metres and the average distance between captures was about 40 metres. Long distance movements (beyond 100 metres) are usually undertaken in the dry months of summer in poor habitats where earthworms are scarce. When dispersing from the nursery nest in late spring and summer, however, young Townsend's Moles move considerable distances (up to 800 metres) above ground.

This species possesses a strong homing ability. Individuals displaced short distances (100 to 200 metres) by annual floods usually reoccupy their original tunnel systems quickly after flooding. Moles displaced artificially have successfully returned to their originallocations from distances of up to 450 metres. Although Townsend's Moles are strong swimmers, canals and rivers can be major barriers to their movement.

No density estimates are available for the British Columbia population. In Oregon, population densities may reach 12 per hectare in ideal habitats; as many as 805 mounds per hectare have been counted. Densities may be as low as 0.4 per hectare in areas with few earthworms or unsuitable soil.

Dogs and cats are opportunistic predators of Townsend's Moles, but the major predators are owls, particularly the Barn Owl. Most predation occurs in summer when the young of the year are dispersing above ground at night. The young will cross roads when dispersing, and a few have been found dead on highways in summer. In the dairy farming regions of Oregon, young moles are killed by cattle trampling the nursery nests. In lowland areas, winter flooding also takes its toll. Richard Giger counted 62 Townsend's Moles that had died in a severe January flood in his study area in Oregon. Moles may be trapped in their tunnels or die from exhaustion when attempting to swim to higher ground.

Habitat


Townsend's Mole typically inhabits lowland meadows, cultivated fields, flood plains and prairie habitats. There are also high elevation populations in the Olympic and Cascade mountains of Washington and Oregon. The British Columbian population is associated with agricultural land in the Fraser River valley. Little specific information is available on its habitat requirements in the province; in the United States, Townsend's Mole seems to prefer moister soils than the ubiquitous Coast Mole. The few localities in British Columbia where it is known to occur are associated with moist, well-drained soils with no water table. These are medium-textured soils deposited over gravelly glacial outwash.

Distribution


Townsend's Mole inhabits the Pacific coastal regions of northern California, Oregon and Washington. In British Columbia, where it is at the northern edge of its range, this mole has a very limited distribution that is confined to a localized area around Huntingdon and Abbotsford adjacent to the international border.

Taxonomy


The British Columbian population belongs to the subspecies Scapanus townsendii townsendii (Bachman), a widespread race occupying the entire range of the species except for high elevations in the Olympic Mountains where it is replaced by Scapanus townsendii olympicus Yates and Johnson.

Remarks


Townsend's Mole has one of the smallest distributional areas of any mammal in the province. Because of its rarity and restricted range, it has been placed on the provincial Red List. Until recently, information on this mammal in the province was limited to museum specimens collected 40 to 70 years ago at the Racey farm near Huntingdon. In 1994, Tim Sheehan initiated a detailed field study. He established that a breeding population still exists near Huntingdon and found additional populations east of Abbotsford. Intensive surveys in the Matsqui region are required to delimit the precise range, population density and preferred soil types.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
NativeS1RedE (Nov 2014)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Photo Sources

General References


Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2021-05-12 4:27:39 PM]
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