Coast moles rely heavily on their sense of touch to navigate their underground burrows – they are virtually blind, and their acuteness of hearing is unknown. Thire naked snouts are covered in many small bumps, each one an individual complex of sensitive nerves known as an Eimer’s organ. Coast moles will tap the ground, prey items, and other environmental objects with their snout to distinguish between them. Intraspecific communication is poorly understood, but it is likely that olfactory cues play a role.
Communication Channels: tactile ; chemical
Perception Channels: tactile ; acoustic ; chemical
Coast moles are considered least concern because of their high population numbers and habitat adaptability. There are not considered significant threats to populations currently.
US Federal List: no special status
CITES: no special status
The digging activity of coast moles can cause damage to suburban yards, golf courses and agricultural areas. Although the moles themselves do negligible damage to crops, other small rodents can use mole tunnel system to eat agriculturally important roots and tubers.
Negative Impacts: crop pest
Coast moles may help control some insect pests.
Positive Impacts: controls pest population
In natural ecosystems coast moles may play an important role in maintaining soil quality, aerating soil through their digging activity and aiding in soil drainage. Young coast moles during the over ground dispersal period provide a food source for owls and potentially a much wider variety of species. Scapanus orarius itself hosts an impressive array of parasitic mite species.
Ecosystem Impact: soil aeration
Commensal/Parasitic Species:
The diet of coast moles varies considerably with the large number of habitats these animals can exploit. However, the majority of the diet consists of earthworms. Stomach content analyses of Scapanus orarius find earthworms in almost all individuals surveyed – furthermore, earthworms also make up more than half of stomach content by volume (Whitaker et al. 1979). The teeth of Scapanus orarius are marked by many small scratches from the soil particles present in the earthworm gut, emphasizing the prevalence of earthworms in the diet – in fact, adults eat twice their weight in earthworms each day. Coast moles also eat a variety of small terrestrial arthropods and mollusks, including centipedes, millipedes, the larvae of flies and beetles, and snails and slugs. Coast moles will ocassionaly eat vegetable matter, comprising some plant bulbs and fungi. Foraging occurs in the mole’s shallow burrow or on the surface in the vicinity of fallen logs.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms
Plant Foods: roots and tubers
Other Foods: fungus
Primary Diet: carnivore (Vermivore)
The range of Scapanus orarius extends from southwestern British Columbia along the western coast of Washington and Oregon, terminating in northwestern California. Coast moles can also be found in parts of eastern Washington and Oregon to the extreme east of its range into Idaho. The two subspecies of coast moles, S. o. orarius and S. o. schefferi have differing distributions: S. o. schefferi occupies eastern Washington, Oregon, and Idaho while S. o. orarious is found in the western part of Washington and Oregon.
Biogeographic Regions: nearctic (Native )
Coast moles are fossorial animals that construct burrows in a wide variety of habitats. Unlike the closely related Townsend’s moles which are restricted to burrowing in open pastureland or scrubby forest, coast males are found in nearly every habitat within their range, excluding wet swampy ground. They even burrow in sand in close proximity to shifting dunes. Coast moles are unique in being ubiquitous in all types of forest across the Pacific Northwest - they are particularly widespread in Douglas Fir forests of the Cascades. Coast moles have also been trapped in recently logged forests, indicating their ability to adapt to disturbed habitats. Coast moles are not isolated geographically or in their habitat selection from Townsend’s moles, but will readily inhabit the same open agricultural land, sometimes with the two different species living within very close proximity of each other. Coast moles live exclusively below ground, constructing tunnels at three typical depths. Tunnels just below the surface serve as exits for dispersal or voiding excess soil in the form of molehills. Tunnels regularly used for hunting are located between 7 and 90 cm below ground. Very deep tunnels are located between 1 and 2 meters underground – it is possible that these tunnels are used to access water in subsoil.
Range depth: 0 to 2 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest
Other Habitat Features: agricultural
Coast moles have not been kept in captivity for extended periods of time, nor have individuals been tracked for extended periods of time throughout their lives. Age estimates are based on toothwear observed in captured specimens. A scale proposed by Schaeffer (1978) categorizes individuals as 0 to 1 years old if they have little tooth wear, 1 to 2 years old if they have some wear on the first and second molars, 2 to 3 years old if the molars are worn down to the level of the gums, and 3 to 4 years old if the canines and incisors are also worn down to the gum level. It is presumed that most individuals do not survive past the 3 to 4 year mark with such compromised dentition.
Range lifespan
Status: wild: 3 to 4 years.
Coast moles are adapted for lives spent exclusively underground. Their streamlined bodies are between 133 and 190 mm long and weigh between 61 and 91 grams – males are on average 4 grams larger than females and are longer by 6 to 7 millimeters. Coast moles have small, plantigrade, five-toed hind feet, while their front feet are modified into large spade shaped structures adapted for digging. The widened surface and five elongated nails push dirt behind these moles as it moves through the soil. The head is relatively flat and streamlined. The reduced, tiny eyes and lack of pinnae are further adaptations for a fossorial lifestyle. A short tail 30 to 45 mm long is present. Finally, coast moles are covered in a velvety dark grey pelage that excludes only the tail, the forelimbs, and their sensitive, naked snouts. Coast moles are divided into two subspecies: S. o. orarius is on average smaller and has a darker colored pelage than S. o. schefferi, although intergradations exist between the two subspecies where their ranges overlap in Steven’s Pass, Washington. Coast moles can be distinguished from Townsend's moles, another common mole species of the Pacific Northwest, by size. Townsend’s moles almost always have a length greater than 200 mm.
Range mass: 61 to 91 g.
Range length: 133 to 190 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Owls are known to prey on coast moles when they are foraging or dispersing above ground. Bones of Scapanus orarius have been found in the regurgitated pellets of barn owls and long eared owls. The only other known predators of Scapanus orarius are the semi-fossorial rubber boas.
Known Predators:
Anti-predator Adaptations: cryptic
Little is known about the breeding system of Scapanus orarius since it spends nearly its whole life below ground. Coast moles breed seasonally, since dissections indicate testicular growth between the months of January and March, followed by subsequent shrinkage and a prolonged size reduction until the next year’s bout of breeding. Though normally solitary, males will dig long tunnels connecting with the territories of neighboring females during the breeding season.
Mating occurs in a 3 month interval between January and March when male coast moles experience testicular growth and construct tunnels to meet with females in neighboring territories. By May all females have given birth, but the length of gestation remains unknown. Typical litters consist of 3 to 4 pups, but it is possible that litter size increases with maternal age, meaning that females in their first breeding season only bear 1 to 2 pups. At 2 weeks old the young are naked, unweaned, and weigh between 13 and 15 grams. Weaning probably does not occur until the pups have reached a weight in excess of 40 grams – pups discovered at this stage of development have not exhibited the ability to eat on their own. Offspring become independent of their mothers by July and August. At this time juveniles disperse from their mother’s home territory and can be seen traveling above ground in search of new territories.
Breeding interval: Coast moles breed once per year in late winter or early spring.
Breeding season: Breeding occurs from January to March.
Range number of offspring: 2 to 4.
Range age at sexual or reproductive maturity (female): 9 to 10 months.
Range age at sexual or reproductive maturity (male): 9 to 10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
As far as is known, male coast moles make no contribution to raising offspring. Young are borne and protected by the mother before weaning in a grass-lined nesting chamber about 6 inches below the surface of the ground. Beyond the construction of the nest chamber, little is known about maternal care for coast mole pups. Like all mammals, females invest heavily in their young through gestation and lactation.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
The coast mole or Pacific mole (Scapanus orarius) is a medium-sized North American mole found in forested and open areas with moist soils along the Pacific coast from southwestern British Columbia to northwestern California.
Two subspecies are recognized: the nominate, S. o. orarius, and Scheffer's coast mole, S. o. schefferi.[2] The nominate has a shorter skull and less enlarged maxillary region.[3] The patterns of teeth shearing on dirt and earthworms (their main diet) set both subspecies apart from similar species.[3][4]
The coast mole is generally less than 200 mm long, with the tail being one-fourth of its total length. The fur is uniformly black. The skull is relatively narrow and long, with a sublacrimal-maxillary ridge that is underdeveloped. Teeth are uncrowned and evenly spaced.[3]
The coast mole has a disjunct distribution, occurring from the western end of British Columbia, Canada through the western regions of Oregon and Washington, and in some parts of Northern California (coastal regions). The most extreme divergence of range for the coast mole has been seen to reach some parts of west-central Idaho. The species has a primarily fossorial lifestyle, but is not restricted solely to underground habitats. Like many other species of moles, it is capable of surfacing for scavenging purposes and juvenile dispersals, especially in the summer months. It may inhabit, but is not restricted to, agricultural land, sand dunes, grassy-meadows, sage brush, deciduous forest, and pine forests (woodpine, hemlock, and redwood).[3]
Coast moles eat insects and other small invertebrates including earthworms, which it hunts in moderately moist soil environments. Coast moles will increase their digging activity when they sense shifting densities of earthworms. Food items found in coast mole stomachs included earthworms (the majority by mass), slugs, earthworm eggs, and larval and adult insects.[3][4]
The coast mole is primarily solitary and only become social during mating season. Coast mole populations and their corresponding tunnel systems seem to be larger in areas with damp soil and high earthworm densities. Coast moles are primarily nocturnal, but do not confine their activities to any specific part of the night. It has been found that an individual mole's activities tend to be asynchronous to those of neighboring moles.[3]
Mating usually occurs in period from late January and early March. During this time, coast moles will diverge from their normal solitary lifestyles and begin expanding their tunnel systems, even venturing into other coast mole tunnel systems in attempts to find a mating partner.[3] Little is known about their gestation and nursing behavior. Females produce a single litter per year, and maternal care is limited. Coast mole offspring can become reproductively active within nine to ten months of birth.[3]
Coast moles primarily use their noses for sensing their surroundings underground. Eimer's organ is a small, densely innervated sensory structure found in the nose of most talpid moles, including the coast mole, which seems to play a critical role in tactile discrimination and enables it to differentiate between prey items in an environment with little to no visual input. Moles and monotremes appear to have developed this as a convergent structure, using common components of mammalian skin to maximize tactile sensitivity.[5]
Air supply in coast mole tunnels may be short on oxygen, but enriched with carbon dioxide from respiration.[6] One adaptation to these environmental challenges is an increased blood volume for oxygen storage. Another is a modified hemoglobin, found in the coast mole and the eastern mole, that allows for heightened Cl- ion binding activity that is not affected by the relatively cold temperatures of mole tunnels.[7]
The species has been classified as Least Concern by the IUCN, since it appears to be common in a wide variety of habitats throughout its range.[1]
The coast mole or Pacific mole (Scapanus orarius) is a medium-sized North American mole found in forested and open areas with moist soils along the Pacific coast from southwestern British Columbia to northwestern California.
