Moles

The mammalian family Talpidae includes seventeen genera and forty-two species of moles worldwide in the order Eulipotyphla. Of these, there are four genera and seven species in North America alone. Moles are found in most parts of North America, Asia, and Europe. The family contains all the true moles, and some of their close relatives—including desmans, but these are not normally called “moles” and belong to the subfamily Talpinae. Those species called “shrew moles” denote an intermediate form between the moles and their shrew ancestors. There are three subfamilies of moles, including the Scalopinae (New World moles) with five genera, Talpinae (Old World, desmans, and shrew moles) with nine genera, and Uropsilinae (Asian shrew-like moles) with a single genus. The family is represented in Arkansas by a single species, the eastern mole, Scalopus aquaticus. It is a robust insectivore that has the widest range of any North American mole. It ranges from the northeastern United States west to the Midwest as far as southeastern Wyoming and south through Texas to northern Tamaulipas, Mexico; it is also found in eastern Canada. Two taxa of moles occur in Arkansas: S. a. machrinoides, which occurs along the northern tier of counties, and S. a. aereus, which can be found in approximately the southern two-thirds of the state. The latter is somewhat smaller but differs very little in general coloration from S. a. machrinoides.

Other North American members include the American shrew mole (Neurotrichus gibbsi), broad-footed mole (Scapanus latimanus), coast mole (S. orarius), Townsend’s mole (S. townsendii), hairy-tailed mole (Parascalops breweri), and star-nosed mole (Condylura cristata).

Members of this family are small, heavy-bodied mammals adapted for fossorial living in moist, pliable soils. Moles spend most of their lifespans in subterranean tunnels where they consume 25–100 percent of their weight in food on a daily basis. General characteristics of the family are: (1) very short neck, (2) minute eyes, often concealed by fur, (3) external ears absent, (4) nostrils positioned on the upper-side or laterally (sometimes terminal) on snout, (5) front feet greatly enlarged, with palm held facing outward and not downward, (6) short front legs, (7) enlarged shoulder girdle, (8) united tibia and fibula, (9) long, slender skull with complete zygomatic arches, and (10) dense and velvety fur.

The eastern mole, an Arkansas resident, measures 130 to 185 mm (5.1-7.25 in.) in total body length with a 20 to 35 mm (0.75-1.4 in.), nearly naked tail. It has a long, pointed snout with nostrils opening upward, tiny eyes covered with a thin membrane (eyelids are fused), and no external ears. The front feet are as broad as they are long, with long, stout claws. The pelage is velvety and silvery-gray to brownish gray or clove brown above; the underparts are usually of the same color as the upperparts, but sometimes are faintly washed with orange or with occasional white or orange patches. This mole undergoes spring and autumn molts.

Moles are reported to tolerate higher levels of carbon dioxide than other mammals, because their blood cells have a special form of hemoglobin that appears to have a higher affinity for oxygen than do other forms. Furthermore, moles utilize oxygen more effectively by reusing the exhaled air, and as a result, are able to survive in lower-oxygen environments such as underground burrows.

Mole breeding seasons are species specific but are generally February through May. In Arkansas, the peak of the breeding season is in mid-February. Males search for females by letting out high-pitched squeals and tunneling through foreign areas. The gestation period for S. aquaticus ranges from forty-two to forty-five days. Two to five young are born, mainly in March and early April. The young are naked and blind at birth and resemble adults in all but size. They have a covering of fine, velvety fur by ten to eleven days of age and are more than half grown at five weeks of age. Generally, young moles leave the nest thirty to forty-five days after birth, whereupon they are able to care for themselves and to find territories of their own. Although moles are considered long-lived, few individuals live more than three to four years.

The eastern mole occurs in open pastures, cultivated fields, gardens, lawns, golf courses, and thin woods. It also inhabits bottomland forests. It prefers moist sandy or light loamy, well-drained soils and tends to avoid dry sands, rocky or gravelly soils, and heavy clays. Most of the mole’s life is spent underground, and it seldom ventures above ground. Molehills are used as ventilation shafts, which connect the tunnels and rooms of a mole passageway. The mole digs two types of burrows: shallow surface runs and deep runs. The surface runs, marked by ridges of earth, are temporary and associated with foraging activities; they are seldom used more than a few times. Surface runs can be dug at a rate of three to six m (10 to 20 ft.) per hour. The deep runs are typically dug from 15 to 50 cm (5.9 to 19.7 in.) below the surface and constitute permanent burrows used for protection, rearing of young, and foraging in dry or cold weather.

Two types of underground passageways are utilized: near-surface and deep. The surface is commonly observed with raised ridges while the deep ones provide wintering/breeding areas. The nest is made of dry grass, rootlets, and leaves, and is located with the system of burrows approximately 30 cm (12 in.) below the surface. The nest is constructed in a chamber typically ranging from 12 to 20 cm (5 to 8 in.) in diameter, often located at the end of a deep run and under protection of a surface object (a log, stump, or rock), or near the base of a tree trunk. A single nest site is used in winter, but moles may use more than one nest in summer. Places for depositing feces and urine are found in the deeper tunnels.

The eastern mole, like all other talpids, has a voracious appetite and feeds mainly in surface tunnels on small soil invertebrates such as insects and their larvae, earthworms, snails, slugs, sow bugs, centipedes, and millipedes. Some plant material and seeds are also included in its diet. The mole runs are actually “worm traps,” with the mole sensing when an earthworm falls into the tunnel and quickly running along to kill and eat it. Since their saliva contains a toxin that can paralyze earthworms, moles are able to store their still-living prey for later consumption. They construct underground “larders” for just this purpose; researchers have discovered such larders with over 1,000 earthworms in them. Before eating earthworms, moles pull them between their paws to force the collected earth and dirt out of the worms’ guts.

Little information is available concerning population dynamics of moles; two to three moles per acre is considered to be a relatively high population. The home range can vary from about 0.5 to 4.5 acres; males generally range over a much larger area than females. Moles are generally solitary, except when males seek females; they come together only to mate. Territories may overlap, but moles typically avoid each other, and males may fight violently if they do meet.

Moles are active during all hours of the day or night and in all seasons of the year. Their activity peaks usually before sunrise and after sunset. Scalopus tends to be solitary except during the breeding season, but several individuals sometimes share the same burrow system. During the breeding season, they often travel overland in search of mates. Individuals captured by owls, hawks, and cats, which do not dig for their prey, provide evidence for such surface activity.

Moles can be frequent nuisances in gardens and lawns, and they are considered agricultural pests in some countries. They sometimes do considerable damage to greens at golf courses and can undermine plant roots, indirectly causing damage or death to plants. However, as far as net economic worth is concerned, they are one of the most valuable mammals. The benefits they perform in destroying insects and insect larvae in the soil and in opening up soil for penetration of air and moisture far outweigh the small amount of damage they do. Control measures include placing humane traps in their runs, and when a mole is making a surface run, it can be dug up with a spade tool. Other mole traps (Victor and Tomcat) are also effective, but are kill traps and are not considered humane by some. Moles can be controlled with smoke bombs and fumigants such as calcium carbide (CaC₂) and aluminum phosphide (AlP). High-grade nitrogen gas (N₂) has proven effective at killing moles, with the added benefit of having no polluting effect into the environment. Other common defensive measures include cat litter and blood meal to repel moles, or smoking their burrows.

Several parasites have been reported from moles. Coccidians, trematodes, tapeworms, and nematodes are known from North American moles, as well as ectoparasites. In Arkansas, a flea, Ctenopthalmus pseudagyrtes, was reported from an unknown locality. The same flea species and a mite, Haemogamasus harperi, were found on eastern moles from Union County. Three new species of coccidian parasites were reported from S. aquaticus in Benton and Union counties.

For additional information:
Arlton, A. V. “An Ecological Study of the Mole.” Journal of Mammalogy 17 (1936): 349–371.

Caire, William, Jack D. Tyler, Bryan P. Glass, and Michael A. Mares. Mammals of Oklahoma. Norman: University of Oklahoma Press, 1989.

Conaway, C. H. “The Reproductive Cycle of the Eastern Mole.” Journal of Mammalogy 40 (1959): 180–194.

Connior, Matthew B., Lance A. Durden, and Chris T. McAllister. “New Records of Ectoparasites and Other Epifauna from Scalopus aquaticus and Blarina carolinensis in Arkansas.” Journal of the Arkansas Academy of Science 68 (2014): 137–139. Online at http://scholarworks.uark.edu/cgi/viewcontent.cgi?article=1235&context=jaas (accessed December 17, 2021).

Davis, F. W., and Jerry R. Choate. “Morphologic Variation and Age Structure in a Population of the Eastern Mole, Scalopus aquaticus.” Journal of Mammalogy 74 (1993): 1014–1025.

Duszynski, Donald W., and Steve J. Upton. “Coccidia (Apicomplexa: Eimeriidae) of the Mammalian Order Insectivora.” Special Publication of the Museum of Southwestern Biology 4 (2000): 1–67.

Hartman, G., and Terry Yates. “Moles.” In Wild Mammals of North America: Biology, Management, and Conservation. 2nd ed., edited by G. Feldhamer, B. Thompson, and J. Chapman. Baltimore: Johns Hopkins University Press, 2003.

Jackson, H. H. T. “A Review of the American Moles.” North American Fauna 38 (1915): 1–100.

McAllister, Chris T., Dagmara Motriuk-Smith, and Catherine M. Kerr. “Three New Coccidians (Cyclospora, Eimeria) from Eastern Moles, Scalopus aquaticus (Mammalia: Soricomorpha: Talpidae) from Arkansas, USA.” Systematic Parasitology (2018). https://doi.org/10.1007/s11230-018-9782-4 (accessed December 17, 2021).

Reid, Fiona A. Mammals of North America. Boston: Houghton Mifflin Company, 2006.

Schmidly, David J., and Robert D. Bradley. The Mammals of Texas. 7th ed. Austin: University of Texas Press, 2016.

Sealander, J. A., and G. A. Heidt. Arkansas Mammals: Their Natural History, Classification, and Distribution. Fayetteville: University of Arkansas Press, 1990.

Wilson, Don E., and D. M. Reeder, eds. Mammal Species of the World: A Taxonomic and Geographic Reference. Baltimore: Johns Hopkins University Press, 2005.

Yates, Terry L. “Eastern mole/Scalopus aquaticus.” In Smithsonian Book of North American Mammals. Edited by Don E. Wilson and S. Ruff. Washington DC: Smithsonian Institution Press, 1999.

Yates, Terry L., and G. D. Hartman. “Moles: Talpidae.” In Wild Mammals of North America: Biology, Management and Conservation. Edited by G. A. Feldhamer, B. C. Thompson, and J. A. Chapman, 2nd ed. Baltimore: Johns Hopkins University Press, 2003.

Yates, Terry L., and R. J. Pedersen. “Moles (Talpidae).” In Wild Mammals of North America. Edited by J. A. Chapman and G. A. Feldhamer. Baltimore: Johns Hopkins University Press, 1982.

Yates, Terry L., and Ira F. Greenbaum. “Biochemical Systematics of North American Moles (Insectivora: Talpidae).” Journal of Mammalogy 63 (1982): 368–374.

Yates, Terry L., and Dwight W. Moore. “Speciation and Evolution in the Family Talpidae (Mammalia: Insectivora).” In Evolution of Subterranean Mammals at the Organismal and Molecular Levels. Edited by E. Nevo and R. Reig. New York: Wiley-Liss, 1990.

Chris T. McAllister
Eastern Oklahoma State College