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Scalopus aquaticus (Linnaeus 1758)

Order Soricomorpha : Family Talpidae

DESCRIPTION.  A relatively small, robust, burrowing mammal with broadened, shovel-like front feet webbed to base of claws; no visible eyes or ears; sharp-pointed nose; plush-like fur; short, sparsely haired tail. Dental formula: I 3/2, C 1/0, Pm 3/3, M 3/3 × 2 = 36; middle upper incisors enlarged; canines small and undifferentiated; molars with W-shaped outline when viewed from biting surface. Color brown, often with silvery sheen; suffusion of orange on nose and wrists; underparts silvery gray, faintly washed with orange. Averages for external measurements: total length, 165 mm; tail, 29 mm; hind foot, 22 mm. Weight, 60–90 g.

Scalopus aquaticus

DISTRIBUTION. Eastern two-thirds of the state, including eastern portions of South Texas. In the northern Panhandle, they extend to the New Mexico line along the Canadian River drainage. Isolated record from Presidio County.

Distribution of Scalopus aquaticus

SUBSPECIES. Five known in Texas: S. a. aureus in the extreme east and also the Panhandle region; S. a. alleni in south-central Texas; S. a. cryptus in the east-central
part of the state; S. a. inflatus on the southern part of the Rio Grande Plains; and S. a. texanus in Presidio County.

HABITS. Eastern moles spend most of their life in underground burrows they excavate for themselves or usurp from other mammals, particularly pocket gophers (genus Geomys). Because of this, they are restricted in their distribution by the nature of the soil. In Texas they occur largely in moist (not wet), sandy soils. Deep, dry sands and heavy clays are avoided.

Two types of underground burrows are used: (1) the shallow surface run, which is associated with feeding activities; and (2) the deep burrow for protection and rearing of the young. The deep burrow is marked by conical mounds of earth the occupant has pushed to the surface, whereas the shallow burrow is marked by a meandering ridge of earth pushed up by the mole as it tunnels through the loose topsoil. Moist, well-drained fencerows, terraces, lawns, and knolls rich in organic matter are favored areas for surface burrows because food is more abundant. Surface burrows are used frequently as highways; others, especially intricate side branches, are used but once in the food-getting process and are then allowed to collapse.

Moles cannot see and spend almost all of their time underground. They may be found active at any hour of the day but generally are more active by day than by night in response to the movement of earthworms in and out of the soil. Also, they are active throughout the year.

The mole excavates its burrow by backward strokes and lateral thrusts of the front feet. Loose earth is moved and pushed to the surface by thrusts of the front feet. In excavating shallow runs, the mole merely pushes up the earth to form a ridge, again by lateral thrusts of the front feet while the mole is turned partly on its side.

The home range of individual moles consists of several hunting grounds along with surface burrows on knolls, terraces, or along fencerows, all of them connected by a single long burrow. One burrow along a fencerow in Van Zandt County was 360 m (1,050 ft.) long. Such systems may be in continual use for as long as 5 years, either by one mole or by successive occupants. At times, moles travel overland in search of new locations or, perhaps, of mates. This is evidenced by the occasional appearance of dead moles on the highways.

Throughout most of the year eastern moles are solitary, but in late winter and early spring males seek out females. In south-central Texas, the breeding season begins in February, as evidenced by the large testes of males and the swollen uteri of females. Although the breeding period may last 3–4 months, peak activity occurs in a short period of 3–4 weeks. A single litter of two to five young is produced each year. The gestation period is about 4–6 weeks. The young are born hairless but otherwise are miniature adults. Females reach sexual maturity in 1 year.

Moles feed largely on earthworms and grubs, although beetles, spiders, centipedes, insect larvae and pupae, and vegetable matter also may be eaten. In captivity, they have consumed mice, small birds, and ground beef.

The average daily food consumption is about 32% of the body weight of the animal, although a mole can consume >66% of its body weight in 18 hours. Active prey is killed by crushing it against the sides of the burrow with the front feet or by piling loose earth on the victim and biting it while it is pinned. Captive moles kill earthworms by biting them rapidly in several places, often nearly cutting the worm in two.

Moles do damage by their burrowing activities, especially on the greens of golf courses, in lawns, and in situations where accelerated soil erosion may result. Also, they may destroy row crops by burrowing along a row and killing the plants. It must be kept in mind, however, that the mole usually is searching out animal food and that often the larval insects taken do far more actual damage to the vegetation than does the mole. Larval June beetles, for example, feed on the roots of grasses and may, if present in large numbers, completely destroy the sod in an area. The burrowing activities of the mole also tend to aerate the soil, with beneficial results to plants.

POPULATION STATUS. Common. Stable and perhaps increasing populations exist throughout the eastern half of the state and in portions of the Panhandle region. In urban areas and other suitable habitat, eastern moles can be locally abundant.

CONSERVATION STATUS. The IUCN status is listed as least concern, and the eastern mole does not appear on the federal or state lists of concerned species. Moles remain common in Texas wherever suitable soils exist. The subspecies S. a. texanus, however, from Presidio County, has not been documented since its discovery in 1887. In 1951, the late Rollin Baker also documented a mole from the Sierra del Carmens in northern Coahuila, Mexico, just across the border from the Big Bend of Texas. A concerted effort is needed to determine if moles still occur in those regions and to monitor their status.

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From The Mammals of Texas, Seventh Edition by David J. Schmidly and Robert D. Bradley, copyright © 1994, 2004, 2016.  Courtesy of the University of Texas Press.

Natural Science Research Laboratory