Scalopus aquaticus - Eastern mole

(http://home.cc.umanitoba.ca/~rmacarth/easternmole.html)

Scientific Name:

The genus Scalopus is from the Greek word skalops (blind rat). The Latin specific name aquaticus (water dwelling) is the inappropriate name given by Karl Linnaeus, the man who first described this species in 1758. Since Linnaeus lived in Sweden and never saw this species in the wild he thought this mole lived in water because of its large, webbed front feet (Georgia Museum of Natural History and Georgia DNR, June 1, 2000).

Physical Description:

Males- total length = 103-208mm, length of tail = 16-38mm, weight = 40-140 grams.

Females- total length = 129-168mm, length of tail = 20-28mm, weight = 32-90 grams (Wilson and Ruff, 1999).  The large geographic distribution of Eastern moles has resulted in a corresponding degree of variation in color and size.  In the northern part of their range Scalopus aquaticus are generally larger in size and almost completely black in color.  In the western and southern part of their range are they are generally smaller and brown to gold in color (Chapman and Feldhamer, 1982).  Males tend to be larger than females in all Scalopus aquaticus.  The body is streamlined and covered with thick velvety fur that acts as it were hinged so it can bend forward and backward with little friction and resistance.  The eastern mole does not possess external eyes or ears.  The eyes are completely covered with skin.  The ocular muscles are present, but oculomotor nerves are lacking; the optic nerve is present but attenuated (Meyer and Nauvoo, 2001).  Although it has not been proven, it is thought that the poorly developed eyes may be effective in detecting light.

The feet have webbing between the toes of each foot to aid in digging.  The dental formula of the Eastern mole is 3/3, 1/1, 4/4, 3/3 (Wilson and Ruff, 1999).  The premolars are sharply differentiated from the molars and the upper molars are dilambdodont.  The 1st upper incisor is flattened and lacks the elongated crown characteristic of shrew incisors.  The cranium is dorsoventrally compressed and the rostrum is long and narrow.  The zygomatic arch is complete but lacks jugal bones.

Distribution:

The Eastern Mole is located in the south western portion of Wisconsin.  A few Eastern Moles are located as far north as central Wisconsin but these populations are very sparse in numbers.  The range of the Eastern mole is distributed from northern Tamaulipas, Mexico to southern South Dakota, eastward to Massachusetts, and south to the southernmost tip of Florida (Harvey, M.J., 1976).This is the largest range of any North American mole.  The Eastern mole prefers moist loamy or sandy soils.  It is scarce or absent in heavy clay, stony, or gravelly soils, and avoids otherwise suitable soil types that are too wet or too dry.  They prefer fields, meadows, pastures, and open woodlands. Human activities such as building roads and golf courses benefit the Eastern mole by creating high quality soils with the adequate amount of moisture.  Fossil remains of this species have been recovered from the upper Ohio Valley of Pennsylvania and West Virginia and from Pleistocene cave deposits in Texas (Antonia Gorog, 1996).

Ontogeny and Reproduction:

Scalopus aquaticus are solitary animals except during the breeding season.  The breeding season extends from January to May.  The peak of the breeding season in Wisconsin is the last week in March through the first week in April (Wisconsin DNR, 2001).  The gestation period is assumed to be 4-6 weeks and the average litter size is 2-5 moles (Hartman, G.D., 1995).  In males the testes and associated glands become greatly enlarged prior to mating (Hall, Raymond E. 1981).  If moles meet in a tunnel outside of the breeding season they will attack each other and will continue to fight until one retreats or is killed.

Ecology and Behavior:

The Eastern mole is active year round with no torpor or hibernation. They dig two types of tunnels:  deep, more permanent tunnels primarilyused for nesting, and shallow surface  runways that are primarily used for feeding.  The depth of the deep tunnels ranges from 15-60 cm. (Yates, T.L. and D.J. Schmidly, 1977).  The mole will repair all breaks in the tunnel when first encountered and will not tolerate openings in their burrow system.  Moles do not “swim” through the soil as was commonly believed, but actually dig burrows primarily with their powerful forepaws.  In constructing a surface run, a lateral stroke type of digging is employed that involves one fore foot at a time.   The body is rotated 45 degrees to the right if the left foot is involved.  The forepaws are brought together several times to position the claws and the left forepaw is thrust upward rapidly.  At the same time, the opposite foot, which is braced against the burrow, is extended to create more force.  The dirt is thus forced upward forming the surface ridge.  The nose is not used in loosening dirt but serves a tactile function in directing the forepaws.  The procedure for forming deeper runways is basically the same except that the loose dirt is either brought to the surface to form mounds (mole hills) or deposited in abandoned surface tunnels (Chapman, Joseph A. and Feldhamer, George A., 1982).  When a soil is in good condition, like after a rain, moles can tunnel at a rate of 18 feet per hour (INHS Reports, September-October 1997). A single mole will use 2-7 nests.  The nests are 15-25cm beneath the surface composed of coarse grass, and or leaves.  The nests are 18-22cm in length, 10-12cm wide, and are enlargements of deep runs.  The young share the tunnel system with their mother until they can forage on their own.  At that time they establish their own tunnels away from the mother range.

 

The Eastern mole has a voracious appetite and consumes a large % of its body weight in food each day.  In captivity they eat 32-55 percent of their body weight in a 24 hour period.  They eat earthworms, white grubs, insect larvae, adult insects, and vegetable matter in that order of preference (Hall, Raymond E., 1981).

The fossorial lifestyle of the mole eliminates most major predators except humans.  However, when moles emerge to the surface their main predator is the owl, but also are hunted by cats, foxes, and other carnivorous mammals.

Literature Cited:

Chapman, Joseph A. and Feldhamer, George A. (1982). Wild Mammals of North America. The John Hopkins University Press, pgs: 37,39,40,42-47.

Hall, Raymond E.  (1981). The Mammals of North America.  Pg: 73.

Hartman, G.D. (1995).  Age determination, age structure, and longetivity in the mole, Scalopus aquaticus (Mammalia, Insectivora). Journal of Zoology 237: 107-122.

Harvey, M.J. (1976).  Home Range, Movements and Diel Activity of the Eastern Mole, Scalopus aquaticus. The American Midland Naturalist, Vol. 95, No.2.

Meyer and Nauvoo. (2001). Encyclopedia Americana, v. 19.

Wilson and Ruff.  (1999). The Smithsonian Book of North American Mammals.

Yates, T.L., and D.J. Schmidly.  (1978). Scalopus aquaticus, Mammalian Species, No. 105: 1-4.

Yates, T.L. and D.J. Schmidly. (1977). Systematics of Scalopus aquaticus (Linnaeus) in Texas and Adjacent States.  Occasional Papers, The Museum, Texas Tech University, 45:1-36.

The Georgia Museum of Natural History and Georgia Department of Natural Resources.  2000.  <http://mseum.nhm.uga/gawildlife/mammals/insectivora/talpidae/saquaticus.html>.

http://animaldiversity.ummz.umich.edu/accounts/scalopus/s._aquaticus$narrative.html

http://www.inhs.uiuc.edu/chf/pub/surveyreports/sep-oct97/mole.html

http://home.cc.umanitoba.ca/~rmacarth/easternmole.html

 
Reference written by Ross Arndt, Biol 378: Edited by Chris Yahnke.
Page last updated 4-29-04.