Shrew Damage Assessment

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A masked shrew, Sorex cinereus

A masked shrew, Sorex cinereus

Most species of shrews do not have significant negative impacts and are not abundant enough to be considered pests (Schmidt 1984). Shrews sometimes conflict with humans, however. The vagrant shrew (Sorex vagrans) has been reported to consume the seeds of Douglas-fir (Pseudotsuga menziesii), although the seeds constitute a minor part of the diet. The masked shrew (Sorex cinereus) destroyed from 0.3% to 10.5% of white spruce (Picea glauca) seeds marked over a 6-year period (Radvanyi 1970). Lodgepole pine (Pinus contorta) seeds are also eaten by the masked shrew. Radvanyi (1966, 1971) has published pictures of shrew, mouse (Peromyscus, Microtus, and Clethrionomys spp.), and chipmunk (Eutamias spp.) damage to lodgepole pine seeds, and describes shrew dam-ge to white spruce seeds.

The northern water shrew (Sorex palustris) may cause local damage by consuming eggs or small fish at hatcheries. The least shrew (Cryptotis parva), also known as the bee shrew, sometimes enters hives and destroys the young brood (Jackson 1961). The northern short-tailed shrew (Blarina brevicauda) has been reported to damage ginseng (Panax spp.) roots. Short-tailed and masked shrews reportedly can climb trees where they can feed on eggs or young birds in a nest or consume suet in bird feeders.

The pugnacious nature of shrews sometimes makes them a nuisance when they live in or near dwellings. Shrews occasionally fall into window wells, attack pets, attack birds or chipmunks at feeders, feed on stored foods, contaminate stored foods with feces and urine, and bite humans when improperly handled. Potential exists for the transmission of diseases and parasites, but this is poorly documented.

The house shrew (Suncus murinus) is an introduced species to Guam. It has
been reported as a host for the rat flea (Xenopsylla cheopis) which can carry the plague bacillus (Yersinia pestis) (Churchfield 1990). Compared to rat (Rattus spp.) numbers, however, house shrew numbers are usually low, and risk of plague transmission is probably minimal. The house shrew is accustomed to living around humans and houses, which increases its damage
potential. It is considered smelly and noisy, making incessant, shrill, clattering sounds as it goes along (Churchfield 1990:149). On occasion it destroys stored grain products.

Legal Status

Shrews are not protected by federal laws, with one exception. The south-eastern shrew (Sorex longirostris fischeri) is protected in the Great Dismal Swamp in Virginia and North Carolina by the Endangered Species Act of 1973. Nowak and Paradiso (1983:131) list the following additional species or populations of concern: Sorex preblei, Sorex trigonirostri, and Sorex merriami in Oregon; Sorex trigonirostri eionis in Florida along the Homossassee River; and Sorex palustris punctulatus in the southern Appalachians.

Some states may have special regulations regarding the collection or killing of nongame mammals. Consult your local wildlife agency or Cooperative Extension office for up-to-date information.

Economics of Damage and Control

No studies concerning the economics of shrew damage and control are available. In Finland, shrews appear to play a more important role as predators of conifer seeds than they do in North America. Overall, the economics of damage by shrews is not considered great.

Folklore and Etymology

Chambers (1979) reviewed some aspects of shrew biology and folklore: At one time in Europe it was thought that if a shrew ran across a farm animal that was lying down, the animal would suffer intense pain. To counter-act this, a shrew would be walled up in an ash tree (a ‘shrew ash’), and then a twig taken from the tree would be brushed onto the suffering animal to relieve the pain. The ancient Egyptians believed the shrew to be the spirit of darkness. The shrew has also been mentioned as a Zuni beast god, providing protection for stored grains from raids by rats and mice (Hoffmeister 1967).

At least one tall tale involving shrews has been found to be true. The discovery that some shrews possess toxic venom confirms stories about the poisonous bite of shrews.

The etymology of the word shrew is also interesting. The Old English form of the word was screawa, or shrew-mouse. The Middle English form was shrewe, meaning an evil or scolding person. Thus shrew has a double meaning. It defines the small mammal as well as an ill-tempered, scolding human (usually female).

Shrews are in the family Soricidae. Soricis is the genitive form of sorex, a Latin word for shrew-mouse.

Shrews | Shrew Overview | Shrew Damage Assessment | Shrew Damage Management | Shrew Acknowledgments | Shrew Resources | ICWDM | Wildlife Species Information