Shrew

Shrews do occur in urban and suburban areas, particularly where the residential landscaping or surrounding natural vegetation supports high populations of the shrews’ preferred foods. As predators, shrews tend to focus their activity in areas where prey is plentiful. Since they feed primarily on insects, snails, slugs, and mice (and devour enormous numbers of them), shrews should be protected. Occasionally shrews enter dwellings, but they seldom cause damage. The presence of shrews in large numbers may indicate that household pests such as mice or large insects are also present. Investigate thoroughly for signs of these pests.

Besides cats, owls mowing grass you can remove shrews by live trapping, using the smallest size traps (Havahart 1020). Appropriate baits include peanut butter, chocolate, small squares of bacon, Ham, or raw beef. Or catch them with Cooper's Vole and Shrew Control trap, and bait these traps with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait.

Pick up with plastic bag. Turn bag inside out close and seal bag discarding in garbage. Using bag in this manor will reduce the potential for flea, tick, helmith parasite or disease transmission.

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 damage to white spruce seeds.BR>
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.BR>
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.

Shrews are broadly distributed throughout the world and North America. For specific range information, refer to one of the many references available on mammal distribution for your region. Publications by Burt and Grossenheider (1976), Hall (1981), and Junge and Hoffmann (1981) are particularly helpful.

Shrews vary widely in habitat preferences throughout North America. Shrews exist in practically all terrestrial habitats, from montane or boreal regions to arid areas. The northern water shrew (Sorex palustris) prefers marshy or semiaquatic areas. Regional reference books will help identify specific habitats. Sometimes birds are captured in snap-traps. In this case use Cooper's Vole and Shrew Control trap set for shrews with a cover over the traps and bait. Bait these traps with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait.

Shrews are in the taxonomic order Insectivora. As the name implies, insects make up a large portion of the typical shrew diet. Food habit studies have revealed that shrews eat beetles, grasshoppers, butterfly and moth larvae, ichneumonid wasps, crickets, spiders, snails, earthworms, slugs, centipedes, and millipedes. Shrews also eat small birds, mice, small snakes, and even other shrews when the opportunity presents itself. Seeds, roots, and other vegetable matter are also eaten by some species of shrews.

Shrews are among the world’s smallest mammals. The pigmy shrew (Sorex hoyi) is the smallest North American mammal. It can weigh as little as 0.1 ounce (2 g). Because of their small size, shrews have a proportionally high surface- to-volume ratio and lose body heat rapidly. Thus, to maintain a constant body temperature, they have a high metabolic rate and need to consume food as often as every 3 to 4 hours. Some shrews will consume three times their body weight in food over a 24-hour period.

Shrews usually do not live longer than 1 to 2 years, but they have 1 to 3 litters per year with 2 to 10 young per litter. Specific demographic features vary with the species. The gestation period is approximately 21 days. Shrews have an acute sense of touch, hearing, and smell, with vision playing a relatively minor role. Some species of shrews use a series of high-pitched squeaks for echolocation, much as bats do. However, shrews probably use echolocation more for investigating their habitat than for searching out food. Glands located on the hindquarters of shrews have a pungent odor and probably function as sexual attractants. Blarina brevicauda, and presumably B. carolinensis and B. hylophaga (the short-tailed shrews), have a toxic venom in their saliva that may help them subdue small prey. Some shrews are mostly nocturnal; others are active throughout the day and night. They frequently use the tunnels made by voles and moles. During periods of occasional abundance, shrews may have a strong, although temporary, negative impact on mouse or insect populations. Many predators kill shrews, but few actually eat them. Owls in particular consume large numbers of shrews.

Some shrews exhibit territorial behavior. Depending on the species and the habitat, shrews range in density from 2 to 70 individuals per acre (1 to 30/ hectare) in North America.

Shrews are not protected by federal laws, with one exception. The southeastern 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.

Damage Prevention and Control Methods

Exclusion

Rodent-proofing will also exclude shrews from entering structures. Place hardware cloth of 1/4-inch (0.6-cm) mesh over potential entrances to exclude shrews. The pygmy shrew (Sorex hoyi) may require a smaller mesh. Coarse steel wool placed in small openings can also exclude shrews.

Cultural Methods

Regular mowing around structures should decrease preferred habitat and food, and may increase predation. Where shrews are eating tree seeds, plant seedlings instead to eliminate damage.

Repellents

No repellents are registered for use against shrews.

Toxicants

No toxicants are registered to poison shrews.

Fumigants

No fumigants are registered for use against shrews. It would be impractical to use fumigants because of the porous nature of typical shrew burrows.

Trapping

Mouse traps (snap traps), box traps, and pit traps have been used to collect shrews. Set mouse traps in runways or along walls, with the traps set at a right angle to the runway and the triggers placed over the runway (Fig. 2a). Small box traps can be set parallel to and inside of runways, or parallel to walls around structures (Fig. 2b). Bait the traps with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait. A pit trap consists of a gallon jar or a large can sunk into the ground under a runway until the lip of the container is level with the runway itself (Fig. 2c). Bait is not necessary. A small amount of bacon grease smeared around the top of the container may be an effective attractant, but this may also attract large scavengers. Pit traps are more effective for capturing shrews than snap traps, although the increased labor involved in setting a pit trap may not be justified when trying to capture only one or two animals. Monitor pit traps daily, preferably in the morning before the temperature gets hot, although Churchfield (1990) recommends checking traps four times in a 24-hour period. Place cotton wool in the pit trap containers to reduce the mortality of trapped animals. This is especially important to ensure the successful release of nontarget animals. Since shrews are generally beneficial in consuming insects, live-captured animals can be relocated in suitable habitat more than 200 yards (193 m) from the capture site.

The traps and placement procedures described above are also effective for catching mice. Note the identification characteristics given above for determining whether the captured animal is indeed a shrew. Sometimes birds are captured in snap-traps. In this case use Cooper's Vole and Shrew Control trap set for shrews with a cover over the traps and bait. Bait these traps with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait.

shrews do occur in urban and suburban areas, particularly where the residential landscaping or surrounding natural vegetation supports high populations of the shrews’ preferred foods. As predators, shrews tend to focus their activity in areas where prey is plentiful. Since they feed primarily on insects, snails, slugs, and mice (and devour enormous numbers of them), shrews should be protected. Occasionally shrews enter dwellings, but they seldom cause damage. The presence of shrews in large numbers may indicate that household pests such as mice or large insects are also present. Investigate thoroughly for signs of these pests.Shrews can not hibernate. They have a very high rate of metabolism and have to eat constantly except when sleeping.

Remove shrews by live trapping, using the smallest size traps (Havahart 1020). Appropriate baits include peanut butter, chocolate, small squares of bacon, Ham, or raw beef. Or catch them with Cooper's Vole and Shrew Control trap, and bait these traps with a mixture of peanut butter and rolled oats. A small amount of bacon grease or hamburger may increase the attractiveness of the bait.

Traps for Capturing Shrews

Fig. 2. Traps and trap placement for capturing shrews: a) mouse trap (snap trap) set perpendicular to wall, with trigger next to wall; b) box trap set parallel to wall; c) pit trap sunk in ground over runway (includes cotton wool).

a

c