Shrews are small, insect-eating mammals that resemble mice but are not rodents. They belong to the family Soricidae and are more closely related to moles and hedgehogs than to rats or mice. Shrews are known for their long, pointed snouts, sharp teeth, extremely high metabolisms, and constant hunting behavior. In many environments, shrews are beneficial because they help reduce populations of insects, grubs, and other invertebrate pests.
Identification & Appearance
Shrews are among the smallest mammals in North America and worldwide. Depending on the species, adults typically measure about 3–15 cm (1.2–6 inches) in body length, not including the tail. Their fur is usually gray, brown, or black, and their eyes and ears are small compared to their head size.
- Body Shape: Small, compact body with a narrow head
- Snout: Long and pointed, used for probing soil and leaf litter
- Teeth: Sharp, pointed teeth (not the gnawing incisors typical of rodents)
- Tail: Varies by species; can be short and stout or long and slender
- Tracks/Signs: Small runways in grass or leaf litter; sometimes found near moisture-rich areas
Taxonomy & Classification
Shrews belong to the order Eulipotyphla, which also includes moles and hedgehogs. The family Soricidae is highly diverse, containing hundreds of species worldwide. Common groups include long-tailed shrews (Sorex), short-tailed shrews (Blarina), and white-toothed shrews (Crocidura).
Many shrews are categorized by tooth characteristics. “Red-toothed” shrews have iron-pigmented enamel that can appear reddish, while “white-toothed” shrews lack this pigmentation. These traits can help biologists identify groups, though homeowners usually rely on body shape and behavior to recognize shrews.
Biology & Metabolism
Shrews have one of the highest metabolic rates of any mammal. To survive, they must eat frequently—often consuming an amount of food equal to or greater than their body weight each day. Because of this intense energy demand, some shrews can become weak or die if they go too long without feeding.
In colder climates, certain species exhibit a seasonal adaptation known as Dehnel’s phenomenon, where the shrew’s body mass (and even skull size) decreases during winter. This change can reduce energy needs when prey is harder to find.
Diet & Feeding Behavior
Most shrews are primarily insectivorous. They hunt constantly, using scent, touch, and sensitive whiskers to locate prey in soil, leaf litter, and dense ground cover. Their diet commonly includes:
- Insects and insect larvae
- Earthworms
- Spiders
- Slugs and snails
- Other small invertebrates
Larger species may occasionally consume small vertebrates such as tiny amphibians, lizards, or even other small mammals. Some shrews also eat small amounts of seeds or fungi, but animal prey makes up the majority of their diet.
Habitat & Where Shrews Live
Shrews are found across much of North America, Europe, Asia, and Africa, occupying a wide variety of habitats. Most prefer areas with moisture and abundant prey, including forests, fields, wetlands, overgrown edges, and gardens. They often move through narrow runways beneath grass or leaf litter, which helps them stay hidden from predators.
Some shrew species are semi-aquatic and may live near streams, ponds, or marshy areas where they hunt aquatic insects and other small prey.
Behavior
Shrews are generally solitary and territorial. They are active hunters and may forage day and night, depending on species and conditions. Because they must eat frequently, shrews spend much of their time moving through ground cover in search of food. When threatened, they may emit high-pitched vocalizations and some species produce strong musky odors that discourage predators.
Reproduction & Life Cycle
Shrews usually have short lifespans—often around 12–24 months—so they reproduce quickly. Many species have multiple litters per year, with gestation commonly around 2–4 weeks. Litters can range from about 3 to 10 young, depending on species and environment.
Young shrews are born blind and hairless but develop rapidly. They become independent in a matter of weeks and begin hunting small prey soon after leaving the nest.
Venom, Odor, and Defense
A few shrew species have venom-like compounds in their saliva, which can help immobilize prey. This is unusual among mammals. Additionally, many shrews have scent glands that produce a strong musky odor, which can make them less appealing to predators and may be noticeable if a shrew dies indoors.
Are Shrews Dangerous or a Pest?
Shrews are generally not considered structural pests. They do not gnaw wood, wiring, or stored materials the way rodents can, and they typically do not infest pantries. Most encounters happen outdoors, where shrews provide a beneficial role by consuming insect pests.
Occasionally, shrews may enter homes, garages, sheds, or basements—usually while hunting insects or seeking shelter. When they get inside, they often struggle to find food and may die quickly if they cannot access prey or moisture.
Signs of Shrew Activity
- Runways: Thin pathways in tall grass or leaf litter
- Droppings: Small droppings similar to mice (but shrews usually do not create large “toilet” areas)
- Odor: A musky smell may be noticeable if a shrew is present or has died indoors
- Outdoor evidence: Increased activity in moist areas with heavy insect populations
Prevention & Control
Because shrews are often beneficial and usually enter buildings by accident, control typically focuses on exclusion and habitat management rather than heavy pesticide use.
- Seal entry points: Close gaps around doors, foundation cracks, vents, and utility lines.
- Reduce ground cover near structures: Keep grass trimmed and avoid thick mulch piled against foundations.
- Fix moisture issues: Address leaking spigots, poor drainage, and damp crawlspaces that attract insects (and therefore shrews).
- Use door sweeps & screens: Install tight-fitting sweeps and repair damaged window or vent screens.
- Remove indoor strays: If a shrew gets inside, gently capture and release (or hire professional removal) is preferred.
When to Call a Professional
If shrews are repeatedly entering your home, a pest professional can help identify entry points, recommend exclusion upgrades, and determine whether another issue (such as high insect activity, moisture problems, or rodent presence) is attracting them. If you’re unsure whether you’re seeing shrews, mice, or voles, professional identification can prevent the wrong control approach.