Shrews occupy nearly every corner of the United States, from the wet old-growth forests of the Pacific Northwest to the leaf litter of Appalachian hardwoods, from Alaskan tundra edges to arid scrublands of the desert Southwest. At least 30 species of shrew are found across the country, and their collective range covers all 50 states. What varies dramatically is which species live where and, just as interesting, the specific micro-scale features of a habitat that make it livable for an animal that burns calories so fast it can starve to death in hours.
The Eastern Deciduous Forest Belt
If you live anywhere east of the Great Plains, the shrew you are most likely sharing land with is the northern short-tailed shrew, Blarina brevicauda. It is one of the most abundant small mammals across eastern North America, thriving in the thick leaf litter and moist soils of deciduous and mixed forests from New England through the mid-Atlantic states and deep into the southern Appalachians.1Journal of Mammalogy. Winter Survival Adaptations of the Short-Tailed Shrew (Blarina brevicauda) in an Appalachian Montane Forest Short-tailed shrews are stocky for their family, weighing up to about 30 grams, and they tunnel aggressively through leaf litter and topsoil. Their range extends west into the eastern Dakotas and south into parts of Alabama and Georgia, but the densest populations sit in the broad band of hardwood and mixed forest stretching from the Ohio Valley through Pennsylvania and into the southern Appalachians.
They are not alone. The masked shrew (Sorex cinereus) is even more widespread, found from Alaska all the way across Canada and south into the northeastern and north-central US. In the southern Appalachians, the smoky shrew (Sorex fumeus) shares forest floors with the masked shrew, and the two manage to coexist despite broadly similar diets. Further south, the southeastern shrew (Sorex longirostris) and the least shrew (Cryptotis parva) fill niches in pine forests, grasslands, and early-successional habitats. The eastern US, with its high rainfall, deep soils, and abundant invertebrate prey, supports the highest shrew diversity on the continent.
Pacific Northwest and the Cascade Forests
The wet forests of Oregon and Washington are another stronghold for shrews, though the cast of characters changes. Vagrant shrews (Sorex vagrans) are especially abundant in young forests on the west side of the Cascades, while Pacific marsh shrews (Sorex bendirii), a semi-aquatic species that hunts invertebrates along stream banks, turn up most often in wet old-growth stands.2U.S. Department of Agriculture, Forest Service. Douglas-fir forests in the Cascade Mountains of Oregon and Washington: is the abundance of small mammals related to stand age and moisture? The distinction matters if you are thinking about forest management: clear-cutting a stand and replanting it shifts the shrew community from species that depend on old, structurally complex habitat toward generalists that exploit the dense ground cover of a young plantation.
California adds its own specialists. The ornate shrew (Sorex ornatus) lives in marshes, riparian corridors, and grasslands across much of the state, while the Trowbridge’s shrew (Sorex trowbridgii) prefers the conifer and mixed forests of the coast ranges. In the San Joaquin Valley, detecting shrews at all can be a challenge. Researchers testing noninvasive survey methods there found that modified close-focus camera traps outperformed both scat tubes and track tubes, with track tubes producing zero positive detections.3Wildlife Society Bulletin. Evaluation of Noninvasive Survey Methods for Detecting Endangered Shrews Shrews are small, fast, and mostly nocturnal or crepuscular, which means their abundance in a given area is almost always higher than casual observation would suggest.
Mountain West and the Water Shrew
The mountain ranges of the western US create isolated pockets of shrew habitat separated by dry lowlands. The American water shrew (Sorex palustris) is the classic example. It lives along cold, fast-moving mountain streams from the Rockies through the Cascades and Sierra Nevada, diving underwater to catch aquatic insects and small fish. Its feet have stiff, fringed hairs that trap air bubbles, letting it literally run across the surface of still water for short distances. Genetic work on water shrew populations across western North America suggests they all descend from a single refugium in the southern part of the range during the last ice age, then expanded northward as boreal forests recolonized the continent.4Journal of Mammalogy. Influence of montane isolation and refugia on population structure of Sorex palustris in western North America
Because suitable stream habitat is scattered across mountain ridges separated by dry valleys, water shrew populations can be genetically isolated from one another even when they are not geographically far apart. The same pattern plays out with montane shrews more broadly. The pygmy shrew (Sorex hoyi), one of the smallest mammals in North America at roughly 3 grams, has a patchy distribution across the northern Great Plains. Range maps have traditionally shown a large gap between Rocky Mountain populations and those in the eastern Dakotas and Minnesota, but newer records from northeastern Montana suggest the gap is narrower than once thought and that the range boundary should be redrawn farther south to include much of Montana north of the Missouri River.5The Canadian Field-Naturalist. Pygmy Shrew (Sorex hoyi) in Montana east of the Rocky Mountains with comments on its distribution across the northern Great Plains
Alaska and the Northern Frontier
Alaska supports several shrew species, including the masked shrew, the dusky shrew (Sorex monticolus), the pygmy shrew, and the tundra shrew (Sorex tundrensis). These animals live at the energy edge: winters are long, prey is sparse, and the metabolic demands on a tiny body are enormous. Climate modeling for Alaska’s small mammals predicts that as temperatures warm, most shrew species there will see their suitable habitat shift northward. The pygmy shrew is projected to gain only about 3.5% in total range area, while species with more southern affinities could see their Alaskan distributions expand by much larger margins.6PubMed Central. Predicted Shifts in Small Mammal Distributions and Biodiversity in the Altered Future Environment of Alaska: An Open Access Data and Machine Learning Perspective
The tundra shrew is one of the few species that genuinely thrives in open, treeless landscapes. Most other US shrews depend on some kind of structural cover, whether that is forest litter, dense grass, or shrubby riparian corridors. Open, dry habitats like the shortgrass prairie or the Great Basin sagebrush steppe tend to have fewer shrew species and lower densities than forested or wetland areas.
The Arid Southwest
Deserts seem like the last place you would look for a shrew, but the desert shrew (Notiosorex crawfordi) manages. It lives across much of the arid Southwest, from west Texas through New Mexico, Arizona, and into southern California, typically hiding under rocks, in pack-rat middens, or beneath woody debris in dry washes. Its range extends north into parts of Oklahoma and Colorado. The desert shrew is physiologically unusual for the family: it can tolerate higher temperatures and lower water availability than its forest-dwelling relatives, and it appears to get much of its moisture from the invertebrates and small lizards it eats rather than from standing water.
Population densities in the desert are low compared to eastern forests, and the desert shrew is rarely encountered even by mammalogists working in the region. But it has been documented across a surprisingly broad swath of the southern tier states, and new locality records continue to push the known boundaries of its range.
What Shrews Actually Need at the Ground Level
Knowing which state a shrew species lives in is only half the picture. What determines whether shrews actually occupy a given patch of ground is the microhabitat: the moisture in the leaf litter, the amount of fallen wood, the depth of the humus layer, and the density of invertebrate prey. These small-scale features matter far more than the broad forest type overhead.
In the southern Appalachians, researchers found that the abundance of smoky shrews could be predicted with remarkable accuracy by a combination of litter moisture, large-diameter coarse woody debris, and the number of invertebrates and salamanders present.7Journal of Mammalogy. Niche Relationships of Two Syntopic Species of Shrews, Sorex Fumeus and S. Cinereus, in the Southern Appalachian Mountains Masked shrews in the same forests keyed more to leaf-litter depth and the size of available invertebrates. These two species overlap heavily in where they are found, sharing about two-thirds of their microhabitat characteristics, yet the smoky shrew’s larger body lets it exploit microsites that the masked shrew cannot easily access, reducing direct competition.
Coarse woody debris, the logs and branches left on the forest floor after trees die and fall, is a recurring theme in shrew ecology across the US. In managed pine forests of the Southeast, removing that debris reduced capture rates of the least shrew (Cryptotis parva) and altered the age structure of southern short-tailed shrew (Blarina carolinensis) populations, with fewer young animals showing up in areas where wood had been cleared.8Forest Ecology and Management. Demographic responses of shrews to removal of coarse woody debris in a managed pine forest A follow-up study in southeastern pine plantations found that shrews were more sensitive to vegetation composition and structure than to the absolute amount of downed wood, suggesting that the relationship is not as simple as “more logs equals more shrews.”9Forest Ecology and Management. Shrew response to variable woody debris retention: Implications for sustainable forest bioenergy The broader point stands, though: shrews need structural complexity at ground level. A manicured lawn or a freshly tilled field offers them almost nothing.
How Winter Shapes Shrew Geography
Winter is a bottleneck for shrews across the northern half of the country. Their metabolic rate is ferocious relative to their body mass, and they cannot hibernate. Instead, northern shrews survive winter by reducing their activity, spending longer periods in the nest, and foraging in short, efficient bursts. In areas with snow cover, they operate in the subnivean zone, the thin airspace between the ground surface and the snowpack, where temperatures stay close to freezing regardless of what is happening above. Their winter diet shifts to whatever the soil and litter surface offers: beetles, spiders, small vertebrates, and carrion.10Mammal Review. Review of winter trophic relations of soricine shrews
Some species even undergo a remarkable physical change called Dehnel’s phenomenon, in which the skull, brain, and several organs shrink in autumn and regrow in spring. This is best documented in European shrews but appears to occur in North American species as well. The shrinkage reduces overall energy demand during the leanest months. It is one of the more bizarre survival strategies in mammalian biology and helps explain how an animal weighing less than a nickel can persist through a Minnesota or Montana winter.
How Ice Ages Built Today’s Shrew Ranges
The distribution of shrew species across the US today is substantially a product of Pleistocene glacial cycles. As ice sheets advanced and retreated over the past two million years, shrew populations were pushed into refugia, fragmented from one another, and then expanded again into newly available territory. The northern short-tailed shrew is a well-studied case. Genetic analysis reveals two deeply divergent lineages separated by the Mississippi River, with roughly 2.5% DNA sequence divergence between them. About two-thirds of the total genetic variation among sampled populations is explained by that east-west split alone.11PubMed. Phylogeography of the Northern short-tailed shrew, Blarina brevicauda (Insectivora: Soricidae): past fragmentation and postglacial recolonization East of the river, further subdivision separates an Appalachian clade from a more central one. Within each group, the genetic signatures point to rapid population expansion after the last glacial retreat.
In the Great Lakes region, these historically separated lineages have since come back into contact. Shrews in Michigan’s Upper Peninsula carry mitochondrial DNA from both the western and central lineages, and their skull shapes show signs of hybridization: proportionally deeper and narrower than either parent population.12Journal of Mammalogy. Consequences of postglacial contact between phylogroups of Blarina brevicauda in North America’s Great Lakes Region This is not just academic curiosity. It means that what looks like one widespread species may actually be a complex of partially differentiated populations, each adapted to slightly different conditions. Conservation decisions that treat all short-tailed shrews as interchangeable could miss meaningful genetic diversity.
Shrews in Yards, Farms, and Cities
Shrews are not strictly wilderness animals. Short-tailed shrews regularly turn up under woodpiles, in garden beds, and along foundation walls in suburban neighborhoods across the eastern US. The least shrew occupies grasslands, old fields, and the weedy margins of agricultural land. If your property has a compost pile, a stone wall, or a thick layer of mulch, you have plausible shrew habitat.
European research on how shrews use urban landscapes offers a useful parallel. In fragmented urban settings, shrew occurrence in gardens was determined largely by how close the garden was to a wooded patch or a vegetated corridor connecting green spaces.13Urban Ecosystems. Ecological corridors also operate in an urban matrix: A test case with garden shrews Shrews were rarely found in isolated gardens far from any continuous strip of vegetation. In agricultural landscapes, shrew communities track soil type and land-use intensity, with some species showing strong preference for heavy clay soils and non-irrigated plots.14PubMed Central. Shrew Communities in Mediterranean Agro-Ecosystems of Central Greece: Associations with Crop Types, Land Uses, and Soil Parameters Though those particular studies focused on European and Mediterranean species, the principle generalizes: shrews can persist in human-modified landscapes as long as ground-level cover and invertebrate prey remain available, and connectivity to larger habitat patches is not completely severed.
Venom and Echolocation
Two features of shrew biology deserve mention because they directly relate to how these animals exploit their habitats. First, several North American shrew species are venomous. The northern short-tailed shrew produces a toxin in its submaxillary glands that it delivers through grooved lower incisors. The venom causes circulation problems, pain suppression, and reduced movement in prey, and it has a remarkably long half-life in the bloodstream, around 16 hours.15PubMed Central. Shrew’s venom quickly causes circulation disorder, analgesia and hypokinesia This allows the shrew to paralyze invertebrates and small vertebrates and cache them alive for later consumption, effectively running a living pantry. For an animal with a metabolism so intense that it must eat nearly its own body weight in food every day, the ability to stockpile immobilized prey is a significant survival advantage, especially in winter.
Second, there is growing evidence that some shrews use a rudimentary form of echolocation. The common shrew (Sorex araneus, a Eurasian species) has been confirmed to produce high-frequency twittering sounds and use them for close-range spatial orientation, and genetic analysis has identified convergent molecular evolution in hearing-related genes shared between shrews, bats, and dolphins.16PubMed Central. Evidence of Echolocation in the Common Shrew from Molecular Convergence with Other Echolocating Mammals North American shrews in the genus Sorex produce similar ultrasonic calls. This is not the sophisticated sonar of a bat, but it likely helps shrews navigate the dark, cluttered environments they inhabit: the interior of a log pile, the subnivean tunnels beneath snow, or the dense root networks of a forest floor. It is yet another adaptation that ties these animals to structurally complex, sheltered microhabitats rather than open ground.
Why Shrew Ranges Are Hard to Pin Down
One practical frustration for anyone trying to answer “where do shrews live” with precision is that shrew distributions are genuinely poorly mapped compared to larger mammals. Shrews are difficult to trap, difficult to identify to species in the hand without examining teeth or skull features, and rarely the primary target of wildlife surveys. Many range maps in field guides are based on scattered specimen records accumulated over decades, with large gaps that may reflect true absence or simply a lack of sampling effort. The pygmy shrew’s patchy Great Plains distribution is a perfect example: every few years a new locality record appears that forces the map to be redrawn.
Environmental DNA (eDNA) sampling from soil and water, along with improved camera-trap technology, may eventually fill in these gaps. But for now, if you are in the US and you have moist ground cover, leaf litter, or dense vegetation within a few hundred meters of your location, there is a good chance a shrew is living within earshot, even if you never see it. The animals are everywhere. We just have not finished documenting everywhere they are.