Shrews are tiny, highly active mammals found across North America. Though often mistaken for rodents due to their small size, they belong to a distinct order of insectivores, making them closer relatives to moles. As ground-level predators, their presence is often a sign of a healthy ecosystem. This article explores the diverse habitats shrews occupy across the United States.
Defining Shrews and Their Universal Habitat Needs
Shrews are classified within the order Eulipotyphla, separate from true rodents. Their defining characteristic is an exceptionally high metabolic rate, forcing them into a near-constant state of foraging. Due to this physiological demand, a shrew may consume the equivalent of its own body weight in food daily.
This voracious appetite dictates their universal habitat requirement: a plentiful supply of invertebrate prey like insects, worms, and spiders. Shrews generally seek environments with high moisture content, which correlates directly with dense invertebrate populations. Ideal habitats include areas with thick leaf litter, heavy ground cover, and moist soil, which also provides protection from predators.
Regional Distribution of Shrew Species
The distribution of shrews across the United States is highly varied, with different species adapting to regional climates ranging from humid coastlines to arid deserts.
Eastern US
The Eastern United States is home to common species like the Masked Shrew (Sorex cinereus), which is widespread in moist woodlands and meadows across the Northeast and Midwest. The Southern Short-tailed Shrew (Blarina carolinensis) inhabits the Southeast, ranging from southern Virginia to eastern Texas. This specialized shrew is often found in pine forests and along swampy boundaries, and it possesses venomous saliva used to subdue larger prey.
Western US
Along the Pacific Coast, the Trowbridge’s Shrew (Sorex trowbridgii) is prevalent from Washington state south through the Sierra Nevada. This species is associated with mature coniferous forests and thrives in both moist and drier environments. In the Rocky Mountain states, the Vagrant Shrew (Sorex vagrans) is common, favoring wet meadows and riparian zones that contrast with the surrounding arid landscapes.
Southern/Arid Regions
Shrews in the Southwest have developed specialized adaptations to survive in regions with limited water. The Desert Shrew (Notiosorex crawfordi) inhabits the arid grasslands and deserts, including the Sonoran Desert. It obtains nearly all its required moisture directly from its prey. Merriam’s Shrew (Sorex merriami) prefers short-grass prairie environments across the western half of the continent, inhabiting dry plains and foothills.
Alaska/Northern Zones
In the far northern United States, the Arctic Shrew (Sorex arcticus) extends into boreal regions. It is found in the northern portions of states like Minnesota, Wisconsin, and the Dakotas. This species occupies cool, moist areas such as spruce-tamarack bogs and clearings in boreal forests. It has a distinctive tricolored coat, which provides camouflage in its northern habitats.
Signs of Shrew Presence
Because shrews are small and spend much time under cover, they are rarely observed directly. However, their constant activity leaves distinct evidence of their presence. One of the clearest signs is the existence of tiny, shallow runways carved through the grass or leaf litter on the ground.
Shrews are not burrowing animals like moles, but they utilize and expand tunnels created by other small mammals. Their droppings are a telltale sign, appearing small, dark, and often with a noticeable corkscrew shape. A pungent, musky odor near ground cover or in basements can also indicate their presence, as shrews use scent glands to mark territory.
Their constant, frenetic foraging for insects can sometimes be heard as a rustling sound in the leaf litter, accompanied by a high-pitched, almost ultrasonic squeak. Though these sounds are used for communication, they are primarily a byproduct of the shrews’ continuous search for food. Shrews are beneficial to the garden ecosystem by preying on common insect pests and should generally be tolerated.