Shrews are native to and found across Texas, though they are often mistaken for rodents. Classified in the order Eulipotyphla, shrews are in a separate evolutionary lineage from true rodents like mice and rats. They are primarily insectivores, feeding mainly on insects, unlike the seed-heavy diet of most rodents. Texas’s vast ecological diversity, ranging from arid deserts to humid eastern forests, provides habitats for several different shrew species. These tiny creatures are characterized by their constantly moving, pointed snouts and almost invisible eyes and ears.
The Specific Shrew Species Found in Texas
Texas is home to at least four distinct shrew species, each adapted to its specific region. The Least Shrew (Cryptotis parva) is one of the smallest mammals in North America, averaging about 79 millimeters in length and weighing between four and seven and a half grams. This species has a grizzled olive-brown coat and a very short tail, which is never more than twice the length of its hind foot. It is notable for being more social than most other shrews, sometimes sharing a communal nest.
Short-tailed shrews of the genus Blarina are found primarily in the moist eastern parts of the state. The Southern Short-tailed Shrew (Blarina carolinensis) is larger and more robust, featuring dense, dark slate-gray fur. Its powerful, wide front feet make it well-suited for digging and burrowing through soft soil and leaf litter. The closely related Elliot’s Short-tailed Shrew (Blarina hylophaga) is known only from a few isolated counties and is often distinguished by chromosomal analysis rather than external appearance.
In the western, more arid regions, the Crawford’s Desert Shrew (Notiosorex crawfordi) is found. This small shrew is generally light lead-gray and possesses a proportionally longer tail than the short-tailed species. Unlike its burrowing relatives, the Desert Shrew’s ears are relatively conspicuous, and it does not typically construct its own tunnels. Identification often requires close examination of dental patterns, as the Desert Shrew has a unique arrangement of 28 teeth, fewer than other Texas shrews.
Habitat and Geographic Distribution Across Texas
The distribution of Texas shrews is directly related to the availability of moisture and specific ground cover, reflecting the state’s varied climate zones. The Least Shrew has the widest range, spanning the eastern, southern, and northwestern portions of Texas, thriving mainly in grasslands and weedy areas. These shrews often utilize the surface runways created by cotton rats and other small grassland rodents for travel and foraging. Their success is linked to their adaptability to open habitats.
Short-tailed shrews are concentrated in the humid, eastern one-fourth of the state, particularly in regions like the Big Thicket. They prefer habitats with high soil moisture and deep organic matter, such as forested areas and associated meadows. These environments allow for easy burrowing and provide the dense cover necessary for protection from predators. Their presence often correlates with the boundary of moist, well-drained hardwood forests.
In contrast, the Desert Shrew is found throughout the western two-thirds of the state, adapting to the drier, arid conditions of the Trans-Pecos and adjacent areas. This species is not restricted to a single habitat type, with specimens collected in environments from cattail marshes to yucca patches and under brush piles. The Desert Shrew demonstrates an adaptation to water scarcity, favoring areas where it can find humid microclimates, such as under rocks or within the nests of woodrats.
Unique Biological Traits and Behaviors
Shrews possess biological traits that set them apart from other small mammals, driven primarily by a high metabolic rate. A shrew’s heart rate can reach between 800 and 1,000 beats per minute, necessitating a constant search for food. They must consume the equivalent of their entire body weight, or more, in prey each day to maintain this high-energy lifestyle. This rapid metabolism means a shrew can starve to death in just a few hours without eating.
Their diet is strictly insectivorous, consisting of arthropods, earthworms, slugs, and snails, which they locate using their highly sensitive, mobile snouts and whiskers. Some Texas species, such as the short-tailed shrews (Blarina), possess a unique adaptation: toxic saliva. This venom, delivered through grooves in their teeth, allows them to subdue and paralyze prey much larger than themselves, sometimes storing the immobilized victims for later consumption.
The Desert Shrew has a specialized trait to survive the unpredictable food availability and extreme temperatures of its arid environment. This species is known to enter a state of torpor, reducing metabolic activity to conserve energy. This temporary lowering of body temperature and heart rate allows the Desert Shrew to decrease its food requirement. This strategy is uncommon among other shrews and is a direct response to the challenges of desert life.