Northern Short-tailed Shrew

Identification

The northern short-tailed shrew is the largest member of the genus Blarina, a compact mammal measuring 108 to 140 mm in total length, with a characteristically short tail comprising less than 25% of its body length. Adults weigh between 15 and 30 grams, with males slightly larger than females. The dorsal fur is thick and velvety, ranging from black and brownish-black to silvery gray, while the ventral fur is lighter and grayer. The shrew undergoes seasonal molting, shedding its shorter, paler summer coat in October and November for a thicker winter pelage, then molting back again between February and July.

A distinctive feature of this species is its red-toothed dentition—a characteristic shared with related shrews. The shrew possesses three well-developed scent glands, including one on each side and one ventral gland, which it uses for territorial marking. Despite these adaptations, the northern short-tailed shrew has poor vision, with degenerated eyes capable only of detecting light; instead, it relies on echolocation and a keen sense of touch to navigate its environment.

Range & Habitat

This shrew is found throughout central and eastern North America, from southern Saskatchewan to Atlantic Canada, extending south to northern Arkansas and Georgia. It is probably the most common shrew in the Great Lakes region. Population densities typically range from five to 30 shrews per hectare, though they rarely exceed 200 per hectare, with individual shrews maintaining home ranges of approximately 2.5 hectares that may slightly overlap with those of other shrews.

Northern short-tailed shrews occupy both disturbed and undisturbed habitats, including grasslands, old fields, fencerows, marshy areas, deciduous and coniferous forests, and household gardens. They show a preference for moist environments with abundant leaf litter or thick plant cover. However, they are slow to recolonize burned-over forests and quickly abandon clear-cut areas, making intact forest structure important for their persistence.

Behaviour & Diet

The northern short-tailed shrew is a highly active, semifossorial insectivore with an extraordinary appetite, consuming up to three times its own weight in food daily. Though it eats small quantities of subterranean fungi and seeds, it is predominantly carnivorous, preferring insects such as beetles, earthworms, voles, snails, and other shrews. Notably, this species consumes vertebrates more frequently than other shrews, and its diet also includes salamanders, frogs, snakes, birds, and mice. The shrew forages primarily within a few hours after sunset, though it remains active during cloudy days. Remarkably, it caches 87% of its captured prey, eating only 9% immediately and leaving 4% at kill sites—a behavior particularly pronounced during fall and winter or times of prey abundance.

One of the few venomous mammals, the northern short-tailed shrew uses a specialized hunting weapon: its saliva contains a kallikrein-like protease secreted from submaxillary glands. This toxin, delivered through grooves in the lower incisors, is potent enough to paralyze and subdue prey larger than the shrew itself, and it produces painful bites in humans who handle the animal.

Best Time & Places to See It

Observing northern short-tailed shrews in the field is challenging due to their small size, cryptic behavior, and primarily nocturnal activity patterns. They are most active during twilight hours and overcast days, making early evening or cloudy afternoon periods the best times for potential encounters. The Great Lakes region offers the highest probability of encountering this species, where it reaches peak abundance.

Search in moist habitats with thick leaf litter and dense plant cover—ideal conditions include the edges of forests, marshy areas, and hedgerows. Since these shrews require access to water sources and prefer undisturbed areas with substantial ground cover, focusing on the margins between open grasslands and forested areas, particularly near streams or wet ground, increases your chances of observation.

Photography Tips

Photographing the northern short-tailed shrew presents considerable challenges. Its small size, poor eyesight, and preference for activity during low-light conditions mean that traditional daytime photography is unlikely to be successful. The best approach involves setting up camera traps with infrared triggers in promising habitat, particularly along foraging routes near water sources and within areas of dense ground cover.

If attempting to photograph this shrew directly, use high-speed flash equipment and be prepared for extremely brief exposure windows. Wide-angle macro lenses will be necessary to capture useful detail of this diminutive animal. Exercise caution when handling the shrew for photography, as its venomous bite can be painful; observation from a distance using telephoto lenses is strongly recommended for both safety and animal welfare.