One observer reported that a captive ate over three times its body weight daily. The species nests under logs, stumps, or rocks, in fist-size nests of leaves, grass and fine rootlets. Breeding runs from March to September. They are blind and helpless but grow quickly and are on their own after about a month. They mature sexually at 20-26 weeks of age.
Masked shrews are active day and night, but especially at dusk.
An individual's heart beats 1,200 times per minute, evidencing its rapid metabolism. Owls, hawks, herons, shrikes, weasels, foxes, cats and the larger shrews kill masked shrews, few of which reach their maximum lifespan is about 18 months. The smoky shrew occurs throughout the Northeast from Nova Scotia to North Carolina. It inhabits most of Pennsylvania but is scarce in southwestern and southeastern counties. Coloration is a uniform dull brown, except for the bicolored tail, brown above and yellowish below, and pale buffy feet.