The northern short-tailed shrew (Blarina brevicauda) is a species of red-toothed shrew of the family Soricidae native to northeastern America and the eastern half of southern Canada. They prefer forests and grasslands that provide cover for them and a steady supply of water, as they can dehydrate quickly. They spend most of their days underground resting in nests lined with plant matter and often times the fur of meadow voles, with short bouts of activity for hunting.
These shrews are mostly insectivores, but will eat seeds and fungus as well as small vertebrates, including other shrews, mice, and salamanders. These shrews eat three times their weight a day, and increase their consumption 43% during the winter in order to maintain body heat. They are well known for being one of the only venomous mammals, with venom that is produced in submaxillary glands and paralyzes prey, and is able to kill small animals larger than itself. The venomous saliva travels into prey through the groove formed by its incisors meeting. It’s mostly harmless to humans, except that it makes their bites much more painful.
Northern short-tailed shrews have poor senses of smell and sight, thought to only be able to detect levels of light with their rudimentary eyes. They make up for this with a very sensitive sense of touch.
They breed from March to September, with males courting females with clicking noises. The pair will become locked together during copulation and the female will simply drag the male along the ground by his genitals. Two litters of four to seven young are typical within a breeding season, with the first litter usually reaching sexual maturity in enough to time to have their own litters before the breeding season they born in ends.