This winter I seem to be seeing more Short-tailed Shrew (Blarina brevicauda) scurrying across the snow then I usually see. Even my daughter reported seeing one of these hyperactive shrews while out sledding the other day.
The Short-tailed Shrew is an aggressive predator constantly on the move looking for its next meal. They are a thick and stocky animals with short legs and dark gray fur. They have a long narrow snout filled with needle-sharp teeth and tiny eyes. Their ears are hidden in their fur. They have an excellent sense of smell but poor eyesight. Their common name comes from the animal’s short tail. Most shrews have short tails but this species has a tail that is shorter than most. In fact their species name brevicauda is Latin and means brevis meaning short and cauda meaning tail.
The Short-tailed Shrew is probably our most common and abundant mammal in the many parts of the country. It’s found in nearly every habitat. Population densities vary from year to year with populations soaring in some years and crashing in others. They have home ranges of only an acre or more. Territories will overlap and fighting between neighbors is usually short and non-lethal but fairly common.
This tiny creature has an enormous appetite. It can eat half its body weight in meat each day. That would be like you and me eating 60 to 80 pounds of food a day. An adult short-tail weights in at .5-1 oz. As a predator the shrew is constantly on the hunt in order to eat. They usually are not scavengers but they will eat what they find. So a dead mouse could be fair game. They also eat insects which are in very short supply during winter so the shrew concentrates most of its time finding mice, voles and other small mammals. Since mice reproduce all year long, baby mice are a favorite food item for the shrew.
All species of shrew are solitary but will seek out a mate for breeding and than return to a solitary lifestyle. Interestingly the shrew will fight with other shrew, sometimes to the death, to defend territories, food sources and to protect their young. Fights are loud affairs with a lot of scuffling. You can hear these fights from 10-15 feet away. They don’t last long, less than a minute, and usually don’t result in death but injuries are not uncommon.
The shrew has very thick fur that ripples when the animal moves. This thick fur is key to winter survival keeping them warm and dry. Their fur also has a nap that runs both ways allowing them to move effortlessly forward and backwards in narrow tunnels without turning around.
Most amazingly the shrew uses ultrasonic sound for echolocation, just like bats. The echolocation detect objects, openings or if something is blocking their tunnels in the blackness of their underground world. The Short-tailed Shrew is also the only mammal with toxic saliva. The toxic bite helps to immobilize and kill its prey. The saliva is both a neurotoxin and hemotoxin, much like snake venom but the shrew cannot inject the toxin into its prey like a snake. It must chew the saliva into a wound in order for it to take effect so some believe it’s not much help to the shrew. It is also not powerful enough to have any affect on humans.
The shrew has musk glands that exude an odor thought to repel some predators of shrews such as fox, coyote, and cats which often kill them but rarely eat them. The glands are probably used more for marking territories and sexual recognition than anything else.
This winter keep your watchful nature eye to the ground for a fast moving dark object with a short tail. It just might be the Short-tailed Shrew. Until next time…