No Taming of the Shrew by Josh Palumbo, Forest Management Coordinator.
When considering the world’s greatest predators, the mind goes to the likes of Siberian tiger, saltwater crocodile, or the elusive jaguar. If this list of the world’s greatest predators allows for pound-pound consideration, you must add our native shrew. This edition of the Nine Minute Naturalist will delve into the fascinating creature that roams our ecosystem, the northern short-tailed shrew.
When seen scurrying across the forest floor or across the living room carpet, the first impression is of a mouse. Shrews are not mice nor even rodents. They are in the family Soricidae which consists of mole-like mammals. While shape and size indicate mouse, they lack outward ear flaps, have tiny eyes and a short stubby tail. This grayish-black mammal is built for a life underground, under leaf litter or in a winter like this life under snow.
When I reach intense hunger levels, I get a bit angry (“hanger” is real people!) Few animals can compare in “hanger” levels to the shrew. They have such an intense metabolism they need to eat every three hours, or they are in danger of starvation. This requirement creates a predator that must eat 1 to 3 times its body weight in food each day! The result is a high-strung hunter on a constant search for their next meal. These omnivores pursue snails, insects, spiders, small mammals/birds but will settle for seeds and nuts if live prey is not available.
While the metabolism of the shrew is quite unique, the most exceptional aspect of this predator is its venom. In comparison to snakes which inject venom through fangs, the shrew injects venom by chewing on its prey. Salivary glands in the lower jaw excrete the venom when the shrew bites and holds on to its prey. For small prey items, the venom is toxic enough to kill outright. Some victims become paralyzed which makes for a food item that can be stashed and eaten at the shrew’s convenience. Humans that get bite will usually suffer a bit of swelling and pain at the bite location. Shrew venom is so unique it is the current subject of medical studies pertaining to pain relief, skin health and killing cancer cells.
Another attribute that is special is the shrews use of echolocation. While not as precise as bats, the shrew’s echolocation system allows the examination of the environment to aid in navigation. This is necessary because these mammals’ tiny eyes are good for determining between light and dark and not much else.
One of my favorite attributes of the shrew is its general conceit. The shrew needs to eat, and it does not care what is in the way. Every winter the Nature Foundation is home to a shrew or two. We know because they will run right across the floor no matter who is present or what time of day it is. They just do not care. Their hunger plus being loaded with venom makes for an attitude that is quite remarkable for such a small creature. Another element that adds to this overall conceit is it stinks. The shrew has musky glands that make it inedible for other mammals. Its main predators are hawks, owls, and snakes, all of which do not care about their smelly glands.
The conceited life of the shrew burns bright from start to finish. With such a demanding metabolism, the shrew’s lifespan is truly short. They rarely live past their second autumn and have mass die-offs each fall. If they do live into their second winter, the easy insect pickings are gone, and they must hunt hard to catch prey such as mice. This especially common mammal uses death to make more room in the ecosystem for the next generation of shrew leave corpses across the landscape to aid the life of other shrews.
Shrews are quite possibly the most unique mammal we have in our forest at Wintergreen. While we are fortunate to be lacking in tigers and crocodiles, our environment is full of this tiny terror known as the northern short-tailed shrew. Next time one crosses your path, empathize with “hanger” in it’s greatest form.