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Flight Lines: The shrew, small but feisty

A rare encounter with a shrew recently south of Fargo. It is likely a Hayden's shrew or a masked shrew. By Keith Corliss.

The first definition of the word shrew at dictionary.com reads, "a woman of violent temper and speech."

William Shakespeare's title character, Kate, in his play, The Taming of the Shrew, is just such a person. She's hot-tempered, slaps people around, and cuts men to ribbons with her razor sharp tongue. But there is a second definition of the word. In fact it's the original one. And the one from which the first definition derives. It reads, "any of several small, mouselike insectivores of the genus Sorex and related genera, having a long, sharp snout."

While those words might be somewhat accurate (they are not restricted to eating insects), they don't begin to truly capture the energy and attitude these small mammals bring to the animal world. They'll eat small birds, mice, small snakes, or just about living thing it can handle. And with reckless abandon. These are easily one of the most voracious mammalian predators on the planet.

Despite their resemblance to small mammals such as mice and voles, they are not rodents. The shrew family—Soricidae—contains more than 385 species. Found on five continents they are considered very common in most places. However, most people have never seen one. They spend their days in a variety of habitats constantly seeking food, usually moving quickly and out of sight. With tiny eyes these small animals forage mainly with long sensitive whiskers, feeling constantly for any movement which would betray the presence of potential food.

In all my hours spent outdoors--and trust me, I've spent a lot of time there—I can recall only seeing three in my lifetime. My latest chance encounter was this summer south of Fargo when, surprisingly, one was foraging out in the open on a mowed lawn. Incredibly it sat still enough for me to take a cell phone photo of it.

Robert Seabloom's Mammals of North Dakota lists six species in the state. Given the distinctly long tail of the one I photographed, mine was likely either a Hayden's shrew (Sorex haydeni) or a masked shrew (Sorex cinereus).

With metabolic rates that are off the charts, shrews live frantic lives of constant motion with their heart rates falling in the neighborhood of 800 to 1000 beats per minute. The penalty for this high energy lifestyle is the never ending need for food. In order to maintain themselves shrews must eat amounts of prey nearly equal to their body weights every day. A few hours without food and a shrew will die of starvation.

Just to up the ante in the nastiness category there's also this little ghoulish element: many species of shrew are venomous; not with hollow fangs like some snakes, but with a gland that allows venom to flow with its saliva, entering the bodies of its victims during its bite. In some cases it is used for something more reserved for horror movies. That is, once venom enters the body, the prey is rendered paralyzed leaving it alive and intact for future feeding in a process called live hoarding or caching.

Shrews do not hibernate and so must continue feeding all winter, mostly under the snow pack. Seabloom lists the common causes of mortality as, "starvation, cold, and predation." Several different animals will kill shrews but they are rarely eaten due to their strong musky odor.

While I've only seen three shrews, it is very likely that I've heard many more. Walking through grassy or brushy areas I will occasionally hear a high-pitched twitter coming from the ground. While it could be other small rodents, shrews are highly vocal, emitting a variety of squeaking noises. Seabloom even notes, "They are also known to emit ultrasound which functions in echolocation."

Today it's probably lacking some political correctness to refer to a woman as a shrew. But it's not difficult to tie this meaning of the word to the animal. The usage is centuries old and, according to dictionary.com, was, "said to derive from some supposed malignant influence of the animal, which was ...once held in superstitious dread."