Saturday, March 21, 2009

A Shrew's Tale

The most common mammal in New England yards, is a stocky, little creature that most people never see -- the short-tailed shrew (Blarina brevicauda). This large (relative to other shrews), satiny-gray shrew rules the underground. They tunnel through leaf litter and moist soil day and night, year-round, on the hunt for earthworms, millipedes, insects, snails, and even prey larger than themselves such as mice, small birds, snakes. Blarina eats about anything that moves and material that doesn't, including plant parts, berries, nuts, fungi.

Some shrews have one thing in common with the platypus, they have venomous saliva; the shrew excretes it from a duct at the base of the lower incisors. The teeth are pigmented a deep red-brown color, although I am not sure what purpose that serves, but it makes it easy to identify it as a shrew.

The short-tail also echolocates (like whales and bats) -- emitting a series of ultrasonic clicks as it moves through tunnels, sensing and distinguishing objects. It is known to subdue its prey, storing it alive, to eat later. Ouch. This shrew also gives off a musky odor from scent glands on its sides and belly when it gets excited or stressed. Predators find it distasteful. Perhaps that is why I occasionally find dead short-tailed shrews, perfectly intact. I can image a fox pouncing on a short-tailed shrew, what looks like a tasty morsel, and then spitting it out in disgust.

Although active day and night, the short-tailed shrew spends a great deal of time resting in between short bursts (4-5 minutes) of activity. The females will be nesting soon. When born, the young shrews are the size of a honeybee! Within 25 days they are nearly full grown and able to leave the nest and live on their own. By three months of age they can breed.

Shrews have pointy noses, tiny eyes, and ears hidden by fur. Features that help distinguish them from the other small mammals in our yard -- moles, voles, and mice. Yesterday, as spring dawned, a short-tailed shrew poked his head out a hole near the base of the bird feeder. A chipmunk sat nearby, unfazed, stuffing his cheek pouches with sunflower seeds. The shrew's pink nose twitching, with a dense set of whiskers, sensing the air. He darted in and out of his hole, preferring to stay mostly in his fossorial haunts, where he controls the tunnels. He is considered solitary and unfriendly (I guess so with those teeth, venom, and musky odor). There is no taming of this shrew.

I like the thought that there are many short-tailed shrews busy foraging beneath our yard, helping to control insects and other animals that might otherwise pester our vegetable and perennial gardens. Carry on furry friend, but I'll keep my distance.

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