Speaking of Nature: A small surprise: The short-tailed shrew

  • This photo of a short-tailed shrew shows it all.  Note the short tail (for which the species is named), the short, velvety fur, the small ears and the tiny eyes that all prove useful for an animal that spends much of its time underground. PHOTO BY BILL DANIELSON

For the Recorder
Published: 10/2/2022 4:00:19 PM

As the month of September came to a close my efforts to collect as many bird observations as possible paid off. Somehow, despite the fact that school had started again and my time was limited to weekends only, I managed to set a new record for the number of species observed. The previous record, set in 2021, was 50 species. As of the writing of this particular column, I had recorded 52 species and it all came down to time spent in my Thinking Chair.

This may shed some light onto the qualities of birds that make them so interesting to observe. In all of that time, while collecting a list of 52 bird species, I only managed to see 6 species of mammals. On two occasions I saw an eastern cottontail, on three occasions I saw a red squirrel, on two occasions I saw a gray squirrel and on one occasion I saw a meadow vole. Then there was one day that I observed a chipmunk at the seeds. These 5 species of mammals are species that one might normally expect to see in location where short grass and birdseed are available, so there was nothing particularly surprising on this list.

But where were the deer? Why is it that I never saw a fox, a coyote, a raccoon, an opossum, a skunk, a bobcat or a weasel of some sort? The simple answer is: I don’t know. Perhaps my presence, quiet though it is, is still bold enough to warn off these species. Or, more likely, these species are much lower in number and have no particular reason to walk down the trails too often. Perhaps if I put a motion-sensitive camera down at the Thinking Chair I would see all sorts of mammals at different times of day. Who knows?

But there was a sixth species of mammal that made a surprise visit on two occasions last month. In the same patch of short grass where I place seed for the song sparrows and where I have previously seen meadow voles, another species of mammal showed interest in the food that I had placed there. It was a short-tailed shrew (Blarinabrevicauda) and its behavior pointed to the unbelievable value of birdseed as a food source.

The short-tailed shrew is an animal that falls into a category called “insectivores.” About the same size as a mouse, or a vole, the short-tailed shrew has a very different body type. Rather than being plump, the shrew is more lean and slender. Covered with short gray hair that reminds me of velvet, the shrew also has very small ears and extremely small eyes that might be on the verge of becoming vestigial.

The reason for all of these physical characteristics becomes obvious when you consider the shrew’s diet and its method of hunting for food. Largely carnivorous, the short-tailed shrew has an extremely high metabolism that requires that it eat up to three times its own body weight every day.

Shrews are ravenous predators and this particular species likes to spend most of its time underground where it can find worms, insect, and other small animals to feed upon. To help it dispatch its prey the shrew has venomous saliva. In essence, the shrew is the mammalian equivalent of a rattlesnake and its bite contains enough toxin to paralyze an animal slightly larger than itself. Thus, mice, voles and even other shrews must be wary if a hungry shrew is on the prowl.

But despite the fact that the shrew is a carnivore, and despite the fact that its teeth are all adapted to the killing and consumption of animal prey, it appears that a metabolism of such a high rate will compel the shrew to eat whatever else might be edible and available. This means that edible fungi will be consumed and, as luck would have it, so also will birdseed be devoured. I can’t imagine that there is much difference between a small beetle and a sunflower seed. They both have hard shells and something delicious hidden inside.

So, while watching the birds coming and going I happened to notice that there was another little visitor darting in and out of the tall grass to snatch seeds and eat them in the more private gloom of the undergrowth. A shrew is a small and vulnerable species that faces heavy predation from owls and a wide variety of mammalian predators, but the need for food is so great that a shrew simply cannot pass up an opportunity when it finds something so nutritious just lying there. All I had to do was aim my camera and take what felt like a hundred photos until I finally got one photo that showed some details. If you ignore the fact that I was sitting in a wet plastic chair early on a Sunday morning when the temperature was only 42 degrees, then it was a piece of cake.

Bill Danielson has been a professional writer and nature photographer for 25 years. He has worked for the National Park Service, the US Forest Service, the Nature Conservancy and the Massachusetts State Parks and he currently teaches high school biology and physics. For more in formation visit his website at www.speakingofnature.com, or head over to Speaking of Nature on Facebook.


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