On January 13, 2021, Ian Stewart, Delaware Nature Society Ornithologist, and I found a small, deceased, Sorex genus shrew at the Flint Woods Preserve near Centreville, Delaware. At first we thought it was a North American Least Shrew (Cryptotis parva), but upon further investigation, we realized that the tail looked too long for that species, and that it could be a Masked Shrew. I’ve seen a few Least Shrews over the years, always dead on a trail. I commonly find the Northern Short-tailed Shrew, (Blarina brevicauda), dead on trails. I had never seen a Masked Shrew.
I contacted Holly Niederriter at Delaware Fish and Wildlife and she confirmed that our recent find was a Masked Shrew (Sorex cinereus) based on the tail length and the darker, bushy tip that Least Shrew does not have. I asked her if Masked Shrews were common in Delaware, and the answer was…nobody really knows.
Masked Shrews and Least Shrews are very small, brownish mammals which look like a mouse, but aren’t mice at all. Shrews are members of the Order Insectivora which includes the shrews, moles, hedgehogs, and the nearly-extinct solenodons of the West Indies. Insectivores capture and eat small prey such as insects, worms, slugs, small amphibians and even other small mammals. Some Insectivores have poisonous saliva to subdue their prey, and others use echolocation to find their food, like a bat. Mice look similar to shrews, but are members of the Order Rodentia…they are rodents and aren’t related to shrews at all.
As I mentioned, I commonly find the Short-tailed Shrew dead on trails. It is known that animals like foxes will capture them, walk away, then get a taste of the shrew, which is bad, and drop the shrew on the ground. This is the reason you might come across a dead shrew on a hike, right on a path.
The Short-tailed Shrew is a large beast compared to the Masked Shrew and Least Shrew. The body of a Short-tail is around 4 inches long (not including the tail). The body of a Masked or Least Shrew is about 2&1/2 inches, which is about the size of a hummingbird. The Short-tailed is dark gray or lead-colored. The Masked and Least are brownish. See the photos above for comparisons of how big they are in a human hand, and the differences in color.
All of these creatures spend most of their time under forest leaf-litter, under the dead grass in a meadow, and are extremely secretive. One time I caught a Short-tailed Shrew in a mouse trap in my attic, which really had me wondering how a forest leaf-litter animal ended up there. These are fascinating tiny predators which have miniscule eyes and poor eyesight, relying on smell and hearing to capture their prey.
The larger Short-tailed Shrew is very common, but if you find a very small, brown shrew that is deceased, make sure you collect it and bring it to a museum or nature center for identification. The more we know about these tiny predators, the better we will be able to protect their habitat and keep them as a common species.