Strange and Unbelievable Facts About Shrews

You’re walking along some bushes in a park, and suddenly see a tiny gray creature skittering into the fallen leaves. At first you might think it’s a rodent, but this frenetic ball of energy is actually a shrew.

While it may appear small and gray, shrews are one of the most voracious mammalian predators on the planet. And they’re abundant and widespread, found on five continents in a variety of habitats. In the United Kingdom, there are an estimated 50 shrews per hectare in woodlands, with a country-wide population of more than 40 million shrews. The northern short-tailed shrew may be the most common mammal of the eastern United States.

Soricidae, the shrew family, contains more than 385 species. Superficially, many of these species look similar, with most having pointy snouts, a streamlined body and a grayish coloration. But they exhibit a diversity of behaviors. Even though they’re common and widespread, few people see them and fewer know their crazy habits and adaptations.

Let’s take a look at just some of the many reasons to marvel at shrews.

  1. Life in the Fast Lane

    If you’re lucky enough to see a shrew, you’ll notice that it’s moving rapidly, with rapid, jerky movements. This isn’t because you scared it; shrews just live life fast and furious. Your most highly caffeinated, Type A colleague will appear downright slothful compared to a shrew.

    While this varies among species, a shrew’s heart rate beats 800 to 1000 times per minute. The Etruscan shrew, the smallest terrestrial mammal on earth, has a heart rate that can reach 1500 beats per minute, more than any other mammal and more even than the hummingbird.

    Shrews have been recorded making 12 body movements per second. (Go ahead and try to duplicate this feat). They’re in constant motion, rarely stopping to sleep. They have a high metabolism, which means they have to eat. A lot.

    A shrew’s life is a constant search for prey. Many species must eat their body weight’s worth of food each day. (I advise you not to attempt this one). If a shrew doesn’t eat within a few hours, it dies. This constant need for food has led to some truly bizarre and even disturbing adaptations.

  2. Watch Those Whiskers

    Northern Short-tailed Shrew. Photo © Gilles Gonthier / Flickr

    Shrews must find and subdue prey fast. They have poor eyesight and often live in thick cover filled with obstacles. How do they manage?

    Many sources mention that some shrews use echolocation: they emit sounds producing sonar that helps them navigate their world (much like bats). Shrews emit a sound described as a “twitter” and it is often assumed this is used in echo-location. However, much of the evidence appears anecdotal.  An article in the journal Biology Letters found “shrew-like calls can indeed yield echo scenes useful for habitat assessment at close range.”

    There isn’t evidence that this echolocation is used to find prey. Instead, shrews rely on their long, highly sensitive whiskers, also known as vibrissae. According to a study published in Philosophical Transactions B, the Etruscan shrew hunts in an environment where crickets are particularly abundant. It moves its whiskers constantly –  a motion called, appropriately enough, whisking – until it brushes its prey. Then it strikes quickly and with great precision.

    Of course, wasting time attacking non-prey items that the whiskers brush against would burn precious energy. The researchers conducted an intriguing test:

    “Experiments with dummy prey objects showed that shrews attacked a plastic replica of a cricket but not other plastic objects of similar size. Altering the shape of crickets by gluing on additional body parts from donor animals revealed that the jumping legs but not the head are key features in prey recognition.”

  3. Shrew Venom, A Horror Story

    You can spend way too much time on YouTube watching videos of shrews attacking mice, scorpions, snakes and other larger creatures. Spoiler alert: the shrew wins.

    This is because many shrew species are venomous. Research has found that an individual shrew stores enough venom to kill 200 mice. Some shrews also use this venom for something called live hoarding.

    Live hoarding sounds innocuous enough, but in reality it shares numerous plot points with that terrifying movie Hostel. Here’s how it works.

    The shrew lacks hollow fangs (as in venomous snakes) but instead has a gland that allows saliva to flow with the venom. When the shrew encounters its prey – often an invertebrate, but it can also be a mouse or other vertebrate – it begins biting it, allowing the venomous saliva to flow into the wound.

    For the prey, this is the beginning of a very bad day. The venom paralyzes the creature, but keeps it very much alive. The shrew can then move it to a cache, available for whenever hunting is not going so great. For an animal that has to eat constantly, this keeps a fresh if unsavory meal always at the ready.

    The American Chemical Society reports that a mealworm can be kept, paralyzed but alive, for 15 days.

    Shrew bites on humans are reportedly painful but fade in a few days. Be very, very glad these animals are not larger.

  4. Following the Herd

    Mormon crickets in Nevada, 2006. Photo © katie madonia / Wikimedia Commons through a CC BY 2.5 license

    In the sagebrush country of the western United States, one species of shrews may follow the thundering herds … of Mormon crickets. Mormon crickets (actually a species of katydid) are prone to periodically have population explosions resulting in large swarms.

    Vladimir Dinets, in the Peterson Field Guide to Finding Mammals, includes this intriguing description: “On arid plains these shrews follow swarms of Mormon crickets the same way Gray Wolves follow migrating Caribou herds. If you encounter a swarm, look for shrews scurrying along its tail edge.”

    Dinets’ book, by the way, is like a shrew spotter’s bible, including tips on where and how to seek all the North American species.

  5. Walking on Water

    Water shrew on Pebble Creek. © NPS/April Henderson / Flickr

    You can find a shrew species in just about any habitat. Several species of water shrews even take to streams. The water shrew has stiff hairs on its feet that allow it to scamper across the surface of the water. Its stiff fur also traps air bubbles, allowing it to stay underwater for short bursts. It must stay in constant motion underwater, or it pops back up to the surface. It hunts caddis larvae and other small aquatic prey.

    Theodore Roosevelt (yes, the president) observed a water shrew catching a minnow in North Idaho. He described it in his book The Wilderness Hunter: “It was less in size than a mouse, and as it paddled rapidly underneath the water its body seemed flattened like a disk, and was spangled by tiny bubbles, like flecks of silver.”

    As a side note, Theodore Roosevelt also kept a shrew in captivity (he fed it a mouse and garter snake) and observed, wrote about and collected shrew species on his lengthy African safari. He even has a shrew species named after him. I’m not surprised that he had a love of shrews, given his accomplishments as a conservationist, naturalist and outdoors enthusiast. I wish for another politician like him nearly every day.

  6. The Incredible Shrinking Brain

    Common shrew (Sorex araneus). Photo © Dr Mary Gillham Archive Project / Flickr through a CC BY 2.0 license

    Many wildlife species feast and bulk up for the cold winter months. With the shrew’s metabolism, weight gain is not an option. And so at least one shrew species shrinks. A recent study, published in the journal Nature, found that in common shrews in Germany, “Their spines also got shorter, and major organs, including the heart, lungs and spleen, shrank. Even their brain mass dropped by 20–30%.”

    Researcher Javier Lazaro hypothesized that “reducing their body mass during winter might increase their chances of survival, because they wouldn’t need so much food.” The brain in particular has high energy requirements, but the study could not determine if shrews experienced decreased cognitive functions.

  7. Foxes Hate Them, Trout Love Them

    The shrew-eating trout of Togiak National Wildlife Refuge. Photo: U.S. Fish and Wildlife Service.

    Shrews may be fierce predators, but they’re small, which means they in turn become prey. Many mammalian predators, including red foxes, raccoons and cats, will attack them but rarely actually eat them. That’s because shrews emit an unpleasant musk that some liken to the smell of skunk.

    This does not deter other predators, like owls and snakes. But my favorite incidence of shrew predation is a rainbow trout caught at Alaska’s Togiak National Wildlife Refuge that had 19 shrews in its stomach. These were not water shrews, but other species that fell into the water and became prey. You can read the full account in my previous blog.

  8. Shakespeare and Shrews

    Petruchio (Kevin Black) and Katherina (Emily Jordan) from the 2003 Carmel Shakespeare Festival production at the Forest Theater. Photo © Smatprt / Wikimedia Commons through a CC BY-SA 3.0 license

    And then there’s the literary work, Shakespeare’s Taming of the Shrew. During my Shakespearean literature class in college, my professor stated that the Bard did not refer to the literal shrew, as such a benign, inconsequential mammal wouldn’t fit the theme of the play.

    As a lifelong mammal nerd, this amounted to heresy. I decided to make my final paper for the class a detailed comparison of the real shrew with the literary one. This, in retrospect, was a bit of a gamble. I relied on a store of shrew facts, many of which now appear in this blog.

    As I read my professor’s comments on the paper, I could sense that she was initially annoyed at my topic, then became increasingly alarmed as she realized I was quite serious. The paper received an “A”, along with the pointed suggestion that I pursue a career in nature writing as opposed to academia.

    And here I am, still sharing shrew facts.

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  1. Joelee Salvalaggio says:

    I just found a shrew in my apt. Sorry my cat found it lol Sept 6th 2022. At 3am, I heard a loud sqeak and new my cat would have eventually killed it. I don’t like seeing any animal hurt so I locked my cat in the bedroom and covered the entrance of the door. Took me over half hour to get it out, he or she moved very fast. Finally it was on top of a board but under a square piece of carpet so I carried the whole thing outside and it was finally freed. I live in Ontario, Canada and never seen this type of mammal before, so decided to look up small mice with pointed nose. Happy he survived.

  2. ava young says:

    I have browse a couple of of the articles on your web site currently, and that i adore your vogue.

  3. Amara Martin says:

    Great post. Very interesting

  4. Rosemary Turner says:

    Enjoyed reading Facts About Shrews!

  5. Mary ODell says:

    I adore shrews and now have many more reasons!

  6. Priscilla Iasimone says:

    I have a shrew in my bedroom. It was camping out under my bed to I put my mattress on the floor. Will the shrew crawl on me while Im sleeping and bite or attack me? Thank you for your help because I was sleeping in my car because my back is killing me!
    Sincerely Priscilla

  7. sabine kirst says:

    Mice will pee and s— everywhere so it is easy to know there is one in the house. I recently moved to PEi and had a shrew in the kitchen. It ate food on my counter but left no excrement. Then I knew something was up – not a mouse. Is this because they burn up their food quickly?

  8. Stuart Blum says:

    53 years ago I attended a few weeks of Hebrew School at my parents behest. It wasn’t for me. However, I vaguely remember a discussion that we likely evolved from shrews. Do you have any thoughts or information on that, putting creationism v. evolution aside? Strictly a theoretical conversation.

  9. Tammie Taylor says:

    I understan they are doing cancer research. My house here is totally infested with shrew. Do you know who i contact

  10. sergio maranzana says:

    I’ll wold be happy to find someone to answer my question about shrews : filmed about 7 of them in my home 2020 2021,2022 . Only once two at same time for 0.2s. Last one, still with me, appeared in my bed
    and thereafter keep distance.
    Feed him with ground meat and water. Hope he find insect somewhere
    Thanks to anybody who will contact me

  11. Mi Ziggie says:

    Wow! Amazing info!

  12. sergio maranzana says:

    from december 2019 when I first found a shrew in my kitchen, I begin to collect foto and movies of them.
    I buried 6 of them. I think killed by their own. I think that when you see them in daytime they are already dying , slowing of movement is barely noticeable at first. I have many movie mostly nocturnal from hunting camera but some color by day. There are interval of months but maybe due that I was not aware od their presence and so don’t used the camera. Willing to learn and share my photo an movies

  13. Cheri Champagne says:

    My husband and I think we have a shrew living among the trees in a hole in our back yard. Should we leave it alone and let it do it’s natural job, or should we try to get rid of it? Honestly, I like the idea of keeping it around because it takes care of other pests, but I want to make sure it isn’t a threat to my grandchildren.

    1. Hi Cheri,
      Thanks for your comment. Shrews won’t pose any threat to your grandchildren. They are very secretive and fast, and don’t pose a realistic danger to humans of any size.


  14. Craig Phillips says:

    A shrew approached me in the wild when I was mountain biking one day. The shrew came right up to me and did several somersaults, then just stared at me. I squatted down and the shrew came even closer, then wandered away into some brush, never to be seen again. Is this normal?

    1. Hi Craig,
      Thanks for your question. This is highly unusual behavior. Shrews are quite tiny and have poor eyesight, so I am surprised it was staring at you. Could it possibly be another mammal?


  15. Becky Cole says:

    Woah! It’s nice to know that there are still people who care this much about species like this!