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Where We Left Off:
In our previous case file, the cat detectives and humans conducted an experiment to see which types of animals would appreciate homemade snacks.
The Killer Shrews:
The temperatures have hovered around the high 40s sometimes hitting 50ºF which is a fantastic temperature for exploring outside! There are not as many birds as some have migrated, but the winter birds are still here. The chipmunks aren’t hibernating yet. And the big creatures are dealing with their various hunting seasons.
In this week’s case, Gus shares his evidence of an increase in the northern short-tailed shrew population. We haven’t seen any adorable meadow voles or moles this year! The ground was dosed with rodent poison that was safe for the chipmunks, though we suspect not safe enough since their numbers took a slight decline.
In this case, not only did we uncover a ton of useful information about the creatures, but there is also a suspicion that one of the bodies Gus and I discovered was left by a free-roaming feline. Can you guess why it was left behind?
What Makes the Northern Short-Tailed Shrew Different?
Gus was excellent at spotting the twitches in blades of grass or a gentle rustle of leaves leading him to critters. I kept expecting meadow voles, but each time that I was able to see what his senses detected, it was a shrew. When they’re young, they are as small as a mole and because they have pink noses and feet, it’s easy to mistake them for moles at first glance. The feature I look at is the feet. Moles have distinctive feet that are not like shrews or voles at all (if you can get a good look).
Another important fact about shrews is that they are not rodents. After their classification as mammals, they are in the order, Soricomorpha (insectivores). The taxonomic names can be confusing since classification names get updated with new research. In other words, northern short-tailed shrews are also part of Eulipotyphla.
Some days, I felt like Gus and I were in a sci-fi movie as we followed the grass moving, but couldn’t see the creature causing it. Even above the dirt, these shrews maneuver through the lush grass unseen. Do they have a cloaking mechanism like Gus?
Gus uses his Super Smeller to follow along the critters’ paths. Then he takes both paws and tries to pin down his prey. They usually get away and can withstand many of these murder-mitten smackdowns. I hear high-pitched “squeak” sounds with each clobber. It sounds like the other critters we’ve gotten to study.
Even though this small critter is adorable, it harbors a defense system like no other tiny mammal. When Gus decides to forcefully stick his face into the ground, he may or may not come up with one of these shrews. Now we know why! The first defense of the northern short-tailed shrew is to release a stinky musk that predators don’t like. It can be enough to make the predator give up and release the tiny critter from its jaws. No one wants to taste the shrew equivalent of Axe Toxic Masculinity Body Spray. Maybe if COVID killed your tastebuds, maybe. But otherwise, no. No one wants to taste that.
After several encounters with shrews of different sizes, I studied the photographs with Oliver. We noticed that the shrews appeared to have something on their fur. Was it cat saliva? Was it excreted musk? Now we’re not sure. Gus and I left the bodies outside hoping owls, hawks, or snakes would eat them. There aren’t too many predators for this stalwart little mammal. That potent musk comes out of scent glands when they die too. This also explains why Gus didn’t go back for the one body he was responsible for killing in order to continue “studying” it like he does with mice and voles.
Camouflage and a repelling odor aren’t the only superpowers these shrews have. They also rely on echolocation for their “sight.” I got a close look into the eyes of a large shrew. I was surprised to see decent eyes at all. They are quite tiny, but they were round, bright blue, and had perfectly circular black pupils. This echolocation that they have is not as precise at what we know about bats.
Their eyesight isn’t their primary sense and that’s obvious when observing them. Gus decided he didn’t care and turned his back while I placed peanuts on the ground and watched the adult shrew sniff to find it. It wasn’t afraid of us at all by then. I suppose a scientist would not attribute human traits to an animal subject, but I swear, this shrew was happy. It was enjoying those peanuts and its aura grew and sparkled.
These petite rodents have another secret weapon to protect them from predators. According to our research, this shrew is venomous! It doesn’t have fangs like a snake (or Gus) or any kind of poking injection stabby thing like a scorpion. This shrew needs to chew on an opponent in order to release the neurotoxin. The poison can be enough to paralyze or kill!
These are the not-gross/censored photos of the two dead shrews. The uncensored will be after the Resources:
Humans, being the entitled jerks that we are, apparently have plans for shrew toxin:
“Shrew venom is currently the subject of several medical studies. Some researchers hope it can be part of new suite of miracle drugs that will do everything from smooth out wrinkled skin, to alleviate pain, and even kill certain kinds of cancer cells.”—National Park Service
Shrews have an awareness that humans simply do not. They are fighters, as we’ve seen. They are smart and use their paralyzing venom to stun mealworms and other food animals for future consumption when times are tough. They are also considerate of the next generation—something most humans definitely are not. Shrews live around two years and then something miraculous happens. It’s extraordinary. There will be mass natural deaths of the northern short-tailed shrew all around their habitats. Oliver and I discovered why when we were researching. The adults die so that the younger generation doesn’t have to compete with them for food!
“By taking that final dirt nap as it were, these venerable 2-year old shrews gift their maturing offspring a better shot at finding enough food to survive winter without having to compete with their parents’ generation.”—National Park Service
In spite of that sweet story about caring for other shrews, these are not social animals. They keep to their own territory and don’t co-mingle. Opposite sexes may have areas where their territories crossover. They are considered aggressive and dangerous, yet beneficial because of their penchant for eating insects. Only attempt to handle a northern short-tailed shrew with appropriate protective gear.
Case Findings:
Oliver, Gus, and I learned so much about the northern short-tailed shrews in our backyard. We have answers now as to why Gus did not continue to pursue a shrew once he tried to bite it and why he didn’t return to the dead bodies later. The toxic secretions from northern short-tailed shrews make them unsuitable prey for felines. It also makes me wonder why there aren’t super heroes or villains with shrew traits like the Mole Man.
One other question remains: Why do our local northern short-tailed shrews love peanuts so much when they supposedly devour insects in massive quantities because of their metabolism?
Case Status: Closed (mostly)
Resources:
- No Author Listed. (no date) NETN Species spotlight, National Parks Service. Available at: https://www.nps.gov/articles/netn-species-spotlight-short-tailed-shrew.htm (Accessed: 13 November 2023).
- Ballenger, L. 2011. “Blarina brevicauda” (On-line), Animal Diversity Web. Accessed November 13, 2023 at https://animaldiversity.org/accounts/Blarina_brevicauda/
- For more information on unlikely venomous or poisonous creatures, check out this episode of Creature Feature where they discuss the poison inside the leg spurs of male platypuses!
